WO2025165692A1

WO2025165692A1 - Sensing balloon catheter

Info

Publication number: WO2025165692A1
Application number: PCT/US2025/013176
Authority: WO
Inventors: Dishuan Chu; Carlos H. LIMA; Neil VOSKOBOYNIKOV; Alessandro T. FISHER; Sabrina Hua
Original assignee: Medtronic Vascular Inc
Current assignee: Medtronic Vascular Inc
Priority date: 2024-01-30
Filing date: 2025-01-27
Publication date: 2025-08-07
Anticipated expiration: 2026-07-30

Abstract

A medical device system includes an elongated body configured to be inserted into a blood vessel of a patient. The medical device system further includes an expandable structure at a distal portion of the elongated body. The medical device system further includes a plurality of sensors carried by at least one of the elongated body or the expandable structure. The medical device system further includes processing circuitry configured to receive, via the plurality of sensors, one or more signals, and determine, based on the one or more signals, at least one of an indication of a morphology of a lesion of the blood vessel, or one or more diameters of the expandable structure or the blood vessel.

Description

SENSING BALLOON CATHETER

[0001] This application claims priority to, and the benefit of, U.S. Provisional Application No. 63/626,757, filed January 30, 2024, and entitled, “SENSING BALLOON CATHETER,” the entire contents of which is incorporated herein by reference.

TECHNICAL FIELD

[0002] This disclosure relates to medical catheters.

BACKGROUND

[0003] Medical devices including stents, such as bare metal stents or drug coated stents, may be delivered to passages of the body (e.g., blood vessels, ureters and other hollow structures) and expanded to hold open the passage of the body. In some examples, stents are delivered to narrowed arteries to facilitate increased blood flow through the artery. Catheters may be used to deliver and/or expand stents at locations of interest.

SUMMARY

[0004] This disclosure describes medical device systems including catheter systems configured to perform multiple functions during a medical procedure, such as a percutaneous coronary intervention (PCI) procedure. Such medical procedures can include stent delivery and expansion via a minimally invasive procedure using a catheter. For example, the systems described herein include catheter system configured to both expand against a blood vessel wall and/or a stent as well as determine one or more clinically relevant parameters, measurements, or indices related to the blood vessel or the stent. The medical device systems described herein are configured to perform multiple functions while maintaining a small form factor, such that the systems remain able to navigate to treatment locations within blood vessels of interest (e.g., in the coronary anatomy).

[0005] In examples described herein, catheter systems may be able configured to perform multiple functions historically performed by separate systems, which may in some cases reduce or obviate the need for using one or more of the separate systems. For example, the need for separate systems that assess or confirm information about blood vessels or stents, including intravascular imaging systems, such as intravascular ultrasound (IVUS) or optical coherence tomography (OCT) systems, may be obviated by the systems described in this disclosure.

[0006] In examples described herein, the catheters (e.g., balloon catheters) are configured to both expand against a vessel wall and/or a stent to open up the vessel and/or expand the stent, as well as determine one or more clinically relevant parameters, measurements, or indices related to dilatation and stent expansion (e.g., diameters of the vessel, balloon, stent, as well as information about a blood vessel, including lesion morphology). Using such a multi-functional system may reduce procedure time and risk for complications by reducing the number of catheters that need to be inserted and removed from the patient. For example, the need for intravascular imaging systems (e.g., IVUS or OCT systems) may be reduced or eliminated, as the catheter systems described in this disclosure may be configured to determine or confirm the parameters and/or measurements that intravascular imaging systems (e.g., IVUS or OCT systems) would normally generate.

[0007] In one example, a medical device system includes an elongated body configured to be inserted into a blood vessel of a patient. The medical device system further includes an expandable structure at a distal portion of the elongated body. The medical device system further includes a plurality of sensors carried by at least one of the elongated body or the expandable structure. The medical device system further includes processing circuitry configured to receive, via the plurality of sensors, one or more signals, and determine, based on the one or more signals, one or more of: an indication of a morphology of a lesion of the blood vessel, or one or more diameters of the expandable structure or the blood vessel.

[0008] In another example, a method includes receiving, by processing circuitry, one or more signals from a plurality of sensors carried by an elongated body or an expandable structure at a distal portion of the elongated body, the elongated body configured to be inserted into a blood vessel. The method further includes determining, by processing circuitry and based on the one or more signals, one or more of: an indication of a morphology of a lesion of the blood vessel, or one or more diameters of the expandable structure or the blood vessel.

[0009] In another example, a method includes delivering to a treatment location in a blood vessel of a patient via a first catheter, a stent. The method further includes inflating the first catheter to expand the stent at the treatment location in the blood vessel. The method further includes inserting, into the blood vessel and to the treatment location, a second catheter, the second catheter including: an elongated body; an expandable structure at a distal portion of the elongated body; and a plurality of sensors carried by at least one of the elongated body or the expandable structure, the plurality of sensors coupled to processing circuitry configured to determine one or more diameters of the expandable structure, the stent, or the blood vessel. The method further includes inflating the expandable structure of the second catheter to further expand the stent based on the one or more determined diameters. [0010] In another example, a medical device system includes an elongated body configured to be inserted into a blood vessel of a patient. The medical device system further includes a balloon at a distal portion of the elongated body, the balloon configured to inflate and expand a stent against a wall of the blood vessel. The medical device system further includes a plurality of sensors carried by elongated body, wherein each sensor of the plurality of sensors is longitudinally spaced apart along the elongated body. The medical device system further includes processing circuitry configured to: apply an electrical current to a first set of the plurality of sensors, receive, via a second set of the plurality of sensors, one or more resulting voltages, determine, based on the one or more resulting voltages, one or more diameters or one or more cross-sectional areas of the balloon, the stent, or the blood vessel, and output, to a user, an indication of the one or more diameters or the one or more cross-sectional areas.

[0011] This summary is intended to provide an overview of the subject matter described in this disclosure. It is not intended to provide an exclusive or exhaustive explanation of the devices, systems, and/or methods described in detail within the accompanying drawings and description below. The examples described herein may be combined in any permutation or combination. Further details of one or more examples are set forth in the accompanying drawings and the description below.

BRIEF DESCRIPTION OF DRAWINGS

[0012] FIG. 1 A is a schematic illustration of an example medical device system including a catheter system.

[0013] FIG. IB is a schematic illustration of an example distal portion of the catheter of FIG. 1A.

[0014] FIG. 1C is a schematic illustration of an example distal portion of the catheter of FIG. 1A.

[0015] FIG. 2 is a functional block diagram illustrating components of the catheter system of FIG. 1A.

[0016] FIG. 3A is a schematic illustration of the catheter system of FIG. 1 A accessing a blood vessel of a patient.

[0017] FIG. 3B is a schematic illustration of the catheter system of FIG. 1 A with a portion of the catheter expanded.

[0018] FIG. 3C is a schematic illustration of the catheter system of FIG. 1 A with a portion of the catheter expanded. [0019] FIG. 4A is a schematic illustration of an example of a catheter system accessing a blood vessel of a patient with a portion of the catheter expanded.

[0020] FIG. 4B a is schematic illustration including a cross-sectional representation of the catheter system of FIG. 4 A, the cross-section taken transverse to the longitudinal axis of the catheter system.

[0021] FIG. 5 is a flow diagram illustrating an example technique for determining lesion morphology and/or one or more diameters using the catheter system of FIG. 1 A, FIG. IB, and/or FIG. 1C.

[0022] FIG. 6 is a flow diagram illustrating an example technique for delivering and expanding a stent using the catheter system of FIG. 1 A, FIG. IB, and/or FIG. 1C.

[0023] Like reference characters denote like elements throughout the description and figures.

DETAILED DESCRIPTION

[0024] This disclosure describes devices, systems, and methods relating to medical device systems, including catheter systems used during percutaneous coronary intervention (PCI) procedures. An example PCI procedure includes balloon angioplasty and/or stent placement in a hollow anatomical body (e.g., a blood vessel). Angioplasty balloons and/or stents are configured to expand radially outward at a treatment location, such as to open up a narrowed portion of a blood vessel, which may include an abnormal narrowing or blockage of the blood vessel. During an angioplasty or stent placement procedure, a clinician may insert a first balloon catheter into a blood vessel and inflate the balloon to open up a blood vessel prior to placement of a stent (e.g., as may be referred to herein as pre-dilatation procedure). The clinician may then deliver the stent on a second balloon catheter to the treatment location and expand the stent to further open the narrowed portion of the blood vessel. After placement and expansion of the stent the clinician may further expand the stent or ensure uniform expansion with a third catheter (e.g., as may be referred to herein as post-dilatation procedure).

[0025] In some examples, clinicians may use feedback from various imaging and/or measurement modalities to determine whether a stent has been sufficiently expanded, or whether further expansion is warranted. For example, clinicians may receive feedback from imaging modalities or other measurement tools to determine whether a stent has been sufficiently expanded, such after initial delivery and initial expansion and/or after a post-dilatation expansion performed with a different catheter. Information about stent deployment and/or expansion may correlate with potential complications, including stent migration, dissection, and longer-term complications such as late stent thrombosis, in-stent restenosis, etc. [0026] One measure of sufficient stent expansion includes a minimum stent area (MSA) of the stent, which is the smallest cross-sectional area of the stent over the longitudinal length of the stent. In some examples, MSA is referenced as a numerical value (e.g., 4.73 mm²) which is compared to a minimum threshold value (e.g., 5 mm², 5.5 mm², etc.). In some examples, the desired MSA may be referenced as a percentage of a reference lumen area (e.g., the area of the blood vessel proximal and/or distal to a lesion, such as considered to be a “normal” vessel cross- sectional area). For example, an acceptable MSA percentage may be 80 percent or greater, meaning that the minimum cross-sectional area of the stent is 80 percent of the reference blood vessel cross-sectional area. However, other minimum acceptable MSA percentages are contemplated (e.g., 60 percent, 70 percent, 75 percent, 85 percent, 90 percent, 95 percent, or another suitable value). Other measures of sufficient stent expansion include a degree of stent expansion (e.g., a degree of how much a stent expands compared to a threshold expansion value) or a degree or stent apposition (e.g., a degree of how much a stent expands to press against a vessel wall, which may depend on a gap between the stent and the vessel wall).

[0027] While the imaging and/or measurement systems used separately from the dilatation and stent delivery catheters may be useful for assessing or confirming clinically relevant information related to stent delivery and stent placement, these separate systems may lead to extra procedure time, cost, and potential for complications, e.g., because these systems are separate (e.g., physically and communicatively) from the dilatation and stent delivery catheters. For example, after a post-dilatation expansion of the stent, a clinician may need to remove the post-dilatation catheter from the patient in order to insert a separate catheter or medical device system configured for imaging and/or measurement (e.g., a device and/or catheter that is a part of an intravascular imaging system). Examples of such separate and independent intravascular imaging system include intravascular ultrasound (IVUS) or optical coherence tomography (OCT) systems. Additionally, other non-invasive methods of confirming vessel opening (e.g., angiography) may not be accurate and/or precise enough to measure and/or confirm relevant measures of clinical effectiveness, including the degree of stent expansion or the degree of stent apposition.

[0028] In examples described herein, the catheters (e.g., balloon catheters) are configured for expansion against a vessel wall and/or against a stent to open up the vessel and/or expand the stent, as well as determine one or more clinically relevant parameters, measurements, or indices related to dilatation and stent expansion (e.g., diameters of the vessel, balloon, stent, as well as information about a blood vessel, including lesion morphology). In other words, the devices described herein may be configured to perform one or more of pre-dilation, stent delivery, stent expansion, and/or post-dilation stent expansion. Using such a multi-functional system may reduce procedure time and risk for complications by reducing the number of catheters that need to be inserted and removed from the patient. For example, the need for intravascular imaging systems (e.g., IVUS or OCT systems) may be reduced or eliminated, as the catheter systems described in this disclosure may be configured to determine or confirm the parameters and/or measurements that intravascular imaging systems (e.g., IVUS or OCT systems) would normally generate. Particularly in emergency cases where time is limited, using the multi-functional devices described herein may lead to improved patient outcomes, e.g., by sufficiently restoring blood flow to a sufficient level in less time as compared to when separate systems are used. It should be understood that it may still be possible to use intravascular imaging systems (e.g., IVUS or OCT systems) in addition to the techniques described in this disclosure.

[0029] Additionally, the systems may be configured to be a “smart” feedback system, such that balloon and/or stent expansion is automatically driven based on measurements (e.g., diameters, morphologies, etc.) of the system. Such “smart” systems may reduce or eliminate the need for clinician input, which may reduce time and the potential for human error while increasing safety for patients. For example, the systems described herein may provide (e.g., generate) recommendations to a clinician related to one or more medical procedures, such as angioplasty, stenting, assessment of lesion morphology, or related medical procedures.

