Patent Description:
The human heart routinely experiences electrical impulses traversing its many surfaces and ventricles, including the endocardial chamber. As part of each heart contraction, the heart depolarizes and repolarizes, as electrical currents spread across the heart and throughout the body. In healthy hearts, the surfaces and ventricles of the heart will experience an orderly progression of depolarization waves. In unhealthy hearts, such as those experiencing atrial arrhythmia, including for example, ectopic atrial tachycardia, atrial fibrillation, and atrial flutter, the progression of the depolarization wave becomes chaotic. Arrhythmias may persist as a result of scar tissue or other obstacles to rapid and uniform depolarization. These obstacles may cause depolarization waves to electrically circulate through some parts of the heart more than once. Atrial arrhythmia can create a variety of dangerous conditions, including irregular heart rates, loss of synchronous atrioventricular contractions, and blood flow stasis. All of these conditions have been associated with a variety of ailments, including death.

Catheters are used in a variety of diagnostic and/or therapeutic medical procedures to correct conditions such as atrial arrhythmia, including for example, ectopic atrial tachycardia, atrial fibrillation, and atrial flutter.

Typically in a procedure, a catheter is manipulated through a patient's vasculature to, for example, a patient's heart, and carries one or more electrodes which may be used for mapping, ablation, diagnosis, or other treatments. Where an ablation therapy is desired to alleviate symptoms including atrial arrhythmia, an ablation catheter imparts ablative energy to cardiac tissue to create a lesion in the cardiac tissue. The lesioned tissue is less capable of conducting electrical impulses, thereby disrupting undesirable electrical pathways and limiting or preventing stray electrical impulses that lead to arrhythmias. The ablation catheter may utilize ablative energy including, for example, radio frequency (RF), cryoablation, laser, chemical, and high-intensity focused ultrasound. As readily apparent, such an ablation treatment requires precise positioning of the ablation catheter for optimal results.

Typically, ablation therapies have been delivered by making a number of individual ablations in a controlled fashion in order to form a lesion line. Such lesion lines are often desirable around/between the pulmonary veins in the left atrium of the heart which have been associated with the introduction of erratic electric impulses into the heart. There are devices in development or being commercialized that attempt to achieve a sufficient lesion line with minimal applications of energy. Existing designs range from diagnostic catheters with a hoop and balloon mounted designs with energy applying or extracting features. The existing designs often suffer from a lack of continuous contact around a circumference of the pulmonary vein during therapy delivery, resulting in inconsistent lesion lines and incomplete electrical impulse blockage.

The foregoing discussion is intended only to illustrate the present field and should not be taken as a disavowal of claim scope.

<CIT> relates to medical devices comprising first and second balloons, wherein the first balloon may include a proximal waist coupled to an outer surface of a first tubular member.

<CIT> relates to a cryotherapy system including a cryotherapy catheter having an inflatable balloon portion and a pressure regulator.

<CIT> relates to a method and system for treating cardiac conditions, wherein a medical devide has an adjustable treatment element.

<CIT> relates to improved apparatus and methods for cryogenically treating a lesion within a patient's vasculature to inhibit hyperplasia.

<CIT> relates to EP catheters for mapping and/or ablation in the heart.

<CIT> relates to cardiac catheterization by using a probe having a balloon assembly.

<CIT> relates to an elongated catheter device with a distal balloon assembly adapted for endovascular insertion.

<CIT> relates to a neurosurgical apparatus comprising a plurality of tubes for insertion into the brain.

<CIT> relates to tubing utilized for medical purposes and in particular providing perforated tubing suitable for surgical drainage and the like.

Dependent claims relate to exemplary embodiments.

The instant disclosure relates to electrophysiology catheters for tissue ablation within a cardiac muscle. In particular, the instant disclosure relates to an electrophysiology catheter including a dual-layer ablation balloon that contains a cryogenic fluid for administering an ablation therapy on a pulmonary vein.

Aspects of the present disclosure are directed to an ablation catheter system including a catheter shaft including proximal and distal ends, dual cryogenic ablation balloons coupled to the distal end of the catheter shaft, an interstitial space between the inner and outer balloons, a manifold, and a first and second lumen in fluid communication with the interstitial space. The dual cryogenic ablation balloons include inner and outer balloons. The interstitial space captures cryogenic fluid that escapes from an internal cavity of the inner balloon. The manifold delivers cryogenic fluid to the internal cavity of the inner balloon. In some more specific embodiments, the first lumen is a vacuum lumen that draws a vacuum within the interstitial space and further draws captured cryogenic fluid out of the interstitial space and into the vacuum lumen.

Various embodiments of the present disclosure are directed to a dual-layer ablation balloon that includes an inner balloon including an internal cavity, an outer balloon that encapsulated the inner balloon, an interstitial space between the inner and outer balloons, and a spacer coupled between proximal portions of the inner and outer balloons. The internal cavity of the inner balloon receives a cryogenic fluid in a liquid state and facilitates a state transfer of the cryogenic fluid into a gaseous state. The spacer maintains the interstitial space between the inner and outer balloons in response to a vacuum pressure within the interstitial space. In some specific embodiments, the interstitial space is configured and arranged to capture cryogenic fluid that escapes from the internal cavity of the inner balloon.

Some embodiments of the present disclosure are directed to a dual-layer ablation balloon including an inner balloon including an internal cavity, an outer balloon that encapsulates the inner balloon, an interstitial space between the inner and outer balloons, and an adaptor that mechanically couples the inner and outer balloons to a catheter shaft, and radially and longitudinally offsets proximal portions of the inner and outer balloons. The internal cavity of the inner balloon receives a cryogenic fluid in a liquid state and facilitates a state transfer of the cryogenic fluid into a gaseous state. In specific embodiments, the dual-layer ablation balloon further includes a first lumen in fluid communication with the interstitial space. The first lumen draws a vacuum within the interstitial space and further draws captured cryogenic fluid out of the interstitial space and into the vacuum lumen.

