WO2021142352A1

WO2021142352A1 - Methods and apparatus to assess and prevent hypothermic injury related to cryoablation of the pulmonary vein antra

Info

Publication number: WO2021142352A1
Application number: PCT/US2021/012817
Authority: WO
Inventors: Dhanunjaya LAKKIREDDY; Jie Cheng
Original assignee: Chelak Medical Solution Inc.
Priority date: 2020-01-10
Filing date: 2021-01-08
Publication date: 2021-07-15

Abstract

The present disclosure describes technology for preventing hypothermal injuries that are related to cryoablation. In some variations, a device may comprise a cryoballoon that is coupled to an elongate member at a proximal portion of the cryoballoon. A temperature probe may be disposed via the elongate member and may be configured to extend from a distal portion of the cryoballoon to one or more structures that are distal to the site of occlusion from the cryoballoon. Additionally or alternatively, in some variations, a device can include a cryoballoon protection device that is disposed distal to the cryoballoon. The cryoballoon protection device may be filled with an inert gas during a cryoablation procedure.

Description

METHODS AND APPARATUS TO ASSESS AND PREVENT HYPOTHERMIC INJURY RELATED TO CRYOABLATION OF THE PULMONARY VEIN ANTRA

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Patent Application Serial No. 62/959,267 filed January 10, 2020, which is hereby incorporated in its entirety by this reference.

TECHNICAL FIELD

[0002] This invention relates generally to the field of medical devices and procedures. In particular, this invention relates to assessing and preventing hypothermic injuring relating to cryoablation of pulmonary vein antra.

BACKGROUND

[0003] Cardiac ablation has become an important procedure in management of cardiac arrhythmias (e.g., atrial fibrillation). Cardiac ablation may be performed in one of two manners: (a) a nonsurgical manner using a catheter; or (b) a surgical manner by making small cuts in the heart and/or around the heart. Of the above two methods, catheter ablation ( i.e using a catheter) is a more common procedure. Catheter ablation techniques generally fall into two categories:

(1) heating procedures that use high temperatures to treat arrhythmia; and (2) cooling procedures that use low temperatures to treat arrythmia.

[0004] The cooling procedures involve using a catheter to position a cryoballoon that can alter an abnormal tissue in the heart. For instance, cold temperatures from the cryoballoon can chill or freeze cells that conduct abnormal heart rhythms. Although, this procedure has proven to be efficacious, there are serious adverse effects. For instance, freezing temperatures (e.g., temperature that freezes a blood column) may cause significant structural and/or functional damage to the surrounding tissues.

[0005] Accordingly, there is an unmet need for assessing and preventing injuries that are related to cryoablation. SUMMARY

[0006] Methods, systems, and devices to assess and prevent hypothermic injury related to cryoablation is disclosed herein. In some variations, a device for performing cryoablation of a tissue in a subject comprises an elongate member, a cryoballoon, and a temperature probe. The elongate member may be configured for insertion into a pulmonary vein of a subject. The cryoballoon may be coupled to the elongate member. The temperature probe may be disposed via the elongate member and may be configured to extend from a distal portion of the cryoballoon.

[0007] In some variations, the cryoballoon may be configured to occlude a site in the pulmonary vein. The temperature probe may be configured to extend from the cryoballoon into at least one segment of the pulmonary vein of the subject. The at least one segment may be distal to the site of occlusion from the cryoballoon. In some variations, a proximal portion of the cryoballoon may be coupled to the elongate member.

[0008] In some variations, the device may further include a lumen. The lumen may be configured to be moveable within the elongate member. At least a portion of the lumen may be disposed within the cryoballoon. The temperature probe may be disposed through the elongate member at a proximal portion of the cryoballoon so as to extend to the distal portion of the cryoballoon via at least the portion of the lumen. In some variations, a second distal portion of the lumen may include an opening. The temperature probe may be disposed into at least one segment of the pulmonary vein through the opening. The at least one segment may be distal to a site of occlusion from the cryoballoon.

[0009] In some variations, the temperature probe comprises at least one temperature sensor. The at least one temperature sensor may be disposed in at least one segment of the pulmonary vein of the subject. The at least one segment may be distal to a site of occlusion from the cryoballoon. In some variations, the temperature probe comprises an optical fiber. At least one temperature sensor may be disposed in the optical fiber.

[0010] In some variations, the at least one temperature sensor may be a Fiber Bragg Grating (FBG). The FBG may be disposed in a core of the optical fiber. In some variations, the at least one temperature sensor may include a plurality of temperature sensors. Each temperature sensor of the plurality of temperature sensors may be a respective individual FBG. In some variations, each respective individual FBG may be spaced along a length of the optical fiber. The refractive index of the core of the optical fiber may vary in a periodic manner along the length of the optical fiber. In some variations, each respective individual FBG may have a different respective characteristic wavelength. A change in the respective characteristic wavelength of the each respective individual FBG may be representative of a change in temperature. In some variations, the temperature probe may be disposed such that the each respective individual FBG may be at a respective location in the at least one segment of the pulmonary vein.

[0011] In some variations, a cryoballoon protection device may be disposed distal to the cryoballoon. The cryoballoon protection device may be configured to be filled with an inert gas. In some variations, a first temperature sensor of the plurality of temperature sensors may measure the temperature of the at least one segment in the pulmonary vein. The cryoballoon protection device may be configured to be filled with the inert gas based on the temperature of the at least one segment. In some variations, the at least one segment may be at least one of an alveolo-venocapillary junction, a secondary pulmonary vein, and a tertiary pulmonary vein.

[0012] In some variations, a system including the device comprises a processor communicably coupled to the temperature probe to determine a change in temperature of the at least one segment of the pulmonary vein based at least in part on a change in wavelength of at least a portion of the temperature probe. The processor may be further be configured to transmit a control signal to a display based at least in part on the change in temperature of the at least one segment. In some variations, the control signal may include an instruction to inflate the cryoballoon protection device with the inert gas. In some variations, the control signal may include an instruction to stop the cryoablation. In some variations, the system may further comprise a display communicably coupled to the processor to display the change in temperature of the at least one segment of the pulmonary vein.

[0013] In some variations, a device for mitigating damage to a pulmonary venous system of a subject during a cryoablation procedure comprises a cryoballoon and a cryoballoon protection device. The cryoballoon may be configured to occlude a site in a pulmonary vein of the subject. The cryoballoon protection device may be disposed distal to the cryoballoon. The cryoballoon protection device may be configured to be filled with an inert gas during the cryoablation procedure.

[0014] In some variations, the cryoballoon protection device may be configured to mitigate injury to at least a portion of the pulmonary venous system. At least the portion of the pulmonary venous system may be a segment of the pulmonary vein that is distal to the site of occlusion from the cryoballoon. In some variations, at least the portion of the pulmonary venous system may be an alveolar capillary interface.

[0015] In some variations, the cryoballoon protection device may be configured to reduce a time taken to reach a freezing temperature at the site of occlusion during the cryoablation procedure. In some variations, the cryoballoon protection device may be configured to seal the site of occlusion during the cryoablation procedure. The shape of the cryoballoon protection device may depend on a shape of the pulmonary vein at the site of occlusion. In some variations, a shape of the cryoballoon protection device may be spherical. In some variations, a shape of the cryoballoon protection device may be disc-shaped. In some variations, a size of the cryoballoon protection device may depend on an amount of inert gas filled in the cryoballoon protection device. In some variations, the inert gas may be at least one of nitrogen and argon. In some variations, the cryoballoon protection device comprises Polytetrafluoroethylene.

[0016] In some variations, the device may further include a lumen. At least a portion of the lumen may be disposed within the cryoballoon. The cryoballoon protection device may be disposed distal to the cryoballoon through the lumen. In some variations, a distal portion of the lumen may include an opening. The cryoballoon protection device may be disposed distal to the cryoballoon through the opening.

[0017] In some variations, the cryoballoon protection device may be disposed distal to the cryoballoon after inflation of the cryoballoon inside the pulmonary vein of the subject. In some variations, the cryoballoon protection device may be disposed distal to the cryoballoon outside the subject before inflation of the cryoballoon.

[0018] In some variations, the device may further include a temperature probe disposed via the cryoballoon and configured to extend from a first distal portion of the cryoballoon and a second distal portion of the cryoballoon protection device. In some variations, the temperature probe may be configured to extend into at least one segment of the pulmonary vein distal to the site of occlusion from the cryoballoon. In some variations, the temperature probe comprises an optical fiber. The optical fiber may include a core. A plurality of Fiber Bragg Gratings (FBGs) may be disposed in the core along a length of the optical fiber.

[0019] In some variations, a refractive index of the core of the optical fiber may vary in a periodic manner along the length of the optical fiber. Each FBG of the plurality of FBGs may have a different respective characteristic wavelength. The temperature probe may be disposed such that each FBG of the plurality of FBGs may be at a respective location in the at least one segment of the pulmonary vein.

[0020] In some variations, a method for monitoring temperature within a pulmonary venous system of a subject during a cryoablation procedure may include receiving the temperature at a location inside a pulmonary vein of the subject from a temperature probe. The location may be distal to a site of occlusion from a cryoballoon. The method may also include determining whether the temperature is below is a threshold. In response to determining that the temperature is below the threshold, the method may include outputting a control signal to perform an action.

[0021] In some variations, the control signal may be configured to shut down a cryoablation energy source. In some variations, the temperature probe comprises an optical fiber. The optical fiber may comprise a plurality of Fiber Bragg Gratings (FBGs). In some variations, the method may further include outputting at least one signal representative of the temperature at the location inside the pulmonary vein. The at least one signal may encode at least one color-coded version of the temperature. The control signal may be further configured to control a speaker to sound an audible alarm.

[0022] In some variations, a method of performing cryoablation of a tissue in a subject may include positioning a temperature probe such that the temperature probe extends to a first location distal to a site of occlusion from a cryoballoon. The method may also include positioning a cryoballoon protection device distal to the cryoballoon.

