INTRAVASCULAR CATHETER SYSTEM

RELATED APPLICATION

[0001 ] This application claims priority on U.S. Provisional Application Serial No. 62/51 1 ,242, filed on May 25, 2017, and entitled "CRYOGENIC BALLOON CONTACT ASSESSMENT ASSEMBLY". As far as permitted, the contents of U.S. Provisional Application Serial No. 62/51 1 ,242 are incorporated in their entirety herein by reference.

BACKGROUND

[0002] Cardiac arrhythmias involve an abnormality in the electrical conduction of the heart and are a leading cause of stroke, heart disease, and sudden cardiac death. Treatment options for patients with arrhythmias include medications and/or the use of medical devices, which can include implantable devices and/or catheter ablation of cardiac tissue, to name a few. In particular, catheter ablation involves delivering ablative energy to tissue inside the heart to block aberrant electrical activity from depolarizing heart muscle cells out of synchrony with the heart's normal conduction pattern. The procedure is performed by positioning the tip of an energy delivery catheter adjacent to diseased or targeted tissue in the heart. The energy delivery component of the system is typically at or near the most distal (i.e. farthest from the user or operator) portion of the catheter, and often at the tip of the catheter.

[0003] Various forms of energy can be used to ablate diseased heart tissue. These can include radio frequency (RF), cryogenics, ultrasound and laser energy, to name a few. During a cryoablation procedure, with the aid of a guide wire, the distal tip of the catheter is positioned adjacent to targeted cardiac tissue, at which time energy is delivered to create tissue necrosis, rendering the ablated tissue incapable of conducting electrical signals. The dose of the energy delivered is a critical factor in increasing the likelihood that the treated tissue is permanently incapable of conduction. At the same time, delicate collateral tissue, such as the esophagus, the bronchus, and the phrenic nerve surrounding the ablation zone can be damaged and can lead to undesired complications. Thus, the operator must finely balance delivering therapeutic levels of energy to achieve intended tissue necrosis while avoiding excessive energy leading to collateral tissue injury.

[0004] Atrial fibrillation (AF) is one of the most common arrhythmias treated using catheter ablation. In the earliest stages of the disease, paroxysmal AF, the treatment strategy involves isolating the pulmonary veins from the left atrial chamber. Recently, the use of techniques known as "balloon cryotherapy" catheter procedures to treat AF has increased. In part, this stems from the balloon cryotherapy's ease of use, shorter procedure times and improved patient outcomes. Despite these advantages, there remains needed improvement to further improve patient outcomes and to better facilitate real-time physiological monitoring of tissue to optimally titrate energy to perform both reversible "ice mapping" and permanent tissue ablation.

[0005] The goal of balloon cryotherapy is to completely isolate one or more pulmonary veins of the patient by creating circumferential transmural lesions around an ostium of the pulmonary vein being treated. During balloon cryotherapy, a balloon is placed against the ostium of the pulmonary vein to occlude the pulmonary vein from blood flow. Pulmonary vein occlusion is typically a strong indicator that complete circumferential contact is achieved between the balloon and ostium of the pulmonary vein for optimal heat transfer during ablation. Thus, the ability of the operator to assess the quality of balloon contact with the ostium can help to provide more effective lesion creation and, consequently, more effective tissue isolation and ablation.

[0006] One common method physicians are currently using to help gauge the quality of vein occlusion is to inject contrast into the pulmonary vein while using fluoroscopy. If good vein occlusion exists, the contrast will remain in the pulmonary vein, and not leak around the balloon into the atrium. If a leak is present, i.e. if the contrast moves into the atrium, then the physician can adjust the position of the balloon relative to the targeted cardiac tissue. The physician will then need to repeat the contrast injection to verify vein occlusion. Unfortunately, multiple attempts at vein occlusion are too often necessary with this method. This is particularly true when trying to occlude veins that have challenging anatomy such as the right inferior pulmonary vein and veins with a common ostium. Such increased fluoroscopy time can be detrimental because it increases the patient's exposure to radiation. Additionally, such method is not satisfactory for all patients because contrast injections are undesirable for patients who have diseased or compromised kidneys since these injections can cause kidney failure. Accordingly, it is desired to develop an improved method for gauging the quality of vein occlusion during balloon cryotherapy procedures.

SUMMARY

[0007] The present invention is directed toward an intravascular catheter system used to treat a condition relative to a blood vessel in a body. In various embodiments, the intravascular catheter system includes a balloon catheter and a contact assessment assembly. The balloon catheter includes a balloon assembly that includes a first balloon having a balloon interior. The contact assessment assembly includes (i) a pressure sensor that senses a balloon pressure within the balloon interior and provides sensor output; and (ii) an interface that provides one of visual and auditory information regarding the balloon pressure based at least in part on the sensor output.

[0008] In some embodiments, the balloon assembly further includes a second balloon that substantially encircles the first balloon. Alternatively, in other embodiments, the balloon assembly further includes a second balloon that is substantially encircled by the first balloon.

[0009] Additionally, in certain embodiments, the pressure sensor is positioned within the balloon interior. [0010] Alternatively, in other embodiments, the pressure sensor is positioned outside of the balloon interior. In some such embodiments, the intravascular catheter system further includes a handle assembly that is configured to be used by an operator to control the balloon catheter. In such embodiments, the pressure sensor can be positioned within the handle assembly. Further, in such embodiments, the contact assessment assembly can further include a tubular member that extends from the pressure sensor to the balloon interior so that the tubular member transmits the balloon pressure to the pressure sensor.

[0011 ] In some embodiments, the interface provides information regarding a position of the first balloon relative to the blood vessel based on the sensor output. Further, in such embodiments, the first balloon can be movable between (i) a non- contact position, where the balloon assembly is spaced apart from an ostium of the blood vessel in the body, and (ii) a contact position, where the balloon assembly is in contact with the ostium of the blood vessel in the body. In certain such embodiments, the pressure sensor senses a non-contact balloon pressure when the balloon assembly is in the non-contact position; and the pressure sensor senses a contact balloon pressure when the balloon assembly is in the contact position. Additionally, the contact balloon pressure can be greater than the non-contact balloon pressure by a pressure difference. For example, in one non-exclusive embodiment, the blood vessel is considered to be occluded when the pressure difference is at least approximately three percent. In another non-exclusive embodiment, the blood vessel is considered to be occluded when the pressure difference is at least approximately five percent. In still another non-exclusive embodiment, the blood vessel is considered to be occluded when the pressure difference is at least approximately eight percent. In yet another non-exclusive embodiment, the blood vessel is considered to be occluded when the pressure difference is at least approximately ten percent.