The foregoing and other aspects, features, details, utilities, and advantages of the present disclosure will be apparent from reading the following description and claims, and from reviewing the accompanying drawings.

Various example embodiments may be more completely understood in consideration of the following detailed description in connection with the accompanying drawings.

It should be understood, however, that the intention is not to limit the scope to the particular embodiments described.

The instant disclosure relates to electrophysiology catheters for tissue ablation within a cardiac muscle. In particular, the instant disclosure relates to an electrophysiology catheter including a dual-layer ablation balloon that contains a cryogenic fluid for administering an ablation therapy on a pulmonary vein. Details of the various embodiments of the present disclosure are described below with specific reference to the figures.

Referring now to the drawings wherein like reference numerals are used to identify similar components in the various views, <FIG> is a schematic and diagrammatic view of a catheter ablation system <NUM> for performing tissue ablation procedures. In an exemplary embodiment, tissue <NUM> comprises cardiac tissue (e.g., myocardial tissue) within a human body <NUM>. It should be understood, however, that the system may find application in connection with a variety of other tissue within human and non-human bodies, and therefore, the present disclosure is not meant to be limited to the use of the system in connection with only cardiac tissue and/or human bodies.

Catheter ablation system <NUM> may include a catheter <NUM> and an ablation subsystem <NUM> for controlling an ablation therapy conducted by an ablation balloon <NUM> at a distal end <NUM> of the catheter <NUM>. The ablation subsystem <NUM> may control the generation and/or application of ablative energy including, in the present embodiment, cryoablation.

In the exemplary embodiment of <FIG>, catheter <NUM> is provided for examination, diagnosis, and/or treatment of internal body tissue such as myocardial tissue <NUM>. The catheter may include a cable connector or interface <NUM>, a handle <NUM>, a shaft <NUM> having a proximal end <NUM> and a distal end <NUM> (as used herein, "proximal" refers to a direction toward the end of the catheter <NUM> near the handle <NUM>, and "distal" refers to a direction away from the handle <NUM>), and an ablation balloon <NUM> coupled to the distal end <NUM> of the catheter shaft <NUM>.

In an exemplary embodiment, ablation balloon <NUM> is manipulated through vasculature of a patient <NUM> using handle <NUM> to steer one or more portions of shaft <NUM> and position the ablation balloon at a desired location within tissue <NUM> (e.g., a cardiac muscle). In the present embodiment, the ablation balloon includes one or more cryoablation manifolds that, when operated by ablation subsystem <NUM>, ablates the tissue in contact with the ablation balloon (and in some cases tissue in proximity to the ablation balloon may be ablated by thermal transfer through the blood pool and to the proximal tissue).

In various specific embodiments of the present disclosure, catheter <NUM> may include electrophysiology electrodes and one or more positioning sensors (e.g., ring electrodes or magnetic sensors) at a distal end <NUM> of catheter shaft <NUM>. In such an embodiment, the electrophysiology electrodes acquire electrophysiology data relating to cardiac tissue <NUM> in contact with the electrodes, while the positioning sensor(s) generate positioning data indicative of the <NUM>-D position of the ablation balloon <NUM> within patient <NUM>. In further embodiments, the catheter <NUM> may further include other conventional catheter components such as, for example and without limitation, steering wires and actuators, irrigation lumens and ports, pressure sensors, contact sensors, temperature sensors, additional electrodes, and corresponding conductors or leads.

Connector <NUM> provides mechanical and electrical connection(s) for one or more cables <NUM> extending, for example, from ablation subsystem <NUM> (through catheter handle <NUM> and shaft <NUM>) to ablation balloon <NUM> mounted on a distal end <NUM> of the catheter shaft <NUM>. The connector <NUM> may also provide mechanical, electrical, and/or fluid connections for cables <NUM> extending from other components in catheter system <NUM>, such as, for example, irrigation subsystem <NUM> (when the catheter <NUM> is an irrigated catheter), vacuum/leak detection subsystem <NUM>, and an electrical monitoring system <NUM>. The vacuum/leak detection subsystem <NUM> may be used to both draw spent cryogenic gas from the ablation balloon <NUM>, and to determine whether a leak has developed in an interstitial space between a dual layer balloon (as discussed in more detail in reference to <FIG>). The connector <NUM> is conventional in the art and is disposed at a proximal end of the catheter handle <NUM>.

Handle <NUM> provides a location for a clinician to hold catheter <NUM>, and may further provide steering or guidance for the shaft <NUM> within patient's body <NUM>. For example, in the present embodiment, the handle includes two actuators <NUM>A-B which facilitate manipulation of a distal end <NUM> of the shaft to steer the shaft in two perpendicularly extending planes. The handle <NUM> also includes a slider <NUM>C which facilitates longitudinal manipulation of an inner shaft relative to an outer shaft (as discussed in more detail in reference to <FIG>). In other embodiments, control of the catheter may be automated by robotically driving or controlling the catheter shaft, or driving and controlling the catheter shaft using a magnetic-based (and/or impedance-based) guidance system.

Catheter shaft <NUM> is an elongated, tubular, and flexible member configured for movement within a patient's body <NUM>. The shaft supports an ablation balloon <NUM> at a distal end <NUM> of catheter <NUM>. The shaft may also permit transport, delivery and/or removal of fluids (including irrigation fluids, cryogenic fluids, and body fluids), medicines, and/or surgical tools or instruments. The shaft, which may be made from conventional materials used for catheters, such as polyurethane, defines one or more lumens configured to house and/or transport electrical conductors, fluids, and/or surgical tools. The catheter may be introduced into a blood vessel or other structure within the body through a conventional introducer sheath.