[0023] In some variations, the first location may be a segment in a pulmonary vein. The method may include repositioning the temperature probe based at least in part on image data of at least the segment. The repositioning may further comprise determining the first location based at least in part on the image data, determining a second location of a temperature sensor included in the temperature probe based at least in part on the image data, and comparing the first location and the second location.

[0024] In some variations, the method may further comprise identifying that the second location is not substantially close (e.g., in close proximity) to the first location based on the comparison. The method may further include repositioning the temperature probe such that the temperature sensor may be disposed at a third location. The third location may be in a vicinity (e.g., close proximity) of the first location.

[0025] In some variations, the temperature probe comprises an optical fiber. In some variations, the optical fiber comprises a plurality of Fiber Bragg Gratings (FBGs). In some variations, the method further comprises coupling the temperature probe with light and analyzing temperature at the first location in the subject. The temperature may be determined based at least in part on light reflected from the temperature probe. In some variations, the method may further include, in response to determining that the temperature is above a threshold, repositioning the temperature probe such that the temperature probe extends to a fourth location. The fourth location may be distal to the first location.

[0026] In some variations, positioning the temperature probe comprises positioning the temperature via a lumen. At least a portion of the lumen may be included in the cryoballoon. In some variations, positioning the temperature probe may further include disposing the temperature probe through an elongate member. The elongate member may be coupled to the cryoballoon at a proximal portion of the cryoballoon.

[0027] In some variations, positioning the cryoballoon protection device may include positioning the cryoballoon protection device through the cryoballoon after inflation of the cryoballoon at the site of occlusion inside the subject. In some variations, positioning the cryoballoon protection device may include disposing the cryoballoon protection device distal to the cryoballoon outside the subject before inflation of the cryoballoon. In some variations, positioning the cryoballoon protection device may include inflating the cryoballoon protection device with an inert gas. In some variations, positioning the cryoballoon protection device may include positioning the cryoballoon protection device at a fifth location and inflating the cryoballoon protection device may include inflating based at least in part on a shape of a pulmonary vein at the fifth location.

[0028] In some variations, the method may further include repositioning the cryoballoon protection device based at least in part on an image data of a pulmonary vein. The cryoballoon protection device may be positioned in a segment of the pulmonary vein. In some variations, the method may further include repositioning the cryoballoon protection device based at least in part on a temperature data obtained from the temperature probe.

[0029] In some variations, positioning the cryoballoon protection device may include inflating the cryoballoon protection device so as to seal the site of occlusion during the cryoablation of the tissue. In some variations, the first location may be a segment in a pulmonary vein of the subject. The first location may include at least a portion of an alveolo-venular interface in the subject. In some variations, positioning the cryoballoon protection device may include positioning the cryoballoon protection device at a distance between about 3 mm - 5 mm from the cryoballoon.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG. 1 illustrates a traditional device used for cryoballoon-based ablation procedure.

[0031] FIG. 2 illustrates an exemplary variation of a device for performing cryoballoon-based ablation while simultaneously assessing and mitigating hypothermal injury to structures that are distal to the site of occlusion from a cryoballoon.

[0032] FIG. 3 illustrates an exemplary variation of a temperature probe for measuring temperature at one or more locations that are distal to the site of occlusion from a cryoballoon.

[0033] FIG. 4 illustrates an exemplary variation of a cryoballoon protection device to prevent and/or mitigate undesirable freezing of blood column and/or structures that are distal to the site of occlusion from a cryoballoon.

[0034] FIG. 5 is a schematic description of an exemplary variation of a system for assessing and mitigating hypothermal injury during a cryoballoon-based ablation procedure. [0035] FIG. 6 is a flow diagram of an exemplary variation of a method for monitoring pulmonary-venous system temperature during cryoballoon-based ablation procedure performed on a subject.

DETAILED DESCRIPTION

[0036] Non-limiting examples of various aspects and variations of the invention are described herein and illustrated in the accompanying drawings.

[0037] Cardiac ablation has proven to be an effective treatment for patients with cardiac arrhythmia (e.g., atrial fibrillation). Cardiac ablation comprises electrical isolation of pulmonary veins at an antral level. This may stop unusual electrical signals in a patient’s heart that may cause unusual heartbeats. Traditional cardiac ablation procedures include using heating procedures to treat arrythmia. For example, radiofrequency ablation uses heat (e.g., heat generated from radiofrequency current) to ablate and/or make scars around a pulmonary vein or a group of pulmonary veins.

[0038] There are several known drawbacks that are associated with radiofrequency ablation. Some of these drawbacks include major complications such as damage to neighboring intracardiac and extracardiac structures. Extracardiac structures at risk from radiofrequency ablation include upper gastrointestinal structures such as esophagus and stomach, pulmonary bronchi, adjacent nerves such as vagus nerve and right phrenic nerve, etc. In particular, the proximity of the esophagus to the posterior wall of the left atrium makes it especially vulnerable. Accordingly, the esophagus may be prone to various degrees of thermal injury due to radiofrequency ablation.

[0039] Furthermore, radiofrequency ablation procedure is often a point-by-point ablation procedure. Contiguous radiofrequency lesions may have to be placed point-by-point around each pulmonary vein antrum. Therefore, achieving complete isolation of all pulmonary veins using radiofrequency ablation may take a substantial amount of time (e.g., 10-30 applications for each pulmonary vein).

[0040] Given the drawbacks of radiofrequency ablation procedure, more recently, cryoballoon-based pulmonary vein isolation and/or cryoballoon-based pulmonary vein antrum isolation (e.g., collectively referred to as “cryoballoon-based ablation” herein) have become popular. Cryoballoon-based ablation generally involves positioning a catheter that is coupled to a balloon ( i.e a cryoballoon) at the ostium of a pulmonary vein. The cryoballoon is typically inflated using a refrigerant (e.g., nitrous oxide). The refrigerant can cause a temperature decrease, thereby absorbing heat from the cryoballoon-tissue interface. The cooling effect can create a circumferential lesion about the pulmonary vein ostium and/or the pulmonary vein antrum. This can disrupt abnormal electrical signals exiting the pulmonary vein.

[0041] Unlike radiofrequency ablation which is a point-by-point ablation procedure, cryoballoon-based ablation is often a single shot procedure. Therefore, in contrast to radiofrequency ablation, cryoballoon-based ablation may take less time (e.g., single application for entire pulmonary vein antrum). Despite providing this significant advantage, cryoballoon- based ablation procedure has several adverse effects.

[0042] Several complications may arise with cryoballoon-based ablation procedures, such as pulmonary vein stenosis, hemoptysis, or bronchial injury. Additionally, right phrenic nerve palsy may occur with cryoballoon-based ablation. Although, the hypothermia created by the cryoballoon-based ablation can cause electrical isolation of the pulmonary vein, hypothermia may also cause significant collateral damage to structures that are distal to the pulmonary vein and outside the atrium including the bronchus. For example, when the refrigerant in the cryoballoon expands into vapor state causing a temperature decrease, the tissue temperature of the tissue interfacing with the cryoballoon may be lowered (e.g., down to -41°C to -45 °C). This may also freeze the blood column distally in the pulmonary vein path, all the way to secondary and tertiary pulmonary vein branches, pulmonary vein capillaries, and the alveolo-venular interface. The freezing of the blood column in turn may potentially cause hypothermia-related injury in at least some of these structures. Additionally, freezing of the blood column may cause significant edema and inflammation (with recruitment of macrophages, neutrophils, and lymphocytes), along with possible pulmonary vein muscle sleeve dissection in the more proximal portions of the pulmonary vein. Hemorrhaging in these structures may explain the hemoptysis (e.g., the expectoration of blood) that patients experience after the cryoballoon-based ablation. [0043] In addition to the significant damages discussed above, the pulmonary arterial wedge capillary pressure (e.g., in the right inferior pulmonary vein) may remain significantly elevated up to about 20 minutes after cryoballoon deflation in the pulmonary veins due to the occlusion of the pulmonary vein. Furthermore, there may be acute elevation of pulmonary and right heart pressures during and shortly after the cryoballoon-based ablation procedure. This may be due to the hypothermia-related injury to the pulmonary vein system (also referred to herein as “pulmonary-venous system”) and the alveolo-venular interface (also referred to herein as “alveolo-venocapillary junction”). The pulmonary vein wall may also be affected by low- temperature blood far more distal than just at the ostium.

[0044] More recently, in addition to the damages discussed above, bronchial injury (e.g., structural damages to at least portions of the lungs) has been observed following a cryoballoon- based ablation procedure. For example, bronchoscopy and/or imaging of the lung(s) following a cryoballoon-based ablation procedure has revealed structural damages in the lungs with swelling and injury to the bronchi, bronchioles and alveoli. This bronchial injury may be occurring due direct freezing effect of the cryoballoon placed in the pulmonary vein antra and transient freezing of the column of blood in the distal pulmonary venous circulation all the way to the alveolo-capillary interface. Additionally, the perceived benefit of a cryoballoon-based ablation procedure in reduction of esophageal injury compared with a radiofrequency ablation procedure has not been confirmed yet. Put differently, although it is believed that there is a reduction of esophageal injury from a cryoballoon-based ablation procedure in comparison to a radiofrequency ablation procedure, this hypothesis have not been confirmed yet.

[0045] Therefore, there is an unmet need for assessing and preventing injuries to structures that are distal to the site of occlusion from a cryoballoon during a cryoballoon-based ablation procedure. Some non-limiting examples of structures that are distal to the site of occlusion include segments in the pulmonary vein distal to the cryoballoon, secondary pulmonary vein branches, tertiary pulmonary vein branches, pulmonary vein capillaries, alveolo-venular interface, portions of the bronchi, esophagus, a combination thereof, and/or the like.