[0012] Additionally, in certain embodiments, the intravascular catheter system further includes a control system including a processor; wherein the sensor output is transmitted from the pressure sensor to the control system via a transmission line. In some such embodiments, the control system receives the sensor output; and the control system controls the interface to provide the one of visual and auditory information regarding the balloon pressure based at least in part on the sensor output.

[0013] In one embodiment, the interface includes an alpha-numeric scale. In another embodiment, the interface includes a plurality of colors that indicate the position of the first balloon within the body.

[0014] In another application, the present invention is directed toward an intravascular catheter system used to treat a condition relative to a blood vessel in a body, the intravascular catheter system including (A) a balloon catheter including a balloon assembly that includes a first balloon having a balloon interior; and (B) a contact assessment assembly including (i) a pressure sensor that senses a balloon pressure within the balloon interior and provides sensor output that relates to a position of the first balloon relative to the blood vessel in the body; and (ii) an interface that provides one of visual and auditory information regarding the balloon pressure based at least in part on the position of the first balloon relative to the blood vessel in the body.

[0015] In still another application, the present invention is further directed toward a method for treating a condition relative to a blood vessel in a body, the method including providing a balloon catheter including a balloon assembly that includes a first balloon having a balloon interior; sensing a balloon pressure within the balloon interior with a pressure sensor; providing a sensor output with the pressure sensor based on the balloon pressure; and providing one of visual and auditory information regarding the balloon pressure with an interface that is based at least in part on the sensor output.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which:

[0017] Figure 1 is a simplified schematic side view illustration of a patient and one embodiment of an intravascular catheter system including a balloon contact assessment assembly having features of the present invention;

[0018] Figure 2A is a simplified schematic side view illustration of a portion of the patient and a portion of an embodiment of the intravascular catheter system including a balloon catheter illustrated in a non-contact position and one embodiment of the balloon contact assessment assembly;

[0019] Figure 2B is a simplified schematic side view illustration of a portion of the patient and a portion of an embodiment of the intravascular catheter system including the balloon catheter illustrated in a contact position and the balloon contact assessment assembly illustrated in Figure 2A;

[0020] Figure 3 is a simplified schematic side view illustration of a portion of the patient and a portion of an embodiment of the intravascular catheter system including the balloon catheter illustrated in the contact position and another embodiment of the balloon contact assessment assembly;

[0021 ] Figure 4 is a simplified schematic side view illustration of a portion of the patient and a portion of an embodiment of the intravascular catheter system including the balloon catheter illustrated in the contact position and yet another embodiment of the balloon contact assessment assembly;

[0022] Figure 5 is a simplified schematic side view illustration of a portion of the patient and a portion of an embodiment of the intravascular catheter system including the balloon catheter illustrated in the contact position and still another embodiment of the balloon contact assessment assembly;

[0023] Figure 6 is a representative graph depicting balloon pressure versus time of the intravascular catheter system in the non-contact position and the contact position;

[0024] Figure 7A is an illustration of one embodiment of a contact position indicator, showing the intravascular catheter system in both the non-contact position and the contact position; and

[0025] Figure 7B is an illustration of another embodiment of the contact position indicator, showing the intravascular catheter system in both the non-contact position and the contact position. DESCRIPTION

[0026] Embodiments of the present invention are described herein in the context of a balloon contact assessment assembly (also sometimes referred to herein as a "contact assessment assembly") for use within an intravascular catheter system. In particular, in various embodiments, the contact assessment assembly can include a pressure sensor that senses a balloon pressure within a balloon interior of a balloon of the intravascular catheter system and provides a sensor output, and a graphical display (or interface) that provides information to an operator regarding the balloon pressure that is based, at least in part, on the sensor output. Additionally, or in the alternative, the sensor output can relate to the position of the balloon relative to a blood vessel (or tissue) in a body of a patient, and the graphical display (or interface) can provide information to the operator regarding the balloon pressure that is based, at least in part, on the position of the balloon relative to the blood vessel (or tissue) in the body of the patient.

[0027] Those of ordinary skill in the art will realize that the following detailed description of the present invention is illustrative only and is not intended to be in any way limiting. Other embodiments of the present invention will readily suggest themselves to such skilled persons having the benefit of this disclosure. Reference will now be made in detail to implementations of the present invention as illustrated in the accompanying drawings.

[0028] In the interest of clarity, not all of the routine features of the implementations described herein are shown and described. It will, of course, be appreciated that in the development of any such actual implementation, numerous implementation-specific decisions must be made in order to achieve the developer's specific goals, such as compliance with application-related and business-related constraints, and that these specific goals will vary from one implementation to another and from one developer to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking of engineering for those of ordinary skill in the art having the benefit of this disclosure.

[0029] Although the disclosure provided herein focuses mainly on cryogenics, it is understood that various other forms of energy can be used to ablate diseased heart tissue. These can include radio frequency (RF), ultrasound and laser energy, as non-exclusive examples. The present invention is intended to be effective with any or all of these and other forms of energy.

[0030] Figure 1 is a simplified schematic side view illustration of an embodiment of a medical device 10 for use with a patient 12, which can be a human being or an animal. Although the specific medical device 10 illustrated and described herein pertains to and refers to an intravascular catheter system 10 such as a cryogenic balloon catheter system, it is understood and appreciated that other types of medical devices 10 or systems can equally benefit by the teachings provided herein. For example, in certain non-exclusive alternative embodiments, the present invention can be equally applicable for use with any suitable types of ablation systems and/or any suitable types of catheter systems. Thus, the specific reference herein to use as part of an intravascular catheter system is not intended to be limiting in any manner.

[0031 ] The design of the intravascular catheter system 10 can be varied. In certain embodiments, such as the embodiment illustrated in Figure 1 , the intravascular catheter system 10 can include one or more of a control system 14 (illustrated in phantom), a fluid source 16 (illustrated in phantom), a balloon catheter 18, a handle assembly 20, a control console 22, a graphical display 24 (or "interface"), and a balloon contact assessment assembly 26 (also sometimes referred to herein as a "contact assessment assembly").

