Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
  • A61B5/021—Measuring pressure in heart or blood vessels
  • A61B5/0215—Measuring pressure in heart or blood vessels by means inserted into the body
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
  • A61B5/6846—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive
  • A61B5/6847—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive mounted on an invasive device
  • A61B5/6851—Guide wires
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B2560/00—Constructional details of operational features of apparatus; Accessories for medical measuring apparatus
  • A61B2560/04—Constructional details of apparatus
  • A61B2560/0443—Modular apparatus
  • A61B2560/045—Modular apparatus with a separable interface unit, e.g. for communication
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
  • A61B5/02028—Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
  • A61B5/6846—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive
  • A61B5/6847—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive mounted on an invasive device
  • A61B5/6852—Catheters

Definitions

• the present invention relates to a medical system, and to a method in relation to the medical system, according to the preambles of the independent claims.
• the invention relates to a medical system including a pressure measurement system adapted to determine the Fractional Flow Reserve value. Background of the invention
• physiological conditions present within a body cavity need to be monitored. These physiological conditions are typically physical in nature - such as pressure, temperature, rate-of-fluid flow, and provide the physician or medical technician with critical information as to the status of a patient's condition.
• a blood pressure sensor senses the magnitude of a patient's blood pressure, and converts it into a representative signal that is transmitted to the exterior of the patient.
• the sensor includes elements that are directly or indirectly sensitive to the parameter.
• One known sensor wire has a typical length of 1.5-2 meter, and comprises a hollow tubing running along a major part of the wire and having an outer diameter in the range of 0.25 - 0.5 mm, typically approximately 0.35 mm.
• a core wire is arranged within the tubing and extends along the tubing and often extends out from a distal opening of the tubing.
• the sensor or sensors is/are preferably arranged in connection with the distal portion of the core wire, e.g. at the distal end of the sensor wire.
• the present invention is applicable e.g. in relation with a sensor wire of the type described above, but can also be applied to other types of sensor assemblies, e.g. where the sensor is arranged at the distal end of a catheter.
• the sensor wire of the type described above is used to measure pressure in blood vessels, and in particular in the coronary vessels of the heart, e.g. to identify constrictions in the coronary vessels.
• Fractional Flow Reserve This may be performed by determining the so-called Fractional Flow Reserve (FFR) value related to the vessel.
• the sensor wire is typically inserted by use of an insertion catheter, which in turn is inserted via the femoral vein or the radial artery, and guided by the inserted catheter to the measurement site.
• one or more cables or leads for transmitting the signals are connected to the sensor, and are routed along the sensor wire to be passed out from the vessel to the external physiology monitor, via physical cables or wirelessly.
• the sensor element further comprises an electrical circuitry, which generally is connected in a Wheatstone bridge-type of arrangement to one or several piezoresistive elements provided on a membrane.
• an electrical circuitry which generally is connected in a Wheatstone bridge-type of arrangement to one or several piezoresistive elements provided on a membrane.
• a certain pressure exerted on the membrane from the surrounding medium will thereby correspond to a certain stretching or deflection of the membrane and thereby to a certain resistance of the piezoresistive elements mounted thereon and, in turn, to a certain output from the sensor element.
• US-2006/0009817 which is incorporated herein in its entirety, and which is assigned to the present assignee, an example of such a sensor and guide wire assembly is disclosed.
• the system comprises a sensor arranged to be disposed in the body, a control unit arranged to be disposed outside the body and a wired connection between the sensor and the control unit, to provide a supply voltage from the control unit to the sensor and to communicate a signal there between.
• the control unit further has a modulator, for modulating the received sensor signal and a communication interface for wireless communication of the modulated signal.
• US-7,724, 148 which is incorporated herein in its entirety, and which also is assigned to the present assignee, another example of such a pressure measurement system is disclosed.
• the pressure sensor wire is adapted to be connected, at its proximal end, to a transceiver unit that is adapted to wirelessly communicate via a communication signal with a communication unit arranged in connection with an external device.
• the human vascular system may suffer from a number of problems. These may broadly be characterised as cardiovascular and peripheral vascular disease. Among the types of disease, atherosclerosis is a particular problem.