[0046] FIG. 1 illustrates a traditional device used for a cryoballoon-based ablation procedure. The device may include an elongate member 110 (e.g., a catheter or a sheath) and a cryoballoon 102. The cryoballoon 102 may include a proximal portion 102a and a distal portion 102b. The proximal portion 102a of the cryoballoon 102 may be one of disposed on, coupled to, integrated with, attached to, and/or affixed to the elongate member 110.

[0047] In some variations, the cryoballoon 102 may include one or more balloons (not shown) disposed within each other. For example, the cryoballoon 102 shown in FIG. 1 may be an outer balloon that contacts with and/or interfaces with one or more tissues within a subject. An inner balloon may be disposed within the outer balloon such that a refrigerant (e.g., nitrous oxide) may be delivered to the distal portion of the inner balloon. In such variations, at least one of the proximal portion of the inner balloon or the proximal portion of the outer balloon may be one of disposed on, coupled to, integrated with, attached to, and/or affixed to the elongate member 110.

[0048] In some variations, a movable shaft (not shown in FIG. 1) may lie within the elongate member 110. The distal portion 102b of the cryoballoon 102 may be one of disposed on, coupled to, integrated with, attached to, and/or affixed to a distal portion of the shaft. The shaft may be moveable along the elongate member 110. For example, the shaft 110 may be mechanically coupled to knobs, levers, pullwires, and/or the like at the proximal portion of the shaft 110. The shaft may extend a partial length of the elongate member 110 or substantially the entire length of the elongate member 110.

[0049] In some variations, the device may include one or more lumens (not shown in FIG. 1). The lumen(s) may be disposed within or lie within the shaft. Alternatively, the shaft may define one or more lumen(s). The lumen(s) may be longitudinally movable within the elongate member 110 such that at least a portion of the lumen(s) is disposed within the cryoballoon 102. The lumen(s) may extend a partial length of the elongate member 110 or substantially the entire length of the elongate member 110. For example, the device may include a central guidewire lumen (e.g., a lumen comprising a tubular portion) through which a guidewire can extend. The distal portion of the central guidewire lumen may have an opening such that a distal portion of the guidewire extends out of the distal portion 102b of the cryoballoon 102. Additionally or alternatively, the device may include an intake lumen and an exhaust lumen to deliver the refrigerant and to recover the expended refrigerant.

[0050] FIG. 1 shows the effects of cryoballoon-based ablation using the traditional device.

FIG. 1 illustrates the right superior pulmonary vein 109a, the left superior pulmonary vein 109b, left atrium 107, right inferior pulmonary vein 105a, left inferior pulmonary vein 105b, left lung 103a, and right lung 103b in a subject. As seen in FIG. 1, the alveolo-venocapillary junction 113 (e.g., alveolo-venular interface) is distal to the pulmonary venules 111.

[0051] To perform cryoballoon-based ablation, the device is advanced over a guidewire (e.g., guidewire inserted in central guidewire lumen) into a treatment site. As an example, the treatment site in FIG. 1 is illustrated to be a portion of the right superior pulmonary vein 109a. Accordingly, the device is advanced over a guidewire to the right superior pulmonary vein 109a such that the cryoballoon 102 is disposed between the left atrium 107 of the heart and the pulmonary venous system 111.

[0052] Pressurized refrigerant may be delivered via an intake lumen in the device to the distal portion 102b of the cryoballoon 102. The refrigerant may freeze the adjacent tissue (e.g., tissue adjacent to the cryoballoon 102 in the pulmonary vein 111). Heat may be absorbed from the adjacent and the surrounding tissue, thereby occluding the segment of the pulmonary vein adjacent to and surrounding the cryoballoon 102. The expended refrigerant may be returned via an exhaust lumen. In some variations, one or more thermocouples may be disposed inside the cryoballoon 102 or on the surface of the cryoballoon 102 (e.g., surface of the distal portion 102b of the cryoballoon) to monitor the temperatures within the cryoballoon and/or the temperature of the adjacent tissue.

[0053] As seen in FIG.1, when the cryoballoon 102 occludes the pulmonary vein ostium, it creates stasis of blood within the pulmonary venules 111 all the way from a pulmonary vein segment 11 G that is proximal to the site of occlusion from the cryoballoon 102 down to pulmonary vein segments 111” and/or 11 G ” that are distal to the site of occlusion further down to alveolo-venocapillary junction 113. Put differently, when the cryoballoon 102 occludes the pulmonary vein ostium, the blood column distal to the site of occlusion from the cryoballoon 102 (e.g., blood column in pulmonary vein segment 111”, pulmonary vein segment 11G”, alveolo-venocapillary junction 113, etc.) freezes. This freezing may impact the structural and/or functional integrity of the structures that are distal to the site of occlusion from the cryoballoon 102. The increased intracapillary pressure and alveolar disruption may make these structures that are distal to the site of occlusion more vulnerable to injury. Subjects on blood thinners who experience injuries in the pulmonary venous system may experience hemorrhage in the lung tissue (e.g., right lung 103a).

[0054] As discussed above, current methodologies don’t offer a tool to monitor temperature changes in structures that are distal to the site of occlusion, such as distal segments of the pulmonary vein (e.g., segment 111”, segment 111”’), alveolo-venocapillary 113, portions of the right lung 103a, a combination thereof, and/or the like. Existing technologies do not prevent hypothermal injury distal to the site of occlusion from the cryoballoon 102. Accordingly, certain aspects of the present disclosure provide techniques and apparatus for monitoring temperature of distal portions of the pulmonary vein system beyond the cryoballoon 102 occlusion. The present disclosure also provides techniques, device, and apparatus for preventing, or at least mitigating, hypothermic injury related to cryoballoon-based ablation of the pulmonary vein antra.

[0055] Accordingly, in some variations, a device for performing cryoablation (e.g., cryoballoon-based ablation procedure) of a tissue in a subject is described herein. The device can comprise a cryoballoon that is coupled to an elongate member at a proximal portion of the cryoballoon. A temperature probe may be disposed (e.g., placed, deployed, positioned, routed, or guided) via the elongate member and may be configured to extend from a distal portion of the cryoballoon. The temperature probe may be disposed such that the temperature probe can measure the temperature(s) of one or more structures that are distal to the site of occlusion. For instance, the temperature probe may extend from the cryoballoon to the one or more structures that are distal to the site of occlusion.

[0056] Additionally or alternatively, in order to mitigate damage to the pulmonary venous system and/or to one or more structures that are distal to the site of occlusion, in some variations, a device can include a cryoballoon protection device that is disposed distal to the cryoballoon. The cryoballoon protection device may be filled with an inert gas during a cryoablation procedure (e.g., cryoballoon-based ablation procedure). In some variations, the cryoballoon protection device may be inflated with inert gas in response to the temperature in one or more structures that are distal to the site of occlusion falling below a threshold value (e.g., temperature value that freezes the blood column in structures distal to the site of occlusion). Exemplary Device(s)

[0057] FIG. 2 illustrates an exemplary variation of a device for performing cryoballoon-based ablation while simultaneously assessing and mitigating hypothermal injury to structures that are distal to the site of occlusion from a cryoballoon 202. The device includes an elongate member 210, a shaft 208, a cryoballoon 202, one or more lumen(s) 214, and a temperature probe 204.

The cryoballoon 202 may include a proximal portion 202a and a distal portion 202b.

[0058] In some variations, the elongate member 210 may be similar to the elongate member 110 in FIG. 1 and the cryoballoon 202 may be similar to the cryoballoon 102 in FIG. 1.

Similarly, the shaft 208 may be similar to the shaft described above and the lumen(s) 214 may be similar to the lumen(s) described above. Some additional aspects of these components that are related to assessing and mitigating hypothermal injury to structures that are distal to the site of occlusion are described in further detail below.

[0059] The device includes an elongate member 210 passable through a subject’s vascular system. The elongate member 210 may be steered and positioned in a tissue region for cryoballoon-based ablation. The elongate member may be one of a catheter or sheath that can support a cryoballoon 202. In some variations, the elongate member 210 may be a steerable transseptal sheath. Some non-limiting examples of a transseptal sheath 210 include FlexCathAdvance™, Agilis™ NxT steerable introducer, HeartSpan® Fixed Curve Braided Transseptal Sheath, TorFlex™ Transseptal Guiding Sheath, etc.

[0060] A shaft 208 may be disposed and/or may lie within the elongate member 210. For instance, the shaft 208 may extend from the distal portion 210b of the elongate member 210. Additionally or alternatively, the shaft 208 may protrude from the distal portion 210b of the elongate member. In some variations, the shaft 208 may be movable (e.g., longitudinally and/or rotatably) along the elongate member. In some variations, the shaft 208 may be disposed partially within the elongate member 210 and may extend a partial length of the elongate member 210. Alternatively, the shaft 208 may extend the entire length of the elongate member 210. The distal portion 202b of the cryoballoon 202 may be one of disposed on, coupled to, integrated with, attached to, and/or affixed to a distal portion of the shaft 208. [0061] The shaft 208 may define one or more lumen(s) 214. Alternatively, the one or more lumen(s) 214 may be disposed within or may lie within the shaft 208. In some variations, the one or more lumen(s) may be disposed within the elongate member 210. The lumen(s) 214 may be longitudinally and/or rotatably moveable within the elongate member 210. In some variations, the lumen(s) 214 (e.g., central guidewire lumen discussed above) may include an opening in the distal portion 214b of the lumen(s) 214. The lumen(s) 214 may provide a pathway for a temperature probe 204 such that at least a portion of the temperature probe 204 may extend through the opening in the distal portion 214b of the lumen(s) 214. In some variations, the temperature probe 204 may extend out of the distal portion 202b of the cryoballoon 202 through the opening in the distal portion 214b of the lumen(s) 214.