In an exemplary cardiac ablation therapy, to correct for atrial arrhythmia, the introducer sheath is introduced through a peripheral vein (typically a femoral vein) and advanced into the right atrium. In what is referred to as a transseptal approach, the introducer sheath then makes an incision in the fossa ovalis (the tissue wall between the left and right atriums), extends through the incision in the fossa ovalis, and may be anchored thereto. The ablation catheter may then be extended through a lumen of the introducer sheath into the left atrium. Catheter shaft <NUM> of ablation catheter <NUM> may then be steered, or otherwise guided (e.g., via guidewire which extends through a guidewire lumen that extends through a length of the ablation catheter), through the left atrium to position an ablation balloon <NUM> into a desired location within the left atrium (e.g., a pulmonary vein).

During cardiac ablation therapy, it is desirable to align the longitudinal axis of ablation balloon <NUM> with a centerline of a target pulmonary vein at which the ablation therapy is to take place. Proper alignment may be particularly difficult, in many embodiments, due to the transseptal approach through the fossa ovalis which causes catheter shaft <NUM> to be biased toward a right-side of a patient's body <NUM>. This bias places an additional torque on ablation catheter system <NUM>, which may result in the ablation balloon <NUM>, after alignment with the pulmonary vein, to bias away from the centerline of the pulmonary vein. Where the ablation balloon is deployed and extended into contact with the pulmonary vein, but off-axis from the pulmonary vein, the ablation balloon may unevenly contact the pulmonary vein resulting in non-circumferential ablation of the pulmonary vein tissue.

Various embodiments of the present disclosure are directed to ablation therapy of one or more pulmonary veins via cryoablation. To achieve the desired cooling within the ablation balloon <NUM>, cryogenic fluid (also referred to as cryofluid) delivered to the balloon must sufficiently expand within the balloon to phase change from a liquid to a gas. The phase change of the cryofluid requires a large amount of energy which has a cooling effect in proximity to the phase change. As the cryofluid expands to its gaseous state, the pressure within the balloon increases. Aspects of the present disclosure are directed to controlling the pressure within the ablation balloon <NUM>. Further, aspects of the present disclosure are directed to safety features intended to prevent and/or sense a cryogenic fluid leak. For example, embodiments of the present disclosure are directed to a dual-layer balloon with an interstitial space therebetween. Where the inner balloon ruptures (or otherwise leaks cryogenic fluid), the outer balloon contains the cryogenic fluid to prevent a leak of cryofluid into the cardiovascular system of the patient. Where a leak of cryogenic fluid into the interstitial space occurs, a vacuum source which may be fluidly coupled to the interstitial space via a lumen extending a length of the catheter shaft <NUM> will experience a reduced vacuum state. A vacuum/leak detection subsystem <NUM> (including the vacuum source) will receive a signal indicative of the reduced vacuum state and take corrective action. For example, the vacuum/leak detection subsystem <NUM> may abort the ablation therapy by shutting one or more valves or delivery paths that deliver the cryofluid to the balloon <NUM>. In more specific embodiments, other actions may be taken to quickly alleviate pressure within the balloon; for example, dumping the head pressure and/or exhaust pressure.

Aspects of the present disclosure improve the efficacy of the various ablation balloon safety features by reducing pressure sensing lag times, allowing for more timely preventative measures in response to a leak/rupture event of the inner balloon-reducing the likelihood of a dual-balloon failure.

<FIG> is a cross-sectional side view of one implementation of an ablation catheter <NUM> of the catheter system <NUM> shown in <FIG>. In the present embodiment, a distal end of the ablation catheter <NUM> includes a balloon <NUM> that may be delivered and inflated near a target portion of a patient's body via the cardio-vasculature system. The balloon <NUM> may be stored during delivery within an interstitial space between inner shaft <NUM> and delivery sheath <NUM> (also referred to as a steerable catheter sheath). Pull wires <NUM>A-D, extending a length of the outer sheath <NUM>, and coupled to one or more pull rings <NUM> near a distal end of the ablation catheter <NUM> facilitate positioning of the distal portion of the catheter in proximity to the target. A handle <NUM> of ablation catheter <NUM> may include rotary actuators <NUM>A-B which facilitate manipulation of the pull wires <NUM>A-D, and thereby steer a distal end of the sheath <NUM>. To facilitate deployment of the ablation balloon <NUM>, a clinician, upon arriving at the target location, may manipulate linear actuator 161c (also referred to as a slider) to extend a distal end of inner shaft <NUM> out of sheath <NUM> (as shown in <FIG>).

Once the ablation balloon <NUM>, coupled to inner shaft <NUM>, has extended out of the sheath <NUM>, the balloon may be inflated and extended into contact with tissue targeted for ablation (e.g., an ostium of a pulmonary vein).

A proximal end of ablation catheter <NUM> may include a cable connector or interface <NUM> coupled to handle <NUM> which facilitates coupling the ablation catheter <NUM> to other elements of the catheter system <NUM> (e.g., irrigation subsystem <NUM>, vacuum/leak detection subsystem <NUM>, and electrical monitoring system <NUM>, as shown in <FIG>) via cables <NUM>.

<FIG> is a cross-sectional front-view of a portion of cardiac muscle <NUM> with an ablation balloon catheter <NUM> locating a pulmonary vein (e.g., <NUM>, <NUM>, <NUM>, and <NUM>) for performing therapy for a cardiac arrhythmia, such as atrial fibrillation. As shown in <FIG>, the cardiac muscle <NUM> includes two upper chambers called left atrium <NUM> and right atrium 212R, and two lower chambers called the left ventricle and right ventricle (partially shown).

Aspects of the present disclosure are directed to ablation therapies in which myocardial tissue in pulmonary veins <NUM>, <NUM>, <NUM>, and <NUM>, which form conductive pathways for electrical signals traveling through the tissue, is destroyed in order to electrically isolate sources of unwanted electrical impulses (arrhythmogenic foci) located in the pulmonary veins. By either destroying the arrhythmogenic foci, or electrically isolating them from the left atrium <NUM>, the symptoms of the arrhythmia can be reduced or eliminated.