[0032] It is understood that although Figure 1 illustrates the structures of the intravascular catheter system 10 in a particular position, sequence and/or order, these structures can be located in any suitably different position, sequence and/or order than that illustrated in Figure 1 . It is also understood that the intravascular catheter system 10 can include fewer or additional components than those specifically illustrated and described herein.

[0033] In various embodiments, the control system 14 is configured to monitor and control various processes of the ablation procedure. More specifically, the control system 14 can monitor and control release and/or retrieval of a cooling fluid 28 (e.g., a cryogenic fluid) to and/or from the balloon catheter 18. The control system 14 can also control various structures that are responsible for maintaining and/or adjusting a flow rate and/or pressure of the cryogenic fluid 28 that is released to the balloon catheter 18 during the cryoablation procedure. In such embodiments, the intravascular catheter system 10 delivers ablative energy in the form of cryogenic fluid 28 to cardiac tissue of the patient 12 to create tissue necrosis, rendering the ablated tissue incapable of conducting electrical signals. Additionally, in various embodiments, the control system 14 can control activation and/or deactivation of one or more other processes of the balloon catheter 18. Further, or in the alternative, the control system 14 can receive data and/or other information (hereinafter sometimes referred to as "sensor output") from various structures within the intravascular catheter system 10 and/or from the contact assessment assembly 26. In some embodiments, the control system 14 can receive, monitor, assimilate and/or integrate the sensor output, and/or any other data or information received from any structure within the intravascular catheter system 10 in order to control the operation of the balloon catheter 18. As provided herein, in various embodiments, the control system 14 can initiate and/or terminate the flow of cryogenic fluid 28 to the balloon catheter 18 based on the sensor output. Still further, or in the alternative, the control system 14 can control positioning of portions of the balloon catheter 18 within the body of the patient 12, and/or can control any other suitable functions of the balloon catheter 18.

[0034] The fluid source 16 contains the cryogenic fluid 28, which is delivered to the balloon catheter 18 with or without input from the control system 14 during a cryoablation procedure. Once the ablation procedure has initiated, the cryogenic fluid 28 can be delivered to the balloon catheter 18 and the resulting gas, after a phase change, can be retrieved from the balloon catheter 18, and can either be vented or otherwise discarded as exhaust. Additionally, the type of cryogenic fluid 28 that is used during the cryoablation procedure can vary. In one non-exclusive embodiment, the cryogenic fluid 28 can include liquid nitrous oxide. However, any other suitable cryogenic fluid 28 can be used. For example, in one non-exclusive alternative embodiment, the cryogenic fluid 28 can include liquid nitrogen.

[0035] The design of the balloon catheter 18 can be varied to suit the specific design requirements of the intravascular catheter system 10. As shown, the balloon catheter 18 is inserted into the body of the patient 12 during the cryoablation procedure. In one embodiment, the balloon catheter 18 can be positioned within the body of the patient 12 using the control system 14. Stated in another manner, the control system 14 can control positioning of the balloon catheter 18 within the body of the patient 12. Alternatively, the balloon catheter 18 can be manually positioned within the body of the patient 12 by a healthcare professional (also referred to herein as an "operator"). As used herein, a healthcare professional and/or an operator can include a physician, a physician's assistant, a nurse and/or any other suitable person and/or individual. In certain embodiments, the balloon catheter 18 is positioned within the body of the patient 12 utilizing at least a portion of the sensor output that is received by the control system 14. For example, in various embodiments, the sensor output is received by the control system 14, which can then provide the operator with information regarding the positioning of the balloon catheter 18. Based at least partially on the sensor output feedback received by the control system 14, the operator can adjust the positioning of the balloon catheter 18 within the body of the patient 12 to ensure that the balloon catheter 18 is properly positioned relative to targeted cardiac tissue (not shown). While specific reference is made herein to the balloon catheter 18, as noted above, it is understood that any suitable type of medical device and/or catheter may be used.

[0036] The handle assembly 20 is handled and used by the operator to operate, position and control the balloon catheter 18. The design and specific features of the handle assembly 20 can vary to suit the design requirements of the intravascular catheter system 10. In the embodiment illustrated in Figure 1 , the handle assembly 20 is separate from, but in electrical and/or fluid communication with the control system 14, the fluid source 16, the graphical display 24, and the contact assessment assembly 26. In some embodiments, the handle assembly 20 can integrate and/or include at least a portion of the control system 14 within an interior of the handle assembly 20. It is understood that the handle assembly 20 can include fewer or additional components than those specifically illustrated and described herein.

[00373] In various embodiments, the handle assembly 20 can be used by the operator to initiate and/or terminate the cryoablation process, e.g., to start the flow of the cryogenic fluid 28 to the balloon catheter 18 in order to ablate certain targeted heart tissue of the patient 12. In certain embodiments, the control system 14 can override use of the handle assembly 20 by the operator. Stated in another manner, in some embodiments, based at least in part on the sensor output, the control system 14 can terminate the cryoablation process without the operator using the handle assembly 20 to do so.

[0038] The control console 22 is coupled to the balloon catheter 18 and the handle assembly 20. Additionally, in the embodiment illustrated in Figure 1 , the control console 22 includes at least a portion of the control system 14, the fluid source 16, the graphical display 24, and the contact assessment assembly 26. However, in alternative embodiments, the control console 22 can contain additional structures not shown or described herein. Still alternatively, the control console 22 may not include various structures that are illustrated within the control console 22 in Figure 1 . For example, in certain non-exclusive alternative embodiments, the control console 22 does not include the graphical display 24.

[0039] In various embodiments, the graphical display 24 is electrically connected to the control system 14 and the contact assessment assembly 26. Further, in some such embodiments, as described in greater detail herein below, the graphical display 24 can be utilized and/or incorporated as part of the contact assessment assembly 26. Additionally, the graphical display 24 provides the operator of the intravascular catheter system 10 with information that can be used before, during and after the cryoablation procedure. For example, the graphical display 24 can provide the operator with information based on the sensor output, and any other relevant information that can be used before, during and after the cryoablation procedure. The specifics of the graphical display 24 can vary depending upon the design requirements of the intravascular catheter system 10, or the specific needs, specifications and/or desires of the operator.