[0062] A proximal portion 202a of the cryoballoon 202 may be one of disposed on, coupled to, integrated with, attached to, and/or affixed to the elongate member 210. As discussed above, the distal portion 202b of the cryoballoon 202 may be one of disposed on, coupled to, integrated with, attached to, and/or affixed to a distal portion of the shaft 208, and consequently the distal portion 214b of the lumen(s) 214. As seen in FIG. 2, at least a portion of the lumen(s) 214 and/or the shaft 208 may be disposed within the cryoballoon 202. Put differently, at least a portion of the lumen(s) 214 and/or shaft 208 that extends from the distal portion 210b of the elongate member 210 may be disposed within the cryoballoon 202. The cryoballoon 202 may include multiple balloons disposed within each other. For example, the cryoballoon 202 may include an outer balloon that contacts with and/or interfaces with one or more tissues within a subject. An inner balloon may be disposed within the outer balloon such that a refrigerant (e.g., nitrous oxide) may be delivered to the distal portion of the inner balloon.

[0063] A temperature probe 204 (not present or described in FIG. 1) may be disposed (e.g., placed, deployed, positioned, routed, or guided) through the lumen(s) 214 (e.g., central guidewire lumen) such that temperature probe may be positioned to measure temperatures in structures that are distal to the site of occlusion from the cryoballoon 202. For example, the temperature probe 204 may extend through an opening in the distal portion 214b of the lumen(s) 214 such that the temperature probe 204 extends out from the distal portion 202b of the cryoballoon 202. Additionally or alternatively, the temperature probe 204 may be disposed (e.g., placed, deployed, positioned, routed, or guided) through the shaft 208 and/or the elongate member 210 such that temperature probe 204 may be positioned to measure temperatures in structures that are distal to the site of occlusion from the cryoballoon 202. In some variations, the temperature probe 204 may be disposed through the elongate member 210 at the proximal portion 202a of the cryoballoon 202 such that the temperature probe 204 may extend to the distal portion 202b of the cryoballoon via the lumen(s) 214. The temperature probe 204 may then further extend from the distal portion 202b of the cryoballoon 202 through the opening in the distal portion 214b of the lumen(s) 214 to structures that are distal to the site of occlusion.

[0064] The temperature probe 204 may be positioned such that the temperature probe 204 can measure the temperature of structures that are distal to the site of occlusion. For example, in FIG. 2, the cryoballoon 202 may be disposed between the left atrium 207 of the heart and the pulmonary venous system 211. More specifically, the cryoballoon 202 may be placed in the right superior pulmonary vein 209a. The site of occlusion from the cryoballoon 202 would include the pulmonary vein ostium (e.g., ostium of the right superior pulmonary vein 209a), and tissues and/or segments in the in the right superior pulmonary vein 209a that are adjacent to and/or surrounding the cryoballoon 202. The temperature probe 204 may be positioned such that the temperature probe 204 extends to structures that are distal to the site of occlusion. For example, in FIG. 2, the temperature probe 204 is positioned such that the temperature probe 204 extends to tertiary pulmonary vein segment 21 G” that is distal to the site of occlusion from the cryoballoon. In some variations, the temperature probe 204 further extends out to the alveolo- venocapillary junction 213 and the alveoli 215.

[0065] A distal segment of the temperature probe 204 may include one or more temperature sensors such as temperature sensor 206a, temperature sensor 206b, temperature sensor 206c, etc. (e.g., collectively referred to as temperature sensor 206). In some variations, the temperature probe 204 may be positioned such that at least one temperature sensor 206 is in the vicinity of and/or in close proximity to a structure that is distal to the site of occlusion so as to measure the temperature of that structure. For example, in FIG. 2, temperature sensor 206a may be positioned to measure the temperature of the pulmonary vein segments 211” and 21 G ” that are distal to the site of occlusion. Temperature sensor 206b may be positioned to measure the temperature of the alveolo-venocapillary junction 213, and temperature sensor 206c may be positioned to measure the temperature of the alveoli 215. In some variations, a temperature sensor 206 may be positioned at a distance of at least 5mm from the structure in order to measure accurate temperature of the structure. In some variations, the distance between two adjacent temperature sensors 206 may be between 5mm to 15mm, such as 10mm in order to obtain accurate temperature measurements of most structures that are distal to the site of occlusion.

[0066] Although FIG. 2 illustrates four temperature sensors 206 on the temperature probe 204, it should be readily understood that a temperature probe 204 may include any number of temperature sensors, for example, two temperature sensors, three temperature sensors, five temperature sensors, six temperature sensors, seven temperature sensors, eight temperature sensors, nine temperature sensors, ten temperature sensors, etc.

[0067] In some variations, the temperature probe 204 may comprise electrically conductive wire(s) that include that include thermocouples 206. For instance, the temperature probe 204 may comprise a conductive wire studded with thermocouples. Alternatively, the temperature probe may comprise one or more optical waveguides 204 (e.g., optical fibers) including one or more temperature measurement sites (e.g., temperature sensors 206). For example, the temperature probe 204 may include an optical fiber comprising a core and a cladding surrounding the core, with one or more Fiber Bragg Gratings (FBGs) 206 disposed in the core of the optical fiber.

[0068] In some variations, the temperature probe 204 may include one or more radiopacifiers disposed at an end (e.g., distal end) of the temperature probe 204. The radiopacifier may be radiopaque, thereby inhibiting penetration by radio frequency and X-ray signals. Accordingly, the radiopacifier may be clearly visible in X-ray images (e.g., fluoroscopy). This enables the temperature probe 204 to be easily positioned and/or repositioned at the desired location in the pulmonary-venous system.

[0069] In some variations, to perform cryoballoon-based ablation, the cryoballoon 202 may be inserted through the elongate member 210. The device may be advanced over a guidewire (e.g., guidewire inserted in central guidewire lumen 214) into the left atrium. The cryoballoon 202 may be inflated with a refrigerant (e.g., nitrous oxide). The elongate member 210 may steer the cryoballoon 202 to the site of occlusion. For example, in FIG. 2, the elongate member 210 may steer the cryoballoon 202 such that the cryoballoon 202 may be placed in the right superior pulmonary vein 209a. [0070] In some variations, the temperature probe 204 may be inserted through the elongate member 210 before inflating the cryoballoon 202. Alternatively, the temperature probe 204 may be inserted via the elongate member 210 (e.g., through the lumen(s) 214) after inflating the cryoballoon 202. The radiopacifier on the temperature probe 204 may enable visibility of a location and/or a position of the temperature probe 204. Accordingly, the temperature probe 204 may be positioned and/or repositioned such that the temperature probe 204 can measure the temperatures of structures that are distal to the site of occlusion.

[0071] The pressurized refrigerant delivered to the cryoballoon 202 may freeze the adjacent tissues, thereby occluding the segment of the pulmonary vein adjacent to and surrounding the cryoballoon 202. The temperature of the structures that are distal to the site of occlusion (e.g., pulmonary vein segment 211”, pulmonary vein segment 21 G”, alveolo-venocapillary 213, alveoli 215) may be monitored frequently. For example, measurements from the temperature sensors 206 included in the temperature probe 204 may be processed (e.g., via a processor placed external to the subject and communicably and/or optically coupled to the temperature probe 204) and analyzed to monitor the temperature of the structures that are distal to the site of occlusion. The cryoballoon-based ablation may be altered if the temperature of one or more structures drops below a threshold. For example, the cryoballoon-based ablation may be altered by inflating a protective device (e.g., a cryoballoon protective device described herein) distal to the cryoballoon if the temperature of one or more structures drops below a threshold. This may prevent the freeze injury to structures that are distal to the site of occlusion (e.g., structures that are distal to the occluded pulmonary vein ostium). Additionally or alternatively, the cryoballoon- based ablation may be altered by shutting down and/or stopping an energy source to the cryoballoon if the temperature of one or more structures drop below a threshold. In this manner, damages and/or injuries to structures that are distal to the site of occlusion may be mitigated. In some variations, damages and/or injuries to one or more portions of the lungs may be mitigated and/or prevented in this manner.

Exemplary Temperature Probe

[0072] FIG. 3 illustrates an exemplary variation of a temperature probe 304 (e.g., structurally and/or functionally similar to temperature probe 204 in FIG. 2) for measuring temperature at one or more locations that are distal to the site of occlusion from a cryoballoon. In some variations, the temperature probe 304 may comprise one or more optical waveguides (e.g., optical fibers). The optical fiber may comprise a core 322 that is surrounded by a cladding 324. The refractive index of the cladding 324 may be different from the refractive index of the core 322. This may provide for total internal reflection within the optical fiber.

[0073] One or more fiber Bragg gratings (FBGs) 306 (e.g., structurally and/or functionally similar to temperature sensors 206 in FIG. 2) may be deployed along the length of the optical fiber. For example, the individual FBGs 306 may be fabricated by inscribing an invisible periodic refractive index change in the core 322 of the optical fiber. Put differently, the individual FBGs 306 may be written into the core 322 of the optical fiber such that the refractive indexes of the FBGs 306 vary in a periodic manner along the length of the core 322. Alternatively, multiple optical fibers, each including FBGs 306 may be spliced together.

[0074] Each of the FBGs may have a different characteristic wavelength. For example, in FIG. 3, the temperature probe 304 includes five FBGs 306 having characteristic wavelengths li, li, l3, lt, and l5. Each of the FBGs may be spaced along a length of the optical fiber (e.g., a distal portion of the optical fiber and/or a distal portion of the temperature probe 304). The length (/) denotes the space between two adjacent FBGs. In some variations, each of the FBGs may be equally spaced from their corresponding adjacent FBGs. Alternatively, the space between two adjacent FBGs in a temperature probe 304 may be unequal. The number of FBGs and the length (/) between the adjacent pairs of FBGs may be selected based on the farthest structure that is distal to the site of occlusion for which temperature is to be measured. For example, the length between the distal portion of the cryoballoon and the farthest structure that is distal to the site of occlusion may determine the number of FBGs that are to be included in the temperature probe 304 and the length (/) between the adjacent pairs of FBGs. In some variations, the length (I) along the optical fiber between an adjacent pair of FBGs 306 may be in a range from 0.5 to 1.5 cm, such as /= 1.0 cm.