In an exemplary embodiment of the present disclosure, an ablation balloon catheter <NUM> may be introduced into the left atrium <NUM> by a steerable catheter sheath <NUM> (commonly referred to as an introducer). An inner shaft <NUM> may guide the catheter tip <NUM> once introduced into the left atrium by the sheath <NUM>. Optionally, the ablation balloon catheter may include mapping electrodes <NUM> at a distal end of the ablation balloon catheter <NUM>. In operation, the sheath <NUM> has its distal end positioned within left atrium <NUM>. As shown in <FIG>, a transseptal approach <NUM> may be utilized in which the introducer sheath is introduced through a peripheral vein (typically a femoral vein) and advanced to right atrium 212R. The transseptal puncture kit makes a small incision into the fossa ovalis <NUM> which allows the distal end of the sheath <NUM> to enter the left atrium <NUM>.

In other embodiments, ablation balloon catheter <NUM> may be introduced into left atrium <NUM> through the arterial system. In that case, introducer sheath is introduced into an artery (such as a femoral artery) and advanced retrograde through the artery to the aorta, the aortic arch, and into the left ventricle. The ablation balloon catheter <NUM> is then extended from within a lumen of the sheath <NUM> to enter the left atrium through mitral valve <NUM>.

Once sheath <NUM> is in position within left atrium <NUM>, steerable ablation balloon catheter <NUM> is advanced out a distal end of the sheath and toward one of the pulmonary veins (e.g., <NUM>, <NUM>, <NUM>, and <NUM>). In <FIG>, the target pulmonary vein is right superior pulmonary vein <NUM>. Steerable sheath <NUM> of the ablation balloon catheter may be manipulated until the distal tip <NUM> of the ablation balloon catheter is substantially aligned with a longitudinal axis of the target pulmonary vein <NUM>, after which the ablation balloon <NUM> is expanded and extended into contact with the target pulmonary vein <NUM>.

Carried near a distal end <NUM> of ablation balloon catheter <NUM>, ablation balloon <NUM> remains in a collapsed condition so that it may pass through sheath <NUM>, and enter left atrium <NUM>. Once in the left atrium, the ablation balloon <NUM> is extended out of introducer sheath <NUM>, deployed, and extended into contact with target pulmonary vein <NUM>. The catheter shaft <NUM> may include steerable elements that allow for precisely positioning the balloon <NUM>.

Optionally, ablation balloon catheter <NUM> may include mapping electrodes <NUM> at a distal end <NUM> of ablation balloon catheter <NUM>. The mapping electrodes may be ring electrodes that allow the clinician to perform a pre-deployment electrical mapping of the conduction potentials of the pulmonary vein. Alternatively, mapping electrodes may be carried on-board a separate electrophysiology catheter, which may extend through a guidewire lumen that extends through a length of catheter shaft <NUM>. In some specific embodiments, the distal end <NUM> may include electrodes that may be utilized for touch-up radio-frequency ablation, following a cryoablation treatment for example.

In one exemplary embodiment of the present disclosure, to ablate tissue surrounding the ostia of pulmonary vein <NUM>, once the balloon <NUM> is deployed, a manifold within the balloon fills with a super-cooled liquid (e.g., a cryogenic fluid) that is distributed to cool the targeted tissue of the pulmonary vein <NUM> in response to a phase-change of the liquid to a gas within the balloon in response to a pressure drop within the balloon.

<FIG> shows an ablation balloon catheter <NUM> including an ablation balloon <NUM> advanced through cardiac muscle <NUM> and into contact with an ostia of pulmonary vein <NUM> (or one of the other pulmonary veins <NUM>, <NUM>, and <NUM>). In <FIG>, a catheter sheath <NUM> has been extended through right atrium 312R and fossa ovalis <NUM> (and may be anchored to a wall <NUM> of the fossa ovalis). The catheter sheath <NUM>, once inside left atrium <NUM>, to make contact with some of the pulmonary veins (e.g., <NUM> and <NUM>) must be manipulated by a clinician to make a tight corner near a distal end of the catheter sheath <NUM>. Once aligned with the target pulmonary vein <NUM>, the balloon <NUM> and a distal portion of catheter shaft <NUM> may be extended out of the catheter sheath <NUM> and the balloon <NUM> expanded before making contact with the ostia of the target pulmonary vein <NUM>. As the ablation balloon catheter contacts the pulmonary vein, mapping may be conducted using electrodes <NUM> (within or adjacent to the ablation balloon) in order to verify proper location prior to deployment of the ablation balloon, as well as confirm diagnosis prior to conducting an ablation therapy.

To expand the balloon <NUM> of ablation balloon catheter <NUM>, a flow of cryogenic fluid is released into an interior of the balloon via a manifold. Where the balloon suffers from a manufacturing defect, damaged during delivery through catheter sheath <NUM>, exposes to an overpressure condition, or otherwise, the balloon may be subject to leaking and/or failure which could potentially release cryogenic fluid into a patient's bloodstream (leading to injury and/or death, in some extreme cases). Accordingly, aspects of the present disclosure are directed to sensing conditions that may lead to a leak and/or failure of the balloon, or identifying the condition shortly thereafter. For example, in some embodiments the balloon <NUM> may include an inner and outer balloon with an interstitial space therebetween. In such embodiments, the interstitial space may be placed under a vacuum and a pressure sensor (which may also sense a vacuum, and/or a vacuum sensor) may be used to determine when the inner balloon has failed. Moreover, in some embodiments the inner balloon may be non-compliant and the outer balloon may be compliant to facilitate capture of expanded cryogen associated with a failure of the inner balloon. In yet other embodiments, both balloons may be compliant or non-compliant. In embodiments where both balloons are compliant, the inner and outer balloons may have the same material properties (e.g., burst pressure) and/or comprise the same material (e.g., Nylon <NUM>, also known as Polyamide <NUM> or PA11), or Polyethylene terephthalate (also referred to as PET).