[0030] In the examples described herein, a catheter system (e.g., a balloon catheter system) includes an elongated body and an expandable structure (e.g., a balloon) at a distal portion of the elongated body, and one or more sensors (e.g., electrodes, or other types of sensors) carried by the elongated body or the balloon. In some examples, the balloon is configured to expand against a wall of a vessel and/or stent, e.g., to expand the stent against the vessel wall. The sensors (e.g., electrodes) may be physically and communicatively coupled to processing circuitry configured to receive and process signals to determine one or more measures, indices, parameters related to the balloon, the blood vessel, or the stent, e.g., while the distal portion of the catheter system is inserted into the blood vessel of the patient. The measures, indices, parameters related to the balloon, the blood vessel, or the stent can include one or more dimensions of the balloon, the blood vessel, or the stent, as well as physiological information of the patient, including lesion morphology, temperature, flow rate, etc. In this way, a clinician may be enabled to receive indications of measures, indices, parameters related to the balloon, the blood vessel, or the stent and/or indications of the physiological information with the same device the clinician would use to expand the blood vessel and/or delivery and/or expand the stent. [0031] One technique for determining diameters of the balloons (which may also serve as a proxy for vessel or stent diameters when the balloon is expanded against such structures) described herein includes estimating diameters based on resulting voltages between two or more electrodes. Such a method of determining diameter based on a supplied current and resulting voltage may generally be referred to as electrical impedance tomography (EIT). For ease of description, the following is an example of EIT, but the example techniques should not be considered limited to EIT or the provided examples.

[0032] In some examples, sensors (which may be electrodes) are separated by a fixed distance (L) and are electrically connected to signal generation circuitry and sensing circuitry, which may include a voltage meter. A constant current source is applied (e.g., via the signal generation circuitry), and an electric field with a resulting voltage (V) is generated in a conductive medium contained in a balloon constrained by walls of a body lumen (e.g., a blood vessel and/or a stent). In some examples, constant current is applied to a first set of sensors, and the resulting voltage is measured via a second set of sensors. In some examples, the first set of sensors and the second set of sensors are the same sensors and/or share at least one sensor or at least some common sensors. In some examples, the first set of sensors and the second set of sensors are different (e.g., mutually exclusive). Resistance (R) or impedance can be determined by the following equation:

[0033] As used in Equation 1, R, a resistance (impedance) given by V/I, can be calculated as the AC current (I) is known and is fixed, and the AC voltage (V) is measured across the pair of sensors (e.g., electrodes). If L is a fixed distance between the electrodes, and the medium conductivity (sigma or G) is known for a given temperature, then an estimated diameter (D) can be determined. In some examples, variations of Equation 1 that may be used for purposes of this disclosure include a temperature variable, as temperature may affect medium conductivity. The estimate of the balloon or cylinder diameter (D) at a given electrode position is derived from the measured cylinder area (A) (e.g., using an assumption that the balloon is symmetrical about its longitudinal axis at that electrode position).

[0034] Equation 1 shows that AC voltage (V) is inversely proportional to the estimated diameter squared (D^A2), therefore, the diameter can be estimated based on the voltage reading between electrodes. If the conductive medium is contained in a flexible balloon and an array of voltage electrodes used, the shape of the balloon can be estimates and/or reproduced based on the voltage readings.

[0035] Although the example techniques described herein are described in many instances with reference to blood vessels (for example, cardiac blood vessels) and stents, the example techniques also have application to other anatomical sites (e.g., other suitable hollow and/or tubular anatomical structures, including brain ventricles, gastrointestinal tract such as the esophagus and/or intestines, the urinary track and associated structures, etc.) and the devices and systems described herein can be configured (e.g., have suitable shape and dimensions) for such sites. For example, a catheter may be configured to access and determine information about other blood vessels, such as the neurovasculature, peripheral vasculature, or other suitable vascular sites.

[0036] As used herein, the terms “distal” and proximal” define a position or direction with respect to the treating clinician or clinician’s control device (e.g., a handle assembly). “Distal” or “distally” can refer to a position distant from or in a direction away from the clinician or clinician’s control device. “Proximal” and “proximally” can refer to a position near or in a direction toward the clinician or clinician's control device.

[0037] While this disclosure is primarily described in term of diameters of vessels, stents, expandable structures, and/or other bodies which are generally tubular structures having generally circular cross-sections, other related and/or derivative measures (including radii, area, volume, surface area, maximum dimension, minimum dimension, etc.) may be understood to be interchangeable where a diameter is determined, evaluated, or otherwise referenced.

[0038] FIG. 1 A is a partially schematic perspective view illustrating a medical device system 100 configured in accordance with examples of the present disclosure. Medical system 100 includes a catheter system 108 defining an elongated body 110 configured to be inserted into a blood vessel 102 of patient 106 (e.g., by a clinician) and positioned within blood vessel 102. Catheter system 108 includes one or more expandable structures such as a balloon 112 configured to expand (e.g., by inflation) when elongated body 110 is positioned within blood vessel 102 of patient 106. Balloon 112 may be configured to expand, for example, to be inflated and expand a stent against a wall 104 of the blood vessel 102 (e.g., either as a stent-delivery balloon or a post-dilatation balloon). In some examples, balloon 112 is configured to expand within vessel 102 against vessel wall 104, such as during a pre-dilatation procedure to open blood vessel 102 or compress plaque before placement of a stent. Elongated body 110 defines a longitudinal axis 159 (e.g., which may be a central longitudinal axis 159 of elongated body 110 and/or balloon 112) extending through a distal end 158 of elongated body 110. Balloon 112 may be configured to expand radially outwards relative to longitudinal axis 159 (e.g., substantially perpendicular to longitudinal axis 159) when balloon 112 is inflated within blood vessel 102 of patient 106.

[0039] Balloon 112 has any suitable configuration. In examples, balloon 112 is configured such that an imaging system (e.g., an imaging system extracorporeal to patient 106) can capture an image of balloon 112 when balloon 112 is within patient 106. In some examples, elongated body 110 and/or balloon 112 includes one or more radiopaque markers for visualization via a suitable medical imaging technique. Balloon 112 may be constructed of any compliant, semi- compliant or non-compliant material, typically a plastic such as polyurethane, nylon, polyethylene, PET or PEBAX. In some examples, balloon 112 (e.g., the balloon body) includes silicone. In some examples, balloon 112 is a dipped balloon fabricated using a dip molding process. In some examples, balloon 112 is expanded such that an exterior surface 138 of balloon 112 (“balloon exterior surface 138”) contacts vessel wall 104 and/or a stent (not shown in the example of FIG. 1 A). The strength of the wall of balloon 112 may be configured (e.g., have sufficient strength) to expand against vessel wall 104 and/or a stent, such as to further open vessel 102 and/or the stent.

[0040] In some examples, balloon 112 is configured to expand to a range of dimensions (e.g., diameters). For example, balloon 112 can be a compliant balloon and configured to expand to define a particular dimension within the range based on an inflation pressure within the balloon. In examples, the expanded dimension of the balloon is selected by a clinician based on a size of the blood vessel, e.g., selected to enable the balloon to contact vessel wall 104 of blood vessel 102. In examples where balloon 112 is a compliant balloon, balloon 112 may be configured to exhibit a radial growth of about 10 percent or greater over a working range of pressures.

[0041] In some examples, balloon 112 is configured to expand to a fixed or relatively fixed dimension (within a tolerance) over a range of pressures. For example, balloon 112 can be a non- compliant balloon and configured exhibit less expansion over a working range of pressures such as to define a particular dimension regardless of what inflation pressure is selected by a clinician. As long as a minimum pressure is supplied to balloon 112, balloon 112 may be configured to expand to define the particular dimension, and remain at the particular dimension with slight or no expansion as pressure is further increased in balloon 112. In examples where balloon 112 is a non-compliant balloon, balloon 112 may be configured to exhibit a radial growth of about 4 to 6 percent over a working range of pressures.

[0042] In some examples, balloon 112 is configured to exhibit growth rates between that of a compliant balloon and a non-compliant balloon. For example, balloon 112 can be a semi- compliant balloon and configured to exhibit a growth of about 8 to 10 percent over a working range of pressures.

[0043] Catheter system 108 includes a plurality of sensors 114 (which may also be referred to herein as electrodes 114, first plurality of sensors 114, and/or first set of sensors 114) carried by at least one of the elongated body 110 (as shown in the example of FIG. 1 A) or balloon 112 (as shown in other examples), or another suitable part of catheter system 108. However, in some examples, catheter system 108 includes plurality of sensors 114 carried by multiple portions of catheter system 108, such as at least two of elongated body 110, balloon 112, or another suitable part of catheter system 108.

[0044] Sensors 114 can be positioned at any suitable location along, around, and/or on elongated body 110 and/or balloon 112. One or more of sensors 114 can be positioned on an outer surface of balloon 112 (e.g., on a radially outer surface of balloon 112 relative to longitudinal axis 159). One or more of sensors 114 can be positioned on an inner surface of balloon 112 (e.g., on a radially inner surface of balloon 112 relative to longitudinal axis 159). In some examples, one or more of sensors 114 extends through a surface of balloon 112 (e.g., such that a first portion of each of the one or more sensors 114 is positioned radially outward of balloon 112 and a second portion of the one or more sensors 114 is positioned radially inward of balloon 112).

[0045] In some examples, sensors 114 are positioned around a circumference of balloon 112 and/or around a circumference of elongated body 110. For example, in examples in which multiple sensors 114 are positioned on or within balloon 112, each of multiple sensors 114 can be positioned at a respective circumferential location with respect to balloon 112 (e.g., around longitudinal axis 159, such that one or more of sensors 114 faces in a unique radial direction outward from longitudinal axis 159). In some examples, each of sensors 114 is positioned at a unique longitudinal and/or circumferential location with respect to balloon 112 and/or elongated body 110.

[0046] Sensors 114 can be positioned at any suitable location with respect to balloon 112. In some examples, one or more of sensors 114 (e.g., all of sensors 114) are proximal to balloon 112 (e.g., positioned on a portion of elongated body 110 or another structure proximal to balloon 112). In some examples, one or more of sensors 114 (e.g., all of sensors 114) are distal to balloon 112 (e.g., positioned on a portion of elongated body 110 or another structure distal to balloon 112). Placing sensors 114 proximal to and/or distal to balloon 112 can enable relatively larger and/or more sensors 114 to be placed on catheter system 108, e.g., because of the greater space availability at these locations proximal and distal to balloon 112. In such cases in which sensors 114 are placed proximal to and/or distal to balloon 112, sensors 114 can be used to measure and signals and/or determine information related to vessel diameter and/or lesion morphology, as discussed more fully herein.

[0047] In examples in which balloon 112 defines a proximal cone portion, a distal cone portion, and a body portion between the proximal cone portion and the distal cone portion, one or more of sensors 114 can be positioned on the body portion of balloon 112 (e.g., such that all of sensors 114 coextensive with the body portion of balloon 112 along longitudinal axis 159). Additionally or alternatively, one or more of sensors 114 can be positioned on the proximal cone portion and/or the distal cone portion of balloon 112. In some examples, as shown in the example of FIG. 1 A, one or more of sensors 114 are positioned on elongated body 110 such that the one or more sensors 114 are within a volume defined by balloon 112. One or more of sensors 114 can be positioned in a lumen defined by balloon 112.

[0048] In some examples, catheter system 108 includes a combination of sensors 114 at multiple positions along and/or on elongated body 110 and/or balloon 112 (e.g., including any of the positions described herein). A combination of sensors 114 at different locations can enable simultaneous sensing and/or determination of multiple relevant parameters (e.g., diameters of balloon 112 and/or blood vessel 102, morphology of vessel wall 104, and/or the like).

[0049] In some examples, one or more of sensors 114 is fixed relative to balloon 112 (e.g., in a fixed spatial relationship to balloon 112). In other examples, one or more of sensors 114 are movable with respect to balloon 112 (e.g., such that one or more of sensors 114 are not in a fixed spatial relationship with respect to balloon 112). In examples in which one or more of sensors 114 is movable with respect to balloon 112, a single sensors can enable determination of relevant parameters (e.g., diameters of balloon 112, vessel 102, morphology, and/or the like) at different axial and/or circumferential locations (e.g., along and/or around longitudinal axis 159).

[0050] As discussed below, system 100 (e.g., device 144) may be configured to apply a current to and/or between sensors 114 to generate a voltage such that one or more dimensions (e.g., diameters) of balloon 112 may be estimated based on the voltage, which may facilitate estimation of one or more dimensions (e.g., diameters) of a stent and/or dimensions (e.g., diameters) of blood vessel 102, such as when balloon 112 is expanded to press against the stent or vessel wall 104 of blood vessel 102. Although this disclosure is discussed primarily in the context of applying current to and/or between sensors and detecting the resulting voltage, system 100 (e.g., device 144) may additionally or alternatively be configured to apply a constant voltage to and/or between sensors 114 in order to generate a resulting current (which can likewise be used for estimation of one or more dimensions of balloon 112, a stent, and/or blood vessel 102). Further, although the example of FIG. 1 A illustrates catheter system 108 with seven sensors 114, catheter system 108 can include any suitable number of sensors 114 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 50 or more sensors, etc.). The number and/or spacing of sensors 114 may correspond to the granularity and number of dimension (e.g., diameters) measurements of balloon 112. For example, including sensors 114 spaced closer together (e.g., closer together along longitudinal axis 159) may facilitate a more granular determination of diameters of balloon 112 along longitudinal axis 159.