[0075] When an incident spectrum of light propagates through the FBGs, a specific wavelength (e.g., Bragg wavelength) may be reflected back. The characteristic wavelengths of the FBGs 306 make them sensitive to temperature. Therefore, changes in a nominal characteristic wavelength reflected by a particular FBG may be used to measure temperature shifts. When FBGs 306 with different characteristic wavelengths are used in a temperature probe 304, in order to distinguish between light reflections from different FBGs, wavelength division multiplexing (WDM) may be utilized. Thus, temperature from different measurement sites (i.e., different FBGs) along the optical fiber (and consequently the temperature probe 304) may be measured.

[0076] Although five FBGs 306 are shown in FIG. 3, the number of FBGs 306 in the temperature probe 304 may be any suitable number, such as between one and ten, or more typically between four and eight.

[0077] In some variations, the temperature probe 304 may include multiple optical fibers.

Each optical fiber may comprise one or more FBGs. In such a scenario, the multiple optical fibers may be bundled together in the temperature probe, such that the multiple optical fibers may be inserted into the lumen and/or the elongate member together.

[0078] In some variations, as discussed above, the temperature probe 304 may include a radiopacifier 328. The radiopacifier 328 may be disposed at a distal portion of the temperature probe 304, such as at the distal end of the optical fiber. The radiopacifier 328 is radiopaque, thereby allowing the temperature probe 304 to be clearly visible during fluoroscopy and, thus, easily positioned (and repositioned) at the desired location within the pulmonary venous system.

[0079] The use of optical waveguides provides several advantages over the metal thermistors of conventional temperature probes. For example, the FBGs have a truly linear correlation between wavelength and temperature, unlike thermistors. In addition, the FBGs are typically made of glass (e.g., silica) or plastic, rather than metal. Consequently, the heat sink effect of the metal thermistors during ablation and the tissue damage caused therefrom is altogether avoided by FBGs, and the FBGs create no metal artifacts during dynamic magnetic resonance imaging (MRI) or computerized tomography (CT) imaging. As another advantage, the FBGs do not exhibit temperature overestimation due to: (1) direct light absorption during laser procedures, (2) sonification effect during low intensity continuous ultrasound (LICU) or high intensity focused ultrasound (HIFU), or (3) high heat conductivity of metallic wires during cryoballoon-based ablation. Furthermore, the non-metallic FBGs do not exhibit temperature underestimation for microwave, radiofrequency, or hot water ablation, in contrast with thermistors. [0080] In some variations, one or more of the FBGs may be a linearly chirped fiber Bragg grating (LCFBG). With an LCFBG, the temperature probe 304 can achieve a spatial resolution of 75 pm on a 1.5 cm length of fiber, providing a far more accurate temperature measurement than can be accomplished with conventional thermistor temperature probes. For example, a multipoint LCFBG probe with 5 mm gratings at 10 mm intervals may be used to cover a desired pulmonary vein length to accurately assess pulmonary vein temperature at segments that are distal to the site of occlusion from a cryoballoon.

[0081] In some variations, the temperature probe 304 may be implemented with at least one optical fiber, where the optical fiber is itself the optical temperature sensor (e.g., temperature sensor 206 in FIG. 2). Such temperature probes 304 may be based on distributed temperature sensing (DTS), utilizing backscattered reflections of optical signals introduced into the optical fiber, the backscattered reflections being along a length of the core of the optical fiber.

Cryoballoon Protection Device

[0082] FIG. 4 illustrates an exemplary variation of a cryoballoon protection device 416 to prevent and/or mitigate undesirable freezing of blood column and/or structures that are distal to the site of occlusion from a cryoballoon 402.

[0083] As discussed above, when a cryoballoon is inflated, the pulmonary vein ostium is occluded. For example, when cryoballoon 402 in FIG. 4 is inflated (e.g., with a refrigerant), the right superior pulmonary vein 409a ostium, and the pulmonary vein segment adjacent to and/or surrounding the cryoballoon 402 may be occluded. Accordingly, the blood column immediately adjacent to the distal portion 402b of the cryoballoon 402 (e.g., blood column in pulmonary vein segment 41 G) may freeze along with the surrounding pulmonary vein tissue (e.g., tissue within the pulmonary vein segment 41 G). Due to this freezing, ice crystals may be formed. This column of ice however, may extend farther down to distal portions of the pulmonary vein segments (e.g., pulmonary vein segment 411”, pulmonary vein segment 411”) all the way to the alveolo-venocapillary junction 413 and the alveoli 415.

[0084] To mitigate and/or minimize the freezing effects of the cryoballoon 402 on distal structures of the pulmonary -venous system, a cryoballoon protection device 416 may be disposed distal to the cryoballoon 402. The cryoballoon protection device 416 may be structurally similar to the cryoballoon 402. For example, the cryoballoon protection device 416 may be a balloon that can inflate and deflate in the pulmonary-venous system. Additionally, the cryoballoon protection device 416 may comprise the same material as the cryoballoon 402 (e.g., a polymer such as Polytetrafluoroethylene).

[0085] In some variations, the cryoballoon protection device 416 may be inflated with an inert gas (e.g., Argon, Neon, Helium, Nitrogen, etc.). This may minimize the freezing effects of the cryoballoon 402 on distal structures of the pulmonary-venous system (e.g., pulmonary vein segment 411”, pulmonary vein segment 411”, alveolo-venocapillary 413, alveoli 415, and/or the like) and/or portions of the lungs.

[0086] In some variations, the cryoballoon protection device 416 may be disposed (e.g., placed, deployed, positioned, routed, or guided) through lumen(s) 414 (e.g., structurally and/or functionally similar to lumen(s) 214 in FIG. 2). The cryoballoon protection device 416 may be disposed such that it is positioned distal to the cryoballoon 402. For example, the cryoballoon protection device 416 may be inserted through the lumen(s) 414 such that it is disposed distal to the cryoballoon 402 through an opening in the distal portion 414b of the lumen(s) 414. Additionally or alternatively, the cryoballoon protection device 416 may be disposed (e.g., placed, deployed, positioned, routed, or guided) through a shaft 408 (e.g., structurally and/or functionally similar to shaft 208 in FIG. 2) and/or an elongate member 410 (e.g., structurally and/or functionally similar to elongate member 210 in FIG. 2). In some variations, the cryoballoon protection device 416 may be inserted through the elongate member 410 such that the cryoballoon protection device 416 is guided through the lumen(s) 414 to be positioned distal to the cryoballoon 402.

[0087] In some variations, the cryoballoon protection device 416 may be positioned distal to the cryoballoon 402 outside the subject before inflation of the cryoballoon 402. Alternatively, the cryoballoon protection device 416 may be disposed and positioned distal to the cryoballoon 402 after the inflation of the cryoballoon 402 in the pulmonary -venous system of the subject. In some variations, the cryoballoon protection device 416 may be inflated with inert gas after inflating the cryoballoon 402. In other variations, the cryoballoon protection device 416 may be inflated with inert gas before inflating the cryoballoon 402. In yet other variations, the cryoballoon protection device 416 may be inflated with inert gas simultaneously when the cryoballoon 402 is inflated with the refrigerant.

[0088] In some variations, the cryoballoon protection device 416 may be placed directly adjacent to the distal portion 402b of the cryoballoon 402 such that a portion of the cryoballoon protection device 416 may touch or contact the distal portion 402b of the cryoballoon 402. Alternatively, the cryoballoon protection device 416 may be placed within a distance ranging between 3mm to 5mm from the distal portion 402b of the cryoballoon 402. In some variations, at least a portion of the cryoballoon protection device 416 may include one or more radiopacifiers. For example, the radiopacifiers may be disposed at a distal end (e.g., distal to the cryoballoon 402) of the cryoballoon protection device 416. The radiopacifier may be radiopaque, thereby inhibiting penetration by radio frequency and X-ray signals. Accordingly, the radiopacifier may be clearly visible in X-ray images (e.g., fluoroscopy). This enables the cryoballoon protection device 416 to be easily positioned and/or repositioned at the desired location (e.g., at a specific distance distal to the cryoballoon 402) in the pulmonary-venous system.

[0089] In some variations, the size of the cryoballoon protection device 416 may be adjusted to allow for partial or complete occlusion of the structures adjacent to the site of occlusion from the cryoballoon 402. For example, the amount of inflation of the cryoballoon protection device 416 ( i.e the amount of inert gas used to fill the cryoballoon protection device 416) may determine the size of the cryoballoon protection device 416. Accordingly, the cryoballoon protection device 416 may be filled with lower amount of inert gas to allow for partial occlusion and the cryoballoon protection device 416 may be filled with higher amount of inert gas to allow for complete occlusion. The cryoballoon protection device 416 may assume a shape depending on the amount of inert gas in the cryoballoon protection device 416. Additionally or alternatively, the shape of the cryoballoon protection device 416 may depend on the size and/or shape of the pulmonary vein segment at which it is located. For example, an inflated cryoballoon protection device 416 may be disc shaped. Alternatively, an inflated cryoballoon protection device 416 may be spherical in shape. In some variations, complete occlusion of the structures adjacent to the site of occlusion may prevent hypothermic damage to structures distal to the site of occlusion (e.g., pulmonary vein segment 411”, pulmonary vein segment 411”, alveolo- venocapillary 413, alveoli 415, bronchi, and/or the like). [0090] The cryoballoon protection device 416 may be deflated after the cryoballoon-based ablation procedure. This allows the blood column to return to structures that are adjacent (e.g., pulmonary vein segment 41 G) to the distal portion 402b of the cryoballoon 402, thereby minimizing freezing and mitigating injury that may be caused to structures distal to the site of occlusion (e.g., since freezing of adjacent structure can lead to freezing of distal structure as discussed above).