<FIG> shows ablation balloon catheter <NUM> with an ablation balloon <NUM> in contact with target pulmonary vein <NUM>. Once steerable catheter sheath <NUM> has positioned the ablation balloon <NUM> into contact with the target pulmonary vein <NUM>, the catheter shaft <NUM> may be extended away from catheter sheath <NUM>. In the present embodiment, the balloon <NUM> is placed into contact with an ostia <NUM> of the target pulmonary vein (as opposed to an antrum <NUM>). Electrophysiology electrodes <NUM> and <NUM> ("EP electrodes") may be used to determine the electrical flow through the pulmonary vein. To expand the balloon <NUM>, cryogenic fluid is introduced to the balloon via manifold <NUM>.

To diagnose a condition, monitor an ablation therapy, and confirm the efficacy of an ablation therapy, ablation balloon catheter <NUM> may include EP electrodes <NUM> and <NUM>, at distal and proximal ends of ablation balloon <NUM>, respectively. As a specific example, the EP electrodes may electrically map the pulmonary vein to determine whether it is associated with a source of electrical impulses that cause atrial arrhythmias with the cardiac muscle. Further, as many ablation treatments require multiple therapies in order to achieve a desired reduction of electrical impulse transmission between the target pulmonary vein and the left atrium <NUM>, the EP electrodes may confirm the efficacy of an ablation therapy by measuring the electrical signals adjacent the lesion line.

In some embodiments, electrodes <NUM> and <NUM> may be used to ensure occlusion of the pulmonary vein prior to initiating cryo-therapy delivery. When the balloon is properly occluding the pulmonary vein, the electrodes <NUM> and <NUM> will be conductively coupled to the myocardial tissue of the pulmonary vein and thereby transmit a signal to controller circuitry indicative of the contact.

As will be discussed in more detail in reference to <FIG>, deployment of ablation balloon <NUM> is achieved by pumping a fluid (gas or liquid) through inner shaft <NUM> (from a proximal to a distal end), and into the ablation balloon via manifold <NUM>. Similarly, in embodiments utilizing cryogenic ablation methodologies, super-cooled fluid for ablating pulmonary venous tissue is pumped into the ablation balloon and ablates the tissue in contact with the ablation balloon (and in some cases in proximity therewith) by drawing heat from the tissue.

Due to the phase-change of the cryogenic-fluid that occurs within balloon <NUM>, the volume of gas that must be exhausted from the balloon is many times the volume of fluid that is delivered to the balloon. In some embodiments, an exhaust lumen may be an annulus within catheter shaft <NUM> that facilitates a large cross-sectional area (e.g., the exhaust lumen may have a clover-leaf like shape). To further facilitate manufacturability and assembly of catheter shaft <NUM>, additional lumens (e.g., vacuum lumen, cryo-delivery lumen, and a pressure-sensor lumen, for example) may be routed through the exhaust annulus. Such routing further facilitates a guidewire lumen to extend through an entire length of balloon catheter <NUM>.

The ablation balloons <NUM>/<NUM>, as shown in <FIG> and <FIG>, are depicted as being translucent (which allows for the visibility of internal components). However, it is to be understood that the ablation balloons <NUM>/<NUM>, disclosed herein, may also be semi-translucent or opaque.

<FIG> is an isometric, cross-sectional side view of a distal portion of a pulmonary vein isolation balloon catheter <NUM> and <FIG> is an isometric, cross-sectional side view of an area in proximity to an adaptor <NUM> of the pulmonary vein isolation balloon catheter <NUM> of <FIG>, consistent with various aspects of the present disclosure. A balloon <NUM> includes a first (inner) layer <NUM> within a second (outer) layer <NUM>, which are coupled to an adaptor <NUM> at two radially and longitudinally offset locations to create an interstitial space between the first and second layers. The adaptor <NUM> may be circumferentially positioned between an outer and an inner catheter shaft (<NUM>' and <NUM>, respectively). In various embodiments of the present disclosure the dual-layer balloon including first and second layers are two entirely separate balloons (e.g., inner and outer balloons).

The radially offset circumferential coupling locations of the first and second balloon layers <NUM> and <NUM>, respectively, on adaptor <NUM> creates an interstitial space <NUM> therebetween. The interstitial space <NUM> extends circumferentially along (at least a portion of) a length of the balloon <NUM>. The adaptor <NUM> also forms an exhaust lumen annulus <NUM> between inner and outer catheter shafts. During an ablation therapy, a cryo-liquid lumen may extend up through the exhaust lumen annulus <NUM> (similar to vacuum lumen 558A and pressure sensor lumen 558B) and be coupled with manifold <NUM> in such a way as to fluidly communicate the cryo-liquid thereto. Once the cryo-liquid is released from apertures in the manifold <NUM> that are distributed longitudinally and circumferentially about the manifold, the reduced pressure within first layer <NUM> of the balloon causes a phase-change of the cryo-liquid to a gas which absorbs a large amount of energy and cools the exterior surface of second layer <NUM>. The cryogenic exhaust gases within the first layer <NUM> may then be exhausted through exhaust lumen annulus <NUM>. The exhaust lumen <NUM> extends through adaptor <NUM>, adaptor extension <NUM>' which couples the balloon <NUM> and adaptor <NUM> to catheter shaft <NUM>. The flow of exhaust through the distal portion of the balloon catheter <NUM> is shown via arrows <NUM>". An annulus between the catheter shaft <NUM> and guidewire lumen <NUM> may run the remaining length of the catheter to the handle.

One or more ring electrodes <NUM> may be used to couple a first layer <NUM> of balloon <NUM> to adaptor <NUM>, adaptor extension <NUM>', among other components.