[0040] In one embodiment, the graphical display 24 can provide static visual data and/or information to the operator. In addition, or in the alternative, the graphical display 24 can provide dynamic visual data and/or information to the operator, such as video data or any other data that changes over time, e.g., during an ablation procedure. Further, in various embodiments, the graphical display 24 can include one or more colors, different sizes, varying brightness, etc., that may act as alerts to the operator. Additionally, or in the alternative, the graphical display 24 can provide audio data or information to the operator.

[0041 ] As an overview, and as provided in greater detail herein, the contact assessment assembly 26 can sense and/or monitor a balloon pressure within a portion of the balloon catheter 18. Further, the contact assessment assembly 26 can provide pressure data and/or information to other structures, within the intravascular catheter system 10, e.g., the control system 14, which can be used to control various functions of the intravascular catheter system 10 as described herein.

[0042] Figure 2A is a simplified schematic side view illustration of a portion of one embodiment of the intravascular catheter system 210 and a portion of a patient 212. In the embodiment illustrated in Figure 2A, the intravascular catheter system 210 includes one or more of a control system 214 (illustrated in phantom), a fluid source 216 (illustrated in phantom), a balloon catheter 218, a handle assembly 220, a control console 222, a graphical display 224, and a contact assessment assembly 226. As shown in Figure 2A, the balloon catheter 218 is in a non-contact position.

[0043] The control system 214 is configured to control various functions of the intravascular catheter system 210. As shown in Figure 2A, in certain embodiments, the control system 214 can be positioned substantially within the control console 222. Alternatively, at least a portion of the control system 214 can be positioned in one or more other locations within the intravascular catheter system 210, e.g., within the handle assembly 220. In one embodiment, the control system 214 can control various functions of the remainder of the intravascular catheter system 210 based at least in part on data or other information received by the control system 214, as provided in greater detail herein.

[0044] The design of the balloon catheter 218 can be varied to suit the design requirements of the intravascular catheter system 210. In this embodiment, the balloon catheter 218 includes one or more of a guidewire 230, a guidewire lumen 232, a catheter shaft 234, an inner balloon 236 and an outer balloon 238. Additionally, the inner balloon 236 defines an inner balloon interior 239. It is recognized that the inner balloon 236 and the outer balloon 238 can also be referred to as a "first balloon" and a "second balloon", and that either balloon 236, 238 can be the first balloon or the second balloon. Alternatively, the balloon catheter 218 can be configured to include only a single balloon. It is also understood that the balloon catheter 218 can include other structures as well. However, for the sake of clarity, these other structures have been omitted from the Figures.

[0045] As shown in the embodiment illustrated in Figure 2A, the balloon catheter 218 is configured to be positioned within the circulatory system 240 of the patient 212. The guidewire 230 and guidewire lumen 232 are inserted into a pulmonary vein 242 (also referred to herein generally as a "blood vessel" or "tissue") of the patient 212, and the catheter shaft 234 and the balloons 236, 238 are moved along the guidewire 230 and/or the guidewire lumen 232 to near an ostium 244 of the pulmonary vein 242. In general, it is the object of the balloon catheter 218 to seal the pulmonary vein 242 so that blood flow is occluded. Only when occlusion is achieved does the cryothermic energy, e.g., of the cryogenic fluid 28 (illustrated in Figure 1 ), cause tissue necrosis which, in turn, provides for electrically blocking aberrant electrical signals that trigger atrial fibrillation.

[0046] In the embodiment illustrated in Figure 2A, the outer balloon 238 of the balloon catheter 218 is illustrated spaced apart from the ostium 244 of the pulmonary vein 242. Stated another way, in Figure 2A, the balloon catheter 218 and/or the balloons 236, 238 are not contacting the ostium 244, and are not occluding the pulmonary vein 242. As such, the balloon catheter 218 and/or the balloons 236, 238 can be said to be in the non-contact position.

[0047] As shown, the guidewire lumen 232 encircles at least a portion of the guidewire 230. During use, the guidewire 230 is inserted into the guidewire lumen 232 and can course through the guidewire lumen 232 and extend out of a distal end 232A of the guidewire lumen 232. In various embodiments, the guidewire 230 can also include a mapping catheter (not shown) that maps electrocardiograms in the heart, and/or can provide information needed to position at least portions of the balloon catheter 218 within the patient 212.

[0048] As illustrated in this embodiment, the inner balloon 236 is positioned substantially, if not completely, within the outer balloon 238. The specific design of and materials used for each of the balloons 236, 238 can be varied. For example, in some non-exclusive embodiments, the balloons 236, 238 can be formed from one or more of various grades of polyether block amides (PEBA), polyurethane, polyethylene terephthalate (PET), nylon, and other co-polymers of these materials. Alternatively, the balloons 236, 238 can be formed from other suitable materials.

[0049] Additionally, in some embodiments, one end of the inner balloon 236 is bonded to a distal end 234A of the catheter shaft 234, and the other end of the inner balloon 236 is bonded near the distal end 232A of the guidewire lumen 232. Further, one end of the outer balloon 238 may be bonded to a neck of the inner balloon 236 or to the distal end 234A of the catheter shaft 234, and the other end of the outer balloon 238 may be bonded to the guidewire lumen 232. It is appreciated that a variety of bonding techniques can be used and include heat bonding and adhesive bonding. Additionally, it is further appreciated that in embodiments that include only a single balloon, the balloon can be secured to the catheter shaft 234 and the guidewire lumen 232 in a similar manner. Alternatively, the balloons 236, 238 can be secured to other suitable structures.