[0051] In some examples, each of sensors 114 disposed on elongated body 110 is separated by a longitudinal distance LI measured along longitudinal axis 159 (e.g., such that at least some sensors of plurality of sensors 114 are longitudinally spaced apart from respective adjacent sensors of sensors 114 along elongated body 110). In the example of FIG. 1 A, all sensors of sensors 114 are equally spaced apart (e.g., are separated by longitudinal distance LI). However, in other examples, some or all of sensors 114 can have unequal spacing.

[0052] Sensors 114 may have any suitable configuration along elongated body 110. In examples, each of sensors 114 may wrap circumferentially around elongated body 110, e.g., such that each sensor of sensors 114 completely circumvents elongated body 110. In some examples, each sensor of sensors 114 wraps partially around elongated body 110. In other examples, multiple sensors 114 are spaced circumferentially around elongated body 110 at a given longitudinal location along axis 159, such that multiple sensors of sensors 114 circumnavigate elongated body 110 at a given longitudinal location along axis 159.

[0053] In some examples, elongated body 110 is configured to support sensors 114 at a fixed longitudinal location (measured along longitudinal axis 159) on elongate body 110 relative to balloon 112. For example, as illustrated in FIG. 1 A, elongate body 110 may support sensors 114 such that sensors 114 are positioned (e.g., disposed) within an interior volume 116 of balloon 112. In examples, elongate body 110 is configured to position sensors 114 such that balloon 112 substantially extends over (e.g., substantially surrounds) sensors 114. However, in some examples (as discussed in relation to FIG. IB and FIG. 1C), catheter system 108 additionally or alternatively includes other sensors on balloon exterior surface 138 and/or an interior surface 140 of balloon 112 (“balloon interior surface 140”), and/or some portion of a balloon body between and/or defining balloon exterior surface 138 and/or balloon interior surface 140.

[0054] Elongated body 110 defines a distal portion 110A (“distal body portion 110A”) and a proximal portion HOB (“proximal body portion HOB”). Plurality of sensors 114 and/or balloon 112 are positioned on and/or carried by distal portion 110A in the example shown in FIG. 1 A. In examples, catheter system 108 is configured to assume a relatively low-profile delivery configuration in which at least one of distal portion 110A and/or balloon 112 defines a dimension Cl (e.g., a diameter), which can be measured in a direction perpendicular to longitudinal axis 159. The dimension Cl may define a dimension sufficient to allow the passage of at least distal body portion 110A and balloon 112 through vasculature of patient 106 to reach a target treatment location within patient 106. In some examples, distal body portion 110A is configured to locate sensors 114 at an intraluminal (e.g., intravascular) location. Intraluminal (e.g., intravascular) locations can include blood vessels with diameters on the order of millimeters, such as about 1 mm to 8 mm. In some examples, target locations include one or more coronary arteries, such as the left main coronary artery (LMCA), left anterior descending artery (LAD), and/or circumflex artery (CX), and Right Coronary Artery (RCA), and their respective side branches. However, other blood vessels of smaller or larger sizes are contemplated (e.g., cranial blood vessels, peripheral blood vessels, etc.). Balloon 112 is configured to expand from the delivery configuration to an expanded configuration (e.g., FIG. 3B, FIG. 3C) to, for example, position and/or stabilize distal body portion 110A and/sensors 114 when distal body portion 110A locates sensors 114 at the target treatment location.

[0055] In some examples, system 100 includes a device 144 configured to control, monitor, supply, and/or otherwise support operation of system 100 (e.g., including catheter system 108). In some examples, device 144 includes one or more of a processing device, power generation device, which may include any suitable configuration of inputs, outputs, displays, power supplies, and/or combinations of hardware and software for functioning of system 100. While device 144 is described in connection with catheter system 108, device 144 may be configured in other ways, such for use with multiple catheters and/or other medical systems, including other medical imaging systems such as intravascular imaging systems (e.g., IVUS and OCT systems). [0056] In some examples, device 144 may include (or be coupled to) a user interface 130 configured to receive input from a user and/or output information to a user. For example, user interface 130 can include a button or keypad, a touch screen, a speaker configured to receive and/or output audible information, and/or a display, such as a liquid crystal (LCD), light-emitting diode (LED), or organic light-emitting diode (OLED). In some examples, user interface 130 is configured to output (e.g., present or display) information, such as one or more an indication of one or more dimensions (e.g., diameters) of balloon 112 or the blood vessel 102. In some examples, user interface 130 is configured to output (e.g., present or display) information, such as one or more an indication if a minimum stent area (MSA) of the stent based on one or more dimensions (e.g., diameters) of balloon 112 or the blood vessel 102. In some examples, user interface 130 is configured to output a graphical representation (e.g., an image, picture, schematic representation, etc.) of vessel 102, stent 160, and/or balloon 112 including one or more determined dimensions (e.g., diameters). The graphical representation can include one or more colors, legends, and/or other keys (e.g., red areas of the stent indicating narrow diameters and green or blue areas indicating larger and/or sufficient diameters).

[0057] Device 144 may be configured to control, monitor, supply, and/or otherwise support operation of catheter system 108. For example, device 144 can be configured to generate a selected form and/or magnitude of energy (e.g., current) to sensors 114. For example, device 144 can include a generator configured to generate energy (e.g., pulsed field, electrical current, microwave, radiofrequency, monopolar, and/or bipolar energy). In other examples, device 144 may be another type of device configured to generate and deliver another suitable type of energy to catheter system 108. In some examples, device 144 is configured to receive one or more resulting signals from sensors 114 based on the signals applied to sensors 114. For example, device 144 can be configured to receive a resulting voltage signal from sensors 114, e.g., for determination of one or more dimensions (e.g., diameters) of balloon 112. As discussed in relation to later examples, device 144 can be configured to determine and/or approximate one or more diameters of a stent, in examples where balloon 112 is expanded against a stent such that the diameter of balloon 112 approximates the diameter of the stent at any given longitudinal position along balloon 112.

[0058] Although not shown in the example of FIG. 1 A, one or more conductive wires may be physically and/or communicatively coupled to each of sensors 114 and device 144, such that electrical signals may be transmitted between sensors 114 and device 144. Sensors 114 and device 144 may additionally or alternatively be communicatively coupled in other ways, including via printed circuits, or other suitable techniques. In other examples, sensors 114 and device 144 are configured to communicate wireless and/or at least partially wirelessly.

[0059] Medical device system 100 includes a cable 147 configured to deliver power and/or facilitate communication between device 144 and catheter system 108. Along cable 147 or at another suitable location within medical device system 100, medical device system 100 may include a control device 145 configured to initiate, terminate, and/or adjust operation of one or more components of catheter system 108 directly and/or via device 144. In some examples, device 144 may be configured to execute an automated control algorithm and/or to receive control instructions from an operator. Similarly, in some implementations, device 144 is configured to provide feedback to an operator before, during, and/or after a treatment procedure via an evaluation/feedback algorithm. [0060] In some examples, catheter system 108 is configured to receive energy (e.g., from device 144) and convert the energy (e.g., electrical current) into a different form of energy, such as acoustic energy (e.g., sound pressure waves). For example, sensors 114 can be include an ultrasound transducer configured to transmit the acoustic energy to vessel wall 104 or another anatomical location of patient 106.

[0061] In some examples, medical system 100 includes a handle portion 150 coupled to proximal body portion HOB, which is configured to remain outside vasculature of patient 106 when distal body portion 110A is within vasculature of patient 106. Handle portion 150 may be configured to allow a clinician to navigate at least distal body portion 110A through the vasculature, allow inflation and/or deflation of balloon 112, and/or enable other functions of medical system 100 which may assist in the delivery of a treatment to patient 106. At least some portion of catheter system 108 (e.g., distal body portion 110A) may be substantially flexible, such that catheter system 108 may flex and/or bend enroute to positioning balloon 112 and/or sensors 114 within blood vessel 102 of patient 106. Hence, although illustrated as substantially linear in FIG. 1 A, catheter system 108 (or portions thereof) may be configured to assume linear, curved, and/or curvilinear shapes. Correspondingly, longitudinal axis 159 (and/or portions thereof) defined by catheter system 108 may be linear, curved, and/or curvilinear.

[0062] In examples, catheter system 108 is configured to inflate and/or expand balloon 112 with a fluid (e.g., liquid) such as water, saline, contrast, conductive fluid, another suitable liquid, or a combination thereof. In some examples, the fluid includes a mixture of saline and contrast fluid, which may include a suitable ratio (e.g., 50:50). In some examples, catheter system 108 is configured such that the fluid may flow into a fluid inlet 118, through an inlet lumen defined by elongate body 110, through interior volume 116, in order to inflate balloon 112. Inlet 118 may also serve as an outlet, e.g., such as to remove fluid and deflate balloon 112. The fluid (e.g., water, saline, contrast, conductive fluid, another suitable liquid, or a combination thereof) used for inflation of balloon 112 may define a known conductivity, which device 144 may use for determination of one or more dimension (e.g., diameters) of balloon 112, such as in the evaluation of equation 1. In some examples, device 144 is configured to inflate balloon 112, e.g., through controlled delivery of a fluid. However, in other examples, a separate automated device (e.g., pump) or manual device (e.g., hand-held syringe or other manual balloon catheter inflation device) inflates balloon 112.

[0063] FIG. IB and FIG. 1C are additional examples of a distal portion of catheter system 108 from FIG. 1A. In some examples, catheter system 108 additionally or alternatively includes a second plurality of sensors 115 (which may also be referred to herein as a second set of sensors 115), which may be structurally and functionally the same as plurality of sensors 114, except as described herein. FIG. IB illustrates catheter system 108 including a second plurality of sensors 115 without sensors 114. FIG. 1C illustrates catheter system 108 with both sensors 114 and sensors 115. As shown, plurality of sensors 115 may be carried by balloon 112 and disposed proximate the surface of the balloon body of balloon 112. In some examples, second plurality of sensors 115 are mounted on balloon exterior surface 138 and extend radially outward from balloon exterior surface 138. In some examples, second plurality of sensors 115 are mounted on balloon interior surface 140. In some examples, second plurality of sensors 115 are mounted in a space between balloon exterior surface 138 and balloon interior surface 140, e.g., such as in examples where the body of balloon 112 includes multiple layers. In some examples, second plurality of sensors 115 may be affixed to the body of balloon 112 such that sensors 115 pass through the body of balloon 112 (e.g., from the interior volume 116 to an external portion of balloon 112). Each sensor of sensors 115 may wrap circumferentially around balloon 112, e.g., such that each sensor completely circumvents balloon 112. In other examples, multiple sensors 115 are spaced circumferentially around balloon 112 at a given longitudinal location along axis 159. Additionally or alternatively, one or more sensors of sensors 115 may be affixed to elongated body 110, either within the area defined by balloon 112, as well as proximal to and/or distal to balloon 112 along elongated body 110.

[0064] As described below, whereas sensors 114 carried by elongated body 110 may be configured and used for estimating one or more dimensions (e.g., diameters) of balloon 112, sensors 115 may be configured to assess information about blood vessel 102 and/or other physiological parameters. For example, device 144 may be configured to receive, via sensors 115, signals indicative of a morphology of a lesion of the blood vessel 102. As described herein, lesion morphology can include classifications of lesions such as calcific, fatty, fibrous, or the like. Other morphological information of lesions may include one or more of concentricity or eccentricity, tortuosity, regularity or irregularity of contour, absence or presence of thrombus, ostial or non-ostial, etc. Sensors 115 can include one or more electrodes, optical sensors, temperature sensors, ultrasound sensors and/or ultrasound transducers, accelerometers, flow sensors, etc., or a combination thereof.

[0065] Other configurations and/or types of sensors are also contemplated, e.g., for estimating dimensions (e.g., diameters) of a stent, balloon 112, and/or vessel 102. For example, sensors 114 and/or sensors 115 can include acoustic sensors and/or accelerometers that are configured to calculate one or more of a Doppler shift and/or transit time difference of signals, e.g., from an inner portion of balloon 112 to a balloon wall that is interacting with the deployed stent.

[0066] Although the examples of FIG. IB and FIG. 1C illustrate catheter system 108 with seven sensors 115, catheter system 108 can include any suitable number of sensors 115 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 50 or more sensors, etc.). As noted above, the number and/or spacing of sensors 115 may correspond the granularity of measurements taken by sensors 115. For example, including sensors 115 spaced closer together (e.g., closer together along longitudinal axis 159) may facilitate a more granular determination measurements. In some examples, a number of plurality of sensors 114 and a number of second plurality of sensors 115 may be equal (as shown in FIG. 1C). However, catheter system 108 may include an unequal number of plurality of sensors 114 and second plurality of sensors 115.