To prevent a failure mode of balloon <NUM> associated with a leak and/or rupture of a first layer <NUM>, aspects of the present disclosure are directed to detecting a leak and/or rupture of the first layer <NUM> and mitigating risk to the patient by terminating the ablation therapy. In one example embodiment, an interstitial space <NUM> formed by adaptor <NUM> between first and second layers of the balloon <NUM>, <NUM> and <NUM>, respectively, is fluidly coupled to a vacuum lumen 558A and a pressure sensor lumen 558B. The vacuum lumen 558A induces a vacuum pressure within the interstitial space <NUM> during an ablation therapy. The pressure sensor lumen 558B is fluidly coupled with a pressure sensor which monitors a change in vacuum throughout the ablation therapy. Where the first layer <NUM> is not containing a cryogenic fluid within the balloon <NUM>, the cryogenic fluid within the first layer of the balloon will be drawn into the interstitial space <NUM> thereby reducing a vacuum pressure therein which will be sensed by a pressure sensor. Controller circuitry of the ablation balloon catheter <NUM> may receive a signal from the pressure sensor indicative of the vacuum pressure within the interstitial space <NUM> at a given time. Where the controller circuitry identified a drop in vacuum pressure during the ablation therapy, the controller circuitry may take corrective measures to mitigate risk to the patient associated with such a leak. Importantly, where the first layer <NUM> of the balloon has ruptured, pressure within the interstitial space may rise eventually causing the second layer <NUM> to also fail - which would cause the dispersion of cryogenic fluid within the patient's bloodstream. Upon detecting a leak in first layer <NUM>, the controller circuitry may take one or more of the following actions: disable further flow of cryogenic liquid into the balloon <NUM>; release the pressure in the exhaust lumen; purge the cryogenic fluid in the cryogenic fluid lumen; and apply a vacuum pressure onto the exhaust lumen.

<FIG> is an isometric, side view of an interstitial space between first and second layers, <NUM> and <NUM>, respectively, of balloon <NUM> of the pulmonary vein isolation balloon catheter <NUM> of <FIG>, consistent with various aspects of the present disclosure. In some embodiments, the first layer <NUM> may comprise a material or composition of materials that facilitate a substantially non-conforming shape once expanded by the introduction of cryogenic fluid therein (e.g., nylon, polyethylene, polyurethane, etc.). The second layer <NUM> may comprise a material or composition of materials that facilitate a substantially conforming shape which facilitates the substantial expansion of the balloon <NUM> in response to a rupture of the first layer <NUM>. The second layer may be either compliant or non-compliant. In some embodiments, the outer balloon may facilitate a larger volume, may be a compliant balloon that has the capacity to grow substantially in response to an inner balloon rupture, and/or be a non-compliant material with a higher rated burst pressure then the inner balloon. The interstitial space <NUM>, during an ablation therapy, may be drawn into a vacuum pressure. While experiencing such a vacuum pressure the interstitial space <NUM> between the first and second layers may be infinitesimally small. However, a rupture or leak through the first layer <NUM> of the balloon and into the interstitial space <NUM> quickly changes the vacuum pressure therein. This change in pressure within the interstitial space <NUM> may be measured and used to identify such a balloon failure.

<FIG> is a diagrammatic view of a safety system for the pulmonary vein isolation balloon catheter <NUM> of <FIG>, consistent with various aspects of the present disclosure. A vacuum source <NUM> is fluidly coupled, via a first fluid path <NUM>', to an interstitial space <NUM> between first and second layers of a dual-layer balloon.

In some embodiments as disclosed in reference to <FIG>, it may be convenient, structurally, to measure a vacuum pressure in-line with a lumen extending between interstitial space <NUM> and vacuum source <NUM>. In such an embodiment, the pressure sensor <NUM> may be fluidly coupled between a first fluid path <NUM>" extending from the interstitial space and a second fluid path <NUM>" extending to the vacuum source. Where the first and second fluid paths have the same inner diameter, a leak may be detected by the pressure sensor in as little as <NUM> second. In more preferred embodiments, a first fluid path <NUM>" may have a larger diameter than a second fluid path <NUM>" - facilitating increased leak response time. For example, where the first fluid path has an inner diameter of <NUM>" and the second fluid path has an inner diameter of <NUM>", a change in vacuum pressure within the interstitial space <NUM> may be detected by the pressure sensor <NUM> in as little as <NUM> milliseconds. In yet other embodiments, the pressure sensor <NUM> may be located within the interstitial space itself, a catheter handle, or within the capital equipment.

In embodiments consistent with <FIG>, to decrease detection time of a change in vacuum pressure within the interstitial space <NUM>, which is indicative of a leak within one or more layers of the balloon, a second fluid path <NUM>' may extend between the interstitial space <NUM> and a pressure sensor <NUM>. Experimental results have demonstrated that the embodiment of <FIG> may reduce detection time of a leak into the interstitial space <NUM> by almost <NUM>%. That is, the <FIG> configuration may detect leaks in less than <NUM> milliseconds.

<FIG> is an isometric view of a spacer assembly <NUM>, consistent with various aspects of the present disclosure. The spacer assembly <NUM> includes a upper spacer <NUM> and a lower spacer <NUM> which may be coupled to one another via coupling features <NUM>A-B. The spacer assembly <NUM> may be circumferentially coupled around an outer diameter of a first balloon layer to hold the balloon in place. Further, the spacer assembly may facilitate radially off-setting the first and second balloon layers near a proximal end of a balloon assembly, which may otherwise be drawn together by a vacuum pressure applied to an interstitial space between the first and second layers of the balloon. The upper spacer <NUM> and the lower spacer <NUM> may be crimped to one another, laser welded, ultrasonically, welded spot welded, adhered, fastened via fasteners, or otherwise coupled to one another using techniques known in the art. The spacer assembly <NUM> includes channels <NUM><NUM>-N circumferentially distributed along an inner diameter, where each channel extends longitudinally along a central axis thereof. The channels <NUM><NUM>-N maintain a space between the first and second layers of the balloon for drawing a vacuum within the interstitial space. In some embodiments, absent the spacer assembly <NUM>, a vacuum may be drawn in a proximal interstitial space between the first and second layers, sealing the first and second layers of the balloon to one another, without creating a vacuum at an intermediate and/or distal region of the interstitial space. The spacer assembly <NUM> of <FIG>, facilitates drawing a complete vacuum within the interstitial space (as discussed in more detail in reference to <FIG>).