[0091] In addition to preventing and/or mitigating undesirable freezing, the cryoballoon protection device 416 may provide further benefits. For example, the cryoballoon protection device 416 may significantly improve the sealing of the pulmonary vein ostium. Typically, cryoballoon-based ablation procedures take 4-5 applications per pulmonary vein owing to the limited ability of cryoballoon 402 to seal the pulmonary vein ostium. By sealing the pulmonary vein ostium using the cryoballoon protection device 416, the duration of cryoballoon-based ablation procedure and the number of applications may be significantly reduced. Furthermore, good sealing enables the blood column and the tissues adjacent to and/or surrounding the site of occlusion from the cryoballoon 402 to quickly arrive at freezing temperatures, thereby further reducing the duration of cryoballoon-based ablation procedure. In this manner, the cryoballoon protection device 416 may prevent structural and/or functional damage to structures in the pulmonary-venous system during cryoballoon-based ablation.

[0092] As seen in FIG. 4, in some variations, the cryoballoon protection device 416 may additionally be disposed along with a temperature probe 404 (e.g., structurally and/or functionally similar to temperature probe 204 in FIG. 2 and temperature probe 304 in FIG. 3).

As discussed above, the temperature probe 404 may be disposed such that it extends to structures that are distal to the site of occlusion. For example, the temperature probe 404 may extend from the distal portion 402b of the cryoballoon 402 to structures such as distal pulmonary vein segment 41 G”, alveolo-venocapillary interface 413, and alveoli 415 that are distal to the site of occlusion. The temperature sensors disposed on the temperature probe 404 may measure the temperature of structures that are distal to the site of occlusion. For example, the temperature sensors may be positioned such that at least one temperature sensor is disposed at close proximity to and/or in the vicinity of each of pulmonary vein segment 41 G”, alveolo- venocapillary 413, and alveoli 415 so as to measure the temperature at each of these structures.

In some variations, the temperature probe 404 may be disposed such that it extends to structures that are distal to the cryoballoon protection device 416. For example, the temperature probe 404 may be disposed such that at least some temperature sensors 406 disposed on the temperature probe 404 are positioned distal to the cryoballoon protection device 416.

[0093] In some variations, the temperature probe 404 may be positioned to extend to structures distal to the site of occlusion after the cryoballoon protection device 416 has been positioned distal to the cryoballoon 402. Alternatively, the temperature probe 404 may be positioned to extend to structures distal to the site of occlusion before the cryoballoon protection device 416 has been positioned distal to the cryoballoon 402. In some variations, the temperature probe 404 may be positioned before the inflation of the cryoballoon protection device 416. In such variations, the cryoballoon protection device 416 may be inflated based on the temperature measurements from the temperature probe 404. For example, if the temperature measurements of structures distal to the site of occlusion (e.g., pulmonary vein segment 41 G”, alveolo- venocapillary 413, and alveoli 415, etc.) fall below a threshold (e.g., temperature that freezes the blood column in these structures), the cryoballoon protection device 416 may be inflated (e.g., with an inert gas) to prevent freeze injury to these structures. Alternatively, the temperature probe 404 may be positioned after the inflation of the cryoballoon protection device 416. By using the cryoballoon protection device 416 and additionally monitoring the temperatures of structures that are distal to the site of occlusion using the temperature probe 404, any damages and/or injuries to these structures may be prevented.

Exemplary System

[0094] FIG. 5 is a schematic description of an exemplary variation of a system for assessing and mitigating hypothermal injury during a cryoballoon-based ablation procedure. The system may include a device 500 for performing the cryoballoon-based ablation procedure, optical system 536, processor 538, display 540, ablation energy source 542, imaging system 534, and a subject 501. The cryoballoon-based ablation procedure may be performed on the subject 501.

For example, the cryoballoon-based ablation procedure may be performed to treat arrhythmias, such as atrial defibrillation in the subject 501. The cryoballoon-based ablation procedure may be performed using a device 500. [0095] The device 500 may include a cryoballoon 502 (e.g., structurally and/or functionally similar to cryoballoon 202 in FIG. 2 and cryoballoon 402 in FIG. 4). The cryoballoon 502 may be steered and/or guided to a location in the pulmonary -venous system of the subject 501 for treating arrhythmia. For example, the cryoballoon 402 may be steered and/or guided to a pulmonary vein ostium in the subject 501. When inflated, cryoballoon 402 may freeze the blood column and the tissues adjacent to and/or surrounding the cryoballoon 402. The cooling effect may create lesion about the pulmonary vein ostium and/or the pulmonary vein antrum in the subject 501, thereby disrupting abnormal electrical signals in the pulmonary vein.

[0096] The device 500 may also include a cryoballoon protection device 516 (e.g., structurally and/or functionally similar to cryoballoon protection device 416 in FIG. 4) disposed distal to the cryoballoon 502 to prevent and/or mitigate hypothermal-injuries to structures in the pulmonary- venous system. The cryoballoon protection device 516 may be a balloon inflated with an inert gas. When inflated, the cryoballoon protection device 516 may prevent undesirable freezing of blood columns and/or tissues in structures distal to the site of occlusion from the cryoballoon 502. Additionally, the cryoballoon protection device 516 may improve the sealing of the pulmonary vein ostium and may reduce the duration of the cryoballoon-based ablation procedure. In some variations, the cryoballoon protection device 516 may include one or more radiopacifiers to enable visibility of a location and/or a position of the cryoballoon protection device 516.

[0097] The device 500 may also include a temperature probe 504 (e.g., structurally and/or functionally similar to temperature probe 204 in FIG. 2, temperature probe 304 in FIG. 3, and temperature probe 404 in FIG. 4). The temperature probe 504 may be configured to extend from a distal portion of the cryoballoon 502. The temperature probe 504 may extend to structures that are distal to the site of occlusion from the cryoballoon 502. In some variations, the temperature probe 504 may include one or more radiopacifiers to enable visibility of a location and/or a position of the temperature probe 504.

[0098] The temperature probe 504 may include temperature sensors that are positioned at close proximity to and/or in the vicinity of structures for which the temperature is to be monitored. In some variations, the temperature probe 504 may be positioned such that the temperature sensors included in the temperature probe 504 are at least at a distance of 5mm from the structure for which the temperature is to be monitored. In some variations, the distance between two adjacent temperature sensors included in the temperature probe 504 may be between 5mm to 15mm, such as 10mm. The temperature probe 504 may comprise optical waveguides, such as optical fibers. The optical waveguide (e.g., optical fiber) may comprise a core surrounded by a cladding, where the cladding has a different refractive index than the core to provide for total internal reflection within the optical fiber. Temperature sensors (e.g., fiber Bragg gratings (FBGs)) may be disposed on the optical waveguides. In some variations, the refractive index of the FBGs may vary along the length of the optical fiber in a periodic manner.

[0099] In some variations, the optical waveguide may be coupled to an optical sensor for measuring the temperature. The optical sensor may use any of various suitable optical techniques for temperature measurement, such as scattering of optical signals (e.g., Raman, Rayleigh, or Brillouin scattering, such as distributed temperature sensing (DTS), based on backscattering of optical signals) or reflection of optical signals (e.g., based on point or continuous fiber Bragg gratings (FBGs)). Alternatively, the optical waveguide itself may function as an optical sensor.

[0100] The temperature probe 504 may be optically coupled to an optical system 536. The optical system 536 may include a light source for introducing light into the temperature probe 504. The optical system 536 may also include an optical circulator. The light may be introduced into the temperature probe 504 via the optical circulator. The optical system 536 may also include a photodetector for receiving reflected light from the temperature probe 504 via the optical circulator. The photodetector may convert the reflected lights to electrical signals. In some variations, the optical system 536 may perform signal processing on the electrical signals (e.g., filtering, amplifying, and/or analog-to-digital converting) before transmitting the electrical signals to the processor 538. In other variations, the optical system 536 may transmit the electrical signals to the processor 538 without performing signal processing on the electrical signals. In some variations, the optical system 536 may also include optical splitters for splitting an optical signal for routing in different optical paths.

[0101] The imaging system 534 may capture images of internal organs (e.g., heart, lungs, etc.) in the subject 501. For example, the imaging system 534 may include an X-ray imaging system for performing fluoroscopy. The radiopacifiers included in the temperature probe 504 and the cryoballoon protection device 516 may inhibit penetration by X-ray signals from the imaging system 534. Therefore, the radiopacifiers may be clearly visible in the X-ray images. The imaging system 534 may transmit the X-ray images to a display 540 (to which it is communicably coupled). In some variations, the imaging system 534 may determine the position and/or orientation of the temperature probe 540. The imaging system may determine whether the position and/or orientation of the temperature probe 540 is appropriate in order to measure the temperature of the structures that are distal to the site of occlusion. The imaging system 534 may also determine the position of the cryoballoon protection device 516. For example, the imaging system 534 may determine the distance between the distal portion of the cryoballoon 502 and the cryoballoon protection device 516. The imaging system 534 may transmit some or all of this data to the display 540 and/or the processor 538. In some variations, the imaging system 534 may be configured to capture contiguous images of the internal organs. In some variations, the imaging system 534 may transmit the data in real-time to the display 540 and/or the processor 538.

[0102] The display 540 may display the X-ray images received from the imaging system 534. In some variations, the X-ray images may be displayed in real-time enabling an operator performing the cryoballoon-based ablation to position and/or reposition one or both of the temperature probe 540 and the cryoballoon protection device 516. In some variations, the position and/or the orientation of the temperature probe 540 may be displayed on the display 540. In some variations, the position of the cryoballoon protection device 516 may be displayed on the display 540. In some variations, temperature measurements received from the processor 534 may be displayed on the display 540. In still other variations, one or more warning signals (e.g., control signals) received from the processor 534 may be displayed on the display 540. For example, signals from the processor 534 may include a visual alarm (e.g., blinking lights), a text alert, etc. In some variations, the control signal may be a text alert instructing that the cryoballoon protection device 516 is to be inflated with inert gas. In some variations, the control signal may be a text alert warning an operator to shut down the ablation energy source 542. The ablation energy source 542 may comprise a liquid refrigerant (e.g., nitrous oxide) that can provide cryo energy to the cryoballoon 502.