[0067] In some examples, each of sensors 115 is separated by a longitudinal distance L2 measured along longitudinal axis 159 (e.g., such that at least some sensors of plurality of sensors 115 are longitudinally spaced apart from respective adjacent sensors of sensors 115). In the example of FIG. IB and FIG. 1C, all sensors of sensors 115 are equally spaced apart (e.g., are separated by longitudinal distance L2). However, in other examples, some or all of sensors 115 can have unequal spacing. In some examples, the longitudinal spacing of sensors 114 (separated by distance LI) is the same or substantially the same as the longitudinal spacing of sensors 115 (separated by distal L2). The number and/or spacing of sensors 115 may correspond the granularity of measurements taken by sensors 115. For example, including sensors 115 spaced closer together (e.g., closer together along longitudinal axis 159) may facilitate a more granular determination of information of vessel 102 along longitudinal axis 159.

[0068] FIG. 2 is a functional block diagram illustrating components of an example device 144, which is configured to receive and process signals related to catheter system 108, as well output information and control one or more operations related to catheter system 108. As described above, device 144 is configured to receive and process signals from the one or more sensors 114 (shown individually as 114A, 114B, 114C, 114D, 114E, 114F, . . ., 114N, which may be referred to herein collectively as sensors 114 or electrodes 114) and/or from the one or more sensors 115 (shown individually as 115A, 115B, 115C, 115D, 115E, 115F, . . ., 115N, which may be referred to herein collectively as sensors 115 or electrodes 115). Device 144 includes processing circuitry 30, memory 32, signal generation circuitry 34, sensing circuitry 36, telemetry circuitry 38, and power source 40. Although processing circuitry 30, signal generation circuitry 34, sensing circuitry 36, and telemetry circuitry 38 are described herein as separate components, one or more functionalities may be attributed generally to the processing capability of device 144. For example, functionalities of signal generation circuitry 34, sensing circuitry 36, and telemetry circuitry 38 may herein be generally described as a functionality of processing circuitry 30. In some examples, device 144 includes user interface 130 (as described in connection with FIG. 1 A), as well as suitable hardware and/or software configuration generating and presenting information via user interface 130.

[0069] Signal generation circuitry 34 includes any suitable configuration (e.g., hardware) configured to generate signals (e.g., electrical signals such as current or voltage, as other types of signals) to and/or between one or more sensors 114. Although primarily described in the context of electrical signals, signal generation circuitry 34 may be configured to deliver any suitable type of signal (e.g., ultrasound, etc.) for determining information about blood vessels and/or stents. Processing circuitry 30 is configured to control signal generation circuitry 34 to generate signals. Plurality of sensors 114 may include a suitable monopolar or bipolar arrangement (e.g., in examples where sensors 114 includes electrodes). Processing circuitry 30 may be configured to control signal generation circuitry 34 to generate signals according to a predefined program, which may define one or more of an amplitude, duration, pulse rate, or another suitable signal parameter. The generated signals may be of any suitable form, such as pulses or continuous-time signals (e.g., sine waves). When processing circuitry (e.g., via signal generation circuitry 34) applies a current to sensors 114, sensors 114 may output a resulting voltage signal. In this way, processing circuitry 30 is configured to apply an electrical current to sensors 114 to induce the voltage signals in the sensors 114. In other examples, the resulting signal from sensors 114 may be one or more of the other signals described herein (e.g., a resulting current from an applied voltage). In some examples, constant current is applied a first set of sensors of sensors 114, and the resulting voltage is measured via a second set of sensors of sensors 114. In some examples, the first set of sensors of sensors 114 and the second set of sensors of sensors 114 are the same sensors and/or share at least one sensor or at least some common sensors. In some examples, the first set of sensors of sensors 114 and the second set of sensors of sensors 114 are different (e.g., mutually exclusive).

[0070] Sensing circuitry 36 is configured to receive, via sensors 114, one or more signals for determination of information, including morphology of a lesion of the blood vessel (e.g., as indicated by different impedance measurements caused by different lesion morphologies), and/or one or more dimensions (e.g., diameters) of balloon 112 or blood vessel 102. Sensing circuitry 36 may include any sensing hardware configured to receive signals from sensors 114, which may include a resulting voltage from sensors 114 based on the electrical signal applied to sensors 114 by signal generation circuitry 34. Processing circuitry 30 may receive, alone or in combination with sensing circuitry 36, the resulting signals from sensors 114. In some examples, processing circuitry 30 additionally receives one or more additional signals, including signals indicative of temperature, for determination of information, including morphology of a lesion of the blood vessel, and/or one or more dimensions (e.g., diameters) of balloon 112 or blood vessel 102. [0071] In some examples, processing circuitry 30, alone or in combination with the sensing circuitry 36, determines, based on the received signals from sensors 114, one or more dimensions (e.g., diameters) of balloon 112, blood vessel 102, and/or a stent. For example, processing circuitry 30 may be configured to receive the resulting voltage values from current applied to sensors 114 and determine dimensions (e.g., diameters) by applying the resulting voltage values to an equation (e.g., Equation 1), model, lookup table, or another relational method to determine dimensions (e.g., diameters) of balloon 112. Each determined diameter may be a diameter approximately at a longitudinal location between a pair of respective sensors of sensors 114 (e.g., a longitudinal location along axis 159 as shown in FIG. 1A). Thus, by determining dimensions (e.g., diameters) corresponding to each pair of sensors of sensors 114, processing circuitry 30 may estimate a plurality of dimensions (e.g., diameters) along balloon 112 (e.g., along longitudinal axis 159). In some examples, processing circuitry 30 determines dimensions by applying more than one type of information (e.g., different types of signals, including resulting voltages and sensed temperatures) to an equation (e.g., Equation 1), model, lookup table, or another relational method to determine dimensions (e.g., diameters) of balloon 112.

[0072] In examples where balloon 112 is expanded against blood vessel 102, the one or more dimensions (e.g., diameters) of the balloon 112 may, in effect, approximate one or more dimensions (e.g., diameters) of the blood vessel, such that processing circuitry 30 determines one or more dimensions (e.g., diameters) of blood vessel 102. In examples where balloon 112 is expanded against a stent (as described in relation to later examples), the one or more dimensions (e.g., diameters) of the balloon 112 may, in effect, approximate one or more dimensions (e.g., diameters) of the stent, such that processing circuitry 30 determines one or more dimensions (e.g., diameters) of the stent. Additionally, as diameters are proportional to cross-sectional area, processing circuitry 30 may be configured to determine a cross-sectional area of balloon 112, blood vessel 102, and/or the stent based on determined diameters of balloon 112, blood vessel 102, and/or the stent. Because processing circuitry 30 determines multiple dimensions (e.g., diameters), processing circuitry 30 may determine or more of a maximum, minimum, average, standard deviation, or aggregate measure of the determined dimensions (e.g., diameters). In some examples, processing circuitry 30 is configured to determine a minimum stent area (MSA) of the stent, e.g., based on the one or more dimensions (e.g., diameters) of the stent and/or the blood vessel 102.

[0073] In examples where processing circuitry 30 is configured to apply voltage signal values to a model to determine dimensions (e.g., diameters) of balloon 112, blood vessel 102, and/or a stent, the model defines a relationship between the one or more voltage signal values and the one or more dimensions (e.g., diameters) of balloon 112. For example, the model may include a include a pre-defined equation (e.g., equation 1) relating the one or more voltage signal values and the one or more dimensions (e.g., diameters) of balloon 112 or blood vessel 102. For example, the model may use sensed and/or user input information to determine dimensions (e.g., diameters) of balloon 112 (e.g., according to Equation 1, or variations thereof). Inputs may include a current value (I), a medium conductivity (sigma or c), temperature, distance between sensors 114. Thus, processing circuitry 30 is configured to determine, based on the one or more voltage signal values and the model, one or more dimensions (e.g., diameters) of balloon 112 and/or the blood vessel 102 and/or a stent. In some examples, the model includes reference information (e.g., reference diameters) for use in determining additional information (e.g., degrees of stent expansion and stent apposition) based on the measured diameters. Reference information, including diameters may include and/or be based on previous measurements of a blood vessel (e.g., before stent deployment), and/or a characterized (nominal) stent size. In some examples, an output of the model (e.g., resulting from the one or more voltage signal values applied to the model) includes the one or more dimensions (e.g., diameters) of balloon 112 and/or the blood vessel 102 and/or a stent.

[0074] In some examples, where processing circuitry 30 is configured to apply voltage signal values to a model to determine dimensions (e.g., diameters) of balloon 112, blood vessel 102, and/or a stent, the model may include a lookup table relating the one or more voltage signal values and the one or more dimensions (e.g., diameters) of the balloon 112, blood vessel 102, and/or a stent. For example, the lookup table may include a table of pre-evaluated solutions to Equation 1 relating voltage values to diameters. In some examples, the lookup table includes experimentally determined values of dimensions (e.g., diameters) of balloon 112, blood vessel 102, and/or a stent based on voltage values.

[0075] In some examples, where processing circuitry 30 is configured to apply voltage signal values to a model to determine dimensions (e.g., diameters) of balloon 112, blood vessel 102, and/or a stent, the model may include an artificial intelligence (Al) or machine learning (ML) model. Additionally or alternatively, processing circuitry 30 is configured to apply signals indicative of lesion morphology to an Al model or ML model to determine one or more measures of lesion morphology. In some examples, the Al model or ML model includes one or more of a statistical machine learning or deep learning model (e.g., neural network) configured to output information (e.g., one or more diameters) based on one or more inputs (e.g., voltage signal values). In some examples, the Al model is trained (e.g., via supervised, semi-supervised, unsupervised, or reinforcement learning) on clinical data or other experimental data. For example, the Al model may be trained with data relating voltage signal values to balloon 112 dimensions (e.g., diameters) and/or morphological data of lesions of vessels from previous procedures and/or experiments (e.g., data measured or verified with other measurement modalities, including intravascular imaging systems, IVUS, OCT, and/or the like). In some examples, the Al model is configured to output the one or more dimensions (e.g., diameters) of balloon 112, blood vessel 102, and/or a stent and/or morphological data of one or more lesions of vessel 102. In some examples, the Al model is additionally configured to output a confidence score indicative of a confidence of the output. The confidence score may indicate an accuracy of the output.

[0076] As well as determining dimensions (e.g., diameters) of balloon 112 and/or blood vessel 102 and/or a stent, processing circuitry 30 may be configured to determine further clinically relevant measures and indices, e.g., by aggregating the dimensions (e.g., diameters) and/or comparing the dimensions (e.g., diameters) to one or more known or received thresholds or reference values. For example, processing circuitry 30 may receive a reference diameter of a stent as fully expanded and compare the determined dimensions (e.g., diameters) with the reference dimensions (e.g., diameters) of the stent as fully expanded. In some examples, a reference diameter of a stent as fully expanded may be an experimentally determined value, a value input by a user into device 144, and/or a value stored in memory 32. In general, reference information, including diameters may include and/or be based on previous measurements of a blood vessel (e.g., before stent deployment), and/or a characterized (nominal) stent size.

[0077] In some examples, processing circuitry 30 determines, based on a determined diameter of the stent as expanded and the reference diameter of the stent, a degree of stent expansion. For example, a reference diameter for a particular stent may be nominal or desired diameter, such as 5 millimeters (mm), and the determined diameter can include the actual or estimated diameter of the stent (e.g., 3 mm, 5 mm, 7 mm, etc.). By comparing the reference diameter for the stent and the determined diameter, the degree of stent expansion can be expressed qualitatively (e.g., under-expanded, optimally expanded, over-expanded, etc.) and/or quantitatively. For example, for a particular stent with a reference diameter of 5 mm, a 3 mm determined expanded diameter may indicate under-expansion, a 5 mm (or nearly 5mm) determined expanded diameter may indicate optimal expansion, and a 7 mm determined expanded diameter may indicate over-expansion. As another example, the degree of stent expansion may be a percentage of the reference diameter of the stent (e.g., 30 percent, 40 percent, 50 percent, 60 percent, 70 percent, 80 percent, 90 percent, 100 percent, 110 percent, 120 percent etc.).

[0078] As another example, processing circuitry 30 may receive a reference diameter of vessel 102 (e.g., an inner diameter of vessel wall 104), which may be a diameter indicative or a normal or otherwise healthy blood vessel and compare the determined dimensions (e.g., diameters) of balloon 112 and/or the stent with the reference dimension of vessel 102. As noted earlier, reference dimensions can include experimentally determined values, a value input by a user into device 144, and/or a value stored in memory 32 that can be accessed by processing circuitry 30. In general, reference information, including diameters may include and/or be based on previous measurements of a blood vessel (e.g., before stent deployment), and/or a characterized (nominal) stent size. In some examples, the reference diameter of vessel 102 may be an experimentally determined value (e.g., as measured downstream or upstream of a lesion), a value input by a user into device 144, or a value stored in memory 32. In some examples, processing circuitry 30 determines, based on a determined diameter of the stent as expanded and the reference diameter of vessel 102, a degree of stent apposition against vessel wall 104. In some examples, processing circuitry 30 determines the degree of stent expansion and/or stent apposition against vessel wall 104 by comparing or performing a mathematical operation on the determined dimensions (e.g., diameters) and the reference dimensions (e.g., diameters) of vessel 102 and/or the stent. In some examples, a degree of stent apposition may include a measure of a gap between the stent as expanded and the inner diameter of vessel 102 (which may be the reference diameter of the vessel). In some examples, processing circuitry 30 determines the degree of stent expansion by dividing a measured value of a stent (e.g., a measured dimension such as diameter and/or a suitable related value such as area) by a reference value (e.g., a nominal or characterized dimension of the stent, and/or a measured dimension such as diameter of the stent or blood vessel).