<FIG> is an isometric, cross-sectional side view of a distal portion of a pulmonary vein isolation balloon catheter <NUM>, and <FIG> is an isometric, cross-sectional side view of the pulmonary vein isolation balloon catheter of <FIG> including a spacer assembly.

In one exemplary embodiment of the isolation balloon catheter <NUM>, after being introduced into a left atrium of a cardiac muscle, the balloon <NUM> may be deployed by injecting a cryogenic fluid through fluid lumen <NUM>', which extends through a length of the catheter shaft <NUM> and into a fluid manifold <NUM> and out one or more apertures in the manifold and into a cavity of a first layer <NUM> of the balloon <NUM>. The fluid lumen <NUM>' may be coupled to an exterior of guidewire lumen <NUM>. The fluid manifold <NUM> may be positioned at a distal end of the balloon <NUM>. Once deployed, the ablation balloon <NUM> may be moved into contact with myocardial tissue and cooled/heated fluid may be injected into the cavity through one or more ports. In very specific embodiments, the ports may include nozzles or other fluid-flow controlling features that direct the flow, and control the velocity, of the fluid exiting the port toward specific target areas on the balloon <NUM>; for example, where the myocardial tissue to be ablated is likely to contact the ablation balloon. In the present embodiment, the balloon <NUM> is substantially bell-shaped (or conically shaped) to provide additional antral contact with target myocardial tissue of a pulmonary vein, and may facilitate more patient-to-patient anatomical and position variation of the pulmonary veins.

To control the pressure exerted on the ablation balloon by cryogenic fluid injected into the balloon via the fluid manifold <NUM>, an exhaust lumen annulus <NUM> along a length of inner shaft <NUM> may exhaust fluid from within the balloon <NUM>. For example, the exhaust lumen annulus <NUM> may receive fluid from within the ablation balloon and deliver the fluid through a length of the shaft <NUM> to a handle with a reservoir or other means of discarding the fluid. In exemplary embodiments of the present disclosure utilizing cryogenic fluid to ablate the myocardial tissue in contact with the ablation balloon, a closed-loop system may be utilized to scavenge the cryogenic fluid, re-pressurize, and return to a tank for later use. In such a closed-loop system, cryogenic fluid may be pumped from a handle of a catheter system through a lumen in the inner shaft to the fluid manifold and circulated around the ablation balloon. Once circulated through the ablation balloon, the exhaust lumen annulus <NUM> draws the fluid back to the handle portion of the catheter system where the fluid is re-pressurized before being injected back into the ablation balloon to continue ablating tissue in contact with the ablation balloon.

Once an ablation therapy is complete, exhaust lumen annulus <NUM> may be coupled to a vacuum to draw out any remaining fluid within ablation balloon <NUM>, thereby collapsing the ablation balloon. The ablation balloon <NUM> and shaft <NUM> may then be retracted into a steerable sheath.

Various embodiments of the present disclosure may further include leak prevention and detection measures to prevent against fluid leaking out of ablation balloon <NUM> into a patient's blood pool. This is particularly advantageous where the cryogenic fluid is a gas (e.g. nitrous-oxide) that may cause negative health affects when introduced into a patient's bloodstream, including pulmonary embolisms and stroke. In the exemplary embodiment depicted in <FIG>, first and second layers <NUM> and <NUM>, respectively, provide additional protection against fluid leakage into the patient's blood pool. Specifically, if the first or second layer is perforated or otherwise rendered incapable of containing a fluid within the ablation balloon <NUM>, the other layer may act as a barrier to fluid escape. As an added measure, a leak detection circuit (see, e.g., 5C and discussion thereof) may be utilized to detect fluid in an interstitial space <NUM> between the first and second layers. Accordingly, if the first layer is perforated, the fluid flows into the interstitial space <NUM>, and is drawn toward vacuum lumen <NUM>A,via channels <NUM> (shown in <FIG>) within spacer assembly <NUM>. The egress of liquid into the interstitial space <NUM> is detected by a pressure sensor which may communicate the change of vacuum pressure with controller circuitry of the isolation balloon catheter <NUM>. The controller circuitry may then take one or more corrective actions.

As shown in <FIG>, a cross-sectional front view of the pulmonary vein isolation balloon catheter of <FIG>, the spacer assembly <NUM> facilitates continuous fluid communication between vacuum lumen <NUM>A, pressure sensor lumen <NUM>B, and interstitial space <NUM>. Though adaptor <NUM> radially and longitudinally offsets the mounting points of the first and second layers <NUM> and <NUM>, respectively, of balloon <NUM> the layers may still be drawn together and create a seal between the lumens <NUM>A-B and interstitial space <NUM>. Spacer assembly <NUM> (and inner diameter channels <NUM> thereof) maintains the radial offset of the first and second layers of the balloon to prevent such a seal between the first and second layers. Without spacer assembly <NUM>, a vacuum pressure may be sensed by a pressure sensor, but not be (adequately) applied to the interstitial space - greatly increasing response time and/or negating a response all together of a leak detection circuit to liquid ingress into the interstitial space <NUM>.

