Patent ID: 12232802

While various embodiments discussed herein are amenable to modifications and alternative forms, aspects thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the scope to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure including aspects defined in the claims. In addition, the term “example” as used throughout this application is only by way of illustration, and not limitation.

DETAILED DESCRIPTION OF EMBODIMENTS

The instant disclosure relates to electrophysiology catheters for conducting diagnostics or tissue ablation within a heart. In particular, the instant disclosure relates to an electrophysiology catheter that conforms to a shape of a pulmonary vein receiving therapy for cardiac arrhythmias, and produces a consistent tissue ablation line along a length and circumference of the pulmonary venous tissue. Details of the various embodiments of the present disclosure are described below with specific reference to the figures.

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 desirably formed around/between the pulmonary veins in the left atrium of the heart which may introduce erratic electric signals into the heart. This type of ablation therapy requires precise positioning of the ablation catheter for optimal results. There are devices in development, or being commercialized, that attempt to achieve a sufficient block of ablations with minimal applications of energy. Existing designs range from diagnostic catheters with hoop and balloon mounted designs with energy applying features. Existing designs suffer from a lack of continuous contact around a circumference and length of the pulmonary vein during therapy deliver, resulting in inconsistent lesion lines and incomplete electrical signal blockage.

Referring now to the drawings wherein like reference numerals are used to identify similar components in the various views,FIG.1is a schematic and diagrammatic view of a catheter ablation system100for performing a tissue ablation procedure. In one example embodiment, tissue120comprises cardiac tissue within a human body140. 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 system100may include a catheter160and an ablation subsystem180for controlling an ablation therapy conducted by an ablation balloon130at a distal end128of the catheter160. The ablation subsystem180can control the application of and/or generation of ablative energy including, for example, radio frequency (RF), direct current (DC), irreversible electroporation, cryoablation, laser, chemical, and high-intensity focused ultrasound. Example embodiments of such ablation subsystems are described in U.S. Pat. Nos. 8,449,538, 9,289,606, 8,382,689, and 8,790,341, which are hereby incorporated by reference as though fully set forth herein.

In the exemplary embodiment ofFIG.1, catheter160is provided for examination, diagnosis, and/or treatment of internal body tissue such as cardiac tissue120. The catheter may include a cable connector or interface121, a handle122, a shaft124having a proximal end126and a distal end128(as used herein, “proximal” refers to a direction toward the end of the catheter160near the handle122, and “distal” refers to a direction away from the handle122), and an ablation balloon130coupled to the distal end128of the catheter shaft124.

Ablation balloon130may be manipulated through vasculature of a patient140using handle122to steer one or more portions of shaft124and position the ablation balloon at a desired location (e.g., within a heart muscle). In various embodiments, the ablation balloon includes ablation elements (e.g., ablation electrodes, high intensity focused ultrasound ablation elements, super cooled/heated fluid, etc.) that when operated by ablation subsystem180ablates the tissue120in contact with the ablation balloon130(and in some cases tissue in proximity to the ablation balloon130may be ablated by conductive energy transfer through the blood pool and to the proximal tissue).

In various specific embodiments of the present disclosure, catheter160may include electrodes and one or more positioning sensors at a distal end128of catheter shaft124(e.g., electrodes and/or magnetic sensors). In such an embodiment, the electrodes acquire EP data relating to cardiac tissue120, while the positioning sensor(s) generate positioning data indicative of the 3-D position of the ablation balloon130. In further embodiments, the catheter160may 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.

Connector121provides mechanical and electrical connection(s) for one or more cables132extending, for example, from ablation subsystem180to ablation balloon130. In other embodiments, the connector may also provide mechanical, electrical, and/or fluid connections for cables extending from other components in catheter system100, such as, for example, a fluid source (when the catheter160comprises an irrigated catheter) and contact/pressure sensing circuitry. The connector121is conventional in the art and is disposed at a proximal end126of the catheter160.