[0050] During use, the inner balloon 236 can be partially or fully inflated so that at least a portion of the inner balloon 236 expands against at least a portion of the outer balloon 238. Stated in another manner, during use of the balloon catheter 218, at least a portion of an outer surface 236A of the inner balloon 236 expands and is positioned substantially directly against a portion of an inner surface 238A of the outer balloon 238. At certain times during usage of the intravascular catheter system 210, the inner balloon 236 and the outer balloon 238 define an inter-balloon space 246, or gap, between the balloons 236, 238. The inter-balloon space 246 is illustrated between the inner balloon 236 and the outer balloon 238 in Figure 2A for clarity, although it is understood that at certain times during usage of the intravascular catheter system 210, the inter-balloon space 246 has very little or no volume. As provided herein, once the inner balloon 236 is sufficiently inflated, an outer surface 238B of the outer balloon 238 can then be positioned within the circulatory system 240 of the patient 212 to abut and/or substantially form a seal with the ostium 244 of the pulmonary vein 242 to be treated. At such time, the balloon catheter 218 and/or the balloons 236, 238 can be said to be in a contact position. Thus, as provided herein, the balloon catheter 218 and/or the balloons 236, 238 can be said to be movable between a non-contact position and a contact position, i.e. relative to the ostium 244 of the pulmonary vein 242. [0051 ] The design of the handle assembly 220 can vary. In the embodiment illustrated in Figure 2A, the handle assembly 220 can include circuitry 248 that can form a portion of the control system 214. Alternatively, the circuitry 248 can transmit electrical signals such as the sensor output or otherwise provide data to the control system 214 as described herein. Additionally, or in the alternative, the circuitry 248 can receive sensor output or other signals from the contact assessment assembly 226. In one embodiment, the circuitry 248 can include a printed circuit board having one or more integrated circuits, or any other suitable circuitry. In an alternative embodiment, the circuitry 248 can be omitted, or can be included within the control system 214, which in various embodiments can be positioned outside of the handle assembly 220, e.g., within the control console 222.

[0052] In the embodiment illustrated in Figure 2A, the contact assessment assembly 226 senses and/or monitors a balloon pressure inside the inner balloon 236, i.e. within the inner balloon interior 239. As used herein, the "balloon pressure" means the pressure inside the inner balloon 236 at or substantially contemporaneously with the time the pressure in the inner balloon interior 239 is measured. In the embodiment illustrated in Figure 2A, the contact assessment assembly 226 can transmit electrical signals to the circuitry 248, which can then be processed and sent to the control system 214, as appropriate. In an alternative embodiment, the contact assessment assembly 226 can transmit electrical signals directly to the control system 214. The design of the contact assessment assembly 226 can be varied. In the embodiment illustrated in Figure 2A, the contact assessment assembly 226 includes one or more of a pressure sensor 250, a transmission line 252 and an interface 254.

[0053] It is appreciated that in certain embodiments, the interface 254 can be included as part of the graphical display 224. Alternatively, the interface 254 can be provided independently of the graphical display 224.

[0054] In this embodiment, the pressure sensor 250 is positioned in the inner balloon interior 239. With this design, the pressure sensor 250 can directly sense, measure and/or monitor the balloon pressure within the inner balloon 236, i.e. within the inner balloon interior 239. The pressure sensor 250 sends a sensor output, e.g., electrical signals regarding the balloon pressure, to the circuitry 248 and/or the control system 214 via the transmission line 252. The control system 214 can then cause a visual display on the interface 254, or can cause an auditory output from the interface 254. As described in greater detail herein, the operator can use the visual display information and/or the auditory output from the interface 254 to determine whether the requisite occlusion between the balloon catheter 218 and the ostium 244 and/or other anatomical parts of the patient 212 has occurred. Further, based on the information received from the interface 254, the operator can abort the delivery of cryogenic fluid 28 (illustrated in Figure 1 ), can increase the fluid flow rate to get more cooling, reduce the flow rate of the cryogenic fluid 28 and/or have an initial flow rate to reduce temperature to a set point then change the flow rate to maintain a set temperature. Additionally, the operator can change the cycle time or amount of fluid delivery to and from the inner balloon 236. Further, the operator can determine when to initiate flow of cryogenic fluid 28.

[0055] As noted herein above, in Figure 2A, the balloons 236, 238 are shown in a non-contact position. As such, when the balloons 236, 238 are in the non- contact position, the pressure sensor 250 senses, measures and/or monitors a non- contact balloon pressure within the inner balloon interior 239.

[0056] The specific type of pressure sensor 250 included in the contact assessment assembly 226 can vary. For example, in some embodiments, the pressure sensor 250 can include a "MEMS" sensor or an optical pressure detector, as non-exclusive examples. Alternatively, any other suitable type of pressure sensor 250 can be used.

[0057] Figure 2B is a simplified schematic side view illustration of a portion of one embodiment of the intravascular catheter system 210, and a portion of the patient 212. In particular, Figure 2B again illustrates the one or more of a control system 214, the fluid source 216, the balloon catheter 218, the handle assembly 220, the control console 222, the graphical display 224 and the contact assessment assembly 226 of the intravascular catheter system 210. As shown in Figure 2B, the balloon catheter 218 is now in a contact position. Stated in another manner, in Figure 2B, the balloon catheter 218 is contacting the ostium 244, and is occluding the pulmonary vein 242.

[0058] In this embodiment, to assess the extent of contact/occlusion between the balloon catheter 218 and the ostium 244 and/or other parts of the circulatory system 240 of the patient 212, the balloon pressure inside of the inner balloon 236, i.e. within the inner balloon interior 239, is monitored. As provided in greater detail herein, when the balloon catheter 218 is in the contact position (as shown in Figure 2B), the balloon pressure within the inner balloon interior 239 is greater than the initial, non-contact balloon pressure when the balloon catheter 218 is in the non- contact position (as shown in Figure 2A). Stated in another manner, with other factors remaining unchanged, a contact balloon pressure is greater than a non- contact balloon pressure.

[0059] In the contact position illustrated in Figure 2B, the outer balloon 238 and/or the inner balloon 236 are deformed due to contact of the outer balloon 238 with the ostium 244 (or other portion of the circulatory system 240 of the patient 212). The ideal gas law PV=NRT shows that as the volume in the outer balloon 238 and/or the inner balloon 236 is reduced, the balloon pressure inside of the inner balloon 236, i.e. within the inner balloon interior 239, will increase. Thus, by monitoring the balloon pressure within the inner balloon interior 239, i.e. with the contact assessment assembly 226, the operator is able to determine when contact has been achieved between the balloons 236, 238 and the ostium 244, and when occlusion of the pulmonary vein 242 has been achieved. As such, the contact assessment assembly 226 can also be said to be sensing, measuring and/or monitoring a position of the balloon catheter 218 and/or the balloons 236, 238 within the body of the patient 212.