• Atherosclerotic plaque can develop in a patient's cardiovascular system.
• the plaque can be quite extensive and occlude a substantial length of the vessel.
• a technique used to identify and measure the extent of a stricture, also denoted lesion, caused by plaque is to measure the pressure inside the vessel in the part of the vessel where the stricture is located.
• catheters suitable to perform pressure measurements there are numerous examples of catheters suitable to perform pressure measurements. Among those may be mentioned US- 6,615,667 related to a guidewire provided with a combined flow, pressure and temperature sensor.
• US-6,565,514 relates to an exemplary measurement system adapted to measure, calculate and display physiological variables related to blood pressure and in particular for calculating the myocardial fractional flow reserve (FFR) being the ratio between the arterial pressure (Pa) and the distal coronary pressure (Pd).
• FFR myocardial fractional flow reserve
• US-2006/0052700 relates to a pressure measurement system comprising a pressure sensor guidewire provided with a pressure sensor at its distal end.
• the guidewire is adapted to be inserted into a vessel.
• the sensor is adapted to be drawn continuously along a section of the vessel under examination, e.g. by a pull-back device, and the recorded pressure data is mapped on a displayed image of the vessel.
• FFR is a measure of coronary lesion severity and is defined as the ratio between distal and aortic blood pressure during maximum hyperemia.
• FFR is calculated using simultaneous pressure readings from two transducers.
• a pressure guide wire provided with a distal pressure sensor at its distal end which is arranged to measure the pressure at a position distal to the lesion, and a fluid filled pressure catheter connected to an external pressure transducer.
• the inventor has identified a need for a less complicated but still a reliable system and method for determining FFR.
• the present invention relates to a system which only uses the pressure measurements from a single pressure transducer on a pressure guidewire or catheter as source for both the distal and the aortic pressures, enabling FFR calculation using only one transducer.
• FFR is measured during maximum hyperemia.
• FFR can be assessed by the system by first recording a pressure from a position distally to the lesion and to the aortic root, pulling back the transducer and then using the pressure recorded by the same transducer now located in the aorta at the end of the pullback as reference pressure for the whole pullback. In this way FFR can be calculated by the system at the end of the pullback, assuming that the aortic pressure at the end of the pullback is representative for the whole pullback.
• a presumption is that the two measured pressure values are obtained essentially during similar states, i.e. the time interval between the points of time when the measurements are performed must not be too long, such that the aortic pressure is relatively stable during the pullback procedure.
• the present invention relates to a medical system and a method for FFR
• the system and method offer a number of advantages.
• the present invention simplifies the procedure of determining FFR.
• the medical system and method according to the present invention may be used in combination with the wireless PressureWireTM AerisTM
• the present invention is generally applicable for any type of pressure measurement device that comprises a pressure sensor at its distal portion.
• the pressure measurement device may e.g. be a pressure wire of the type referred to above, or a thin catheter provided with a pressure sensor at its distal portion, or a rapid-exchange catheter with a pressure sensor at its distal end, to mention some examples.
• the pressure sensor comprises a piezoresistive element provided on a membrane on a chip arranged at the distal portion of the pressure measurement device.
• the pressure sensor is an optical sensor which is connected to an FFR processor via optical cables.
• the present invention may be embodied by using any kind of pressure sensor arranged at the distal end of a pressure measurement device provided that the distal end of the device has a sufficiently small dimension making it possible to insert it into the vessel of interest.
• the treatment of the area may be by any of the usual therapeutic procedures, including localised delivery of a therapeutic agent, delivery of a stent, brachy therapy, ablation of selected tissue etc.
• the pressure sensor guidewire may additionally comprise angioplasty balloons or sleeves.
• Figure 1 is a block diagram schematically illustrating the present invention.
• Figure 2 is a block diagram schematically illustrating a first embodiment of the present invention.
• Figure 3 is a block diagram schematically illustrating a second embodiment of the present invention.
• Figure 4 is a block diagram schematically illustrating an embodiment of the present invention.
• Figure 5 is a diagram and a drawing illustrating the present invention.