[0103] The processor 534 may be communicably coupled to the imaging system 534, the display 540, the optical system 536, and the ablation energy source 542. The electrical signals transmitted from the optical system 536 may be analyzed by the processor 534 to determine the temperature at various locations within one or more structures in the subject 501. The electrical signals may be transformed to temperature measurements (e.g., in Celsius) that may be transmitted to the display 540 for display. In some variations, when the temperature measured within one or more structures falls below a threshold value, the processor 534 may instruct that the cryoballoon protection device 516 distal to the cryoballoon 502 be inflated with an inert gas. Additionally or alternatively, when the temperature measured within one or more structures falls below a threshold value, the processor 534 may automatically shut down the ablation energy source 542. In some variations, the processor 534 may transmit one or more control signals to one of the ablation energy source 542 and/or the display 542. The control signals may include a visual alarm or a text alert to notify an operator performing the cryoballoon-based ablation to halt the ablation procedure and/or make adjustments before resuming the procedure.

[0104] The processor 534 may be any suitable processing device configured to run and/or execute a set of instructions or code, and may include one or more data processors, image processors, graphics processing units, physics processing units, digital signal processors, and/or central processing units. The processor 534 may be, for example, a general purpose processor, a Field Programmable Gate Array (FPGA), an Application Specific Integrated Circuit (ASIC), and/or the like. The processor 534 may be configured to run and/or execute application processes and/or other modules, processes and/or functions associated with the system and/or a network associated therewith. The underlying device technologies may be provided in a variety of component types (e.g., MOSFET technologies like complementary metal-oxide semiconductor (CMOS), bipolar technologies like emitter-coupled logic (ECL), polymer technologies (e.g., silicon-conjugated polymer and metal-conjugated polymer-metal structures), mixed analog and digital, and/or the like.

Method of Performing Cryoballoon-Based Ablation

[0105] In some variations, a method for performing cryoballoon-based ablation may include positioning a temperature probe such that the temperature probe extends to one or more locations that are distal to the site of occlusion from a cryoballoon, and positioning a cryoballoon protection device distal to the cryoballoon. Positioning a Temperature Probe

[0106] Positioning a temperature probe (e.g., structurally and/or functionally similar to temperature probe 204 in FIG. 2, temperature probe 304 in FIG. 3, and temperature probe 404 in FIG. 4) may comprise guiding the temperature probe via one or more lumen(s) (e.g., structurally and/or functionally similar to lumen(s) 214 in FIG. 2 and lumen(s) 414 in FIG. 4) to locations that are distal to the site of occlusion from a cryoballoon. At least a portion of the lumen(s) may be disposed in the cryoballoon. For example, the temperature probe may be disposed through an elongate member such that the lumen(s) within the elongate member may extend the temperature probe from a distal portion of the cryoballoon to structures that are distal to the site of occlusion. The elongate member may be coupled to a proximal portion of the cryoballoon.

[0107] As discussed above, in some variations, one or more radiopacifiers may be disposed on the temperature probe. Accordingly, positioning the temperature probe may comprise analyzing image data of the temperature probe. For example, the image data may be analyzed to identify the position of the temperature sensors disposed on the temperature probe. If at least one temperature sensor is not in close proximity to a structure that is distal to the site of occlusion, then the temperature probe may be repositioned. For instance, the temperature probe may be repositioned such that at least one temperature sensor is now in close proximity to the structure that is distal to the site of occlusion.

[0108] In some variations, positioning the temperature probe may also comprise determining a position for the temperature probe based on temperature measurements obtained from the temperature probe. For example, the temperature probe may be positioned to extend to a first structure that is distal to a site of occlusion. If the temperature at this first structure is above a threshold value (i.e., the first structure is not freezing), then the temperature probe may be repositioned to retract back to a second structure that is proximal to the first structure.

Positioning Cryoballoon Protection Device

[0109] Positioning a cryoballoon protection device (e.g., structurally and/or functionally similar to cryoballoon protection device 416 in FIG. 4) may include positioning the cryoballoon protection device distal to a cryoballoon. The cryoballoon protection device may be inserted through a lumen(s) (e.g., structurally and/or functionally similar to lumen(s) 214 in FIG. 2 and lumen(s) 414 in FIG. 4) such that it is positioned distal to the cryoballoon. In some variations, the cryoballoon protection device may be positioned after the inflation of the cryoballoon. In other variations, the cryoballoon protection device may be positioned before the inflation of the cryoballoon.

[0110] The cryoballoon protection device may be inflated with an inert gas. The amount of inert gas and consequently the shape of the cryoballoon protection device may depend on the shape of the segment of the pulmonary vein at which the cryoballoon protection device is positioned. In some variations, positioning of the cryoballoon protection device may include sealing a pulmonary vein ostium using the cryoballoon protection device.

[0111] As discussed above, in some variations, one or more radiopacifiers may be disposed on the cryoballoon protection device. Accordingly, positioning the cryoballoon protection device may comprise analyzing image data of the cryoballoon protection device. For example, the image data may be analyzed to identify the position of the cryoballoon protection device with respect to the distal portion of the cryoballoon. If the distance between the cryoballoon protection device and the distal portion of the cryoballoon is not between the range of 3mm - 10mm, then the cryoballoon protection device may be repositioned so that the distance falls within the above specified range.

[0112] In some variations, positioning the cryoballoon protection device may include determining a position for the cryoballoon protection device based on temperature data of one or more segments in the pulmonary-venous system. For example, if the temperature data shows that at least some structures distal to the site of occlusion are above a threshold value (e.g., temperature value that freezes the blood column in these structures), then the cryoballoon protection device may be positioned and inflated to partially occlude a pulmonary vein (as opposed to complete occlusion). Alternatively, if the temperature data shows that at least some structures distal to the site of occlusion are below a threshold value (e.g., temperature value that freezes the blood column in these structures), then the cryoballoon protection device may be positioned and inflated to completely occlude a pulmonary vein. In some variations, positioning of the cryoballoon protection device may include inflating the cryoballoon protection device based on the temperature data of one or more segments of the pulmonary-venous system. For example, if the temperature data shows that at least some structures distal to the site of occlusion are below a threshold value (e.g., temperature value that freezes the blood column in these structures), then the cryoballoon protection device may be inflated with inert gas to prevent freeze injury to structures that are distal to the site of occlusion.

Method of Monitoring Temperature During Cryoballoon-based Ablation

[0113] FIG. 6 is a flow diagram of an exemplary variation of a method 600 for monitoring pulmonary-venous system temperature during cryoballoon-based ablation procedure performed on a subject. At 602, the method includes receiving temperatures at one or more locations from inside a pulmonary vein of the subject. As discussed above, a temperature probe (e.g., an optical fiber) may be disposed in the pulmonary vein such that it extends to one or more structures that are distal to a site of occlusion from a cryoballoon. Changes to the characteristic wavelengths of one or more fiber Braggs gratings (FBGs) disposed on the optical fiber may be analyzed to determine changes in temperature at the one or more structures. In some variations, receiving temperatures may include receiving electrical signals (e.g., from a photodetector) that are representative of reflected light from the optical fiber. In some variations, the method may further include performing signal processing on the electrical signals. The received electrical signals may be converted to temperature measurements.

[0114] At 604, the method includes determining whether one or more of the temperature measurements is below a threshold value. For example, determining whether the temperature is below a threshold value that permits freezing the blood column distal to the site of occlusion (e.g., distal to the cryoballoon protection device).

[0115] If it is determined that the temperature is lower than the threshold value, at 606, the method includes outputting a control signal. In some variations, the control signal may include instructions to inflate a protection device (e.g., cryoballoon protection device) distal to the cryoballoon with an inert gas. In some variations, the control signal may be transmitted to an ablation energy source. For example, the control signal may automatically trigger the ablation energy source to shut down. Alternatively, the control signal may be transmitted to a display. For example, the control signal may include an alert to adjust the cryoballoon-based ablation procedure or entirely shut down the cryoballoon-based ablation procedure. [0116] The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the invention. However, it will be apparent to one skilled in the art that specific details are not required in order to practice the invention. Thus, the foregoing descriptions of specific embodiments of the invention are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed; obviously, many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to explain the principles of the invention and its practical applications, they thereby enable others skilled in the art to utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the following claims and their equivalents define the scope of the invention.

Claims

1. A device for performing cryoablation of a tissue in a subject, the device comprising: an elongate member configured for insertion into a pulmonary vein of a subject; a cryoballoon coupled to the elongate member; and a temperature probe disposed via the elongate member and configured to extend from a distal portion of the cryoballoon.

2. The device of claim 1, wherein the cryoballoon is configured to occlude a site in the pulmonary vein.

3. The device of claim 2, wherein the temperature probe is configured to extend from the cryoballoon into at least one segment of the pulmonary vein of the subject, wherein the at least one segment is distal to the site of occlusion from the cryoballoon.

4. The device of claim 1, wherein a proximal portion of the cryoballoon is coupled to the elongate member.

5. The device of claim 1, wherein the device further includes: a lumen, wherein the lumen is configured to be moveable within the elongate member, and wherein at least a portion of the lumen is disposed within the cryoballoon.

6. The device of claim 5, wherein the temperature probe is disposed through the elongate member at a proximal portion of the cryoballoon so as to extend to the distal portion of the cryoballoon via at least the portion of the lumen.

7. The device of claim 5, wherein a second distal portion of the lumen includes an opening.

8. The device of claim 7, wherein the temperature probe is disposed into at least one segment of the pulmonary vein through the opening, wherein the at least one segment is distal to a site of occlusion from the cryoballoon.

9. The device of claim 1, wherein the temperature probe comprises at least one temperature sensor.

10. The device of claim 9, wherein the at least one temperature sensor is disposed in at least one segment of the pulmonary vein of the subject, wherein the at least one segment is distal to a site of occlusion from the cryoballoon.