[0060] The pressure difference between the non-contact balloon pressure and the contact balloon pressure that is indicative of the achievement of good occlusion of the pulmonary vein can be varied. For example, in certain non-exclusive alternative embodiments, the pressure difference between the non-contact balloon pressure and the contact balloon pressure that is indicative of good occlusion can be between approximately two percent (2%) and fifteen percent (15%). Stated in another manner, in such embodiments, good occlusion is indicated when the contact balloon pressure is between approximately two percent and fifteen percent higher than the previously measured (baseline) non-contact balloon pressure. More particularly, in such embodiments, the pressure difference between the non-contact balloon pressure and the contact balloon pressure that is indicative of good occlusion can be approximately two percent (2%), three percent (3%), four percent (4%), five percent (5%), six percent (6%), seven percent (7%), eight percent (8%), nine percent (9%), ten percent (10%), eleven percent (1 1 %), twelve percent (12%), thirteen percent (13%), fourteen percent (14%) or fifteen percent (15%). Alternatively, the pressure difference between the non-contact balloon pressure and the contact balloon pressure that is indicative of good occlusion can be greater than fifteen percent or less than two percent.

[0061 ] It is appreciated, however, that a pressure difference that is too low can allow for fluids to pass between the balloons 236, 238 and the ostium 244 of the pulmonary vein 242, thereby not enabling the creation of circumferential transmural lesions around the ostium 244 of the pulmonary vein 242 being treated. Additionally, it is further appreciated that a pressure difference that is too high can potential result in unwanted distortion of the balloons 236, 238 and/or the pulmonary vein 242, and/or can unnecessarily utilize more energy than is necessary.

[0062] Figure 3 is a simplified schematic side view illustration of a portion of another embodiment of the intravascular catheter system 310, and a portion of the patient 312. In the embodiment illustrated in Figure 3, the intravascular catheter system 310 includes one or more of a control system 314, a fluid source 316, a balloon catheter 318, a handle assembly 320, a control console 322, a graphical display 324, and a contact assessment assembly 326. As shown in Figure 3, the balloon catheter 318 is in a contact position. Stated in another manner, in Figure 3, the balloon catheter 318 is contacting the ostium 344, and is occluding the pulmonary vein 342.

[0063] The control system 314, the fluid source 316, the control console 322 and the graphical display 324 are substantially similar in design and function to what was illustrated and described herein above. Accordingly, such components will not be described again in detail.

[0064] The design of the balloon catheter 318 can be varied to suit the design requirements of the intravascular catheter system 310. In this embodiment, the balloon catheter 318 includes one or more of a guidewire 330, a guidewire lumen 332, a catheter shaft 334, an inner balloon 336 and an outer balloon 338. It is understood that the balloon catheter 318 can include other structures as well. However, for the sake of clarity, these other structures have been omitted from the Figures. In the embodiment illustrated in Figure 3, the balloon catheter 318 is positioned within the circulatory system 340 of the patient 312. The guidewire 330 is inserted into a pulmonary vein 342 of the patient 312, and the catheter shaft 334 and the balloons 336, 338 are moved along the guidewire 330 to near an ostium 344 of the pulmonary vein 342.

[0065] In the embodiment illustrated in Figure 3, the inner balloon 336 and the outer balloon 338 are substantially similar to those previously described herein. Further, the functioning of the inner balloon 336 and the outer balloon 338 is substantially similar to that previously described herein. The inner balloon 336 defines an inner balloon interior 339.

[0066] The design of the handle assembly 320 can vary. In the embodiment illustrated in Figure 3, the handle assembly 320 can include circuitry 348 that can form a portion of the control system 314. In this embodiment, the circuitry 348 can function substantially similarly to the circuitry previously described herein. In an alternative embodiment, the circuitry 348 can be omitted, or the circuitry 348 can be included within the control system 314, which in various embodiments can be positioned outside of the handle assembly 320.

[0067] As with the previous embodiment, the contact assessment assembly 326 senses and/or monitors a balloon pressure inside the inner balloon 336, i.e. within the inner balloon interior 339. As used herein, the "balloon pressure" means the pressure inside the inner balloon 336 at or substantially contemporaneously with the time the pressure in the inner balloon interior 339 is measured. In the embodiment illustrated in Figure 3, the contact assessment assembly 326 can transmit electrical signals, e.g. sensor output, to the circuitry 348, which are then processed and sent to the control system 314. In an alternative embodiment, the contact assessment assembly 326 can transmit electrical signals directly to the control system 314. The design of the contact assessment assembly 326 can be varied. In the embodiment illustrated in Figure 3, the contact assessment assembly 326 includes a pressure sensor 350, a transmission line 352, a tubular member 353 that defines a sensor lumen 356 (an interior of the tubular member 353), and an interface 354.

[0068] It is appreciated that in certain embodiments, the interface 354 can be included as part of the graphical display 324. Alternatively, the interface 354 can be provided independently of the graphical display 324.

[0069] In certain embodiments, the pressure sensor 350 is positioned outside of the inner balloon interior 339. For example, in the embodiment illustrated in Figure 3, the pressure sensor 350 is positioned within the handle assembly 320. Alternatively, the pressure sensor 350 can be positioned anywhere between the inner balloon 336 and the handle assembly 320. Still alternatively, the pressure sensor 350 can be positioned between the handle assembly 320 and the control system 314.

[0070] In the embodiment illustrated in Figure 3, the tubular member 353 extends from the pressure sensor 350 to the inner balloon interior 339. The pressure sensor 350 is in fluid communication with the inner balloon interior 339 via the tubular member 353. The tubular member 353 can be a relatively small diameter tube that can transmit the balloon pressure within the inner balloon interior 339 directly to the pressure sensor 350. The pressure sensor 350 then sends a sensor output, e.g., electrical signals regarding the balloon pressure, to the circuitry 348 and/or the control system 314 via the transmission line 352. The control system 314 can then cause a visual display on the interface 354, or can cause an auditory output from the interface 354. As described in greater detail herein, the operator can use the visual display information and/or the auditory output from the interface 354 to determine whether the requisite occlusion between the balloon catheter 318 and the ostium 344 and/or other anatomical parts of the patient 312 has occurred. Further, based on the information received from the interface 354, the operator can abort the delivery of cryogenic fluid 28 (illustrated in Figure 1 ), can increase the fluid flow rate to get more cooling, reduce the flow rate of the cryogenic fluid 28 and/or have an initial flow rate to reduce temperature to a set point then change the flow rate to maintain a set temperature. The operator can change the cycle time or amount of fluid delivery to and from the inner balloon 336. Additionally, the operator can determine when to initiate flow of cryogenic fluid 28.