Channels <NUM> of spacer assembly <NUM> force a vacuum to extend entirely through an interstitial space <NUM> within the balloon, as opposed to merely extending a vacuum through the most direct route between vacuum lumen <NUM>A and pressure sensor lumen <NUM>B. The most direct route, between the two lumens, is sealed off by spacer assembly <NUM>.

Ablation balloons have been developed for a variety of different applications and take a number of different forms. Aspects of the present disclosure may utilize ablation balloons of various types and different mechanical construction. The ablation balloons may be either of an electrically or thermally conductive material, and can be either self-erecting or mechanically erected, such as through the use of an internal balloon.

Pulmonary vein isolation balloon catheters as disclosed herein may include a handle at a proximal end of a catheter shaft, with the catheter shaft being introduced into a patient's cardiovascular system via an introducer sheath (such as St. Jude Medical, Inc. 's Agilis™ NxT Steerable Introducer sheath).

Various catheter shaft designs consistent with the present disclosure may include a multi-lumen design which allows for input and output flows of cryogenic fluid, electrical lead wires, and guide wires for steering the distal end of the shaft. In some embodiments, three lumens may be radially offset within the shaft from a guidewire lumen. In yet other embodiments, all of the lumens may be radially and circumferentially distributed about a longitudinal axis of the shaft.

In various embodiments of the present disclosure, an ablation balloon is capable of conducting ablation therapy at more than one location of the ablation balloon. For example, energy can be delivered to a proximal, distal, or intermediary portion of the ablation balloon. In some embodiments, the proximal, distal, intermediary portions, or combinations thereof may simultaneously conduct ablation therapy. In more specific embodiments, the amount of ablation therapy (e.g., energy transmitted to the tissue) conducted at a tissue location may be controlled individually.

Based upon the above discussion and illustrations, those skilled in the art will readily recognize that various modifications and changes may be made to the various embodiments without strictly following the exemplary embodiments and applications illustrated and described herein. Such modifications do not depart from the true spirit and scope of various aspects of the disclosure, including aspects set forth in the claims.

Although several embodiments have been described above with a certain degree of particularity to facilitate an understanding of at least some ways in which the disclosure may be practiced, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the scope of the present disclosure and the appended claims. It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting. Accordingly, the examples and embodiments herein should not be construed as limiting the scope of the disclosure. Changes in detail or structure may be made without departing from the present teachings. The foregoing description and following claims are intended to cover all such modifications and variations.

Various embodiments are described herein of various apparatuses, systems, and methods. Numerous specific details are set forth to provide a thorough understanding of the overall structure, function, manufacture, and use of the embodiments as described in the specification and illustrated in the accompanying drawings. It will be understood by those skilled in the art, however, that the embodiments may be practiced without such specific details. In other instances, well-known operations, components, and elements may not have been described in detail so as not to obscure the embodiments described in the specification. Those of ordinary skill in the art will understand that the embodiments described and illustrated herein are non-limiting examples, and thus it can be appreciated that the specific structural and functional details disclosed herein may be representative and do not necessarily limit the scope of the embodiments, the scope of which is defined solely by the appended claims.

The terms "including," "comprising" and variations thereof, as used in this disclosure, mean "including, but not limited to," unless express specified otherwise. The terms "a," "an," and "the," as used in this disclosure, means "one or more," unless expressly specified otherwise.

Reference throughout the specification to "various embodiments," "some embodiments," "one embodiment," "an embodiment," or the like, means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases "in various embodiments," "in some embodiments," "in one embodiment," "in an embodiment," or the like, in places throughout the specification are not necessarily all referring to the same embodiment. Thus, the particular features, structures, or characteristics illustrated or described in connection with one embodiment may be combined, in whole or in part, with the features, structures, or characteristics of one or more other embodiments without limitation.

Although process steps, method steps, algorithms, or the like, may be described in a sequential order, such processes, methods, and algorithms may be configured to work in alternative orders. In other words, any sequence or order of steps that may be described does not necessarily indicate a requirement that the steps be performed in that order. The steps of the processes, methods, and algorithms described herein may be performed in any order practical. Further, some steps may be performed simultaneously.

When a single device or article is described herein, it will be readily apparent that more than one device or article may be used in place of a single device or article. Similarly, where more than one device or article is described herein, it will be readily apparent that a single device or article may be used in place of the more than one device or article. The functionality or the features of a device may be alternatively embodied by one or more other devices which are not explicitly described as having such functionality or features.

Claim 1:
A dual-layer ablation balloon (<NUM>; <NUM>) comprising:
an inner balloon (<NUM>; <NUM>) including an internal cavity configured to receive a cryogenic fluid and facilitate a state transfer of the cryogenic fluid into cryogenic gas;
an outer balloon (<NUM>;<NUM>) that encapsulates the inner balloon (<NUM>; <NUM>);
an interstitial space (<NUM>; <NUM>) between the inner balloon (<NUM>; <NUM>) and the outer balloon (<NUM>; <NUM>); and
an exhaust lumen (<NUM>; <NUM>) in fluid communication with the internal cavity of the inner balloon (<NUM>; <NUM>), the exhaust lumen (<NUM>; <NUM>) configured to exhaust cryogenic gas out of the internal cavity;
characterized in that the dual-layer ablation balloon further comprises
an adaptor (<NUM>; <NUM>) that mechanically couples the inner balloon (<NUM>; <NUM>) and the outer balloon (<NUM>; <NUM>) to a catheter shaft and configured to radially and longitudinally offset proximal portions of the inner balloon (<NUM>; <NUM>) and the outer balloon (<NUM>; <NUM>); and
a spacer (<NUM>) coupled between the proximal portion of the inner balloon (<NUM>; <NUM>) and the proximal portion of the outer balloon (<NUM>; <NUM>), the spacer (<NUM>) configured to maintain the interstitial space (<NUM>; <NUM>) between the inner and outer balloons in response to a vacuum pressure within the interstitial space (<NUM>; <NUM>), wherein the spacer is positioned about the adaptor.