[0079] In some examples, processing circuitry 30 determines a minimum value, maximum value, average, mean, standard deviation, or another statistical measure from multiple determined dimensions (e.g., diameters) or related values (values of the degree of stent expansion of values of the degree of stent apposition). For example, processing circuitry 30 may determine a minimum or maximum dimension of balloon 112 based on all determined diameters between all pairs of sensors 114. Such minimum or maximum dimensions, or other values, may be output to a user (e.g., a clinician) as described elsewhere in this disclosure.

[0080] Further examples of clinically relevant measures and indices which processing circuitry 30 may be configured to determine include one or more of a lesion length, a presence and/or extent of dissection of the lesion or blood vessel 102 (e.g., medial dissection), and/or other clinically relevant information. These other clinically relevant measures may be performed by expanding balloon 112 against the vessel wall 104 of vessel 102, such as before stent placement. [0081] In some examples, processing circuitry 30, alone or in combination with the sensing circuitry 36, determines morphological information based on received signals from sensors 114 and/or sensors 115. For example, processing circuitry 30 may be configured to classify lesions as calcific, fatty (e.g., as containing lipids), fibrous, having fibrin, and/or the like. Other morphological information of lesions may include one or more of concentricity or eccentricity, tortuosity, regularity or irregularity of contour, absence or presence of thrombus, ostial or non- ostial, and/or the like. Morphological information may be determined in accordance with The American College of Cardiology/ American Heart Association (ACC/AHA) lesion morphology classification and/or the subsequent modified ACC/AHA classification.

[0082] In some examples, due to the large difference in measurements (e.g., impedance) associated with different types of morphologies of lesions (e.g., calcific versus fatty), processing circuitry 30 is configured to determine at least one morphology type (e.g., fatty or not fatty) via a given set of sensors 114. In some examples, processing circuitry 30 is configured to receive signals from two different sets of sensors (e.g., of sensors 114 and/or sensors 115) for determining different morphologies. For example, in some examples, processing circuitry 30 receives signals from a first set of sensors (e.g., a first set of sensors 114) for determining whether lesions are fatty and/or for determining the composition of fatty lesions. Additionally, processing circuitry 30 receives signals from a second set of sensors (e.g., a second set of sensors 114) for determining whether lesions are calcific and/or for determining the composition of calcific lesions. In such examples, the first set of sensors (e.g., of sensors 114) can be configured for measuring one or more parameters (e.g., impedance measurements) associated with a first morphology (e.g., fatty lesions) and the second set of sensors (e.g., of sensors 114) can be configured for measuring one or more parameters (e.g., impedance measurements) associated with a second morphology (e.g., calcific lesions). In this way, processing circuitry 30 and catheter system 108 can be used for detecting, measuring, and classifying multiple different types of lesions, e.g., without the need to use a different device for each lesion morphological type. [0083] Once processing circuitry 30 has determined one or more dimensions (e.g., diameters) of balloon 112 and/or the blood vessel 102 and/or a stent, processing circuitry 30 may generate, for output, an indication of the one or more dimensions (e.g., diameters and/or related values, including one or more cross-sectional areas) of balloon 112 and/or the blood vessel 102 and/or a stent. For example, processing circuitry 30 may be configured to generate, for output (e.g., via a display, such as user interface 130 of device 144) a numerical representation (e.g., a value) of the one or more dimensions (e.g., diameters, cross-sectional areas). Additionally or alternatively, processing circuitry 30 may be configured to generate, for output, other determined values, as have been described herein, including the degree of stent expansion, the degree of stent apposition, and/or an indication of the MSA of the stent. For example, an indication of the degree of stent expansion, degree of stent apposition, and/or MSA can include a degree of stent expansion value (e.g., a percentage), a degree of stent apposition value, and/or a MSA value. In examples where device 144 determines morphology of a lesion of blood vessel 102 (including any lesion morphologies), processing circuitry 30 may be configured to generate, for output, and indication of the morphology.

[0084] In some examples, processing circuitry 30 is configured to output, e.g., via user interface 130, a graphical representation (e.g., an image, picture, schematic representation, etc.) of vessel 102, stent 160, and/or balloon 112. Further, processing circuitry 30 may be configured to overlay one or more determined dimensions (e.g., diameters) with or over the graphical representation of vessel 102, stent 160, and/or balloon 112. For example, processing circuitry 30 may overlay particular dimensions, or other determined values including MSA, over a portion of a graphical representation of vessel 102, stent 160, and/or balloon 112 that corresponds to the particular dimension or determined value (e.g., at the location of stent 160 where the smallest diameter of the stent occurs).

[0085] The indication of the one or more dimensions (e.g., diameters) and/or other determined values of the balloon 112 and/or the blood vessel 102 and/or a stent may enable a clinician to make a clinically relevant decision or confirm efficacy of a previous treatment. For example, the indication of the one or more dimensions (e.g., diameters) or other determined values are determined with instruments a clinician would already be using (e.g., a stent delivery catheter or post-dilatation catheter), which may obviate the need for other instruments (e.g., intravascular imaging systems, IVUS and/or OCT) and/or decrease procedure time. For example, a clinician may confirm an acceptable MSA based on the one or more dimensions (e.g., diameters) of the balloon 112 and/or stent. As another example, a clinician may decide that further intervention is necessary based on an MSA below a particular threshold (e.g., an MSA below 80%). In cases where further intervention is necessary, a clinician may further expand the stent with the same balloon catheter used to determine MSA. In this way, the need for additional imaging and/or imaging systems for determining MSA is obviated given the multi-functional catheter system according to this disclosure.

[0086] In some examples, processing circuitry 30 is configured to generate, for output, one or more recommendations to a user (e.g., clinician) based on determined information (e.g., one or more determined diameters or other dimensions, or other determined values). For example, processing circuitry 30 may be configured to generate for output (e.g., on user interface 130), one or more of a recommended position for catheter system 108, such as a position of balloon 112 in relation to vessel 102, a recommended inflation pressure or pressure change (e.g., increase or decrease) to balloon 112, and/or another clinically relevant recommendation. In some examples, such recommendations may facilitate a clinician’s decision to move catheter system 108 (including balloon 112) within vessel 102. In some examples, such recommendations may facilitate a clinician’s decision to further inflate and/or deflate balloon 112 (e.g., for further expansion of a stent or for further compressing balloon 112 against vessel wall 104). In some examples, such recommendation may facilitate a clinician’s decision to take other appropriate course of action, including (but not limited to), delivery of additional stents, introducing a drug into vessel 102, and/or introducing another medical device into vessel 102.

[0087] Although system 100 is primarily described in the context of manual inflation via fluid inlet 118, device 144 (including processing circuitry 30) may be able to control (e.g., automatically control) inflation of balloon 112. For example, device 144 (e.g., processing circuitry 30) may be configured to receive one or more inputs of a pressure value, a level of stent expansion, or another relevant value, such as a dimension of balloon 112 and/or a dimension of the stent, and inflate balloon 112 based on the one or more inputs. In some examples, device 144 (e.g., processing circuitry 30) is configured to automatically inflate balloon 112 to expand (or further expand) a stent according to one or more dimensions (e.g., diameters), or other derivative measures including MSA. For example, where processing circuitry 30 determines an MSA is below a particular threshold (e.g., below 80 percent), processing circuitry 30 may be configured to automatically inflate balloon 112 to further expand a stent, such that the MSA increases above the minimum threshold in response to previously determining the MSA is below the particular threshold.

[0088] In some examples, sensing circuitry 36 is additionally or alternatively configured to sense a physiological parameter of a patient including temperature, pressures, sounds, light, infrared signals such as via one or more electrodes, optical receivers, pressure sensors, or the like. The one or more sensing electrodes can be the same or different from plurality of sensors 114 configured to receive signals via signal generation circuitry 34. Processing circuitry 30 can use the sensed physiological signals to further assess information about blood vessel 102 and/or the stent. For example, sensing circuitry 36 may receive signals indicative of temperature (e.g., via a temperature sensor within a blood vessel). In some examples, processing circuitry 30 uses temperature values for determination of dimensions (e.g., diameters), such as in variations of Equation 1 that include a temperature-dependent variable. In some examples, processing circuitry 30 uses temperature values for determination of morphological information.

[0089] In some examples, sensing circuitry 36 and/or processing circuitry 30 includes signal processing circuitry configured to perform any suitable analog conditioning of the sensed physiological signals. For example, sensing circuitry 36 may communicate to processing circuitry 30 an unaltered (e.g., raw) signal. Processing circuitry 30 may be configured to modify a raw signal to a usable signal by, for example, filtering (e.g., low pass, high pass, band pass, notch, or any other suitable filtering), amplifying, performing an operation on the received signal (e.g., taking a derivative, averaging), performing any other suitable signal conditioning (e.g., converting a current signal to a voltage signal), or any combination thereof. In some examples, the conditioned analog signals may be processed by an analog-to-digital converter of processing circuitry 30 or other component to convert the conditioned analog signals into digital signals. In some examples, processing circuitry 30 may operate on the analog or digital form of the signals to separate out different components of the signals. In some examples, sensing circuitry 36 and/or processing circuitry 30 may perform any suitable digital conditioning of the converted digital signals, such as low pass, high pass, band pass, notch, averaging, or any other suitable filtering, amplifying, performing an operation on the signal, performing any other suitable digital conditioning, or any combination thereof. Additionally or alternatively, sensing circuitry 36 may include signal processing circuitry to modify one or more raw signals and communicate to processing circuitry 30 one or more modified signals.

[0090] Although shown as part of device 144 in FIG. 2, in other examples, sensing circuitry 36 can be a part of a device separate from device 144. For example, sensing circuitry 36 can be included in handle portion 150 of catheter system 108.

[0091] Processing circuitry 30, as well as other processors, processing circuitry, controllers, control circuitry, and the like, described herein, may include any combination of integrated circuitry, discrete logic circuity, analog circuitry, such as one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), or field-programmable gate arrays (FPGAs). In some examples, control circuitry may include multiple components, such as any combination of one or more microprocessors, one or more DSPs, one or more ASICs, or one or more FPGAs, as well as other discrete or integrated logic circuitry, and/or analog circuitry.

[0092] Although shown as part of device 144 in FIG. 2, in other examples, one or more portions of processing circuitry 30 can be a part of a device separate from device 144. For example, a portion of processing circuitry 30 (e.g., an ASIC module and/or multiplexing module) can be formed with and/or positioned on a portion of catheter system 108. In some examples, a portion of processing circuitry 30 (e.g., an ASIC module and/or multiplexing module) is positioned within (e.g., formed with) and/or along (e.g., affixed to) elongated body 110, such as near balloon 112 and/or near sensors 114 (e.g., within 10 inches from balloon 112 and/or sensors 115 as measured along longitudinal axis 159). In some examples, the portion of processing circuitry 30 (an ASIC module) positioned proximal sensors 114 can include a multiplexing module configured to multiplex sensors 114, which can reduce the number of wires or electrical pathways extending along the majority of catheter system 108 (e.g., along the majority of elongated body 110). In some examples, a reduced number, such as a single electrical pathway (e.g., wire, trace, and/or the like) extends between the ASIC module and/or multiplexing module and device 144.

[0093] Memory 32 is configured to store program instructions, such as software, which may include one or more program modules, which are executable by processing circuitry 30. When executed by processing circuitry 30, such program instructions may cause processing circuitry 30 to provide the functionality ascribed to processing circuitry 30 herein. The program instructions may be embodied in software and/or firmware. Memory 32 may include any volatile, nonvolatile, magnetic, optical, or electrical media, such as a random-access memory (RAM), readonly memory (ROM), non-volatile RAM (NVRAM), electrically-erasable programmable ROM (EEPROM), flash memory, or any other digital media.

[0094] Processing circuitry 30 is configured to control telemetry circuitry 38 to send and receive information. Telemetry circuitry 38, as well as telemetry modules in other devices including an external computing device or an external user interface (e.g., display), may accomplish communication by any suitable communication techniques, such as radiofrequency (RF) communication techniques.