[0071 ] The specific type of pressure sensor 350 included in the contact assessment assembly 322 can vary. For example, in some embodiments, the pressure sensor 350 can include a "MEMS" sensor or an optical pressure detector, as non-exclusive examples. Alternatively, another suitable type of pressure sensor 350 can be used.

[0072] Figure 4 is a simplified schematic side view illustration of a portion of yet another embodiment of the intravascular catheter system 410, and a portion of the patient 412. In the embodiment illustrated in Figure 4, the intravascular catheter system 410 includes one or more of a control system 414, a fluid source 416, a balloon catheter 418, a handle assembly 420, a control console 422, a graphical display 424, and a contact assessment assembly 426. As shown in Figure 4, the balloon catheter 418 is in a contact position. Stated in another manner, in Figure 4, the balloon catheter 418 is contacting the ostium 444, and is occluding the pulmonary vein 442.

[0073] In this embodiment, the intravascular catheter system 410 is substantially similar to that previously described relative to Figure 3. In particular, the control system 414, the fluid source 416, the balloon catheter 418 including the inner balloon 436 and the outer balloon 438, the handle assembly 420, the control console 422 and the graphical display 424 are substantially similar to those previously described herein.

[0074] Further, the functioning of the inner balloon 436 and the outer balloon 438 is substantially similar to that previously described herein. In this embodiment, a region or gap between the inner balloon 436 and the outer balloon 438 defines an inter-balloon space 446. It is appreciated that the inter-balloon space 446 is also a portion of an outer balloon interior 457.

[0075] In the embodiment illustrated in Figure 4, the contact assessment assembly 426 senses and/or monitors a balloon pressure inside the inter-balloon space 446 and/or within the outer balloon interior 457 (and not within the inner balloon). As used in this embodiment, the "balloon pressure" means the pressure inside the outer balloon 438 at or substantially contemporaneously with the time the pressure in the outer balloon interior 457 is measured. In the embodiment illustrated in Figure 4, the contact assessment assembly 426 can transmit electrical signals, e.g. sensor output, to the circuitry 448, which are then processed and sent to the control system 414. In an alternative embodiment, the contact assessment assembly 426 can transmit electrical signals directly to the control system 414. The design of the contact assessment assembly 426 can be varied. In the embodiment illustrated in Figure 4, the contact assessment assembly 426 includes a pressure sensor 450, a transmission line 452, a tubular member 453 that defines a sensor lumen 456 (an interior of the tubular member 453), and an interface 454.

[0076] It is appreciated that in certain embodiments, the interface 454 can be included as part of the graphical display 424. Alternatively, the interface 454 can be provided independently of the graphical display 424.

[0077] In certain embodiments, the pressure sensor 450 is positioned outside of the inter-balloon space 446 and/or the outer balloon interior 457. For example, in the embodiment illustrated in Figure 4, the pressure sensor 450 is positioned within the handle assembly 420. Alternatively, the pressure sensor 450 can be positioned anywhere between the outer balloon 438 and the handle assembly 420. Still alternatively, the pressure sensor 450 can be positioned between the handle assembly 420 and the control system 414.

[0078] Somewhat similar to the embodiment described relative to Figure 3, in this embodiment, the pressure sensor 450 then sends a sensor output, e.g., electrical signals regarding the balloon pressure, to the circuitry 448 and/or the control system 414 via the transmission line 452. The control system 414 can then cause a visual display on the interface 454, or can cause an auditory output from the interface 454. As described in greater detail herein, the operator can use the visual display information and/or the auditory output from the interface 454 to determine whether the requisite occlusion between the balloon catheter 418 and the ostium 444 and/or other anatomical parts of the patient 412 has occurred. Further, based on the information received from the interface 454, the operator can abort the delivery of cryogenic fluid 28 (illustrated in Figure 1 ), can increase the fluid flow rate to get more cooling, reduce the flow rate of the cryogenic fluid 28 and/or have an initial flow rate to reduce temperature to a set point then change the flow rate to maintain a set temperature. The operator can change the cycle time or amount of fluid delivery to and from the inner balloon 436. Additionally, the operator can determine when to initiate flow of cryogenic fluid 28. [0079] The specific type of pressure sensor 450 included in the contact assessment assembly 426 can vary. For example, in some embodiments, the pressure sensor 450 can include a "MEMS" sensor or an optical pressure detector, as non-exclusive examples. Alternatively, any other suitable type of pressure sensor 450 can be used.

[0080] Figure 5 is a simplified schematic side view illustration of a portion of still another embodiment of the intravascular catheter system 510, and a portion of the patient 512. In the embodiment illustrated in Figure 5, the intravascular catheter system 510 includes one or more of a control system 514, a fluid source 516, a balloon catheter 518, a handle assembly 520, a control console 522, a graphical display 524, and a contact assessment assembly 526. As shown in Figure 5, the balloon catheter 518 is in a contact position. Stated in another manner, in Figure 5, the balloon catheter 518 is contacting the ostium 544, and is occluding the pulmonary vein 542.

[0081 ] With the exception of the contact assessment assembly 526, the remaining structures are substantially similar to those previously described relative to Figure 2B. For example, the control system 514, the fluid source 516, the balloon catheter 518 including the inner balloon 536 and the outer balloon 538, the handle assembly 520, the control console 522 and the graphical display 524 are substantially similar to those previously described herein.

[0082] Further, the functioning of the inner balloon 536 and the outer balloon 538 is substantially similar to that previously described herein. In this embodiment, a region or gap between the inner balloon 536 and the outer balloon 538 defines an inter-balloon space 546. It is appreciated that the inter-balloon space 546 is also a portion of an outer balloon interior 557.