11. The device of claim 10, wherein the temperature probe comprises an optical fiber.

12. The device of claim 11, wherein the at least one temperature sensor is disposed in the optical fiber.

13. The device of claim 12, wherein the at least one temperature sensor is a Fiber Bragg Grating (FBG).

14. The device of claim 13, wherein the FBG is disposed in a core of the optical fiber.

15. The device of claim 14, wherein the at least one temperature sensor includes a plurality of temperature sensors, and each temperature sensor of the plurality of temperature sensors is a respective individual FBG.

16. The device of claim 15, wherein each respective individual FBG is spaced along a length of the optical fiber.

17. The device of claim 16, wherein a refractive index of the core of the optical fiber varies in a periodic manner along the length of the optical fiber.

18. The device of claim 15, wherein each respective individual FBG has a different respective characteristic wavelength.

19. The device of claim 18, wherein a change in the respective characteristic wavelength of the each respective individual FBG is representative of a change in temperature.

20. The device of claim 15, wherein the temperature probe is disposed such that the each respective individual FBG is at a respective location in the at least one segment of the pulmonary vein.

21. The device of claim 15, further comprising: a cryoballoon protection device disposed distal to the cryoballoon, wherein the cryoballoon protection device is configured to be filled with an inert gas.

22. The device of claim 21, wherein a first temperature sensor of the plurality of temperature sensors measures the temperature of the at least one segment in the pulmonary vein, and wherein the cryoballoon protection device is configured to be filled with the inert gas based on the temperature of the at least one segment.

23. The device of claim 22, wherein the at least one segment is at least one of a alveolo- venocapillary junction, a secondary pulmonary vein, and a tertiary pulmonary vein.

24. A system including the device of claim 23, wherein the system further comprises: a processor communicably coupled to the temperature probe to determine a change in temperature of the at least one segment of the pulmonary vein based at least in part on a change in wavelength of at least a portion of the temperature probe.

25. The system of claim 24, wherein the processor is further configured to transmit a control signal to a display based at least in part on the change in temperature of the at least one segment.

26. The system of claim 25, wherein the control signal includes an instruction to inflate the cryoballoon protection device with the inert gas.

27. The system of claim 25, wherein the control signal includes an instruction to stop the cryoablation.

28. The system of claim 24, further comprising a display communicably coupled to the processor to display the change in temperature of the at least one segment of the pulmonary vein.

29. A device for mitigating damage to a pulmonary venous system of a subject during a cryoablation procedure, the device comprising: a cryoballoon configured to occlude a site in a pulmonary vein of the subject; and a cryoballoon protection device disposed distal to the cryoballoon, wherein the cryoballoon protection device is configured to be filled with an inert gas during the cryoablation procedure.

30. The device of claim 29, wherein the cryoballoon protection device is configured to mitigate injury to at least a portion of the pulmonary venous system.

31. The device of claim 30, wherein at least the portion of the pulmonary venous system is a segment of the pulmonary vein distal to the site of occlusion from the cryoballoon.

32. The device of claim 30, wherein at least the portion of the pulmonary venous system is an alveolar capillary interface.

33. The device of claim 29, wherein the cryoballoon protection device is configured to reduce a time taken to reach a freezing temperature at the site of occlusion during the cryoablation procedure.

34. The device of claim 29, wherein the cryoballoon protection device is configured to seal the site of occlusion during the cryoablation procedure.

35. The device of claim 29, wherein a shape of the cryoballoon protection device depends on a shape of the pulmonary vein at the site of occlusion.

36. The device of claim 29, wherein a shape of the cryoballoon protection device is spherical.

37. The device of claim 29, wherein a shape of the cryoballoon protection device is disc shaped.

38. The device of claim 29, wherein a size of the cryoballoon protection device depends on an amount of inert gas filled in the cryoballoon protection device.

39. The device of claim 29, wherein the inert gas is at least one of nitrogen and argon.

40. The device of claim 29, wherein the cryoballoon protection device comprises

Poly tetrafluoroethy 1 ene .

41. The device of claim 29, further comprising: a lumen, wherein at least a portion of the lumen is disposed within the cryoballoon.

42. The device of claim 41, wherein the cryoballoon protection device is disposed distal to the cryoballoon through the lumen.

43. The device of claim 41, wherein a distal portion of the lumen includes an opening.

44. The device of claim 43, wherein the cryoballoon protection device is disposed distal to the cryoballoon through the opening.

45. The device of claim 29, wherein the cryoballoon protection device is disposed distal to the cryoballoon after inflation of the cryoballoon inside the pulmonary vein of the subject.

46. The device of claim 29, wherein the cryoballoon protection device is disposed distal to the cryoballoon outside the subject before inflation of the cryoballoon.

47. The device of claim 29, further comprising: a temperature probe disposed via the cryoballoon and configured to extend from a first distal portion of the cryoballoon and a second distal portion of the cryoballoon protection device.

48. The device of claim 47, wherein the temperature probe is configured to extend into at least one segment of the pulmonary vein distal to the site of occlusion from the cryoballoon.

49. The device of claim 48, wherein the temperature probe comprises an optical fiber.

50. The device of claim 49, wherein the optical fiber includes a core, wherein a plurality of Fiber Bragg Gratings (FBGs) are disposed in the core along a length of the optical fiber.

51. The device of claim 50, wherein a refractive index of the core of the optical fiber varies in a periodic manner along the length of the optical fiber.

52. The device of claim 50, wherein each FBG of the plurality of FBGs has a different respective characteristic wavelength.

53. The device of claim 50, wherein the temperature probe is disposed such that each FBG of the plurality of FBGs is at a respective location in the at least one segment of the pulmonary vein.

54. A method for monitoring temperature within a pulmonary venous system of a subject during a cryoablation procedure, the method comprising: receiving, from a temperature probe, a temperature at a location inside a pulmonary vein of the subject, wherein the location is distal to a site of occlusion from a cryoballoon; determining whether the temperature is below a threshold; and in response to determining that the temperature is below the threshold, outputting a control signal to perform an action.

55. The method of claim 54, wherein the control signal is configured to shut down a cryoablation energy source.

56. The method of claim 54, wherein the temperature probe comprises an optical fiber.

57. The method of claim 56, wherein the optical fiber comprises a plurality of Fiber Bragg Gratings (FBGs).

58. The method of claim 54, further comprising outputting at least one signal representative of the temperature at the location inside the pulmonary vein.

59. The method of claim 58, wherein the at least one signal encodes at least one color-coded version of the temperature.

60. The method of claim 54, wherein the control signal is further configured to control a speaker to sound an audible alarm.

61. A method of performing cryoablation of a tissue in a subject, the method comprising: positioning a temperature probe such that the temperature probe extends to a first location distal to a site of occlusion from a cryoballoon; and positioning a cryoballoon protection device distal to the cryoballoon.

62. The method of claim 61, wherein the first location is a segment in a pulmonary vein, the method further comprising: repositioning the temperature probe based at least in part on image data of at least the segment.

63. The method of claim 62, wherein repositioning further comprises: determining the first location based at least in part on the image data; determining a second location of a temperature sensor included in the temperature probe based at least in part on the image data; and comparing the first location and the second location.

64. The method of claim 63, further comprising: identifying that the second location is not substantially close to the first location based on the comparison; and repositioning the temperature probe such that the temperature sensor is disposed at a third location, wherein the third location is in a vicinity of the first location.

65. The method of claim 61, wherein the temperature probe comprises an optical fiber.

66. The method of claim 65, wherein the optical fiber comprises a plurality of Fiber Bragg Gratings (FBGs).

67. The method of claim 66, further comprising: coupling the temperature probe with light; and analyzing temperature at the first location in the subject, wherein the temperature is determined based at least in part on light reflected from the temperature probe.

68. The method of claim 67, further comprising: in response to determining that the temperature is above a threshold, repositioning the temperature probe such that the temperature probe extends to a fourth location, wherein the fourth location is distal to the first location.

69. The method of claim 61, wherein positioning the temperature probe comprises positioning the temperature probe via a lumen, wherein at least a portion of the lumen is included in the cryoballoon.

70. The method of claim 61, wherein positioning the temperature probe further includes disposing the temperature probe through an elongate member, wherein the elongate member is coupled to the cryoballoon at a proximal portion of the cryoballoon.

71. The method of claim 61, wherein positioning the cryoballoon protection device includes positioning the cryoballoon protection device through the cryoballoon after inflation of the cryoballoon at the site of occlusion inside the subject.

72. The method of claim 61, wherein positioning the cryoballoon protection device includes disposing the cryoballoon protection device distal to the cryoballoon outside the subject before inflation of the cryoballoon.

73. The method of claim 61, wherein positioning the cryoballoon protection device includes inflating the cryoballoon protection device with an inert gas.

74. The method of claim 73, wherein positioning the cryoballoon protection device includes positioning the cryoballoon protection device at a fifth location, and wherein inflating the cryoballoon protection device includes inflating based at least in part on a shape of a pulmonary vein at the fifth location.

75. The method of claim 61, further comprising: repositioning the cryoballoon protection device based at least in part on an image data of a pulmonary vein, wherein the cryoballoon protection device is positioned in a segment of the pulmonary vein.

76. The method of claim 61, further comprising: repositioning the cryoballoon protection device based at least in part on a temperature data obtained from the temperature probe.

77. The method of claim 61, wherein positioning the cryoballoon protection device includes inflating the cryoballoon protection device so as to seal the site of occlusion during the cryoablation of the tissue.

78. The method of claim 61, wherein the first location is a segment in a pulmonary vein of the subject.

79. The method of claim 61, wherein the first location includes at least a portion of an alveolo-venular interface in the subject.

80. The method of claim 61, wherein positioning the cryoballoon protection device includes positioning the cryoballoon protection device at a distance between about 3 mm - 5 mm from the cryoballoon.