• Figure 6 is a flow diagram illustrating the present invention.
• Figure 7 is a flow diagram illustrating an embodiment of the present invention.
• FIG. 1 is a block diagram illustrating a medical system, according to the present invention, for determining the individual Fractional Flow Reserve (FFR) value for one or many lesions of interest of a blood vessel.
• the system comprises an intravascular pressure measurement device for acquiring pressure measurements in the blood vessel, e.g. a coronary vessel, during continuous blood flow there through.
• the pressure measurement device comprises a pressure sensor at its distal portion.
• the system further comprises an FFR processor adapted to determine the FFR value related to said lesion solely based upon the pressure measurements performed by the pressure sensor.
• the pressure measurement device further comprises a timing unit adapted to control the timing of the pressure measurements and the timing unit is adapted to control the pressure measurements such that a first pressure value (Pd) is measured distally said lesion, and a second pressure value (Pa) is measured proximally the lesion close to the aorta.
• Pd first pressure value
• Pa second pressure value
• the pullback procedure ends when it is determined that the pressure sensor is in the aorta which may be visible at X-ray when the X-ray opaque distal end with the sensor element is just outside the opening of a guiding catheter placed in aorta.
• the first pressure value (Pd) is measured at a first point of time tl and the second pressure value (Pa) is measured at a second point of time t2, and that the time difference t2-tl is greater than a first predetermined time value but less than a second predetermined time value.
• the time difference is typically in the interval of 5-10 seconds.
• the FFR-processor preferably includes a memory where the measured pressure values are stored such that related values, i.e. values from the same measurement session, may be retrieved.
• the FFR-processor may further include a calculating unit for calculating the FFR value, i.e. forming the quotient between related values of Pd and Pa.
• the intravascular pressure measurement device preferably may comprise an elongated sensor wire having an outer diameter of 0.3-0.5 mm and provided with the pressure sensor at its distal end portion, and is further provided with a proximal connector at its proximal end. This is schematically illustrated in figures 2 and 3.
• the pressure elongated sensor wire having an outer diameter of 0.3-0.5 mm and provided with the pressure sensor at its distal end portion, and is further provided with a proximal connector at its proximal end.
• measurement device may comprise a catheter, or a rapid-exchange catheter, provided with the pressure sensor at its distal end portion.
• the pressure measurement device comprises a pull-back device adapted to pull-back the sensor wire from a first position (PI) where the pressure sensor senses a first pressure value (Pd) to a second position (P2) where the pressure sensor senses a second pressure value (Pa).
• the pull-back speed may be adjusted such that the pull-back procedure lasts less than a second predetermined time value, which preferably is in the interval of 5-10 seconds.
• EP-1291034 discloses a typical pull-back mechanism that may be used in connection with the sensor guide wire when implementing the present invention.
• the sensor guide wire is inserted such that a start position is reached when the pressure sensor is positioned distally the lesion to be measured.
• the pull-back device may be controlled by a processing means (not shown) via a pull- back device interface (not shown).
• the system software accesses user-defined
• the medical system according to the present invention may also be applied by manually pulling back the sensor wire (or catheter) from a first position (PI) where the pressure sensor senses a first pressure value (Pd) to a second position (P2) where the pressure sensor senses a second pressure value (Pa).
• the pull-back speed may such that the pull- back procedure lasts less than a second predetermined time value, which preferably is in the interval of 5-10 seconds.
• FIG. 2 is a block diagram schematically illustrating a first embodiment of the present invention.
• the measurement device further comprises a transceiver unit into which the proximal connector is adapted to be inserted and attached, and that the transceiver unit comprises the FFR-processor.
• the transceiver unit comprises a communication module (not shown in the figure) adapted to wirelessly transfer the FFR-value to an external device.
• the transceiver unit may include a presentation unit for displaying said FFR-value.
• FIG. 3 is a block diagram schematically illustrating a second embodiment of the present invention.
• the measurement device further comprises a connector unit into which the proximal connector of the sensor wire is adapted to be inserted and attached.
• the connector unit comprises the FFR-processor.
• the connector unit comprises a communication cable adapted to transfer the FFR-value to an external device, and that the connector unit may comprise a presentation unit for displaying the FFR-value.