[0095] Power source 40 is configured to deliver operating power to various components of device 144. Power source 40 may include a rechargeable or non-rechargeable battery and a power generation circuit to produce the operating power. Power source 40 may be configured to deliver enough power for measuring dimensions (e.g., diameters) of balloon 112. [0096] FIG. 3A, FIG. 3B, and FIG. 3C are schematic cross-sectional illustrations of a portion of catheter system 108 within a blood vessel 102 of patient 106, the blood vessel 102 including vessel wall 104 and an inner dimension VI (which may be a diameter VI in the case of a circular or near-circular cross section). For example, a distal portion of catheter system 108 including distal body portion 110A of elongated body 110 and balloon 112 is inserted and positioned within vessel 102. As discussed in relation to previous examples, catheter system 108 includes a plurality of electrodes 114 (shown individually as 114A, 114B, 114C, 114D, 114E, 114F, . . ., 114N with some electrodes unlabeled for clarity).

[0097] In the example illustrated in FIG. 3 A, FIG. 3B, and FIG. 3C, balloon 112 is delivered intravascularly to the treatment location (e.g., proximate a lesion 105) using a guidewire in an over the wire (OTW) technique or a rapid exchange (RX) technique. Catheter system 108 (e.g., elongate body 110) may define a lumen 111 for receiving the guidewire for delivery of elongate body 110 (e.g., distal body portion 110A) using either an OTW or RX technique. At the treatment location, the guidewire can be left inserted, and balloon 112 may be expanded from the delivery configuration (FIG. 3 A) to a partially expanded configuration (FIG. 3B), and further expanded to a fully expanded configuration (FIG. 3C). In some examples, the guidewire is removed or partially removed prior to inflating and/or expanding balloon 112. Balloon 112 may substantially position electrodes 114 to a portion of vessel 102 that includes lesion 105. In other examples, balloon 112 may be delivered with a different guide device, such as guide sheath (not shown in FIG. 3 A), with or without a using guidewire. In examples in which catheter system 108 includes a guide sheath, when balloon 112 is at the target treatment location, the guide sheath may be at least partially withdrawn or retracted or balloon 112 is advanced beyond the distal end of the guide sheath so that balloon 112 may be transformed into an expanded configuration. In still other examples, elongate body 110 may be steerable itself such that balloon 112 and/or electrodes 114 may be delivered to the treatment location without the aid of a guidewire and/or a guide sheath.

[0098] In the examples of FIG. 3A, FIG. 3B, and FIG. 3C, catheter system 108 additionally includes a stent 160, which may be delivered and/or expanded via catheter system 108. In the example of FIG. 3 A, stent 160 is at least partially expanded against a portion of vessel 102 that includes lesion 105. Stent 160 is partially expanded because a portion of stent 160 abutting lesion 105 is narrowed compared to the largest diameter (e.g., diameter VI) of vessel 102. Lesion 105 may include any abnormal narrowing of vessel 102, including material in or within vessel 102 that be fibrous, calcific, fatty, thrombogenic, or a combination thereof. [0099] In the example of FIG. 3 A, balloon 112 is in a low-profile (e.g., delivery) configuration and defines a diameter small enough to be delivery across stent 160 (e.g., narrow enough to fit through an opening defined by the at least partially expanded stent 160). Although the example of FIG. 3 A depicts stent 160 as having been delivered and at least partially expanded by a previous catheter other than catheter system 108, catheter system 108 may be configured to deliver stent 160 in other examples. In the low-profile (e.g., delivery configuration), balloon 112 defines a plurality internal diameters DI through DN (shown individually as diameters DI, D2, D3, D4, D5, . . ., DN) along longitudinal axis 159. For example, each of the plurality internal diameters DI through DN is located at an axial position along longitudinal axis 159 between adjacent electrodes of electrodes 114. Internal diameters DI through DN may be sufficiently small such that balloon may pass through (e.g., be advanced through) a narrowest internal diameter of stent 160 as shown in the partially expanded configuration. Each of diameters DI through DN may be determined according to the techniques described herein, e.g., where each diameter is determined based a current applied between adjacent electrodes of electrodes 114 and the resulting voltage is proportional to a diameter of balloon 112 at a longitudinal location between the adjacent electrodes. As an illustrative example, diameter DI is depicted between two adjacent electrodes 114A and 114B. Given longitudinal spacing LI between electrode 114A and electrode 114B and a known conductivity of the fluid used to inflate balloon 112, processing circuitry 30 may determine diameter DI, e.g., by evaluating Equation 1.

[0100] Additionally and/or alternatively, diameters or other parameters can be determined between non-adjacent electrodes of electrodes 114. For example, given a known longitudinal distance between electrode 114A and electrode 114C (e.g., 2L1, or two times the longitudinal spacing LI between electrode 114A and electrode 114B), processing circuitry 30 may determine a diameter (e.g., of balloon 112 and/or of vessel 102) at a point between electrode 114A and electrode 114C (e.g., at a point along central longitudinal axis 159 proximate electrode 114B), e.g., by evaluating Equation 1. Any number of diameters or other dimensions of balloon 112 and or vessel 102 can be determined using any suitable number of adjacent electrodes of electrodes 114 and/or non-adjacent electrodes of electrodes 114. Determining multiple diameters of balloon 112 and/or vessel 102 along central longitudinal axis 159 can enable processing circuitry 30 to determine and/or output a representation of the state (e.g., shape and/or inflated size) of balloon 112 along a majority of the length of balloon 112 along longitudinal axis 159.

[0101] FIG. 3 A also includes an example of a dissection 107, which may include a tear (e.g., a partial tear) of lesion 105 and/or vessel wall 104 of vessel 102. In some examples, one or more of stent 160, a guidewire, a portion of a guidewire or another structure may cause dissection 107. In some examples, processing circuitry 30 is configured to identify dissection 107 via electrodes 114 and/or other sensors on or inside balloon 112 or carried by elongated body 110. For example, processing circuitry 30 may be configured to identify one or more discontinuities in a shape of vessel wall 104 of vessel 102 and/or lesion 105 over an axial length (e.g., a length of balloon 112). Processing circuitry 30 may classify the discontinuities in the shape of vessel wall 104 of vessel 102 and/or lesion 105 for determining whether the discontinuities include a dissection. For example, processing circuitry 30 may identify dissection 107 by classifying a discontinuity in the shape of vessel wall 104 of vessel 102 and/or lesion 105 (e.g., as above a predefined discontinuity threshold).

[0102] In the example of FIG. 3B, balloon 112 is shown in an at least partially inflated configuration to press against stent 160 with enough pressure to conform to the at least partially expanded diameter of stent 160, but not enough pressure to further expanded stent 160. At this point, a user (e.g., a clinician) may initiate, or processing circuitry 30 may automatically initiate, determination of one or more dimensions (e.g., diameters) of balloon 112 along the length of balloon 112 according to the techniques of this disclosure described above. In the partially expanded configuration, balloon 112 defines a plurality internal diameters Fl through FN (shown individually as diameters Fl, F2, F3, F4, F5, . . ., FN with some diameters unlabeled for clarity), which may correspond to the axial positions DI through DN from FIG. 3 A. As balloon 112 is expanded to conform to stent 160 (e.g., such that balloon 112 conforms to the inner wall of stent 160), the plurality of internal diameters Fl through FN of balloon 112 may serve as a proxy (e.g., be the same or substantially the same as) for one or more diameters of stent 160. In this way, processing circuitry 30 determines one or more dimensions (e.g., diameters) of stent 160 as expanded (e.g., as at least partially expanded as shown in FIG. 3B) based on diameters of balloon 112 (which may also be diameters of vessel 102). Further, processing circuitry 30 may determine one or more further measures or indices based on the determined dimensions (e.g., diameters) of stent 160 including the degree of stent expansion of stent 160, the degree of stent apposition of stent 160 against vessel wall 104 of vessel 102, a cross-sectional area of the stent, a minimum stent area (MSA), or another value.

[0103] Based on the determined dimensions (e.g., diameters) and/or other indices and measures including MSA, a clinician, or device 144 via processing circuitry 30, may further inflate balloon 112, e.g., to further expand balloon 112, which may further expand stent 160. For example, where processing 30 determines a diameter of balloon 112 and of stent 160, or other index based on the dimensions (e.g., MSA), processing circuitry 30 may generate an indication (e.g., via user interface 130) of the dimensions (e.g., diameters) or indices. In some examples, processing circuitry 30 is configured to generate, for output, an indication of the smallest diameter of the measured diameters Fl through FN, which may indicate a smallest diameter of stent 160. In some examples processing circuitry 30 is configured to generate for output an indication of the MSA of stent 160. Based on the output, a clinician may be enabled to decide whether further medical intervention (e.g., further expansion of stent 160) is warranted. In some examples, processing circuitry 30 is configured to generate, for output, and indication whether one or more diameters Fl through FN does not meet a minimum threshold, such that further intervention may be warranted. In some examples, processing circuitry 30 is configured to generate, for output, and indication whether an MSA of balloon 112 does not meet a minimum threshold (e.g., 80 percent), such that further intervention may be warranted. In such examples where further intervention is warranted, the clinician may further inflate balloon 112, e.g., to a fully inflated configuration. In some examples, processing circuitry 30 is configured to automatically (e.g., without additional user input), cause device 144 to further inflate balloon 112, e.g., to the fully inflated configuration. For example, where one or more diameters Fl through FN is below a minimum threshold or where the MSA of balloon 112 does not meet a minimum threshold (e.g., 80 percent), processing circuitry 30 may configured to automatically (e.g., without additional user input), cause device 144 to further inflate balloon 112, e.g., to the fully inflated configuration.

[0104] In the example of FIG. 3C, balloon 112 is shown in a fully inflated configuration such that stent 160 is in a fully expanded configuration (e.g., expanded beyond the partially expanded configuration described in relation to FIG. 3B to a fully expanded configuration). In the fully expanded configuration, balloon 112 defines a plurality of internal diameters El through EN (shown individually as diameters El, E2, E3, E4, E5, . . ., EN with some diameters unlabeled for clarity), which may correspond to the axial positions of diameters DI through DN from FIG. 3 A and the axial positions of diameters Fl through FN from FIG. 3B. As balloon 112 is expanded to conform to stent 160 (e.g., such that balloon 112 conforms to the inner wall of stent 160), the plurality internal diameters El through EN of balloon 112 may serve as a proxy (e.g., be the same or substantially the same as) for one or more diameters of stent 160. In this way processing circuitry 30 determines one or more dimensions (e.g., diameters) of stent 160 as expanded (e.g., as fully expanded or nearly fully expanded in FIG. 3C). Further, processing circuitry 30 may determine one or more further measures or indices based on the determined dimensions (e.g., diameters) of stent 160 including the degree of stent expansion of stent 160, the degree of stent apposition of stent 160 against vessel wall 104 of vessel 102, a cross-sectional area of the stent, a minimum stent area (MSA), or another value. [0105] Once balloon 112 has been expanded such as to expand stent 160 to a fully deployed diameter as shown in the example of FIG. 3C, a clinician and/or processing circuitry 30 may repeat determination of dimensions (e.g., diameters) of balloon 112, such as to confirm the dimensions (e.g., diameters) or other measures or indices based on the determined dimensions (e.g., diameters) of stent 160 including the degree of stent expansion of stent 160, the degree of stent apposition of stent 160 against vessel wall 104 of vessel 102, a cross-sectional area of the stent, a minimum stent area (MSA), or another value. For example, the clinician and/or processing circuitry 30 may repeat multiple determinations of diameters El through EN while catheter system 108 remains inserted in blood vessel 102. One or more cycles of expansion of balloon 112 and/or stent 160 may be performed, such as reach a desired level of stent expansion, stent apposition, etc. Further, determinations may be repeated a later time, such as after catheter system 108 has been removed from patient 106. In some examples, another device (e.g., a second catheter system 108) is introduced at a later time (e.g., for measurements to determine diameters or other related information). For example, follow up measurements may be taken hours, days, weeks, months, or years after initial placement of stent 160. However, in some examples, a clinician and/or processing circuitry 30 only determines diameters or related information at a single point in time (e.g., before stent placement, after stent placement and before post-dilation, or after post-dilation).