[0083] However, in the embodiment illustrated in Figure 5, the contact assessment assembly 526 senses and/or monitors a balloon pressure inside the inter-balloon space 546 and/or within the outer balloon interior 557. As used in this embodiment, the "balloon pressure" means the pressure inside the outer balloon 538 at or substantially contemporaneously with the time the pressure in the outer balloon interior 557 is measured. In the embodiment illustrated in Figure 5, the contact assessment assembly 526 can transmit electrical signals, e.g. sensor output, to the circuitry 548, which are then processed and sent to the control system 514. In an alternative embodiment, the contact assessment assembly 526 can transmit electrical signals directly to the control system 514. The design of the contact assessment assembly 526 can be varied. In the embodiment illustrated in Figure 5, the contact assessment assembly 526 includes one or more of a pressure sensor 550, a transmission line 552 and an interface 554.

[0084] It is appreciated that in certain embodiments, the interface 554 can be included as part of the graphical display 524. Alternatively, the interface 554 can be provided independently of the graphical display 524.

[0085] In this embodiment, the pressure sensor 550 is positioned in the inter- balloon space 546 between the inner balloon 536 and the outer balloon 538. With this design, the pressure sensor 550 can directly sense, measure and/or monitor the balloon pressure within the outer balloon 538. The pressure sensor 550 sends a sensor output, e.g., electrical signals regarding the balloon pressure, to the circuitry 548 and/or the control system 514 via the transmission line 552. The control system 514 can then cause a visual display on the interface 554, or can cause an auditory output from the interface 554. As described in greater detail herein, the operator can use the visual display information and/or the auditory output from the interface 554 to determine whether the requisite occlusion between the balloon catheter 518 and the ostium 544 and/or other anatomical parts of the patient 512 has occurred. Further, based on the information received from the interface 554, the operator can abort the delivery of cryogenic fluid 28 (illustrated in Figure 1 ), can increase the fluid flow rate to get more cooling, reduce the flow rate of the cryogenic fluid 28 and/or have an initial flow rate to reduce temperature to a set point then change the flow rate to maintain a set temperature. The operator can change the cycle time or amount of fluid delivery to and from the inner balloon 536. Additionally, the operator can determine when to initiate flow of cryogenic fluid 28.

[0086] The specific type of pressure sensor 550 included in the contact assessment assembly 526 can vary. For example, in some embodiments, the pressure sensor 550 can include a "MEMS" sensor or an optical pressure detector, as non-exclusive examples. Alternatively, any other suitable type of pressure sensor 550 can be used. [0087] Operation

[0088] During operation, in various embodiments, while the balloon catheter is in the non-contact position, the operator pressurizes the inner balloon between a pressure of greater than approximately 0.5 psi and less than approximately 8.0 psi. The balloon catheter is then moved into position against the ostium of the pulmonary vein to be treated (for PV isolation) or against the atrial wall. Once the operator finds the position acceptable, he/she can begin the cryoablation. The pressure inside of the inner balloon and/or outer balloon (depending upon the specific embodiment) while the balloon catheter is in the non-contact position (i.e. the non-contact balloon pressure) is to remain static. Thus, movement of cryogenic fluid to or from the inner balloon should be inhibited. This can be accomplished by any known methods, such as by using a solenoid valve to inhibit delivery of cryogenic fluid to the inner balloon and exhaust of cryogenic fluid from the balloon. However, any suitable method for doing so can be utilized for this purpose. The pressure inside the inner balloon or the outer balloon (depending upon the embodiment) is monitored using any one of the embodiments previously described herein. The data is then displayed onto the interface. Once an increase in pressure has met or exceeded a predetermined threshold, the operator can conclude that the requisite level of occlusion has occurred, and the cryogenic fluid can be delivered to the balloon catheter as needed.

[0089] Figure 6 is a representative graph depicting experimental results of balloon pressure versus time of the intravascular catheter system in the non-contact position and the contact position. In this experiment, initial non-contact balloon pressure within one of the balloons of the balloon catheter was approximately 2.80 psi. The contact balloon pressure within the same balloon of the balloon catheter increased to approximately 3.03 psi. This increase was determined to be significant, and provides the operator with sufficient data to determine that adequate (or complete) occlusion has occurred. In this embodiment, the interface described previously herein can visually provide a similar graph to the operator in real-time so the operator can determine that adequate (or complete) occlusion has occurred. Thus, depending upon the extent of the increase in balloon pressure, the operator can determine (or the control system 14 can determine) that sufficient occlusion has occurred. In one embodiment, if the balloon pressure has increased by a predetermined amount or percentage, adequate occlusion can be presumed to have occurred.

[0090] Figure 7A illustrates another embodiment of at least a portion of an interface 754A that includes a contact position indicator 760A (shown in two alternate positions in Figure 7A). In this embodiment, the contact position indicator 760A includes instrumentation in the form of a dial. Further, in this embodiment, the interface 754A includes an alpha-numerical value system that can provide the necessary occlusion information to the operator. In the embodiment in Figure 7A, if the contact position indicator 760A is within a non-contact range 762 (in the 0-6 range in this example), adequate occlusion is not occurring. Once the contact position indicator 760 rotates (shown by arrow 763) is within a contact range 764 (in the 6-10 range in this example), adequate occlusion is occurring.

[0091 ] Figure 7B illustrates another embodiment of at least a portion of an interface 754B that includes a contact position indicator 760B (shown in two alternate positions in Figure 7B). In this embodiment, the contact position indicator 760B also includes instrumentation in the form of a dial. However, in this embodiment, no alpha-numeric scale is provided. Rather, delineation of various contact zones can be provided by any other suitable means. For example, the interface can include a plurality of different colored zones, such as a red zone 766 (no occlusion), a yellow zone 768 (partial occlusion), and a green zone 770 (full occlusion). Any colors or symbols can be used for the various zones. Further, any number of zones can be used.

[0092] In non-exclusive alternative embodiments, the interface can include one or more lights or other visual identifiers, or sounds (different tones, pitches, frequencies, etc.) that indicate whether adequate occlusion is occurring or not occurring.

[0093] It is understood that although a number of different embodiments of the intravascular catheter system 10 and the cryogenic balloon contact assessment assembly 26 have been illustrated and described herein, one or more features of any one embodiment can be combined with one or more features of one or more of the other embodiments, provided that such combination satisfies the intent of the present invention.

[0094] While a number of exemplary aspects and embodiments of a intravascular catheter system 10 and the cryogenic balloon contact assessment assembly 26 have been discussed above, those of skill in the art will recognize certain modifications, permutations, additions and sub-combinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are within their true spirit and scope.