• the FFR-processor is arranged remote from the pressure measurement device, e.g. in an external device, and the detected pressure values, Pa and Pd, are transmitted, via the cable, to the FFR-processor for further processing.
• Figure 5 is a diagram and a drawing illustrating the present invention.
• the graph, above in figure 5, shows the pressure in relation to time, or in relation to the position of the pressure sensor.
• FIG. 5 Below in figure 5 is shown a simplified drawing of a coronary vessel and aorta, and a sensor wire provided with a pressure sensor inserted into the vessel such that the pressure sensor is positioned distally a lesion.
• the pressure sensed by the pressure sensor is Pd, which is denoted by an "X" in the graph.
• the pressure sensor is then pulled back to position P2.
• the pullback is started at the time tl and ends at time t2.
• the pressure sensor In position P2, i.e. when the pressure sensor is in the aorta, or close to where the coronary vessel opens into the aorta, the pressure sensor senses the pressure, which is Pa, and which also is denoted by an "X" in the graph.
• aortic pressure Pa is denoted by a straight dashed line which essentially represents the mean aortic pressure.
• the aortic pressure naturally changes in dependence of the pumping action of the heart.
• the present invention also relates to a method for determining the individual Fractional Flow Reserve (FFR) value for one or many lesions of interest of a blood vessel.
• the method is schematically illustrated by the flow diagram of figure 6.
• the method comprising:
• an intravascular pressure measurement device provided with a pressure sensor, for acquiring pressure measurements in the blood vessel during continuous blood flow there through
• the method in particular comprises controlling the timing of the pressure measurements such that a first pressure value (Pd) is measured distally the lesion, and a second pressure value (Pa) is measured proximally the lesion close to Aorta.
• the first pressure value (Pd) is measured at a first point of time tl and the second pressure value (Pa) is measured at a second point of time t2, and that the time difference t2-tl is greater than a first predetermined time value but less than a second predetermined time value.
• these time values are 5 seconds and 10 seconds, respectively.
• the method comprises pulling back the pressure sensor from a first position where the pressure sensor senses the first pressure value (Pd) to a second position where the pressure sensor senses the second pressure value (Pa) and that the pull-back speed is adjusted such that the pull-back procedure lasts less than the second predetermined time value, which preferably is in the interval of 5-10 s.
• the described method is equally applicable as a manual method or as a method where a pull-back device is used.
• a manual method the physician manually pulls back the sensor wire.
• the physician firstly inserts the sensor wire (or catheter) to a position where the pressure sensor is at a location distally the suspected lesion.
• Pd is registered, e.g. automatically or by manually pressing a button or similar, and the sensor wire is pulled-back at a pull-back speed such that the second pressure value (Pa) may be registered, automatically or manually, 5-10 seconds after the registration of Pd.
• the FFR- value is calculated using the registered Pd and Pa values as described above in connection with the description the medical system.

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• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Heart & Thoracic Surgery (AREA)
• Surgery (AREA)
• Biophysics (AREA)
• Pathology (AREA)
• Engineering & Computer Science (AREA)
• Biomedical Technology (AREA)
• Cardiology (AREA)
• Medical Informatics (AREA)
• Molecular Biology (AREA)
• Physics & Mathematics (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Vascular Medicine (AREA)
• Physiology (AREA)
• Measuring Pulse, Heart Rate, Blood Pressure Or Blood Flow (AREA)

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• 2011
  • 2011-10-28 SE SE1151007A patent/SE537177C2/sv not_active IP Right Cessation
• 2012
  • 2012-10-05 AU AU2012329594A patent/AU2012329594B2/en not_active Ceased
  • 2012-10-05 WO PCT/SE2012/051064 patent/WO2013062464A1/en active Application Filing
  • 2012-10-05 EP EP12790984.4A patent/EP2770903A1/de not_active Withdrawn
  • 2012-10-05 JP JP2014514841A patent/JP6077532B2/ja not_active Expired - Fee Related
  • 2012-10-05 CA CA2835164A patent/CA2835164A1/en not_active Abandoned

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