[0106] FIG. 4A is a schematic cross-sectional illustration of a portion of a catheter system 408 within a blood vessel 102. Catheter system 408 may be constructed and/or configured the same as catheter system 108 as described in connection with FIG. 3A, FIG. 3B, and FIG. 3C, except as described herein. For example, catheter system 408 includes both a first plurality of sensors 114 carried by elongated body 110 as in previous examples, but also includes a second plurality of sensors 115 (shown individually as sensor 115A, 115B, 115C, 115D, 115E, 115F, . . ., 115N, with some sensors unlabeled for clarity, but collectively referred to as sensors 115), such as discussed in relation to FIG. 1C and FIG. 2. As shown in the Example of FIG. 4A, sensors 115 are carried by a body of balloon 112, e.g., such that sensors 115 are proximate (e.g., are positioned adjacent to, and/or are in contact with and/or protrude through) an exterior surface of balloon 112. As discussed previously, sensors 115 may be configured to assess information about blood vessel 102 and/or other physiological parameters. For example, device 144 may be configured to receive, via sensors 115, signals indicative of a morphology (including morphology of lesion 105) of the blood vessel 102. Based on the signals from sensors 115, processing circuitry 30 may be configured to classify one or more lesions 105 into one or more categories, such as calcific, fatty, fibrous, or the like. Other morphological information can include indications of inflammation, plaque burden, or other clinically relevant measures, indices and/or characteristics. Processing circuitry 30 may be configured to receive, via sensors 115, information including density, temperature, water content, or other information about lesions 105 for classifying lesions 105. Sensors 115 can include one or more electrodes, optical sensors, temperature sensors, ultrasound sensors and/or ultrasound transducers, accelerometers, flow sensors, etc., or a combination thereof. In examples where sensors 115 include one or more electrodes, processing circuitry 30 may be configured to determine tissue characteristics (e.g., morphologies) based on the difference in impedance of different tissue types proximate sensors 115, such as can be sensed when a current is supplied between one or more of sensors 115. [0107] FIG. 4B is another cross-sectional view of catheter system 408, the cross section taken at the section line A-A in FIG. 3B as viewed from a distal to proximal viewpoint. In particular, FIG. 4B illustrates the lesion pockets 109 A and 109B, which may correspond to representations of lesion 105 in previous examples. As shown, lesion pockets 109A and 109B may cause deviation from roundness of vessel 102, both on the interior surface of vessel 102 and on the exterior surface of vessel 102. In some examples, processing circuitry 30 is configured to determine one or more measures or parameters of lesion pockets 109A and/or 109B, e.g., based on received signals from electrodes 114D and/or sensors 115D. For example, processing circuitry may be configured to determine an eccentricity value (e.g., a value for a deviation from circular). [0108] An example technique for determining lesion morphology and/or one or more dimensions (e.g., diameters) and/or other information using the catheter system described herein is illustrated in FIG. 5. The technique is described mainly with reference to medical device system 100 of FIG. 1 A, FIG. IB, and FIG. 1C, and processing circuitry 30 as discussed in connection with FIG. 2, however the technique may be applied to other medical systems in other examples.

[0109] The technique includes receiving, by processing circuitry 30, one or more signals from one or more sensors (e.g., electrodes 114 and/or sensors 115) carried by elongated body 110 and/or balloon 112 at distal body portion 110A of elongated body 110 (500). In some examples, processing circuitry 30 applies a signal (e.g., an electrical current signal) to electrodes 114 and/or sensors 115, and an induced signal (e.g., an induced voltage signal) is generated in electrodes 114 and/or sensors 115. Processing circuitry 30 receives the resulting signal (e.g., the induced voltage signal), and determines one or more dimensions (e.g., diameters), morphological information (e.g., of lesion 105), or other information in accordance with this disclosure.

[0110] The technique includes determining, by processing circuitry 30, at least one of an indication of a morphology of lesion 105 of blood vessel 102 or one or more dimensions (e.g., diameters) of balloon 112 or blood vessel 102 (502). Additionally or alternatively, processing circuitry 30 determines one or more other values related to the dimensions (e.g., diameters) of blood vessel 102 or stent 160. For example, the technique may include determining, by processing circuitry 30, a cross-sectional area of the stent 160, a minimum stent area (MSA) of stent 160, a degree of stent expansion of stent 160, and/or a degree of stent apposition of stent 160. In some examples, processing circuitry 30 determines one or more dimensions (e.g., diameters) of balloon 112 or blood vessel 102 based on based on received (e.g., induced) voltage signals from one or more dimensions (e.g., diameters) of balloon 112 or blood vessel 102. In determining the one or more dimensions (e.g., diameters) of balloon 112 or blood vessel 102 based on received (e.g., induced) voltage signals from sensors 114, processing circuitry 30 may apply the received voltage signal values to a model defining a relationship between the one or more voltage signal values and one or more dimensions (e.g., diameters) of balloon 112 or blood vessel 102. As discussed above, the model can include an equation, lookup table, an Al or ML model, or another relational method. In some examples, an output of the model (e.g., resulting from the one or more voltage signal values applied to the model) includes the one or more dimensions (e.g., diameters) of balloon 112 and/or the blood vessel 102 and/or a stent.

[OHl] In some examples, the technique further includes determining, by processing circuitry 30, one or more derivative values (e.g., derived from or otherwise related to) the determined dimensions (e.g., diameters) of balloon 112 or blood vessel 102. In some examples, processing circuitry 30 receives or accesses a reference value, e.g., for comparison to determined dimensions (e.g., diameters) of balloon 112 or blood vessel 102 or related values thereof. For example, processing circuitry 30 may receive a reference diameter of stent 160 (e.g., an experimentally determined diameter of stent 160 as fully expanded or another diameter) and determine a degree of stent expansion by comparing and/or performing a mathematical operation on the reference diameter and a determined (e.g., measured) diameter of stent 160. As another example, processing circuitry 30 may receive a reference diameter of vessel wall 104 of vessel 102 (e.g., an experimentally determined inner diameter of vessel 102, such an inner diameter of vessel 102 measured upstream or downstream of lesion 105, such as dimension VI as shown in the example of FIG. 3 A) and determine a degree of stent apposition against vessel wall 104 by comparing and/or performing a mathematical operation on the reference diameter of vessel wall 104 of vessel 102 and a determined (e.g., measured) diameter of stent 160.

[0112] In some examples, the technique further includes generating, by processing circuitry 30, one or more outputs, such as for presentation via user interface 130 of device 144. In some examples, processing circuitry 30 generates, for output (such as via user interface 130 of device 144), an indication of one or more determined dimensions (e.g., diameters) of balloon 112 or blood vessel 102. In some examples, processing circuitry 30 generates, for output (such as via user interface 130 of device 144), an indication of the cross-sectional area of stent 160. In some examples, processing circuitry 30 generates, for output (such as via user interface 130 of device 144), an indication of a cross-sectional area or the MSA of stent 160.

[0113] An example technique for delivering and expanding a stent using catheter system 108 is illustrated in FIG. 6. The technique is described mainly with reference to medical device system 100 of FIG. 1 A, FIG. IB, and FIG. 1C, and processing circuitry 30 of device 144 as discussed in connection with FIG. 2, however the technique may be applied to other medical systems in other examples. Any of catheters described with respect to the technique of FIG. 6 may be configured to determine (e.g., via processing circuitry 30) one or more dimensions (e.g., diameters) of balloon 112, stent 160, and/or blood vessel 102.

[0114] The technique includes delivering, to a treatment location in blood vessel 102 of patient 106 via a first catheter, a stent 160 (600). In some examples, the treatment location includes a location proximate lesion 105. In some examples, the first catheter includes one or more of the catheters and/or catheter configurations described in this disclosure. For example, the first catheter may include catheter system 108 including elongated body 110, balloon 112 at distal portion of elongated body 110, and electrodes 114 and/or sensors 115.

[0115] The technique includes inflating the first catheter to expand (e.g., at least partially expand) stent 160 at the treatment location in the blood vessel (602). In some examples, the first catheter is removed from vessel 102 subsequent to delivering and at least partially expanding stent 160 and prior to inserting another (e.g., a second) catheter.

[0116] The technique includes inserting, into blood vessel 102 and to the treatment location, a second catheter, the second catheter coupled to processing circuitry 30 configured to determine one or more diameters of balloon 112 and/or vessel 102 (604). In some examples, the second catheter includes one or more of the catheters and/or catheter configurations described in this disclosure. For example, the second catheter may include catheter system 108 including elongated body 110, balloon 112 at distal portion of elongated body 110, and electrodes 114 and/or sensors 115. As described in accordance with the techniques of this disclosure, device 144 may be configured to determine (e.g., via processing circuitry 30) one or more dimensions (e.g., diameters) of balloon 112, stent 160, and/or blood vessel 102. In some examples, the method further includes taking measurements with the second catheter (e.g., catheter system 108). In some examples the method further includes taking multiple measurements (e.g., at different axial positions along stent 160 and/or vessel 102). For example, a clinician may deflate, move (e.g., distally or axially), and reinflate balloon 112 at one or more different axial positions along vessel 102 in order to measure multiple diameters. Multiple measurements may be needed in cases where lesion 105 and/or stent 160 define an axial length longer than balloon 112. In instances where lesion 105 and/or stent 160 define an axial length longer than balloon 112, a single measurement may not otherwise provide a full understanding of dimensions of lesion 105 or stent 160. However, taking multiple measurements may provide a clinician with an estimate of dimensions (e.g., diameters) at various portions of stent 160 where stent 160 is longer than balloon 112, such as a proximal, middle, and distal portion of stent 160.

[0117] The technique includes inflating balloon 112 of the second catheter (e.g., of catheter system 108) to further expand stent 160 based on the one or more determined dimensions (e.g., diameters) of balloon 112, stent 160, and/or blood vessel 102 (606). In some examples, after inflating balloon 112 to expand stent 160, the technique can further include taking additional measurements, e.g., to confirm adequate (e.g., complete) expansion and/or apposition of stent 160 against vessel wall 104, such as apposition against lesion 105.

[0118] In some examples, prior to inserting the first catheter and/or the second catheter (e.g., the stent delivery catheter and/or the post-dilatation catheter), the method includes inserting a third catheter into vessel 102. For example, the method can include determining, with the third catheter before stent delivery, one or more measurements (e.g., diameters, physiological parameters, vessel or lesion morphology) of vessel 102. Such measurements may establish a baseline vessel and/or lesion tomography. In some examples, the method may include inserting the third catheter and pre-dilatating lesion 105 and/or vessel 102 with the third catheter. Additionally, prior to and/or subsequent to the pre-dilatation, the method may include determining, with the third catheter before stent delivery, one or more measurements (e.g., diameters, physiological parameters, vessel or lesion morphology) of vessel 102. In some examples, the third catheter includes one or more of the catheter and catheter configurations described in this disclosure.

[0119] This disclosure includes the following non-limiting examples.

[0120] Example 1 : A medical device system includes an elongated body configured to be inserted into a blood vessel of a patient; an expandable structure at a distal portion of the elongated body; a plurality of sensors carried by at least one of the elongated body or the expandable structure; and processing circuitry configured to: receive, via the plurality of sensors, one or more signals, and determine, based on the one or more signals, one or more of: an indication of a morphology of a lesion of the blood vessel, or one or more diameters of the expandable structure or the blood vessel. [0121] Example 2: The medical device system of example 1, wherein the processing circuitry is configured to generate, for output, an indication of the one or more diameters of the expandable structure or the blood vessel.

[0122] Example 3: The medical device system of any of examples 1 or 2, wherein the expandable structure at the distal portion of the elongated body is configured to inflate and expand a stent against a wall of the blood vessel.

[0123] Example 4: The medical device system of example 3, wherein the processing circuitry is configured to: determine a cross-sectional area of the stent based on the one or more diameters of the expandable structure or the blood vessel, and generate, for output, an indication of the cross-sectional area of the stent.

[0124] Example 5: The medical device system of any of examples 3 or 4, wherein the processing circuitry is configured to: determine a minimum stent area (MSA) of the stent based on the one or more diameters of the expandable structure or the blood vessel, and generate, for output, an indication of the MSA of the stent.

[0125] Example 6: The medical device system of any of examples 3 through 5, wherein the processing circuitry is configured to: determine a diameter of the stent as expanded based on the one or more diameters of the expandable structure or the blood vessel, receive a reference diameter of the stent, determine, based on the diameter of the stent as expanded and the reference diameter of the stent, a degree of stent expansion, and generate, for output, an indication of the degree of stent expansion.

[0126] Example 7: The medical device system of any of examples 3 through 6, wherein the processing circuitry is configured to: determine a diameter of the stent as expanded based on the one or more diameters of the expandable structure or the blood vessel, receive a reference diameter of the wall of the blood vessel, determine, based on the diameter of the stent as expanded and the reference diameter of the wall of the blood vessel, a degree of stent apposition against the wall of the blood vessel, and generate, for output, an indication of the degree of stent apposition against the wall of the blood vessel.

[0127] Example 8: The medical device system of any of examples 1 through 7, wherein the one or more signals include voltage signals, and wherein the processing circuitry is configured to apply a current to induce the voltage signals in the sensors.

[0128] Example 9: The medical device system of example 8, wherein to determine the one or more diameters of the expandable structure or the blood vessel, the processing circuitry is configured to: apply one or more voltage signal values based on the voltage signals to a model, the model defining a relationship between the one or more voltage signal values and the one or more diameters, wherein an output of the model resulting from the one or more voltage signal values applied to the model includes the one or more diameters of the expandable structure or the blood vessel.

[0129] Example 10: The medical device system of example 9, wherein the model includes a pre-defined equation relating the one or more voltage signal values and the one or more diameters of the expandable structure or the blood vessel.

[0130] Example 11 : The medical device system of example 9, wherein the model includes a lookup table relating the one or more voltage signal values and the one or more diameters of the expandable structure or the blood vessel.

[0131] Example 12: The medical device system of example 9, wherein the model includes an artificial intelligence (Al) model, and wherein: an input to the Al model includes the one or more voltage signal values, and an output to the Al model includes the one or more diameters of the expandable structure or the blood vessel.

[0132] Example 13: The medical device system of any of examples 1 through 12, wherein the expandable structure includes a balloon, the balloon configured to be inflated by a liquid. [0133] Example 14: The medical device system of any of examples 1 through 13, wherein at least some sensors of the plurality of sensors are longitudinally spaced apart from respective adjacent sensors.

[0134] Example 15: The medical device system of any of examples 1 through 14, wherein one or more sensors of the plurality of sensors are disposed within a volume defined by the expandable structure.

[0135] Example 16: The medical device system of any of examples 1 through 15, wherein one or more sensors of the plurality of sensors comprise one or more electrodes or ultrasound transducers.

[0136] Example 17: The medical device system of any of examples 1 through 16, wherein one or more sensors of the plurality of sensors comprise one or more ultrasound transducers.

[0137] Example 18: The medical device system of any of examples 1 through 17, wherein the plurality of sensors is carried by the elongated body.

[0138] Example 19: The medical device system of any of examples 1 through 18, wherein the plurality of sensors is carried by the expandable structure.

[0139] Example 20: The medical device system of any of examples 1 through 19, wherein the plurality of sensors includes a first set of sensors carried by the elongated body and a second set of sensors carried by the expandable structure. [0140] Example 21 : A method includes receiving, by processing circuitry, one or more signals from a plurality of sensors carried by an elongated body or an expandable structure at a distal portion of the elongated body, the elongated body configured to be inserted into a blood vessel; and determining, by processing circuitry and based on the one or more signals, one or more of: an indication of a morphology a lesion of the blood vessel, or one or more diameters of the expandable structure or the blood vessel.

[0141] Example 22: The method of example 21, wherein the method further includes: generating for output, by the processing circuitry, an indication of the one or more diameters of the expandable structure or the blood vessel.

[0142] Example 23: The method of any of examples 21 or 22, wherein the expandable structure at the distal portion of the elongated body is configured to be inflated and expand a stent against a wall of the blood vessel, and wherein the method further includes: determining, by the processing circuitry, a cross-sectional area of the stent based on the one or more diameters of the expandable structure or the blood vessel; and generating for output, by the processing circuitry, an indication of the cross-sectional area of the stent.

[0143] Example 24: The method of any of examples 21 through 23, wherein the expandable structure at the distal portion of the elongated body is configured to be inflated and expand a stent against a wall of the blood vessel, and wherein the method further includes: determining, by the processing circuitry, a minimum stent area (MSA) of the stent based on the one or more diameters of the expandable structure or the blood vessel; and generating for output, by the processing circuitry, an indication of the MSA of the stent.

[0144] Example 25: The method of any of examples 21 through 24, wherein the expandable structure at the distal portion of the elongated body is configured to be inflated and expand a stent against a wall of the blood vessel, and wherein the method further includes: determining, by the processing circuitry, a diameter of the stent as expanded based on the one or more diameters of the expandable structure or the blood vessel; receiving, by the processing circuitry, a reference diameter of the stent; determining, by the processing circuitry and based on the diameter of the stent as expanded and the reference diameter of the stent, a degree of stent expansion; and generating for output, by the processing circuitry, an indication of the degree of stent expansion. [0145] Example 26: The method of any of examples 21 through 25, wherein the expandable structure at the distal portion of the elongated body is configured to be inflated and expand a stent against a wall of the blood vessel, and wherein the method further includes: determining, by the processing circuitry, a diameter of the stent as expanded based on the one or more diameters of the expandable structure or the blood vessel; receiving, by the processing circuitry, a reference diameter of the wall of the blood vessel; determining, by the processing circuitry and based on the diameter of the stent as expanded and the reference diameter of the wall of the blood vessel, a degree of stent apposition against the wall of the blood vessel; and generating for output, by the processing circuitry, an indication of the degree of stent apposition against the wall of the blood vessel.

[0146] Example 27: The method of any of examples 21 through 26, wherein the one or more signals include voltage signals, and wherein the method further includes: applying, by the processing circuitry, a current to the one or more sensors to induce the voltage signals in the sensors.

[0147] Example 28: The method of example 27, wherein determining the one or more diameters of the expandable structure or the blood vessel comprises: applying, by the processing circuitry, one or more voltage signal values based on the voltage signals to a model, the model defining a relationship between the one or more voltage signal values and the one or more diameters, wherein an output of the model resulting from the one or more voltage signal values applied to the model includes the one or more diameters of the expandable structure or the blood vessel.

[0148] Example 29: The method of example 28, wherein the model includes a pre-defined equation relating the one or more voltage signal values and the one or more diameters of the expandable structure or the blood vessel.

[0149] Example 30: The method of example 28, wherein the model includes a lookup table relating the one or more voltage signal values and the one or more diameters of the expandable structure or the blood vessel.

[0150] Example 31 : The method of example 28, wherein the model includes an artificial intelligence (Al) model, and wherein: an input to the Al model includes the one or more voltage signal values, and an output to the Al model includes the one or more diameters of the expandable structure or the blood vessel.

[0151] Example 32: A method includes delivering, to a treatment location in a blood vessel of a patient via a first catheter, a stent; inflating the first catheter to expand the stent at the treatment location in the blood vessel; inserting, into the blood vessel and to the treatment location, a second catheter, the second catheter includes an elongated body; an expandable structure at a distal portion of the elongated body; and a plurality of sensors carried by at least one of the elongated body or the expandable structure, the plurality of sensors coupled to processing circuitry configured to determine one or more diameters of the expandable structure, the stent, or the blood vessel; and inflating the expandable structure of the second catheter to further expand the stent based on the one or more determined diameters.

[0152] Example 33: The method of example 32, further includes prior to inserting the second catheter, removing the first catheter from the blood vessel of the patient.

[0153] Example 34: The method of example 33, wherein the treatment location includes a lesion, and wherein the method further includes: prior to inserting the first catheter, inserting a third catheter; and pre-dilatating the lesion with the third catheter.

[0154] Example 35: The medical device system of any of examples 1 through 19, wherein determining the indication of morphology of the lesion includes classifying the lesion as one or more of calcific, fatty, or fibrous.

[0155] Example 36: A medical device system includes an elongated body configured to be inserted into a blood vessel of a patient; a balloon at a distal portion of the elongated body, the balloon configured to inflate and expand a stent against a wall of the blood vessel; a plurality of sensors carried by elongated body, wherein each sensor of the plurality of sensors is longitudinally spaced apart along the elongated body; and processing circuitry configured to: apply an electrical current to a first set of the plurality of sensors, receive, via a second set of the plurality of sensors, one or more resulting voltages, determine, based on the one or more resulting voltages, one or more diameters or one or more cross-sectional areas of the balloon, the stent, or the blood vessel, and output, to a user, an indication of the one or more diameters or the one or more cross-sectional areas.

[0156] The techniques described in this disclosure, including those attributed to system 100, catheter system 108, device 144, or various constituent components, may be implemented, at least in part, in hardware, software, firmware or any combination thereof. For example, various aspects of the techniques may be implemented within one or more processors, including one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate array (FPGAs), or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components, embodied in programmers, such as clinician or patient programmers, medical devices, or other devices. Processing circuitry, control circuitry, and sensing circuitry, as well as other processors and controllers described herein, may be implemented at least in part as, or include, one or more executable applications, application modules, libraries, classes, methods, objects, routines, subroutines, firmware, and/or embedded code, for example. In addition, analog circuits, components and circuit elements may be employed to construct one, some or all of the processing circuitry 30, instead of or in addition to the partially or wholly digital hardware and/or software described herein. Accordingly, analog or digital hardware may be employed, or a combination of the two.

[0157] In one or more examples, the functions described in this disclosure may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on, as one or more instructions or code, a computer- readable medium and executed by a hardware-based processing unit. The computer-readable medium may be an article of manufacture including a non-transitory computer-readable storage medium encoded with instructions. Instructions embedded or encoded in an article of manufacture including a non-transitory computer-readable storage medium encoded, may cause one or more programmable processors, or other processors, to implement one or more of the techniques described herein, such as when instructions included or encoded in the non-transitory computer-readable storage medium are executed by the one or more processors. Example non- transitory computer-readable storage media may include random-access memory (RAM), readonly memory (ROM), programmable ROM (PROM), erasable programmable ROM (EPROM), electronically erasable programmable ROM (EEPROM), flash memory, a hard disk, a compact disc ROM (CD-ROM), a floppy disk, a cassette, magnetic media, optical media, or any other computer readable storage devices or tangible computer readable media.

[0158] In some examples, a computer-readable storage medium includes a non-transitory medium. The term “non-transitory” may indicate that the storage medium is not embodied in a carrier wave or a propagated signal. In certain examples, a non-transitory storage medium may store data that can, over time, change (e.g., in RAM or cache).

[0159] The functionality described herein may be provided within dedicated hardware and/or software modules. Depiction of different features as modules or units is intended to highlight different functional aspects and does not necessarily imply that such modules or units must be realized by separate hardware or software components. Rather, functionality associated with one or more modules or units may be performed by separate hardware or software components, or integrated within common or separate hardware or software components. Also, the techniques could be fully implemented in one or more circuits or logic elements.

[0160] As used herein, “about” may indicate the exact value and/or nearly the exact value to the extent permitted by manufacturing tolerances. “About” can also refer to a certain percentage of the recited value (e.g., within about 1 percent, 5 percent, or 10 percent).

[0161] Various examples of the disclosure have been described. Any combination of the described systems, operations, or functions is contemplated. These and other examples are within the scope of the following claims.

Claims

WHAT IS CLAIMED IS:

1. A medical device system comprising: an elongated body configured to be inserted into a blood vessel of a patient; an expandable structure at a distal portion of the elongated body; a plurality of sensors carried by at least one of the elongated body or the expandable structure; and processing circuitry configured to: receive, via the plurality of sensors, one or more signals, and determine, based on the one or more signals, one or more of: an indication of a morphology of a lesion of the blood vessel, or one or more diameters of the expandable structure or the blood vessel.

2. The medical device system of claim 1, wherein the processing circuitry is configured to generate, for output, an indication of the one or more diameters of the expandable structure or the blood vessel.

3. The medical device system of any of claims 1 or 2, wherein the expandable structure at the distal portion of the elongated body is configured to inflate and expand a stent against a wall of the blood vessel.

4. The medical device system of claim 3, wherein the processing circuitry is configured to: determine a cross-sectional area of the stent based on the one or more diameters of the expandable structure or the blood vessel, and generate, for output, an indication of the cross-sectional area of the stent.

5. The medical device system of any of claims 3 or 4, wherein the processing circuitry is configured to: determine a minimum stent area (MSA) of the stent based on the one or more diameters of the expandable structure or the blood vessel, and generate, for output, an indication of the MSA of the stent.

6. The medical device system of any of claims 3 through 5, wherein the processing circuitry is configured to: determine a diameter of the stent as expanded based on the one or more diameters of the expandable structure or the blood vessel, receive a reference diameter of the stent, determine, based on the diameter of the stent as expanded and the reference diameter of the stent, a degree of stent expansion, and generate, for output, an indication of the degree of stent expansion.

7. The medical device system of any of claims 3 through 6, wherein the processing circuitry is configured to: determine a diameter of the stent as expanded based on the one or more diameters of the expandable structure or the blood vessel, receive a reference diameter of the wall of the blood vessel, determine, based on the diameter of the stent as expanded and the reference diameter of the wall of the blood vessel, a degree of stent apposition against the wall of the blood vessel, and generate, for output, an indication of the degree of stent apposition against the wall of the blood vessel.

8. The medical device system of any of claims 1 through 7, wherein the one or more signals include voltage signals, and wherein the processing circuitry is configured to apply a current to induce the voltage signals in the sensors.

9. The medical device system of claim 8, wherein to determine the one or more diameters of the expandable structure or the blood vessel, the processing circuitry is configured to: apply one or more voltage signal values based on the voltage signals to a model, the model defining a relationship between the one or more voltage signal values and the one or more diameters, wherein an output of the model resulting from the one or more voltage signal values applied to the model includes the one or more diameters of the expandable structure or the blood vessel.

10. The medical device system of claim 9, wherein the model includes a pre-defined equation relating the one or more voltage signal values and the one or more diameters of the expandable structure or the blood vessel.

11. The medical device system of claim 9, wherein the model includes a lookup table relating the one or more voltage signal values and the one or more diameters of the expandable structure or the blood vessel.

12. The medical device system of claim 9, wherein the model includes an artificial intelligence (Al) model, and wherein: an input to the Al model includes the one or more voltage signal values, and an output to the Al model includes the one or more diameters of the expandable structure or the blood vessel.

13. The medical device system of any of claims 1 through 12, wherein one or more sensors of the plurality of sensors comprise one or more electrodes or ultrasound transducers.

14. The medical device system of any of claims 1 through 13, wherein the plurality of sensors is carried by the elongated body.

15. The medical device system of any of claims 1 through 14, wherein the plurality of sensors is carried by the expandable structure.