Handle122provides a location for a user to hold catheter160and may further provide steering or guidance for the shaft124within the body140. For example, the handle122may include means to manipulate one or more steering wires extending through the catheter160to a distal end128of the shaft124, thereby steering the shaft. The handle122is conventional in the art and it will be understood that the construction of the handle may vary. In other embodiments, control of the catheter160may be automated by robotically driving or controlling the catheter shaft124, or driving and controlling the catheter shaft124using a magnetic-based guidance system.

Catheter shaft124is an elongated, tubular, and flexible member configured for movement within a patient's body140. The shaft supports an ablation balloon130at a distal end128of catheter160. The shaft124may also permit transport, delivery and/or removal of fluids (including irrigation fluids, cryogenic ablation fluids, and body fluids), medicines, and/or surgical tools or instruments. The shaft124, 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 body140through 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 transeptal approach. The introducer sheath then makes an incision in the fossa ovalis (the tissue wall between the left and right atriums), and extends through the incision in the fossa ovalis to anchor the introducer sheath in the fossa ovalis. The ablation catheter160may then be extended through a lumen of the introducer sheath into the left atrium. Catheter shaft124of ablation catheter160may then be steered or guided through the left atrium to position an ablation balloon130into a desired location within the left atrium such as a pulmonary vein.

During cardiac ablation therapy, it is desirable to align the centerline of ablation balloon130with a centerline of an antral and/or proximal ostia of a pulmonary vein in which the ablation therapy is to take place. Alignment of the ablation balloon is particularly difficult in many embodiments due to the transeptal approach through the fossa ovalis which causes the shaft124to be naturally biased toward a right-side of a patient's body140. This bias places an additional torque on ablation catheter system100, which may result in the ablation balloon, after placement within the pulmonary vein, to bias away from the centerline of the pulmonary vein. Where the ablation balloon130is deployed away from the centerline of the pulmonary vein, the deployment may result in uneven contact pressure and corresponding uneven pulmonary vein tissue wall stress. It has been discovered that contact area and tissue strain are associated with decreased ablation therapy efficacy. Aspects of the present disclosure improve the efficacy of ablation therapy by more effectively positioning the ablation balloon130circumferential with a centerline of the pulmonary vein. In more specific embodiments, the deployed ablation balloon130further improves ablation therapy efficacy by having improved contour mapping to the pulmonary vein, thereby deploying and engaging the pulmonary vein along an extended and uninterrupted length and circumference of the ablation balloon130.

FIG.2is a cross-sectional front-view of a portion of a heart210with an ablation balloon catheter231locating a pulmonary vein (e.g.,214,216,218, and220) from within left atrium212L, consistent with various aspects of the present disclosure. Such an approach may be used for performing atrial fibrillation therapy. As shown inFIG.2, the cardiac muscle210includes two upper chambers called the left atrium212L and right atrium212R, and two lower chambers called the left ventricle and right ventricle (partially visible).

Aspects of the present disclosure are directed to ablation therapies in which tissue in (or adjacent to) pulmonary veins214,216,218, and220, which form conductive pathways for electrical signals traveling through the tissue, is destroyed in order to electrically isolate sources of unwanted electrical impulses (arrhythmiatic foci) located in the pulmonary veins. By either destroying the arrhythmiatic foci, or electrically isolating them from the left atrium212L, the cause of atrial fibrillation can be reduced or eliminated.

As shown inFIG.2, an ablation balloon catheter231may be introduced into the left atrium212L by an introducer sheath230. A guidewire232and a steerable portion of the catheter shaft234may guide the ablation balloon236once introduced into the left atrium212L by the introducer sheath230. Optionally, the ablation balloon catheter231may include mapping electrodes240and238at proximal and distal ends, respectively, of ablation balloon236. In operation, introducer sheath230has its distal end positioned within left atrium212L. As shown inFIG.2, a transeptal approach may be utilized in which introducer sheath230is introduced through a peripheral vein (typically a femoral vein) and advanced to right atrium212R. The introducer sheath230makes a small incision into the fossa ovalis226which allows the distal end of the introducer sheath230to enter the left atrium212L (through the transeptal wall224) and to anchor itself to the wall of the fossa ovalis226.

Ablation balloon catheter231may also be introduced into left atrium212L through the arterial system. In that case, introducer sheath230is 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 catheter231is then extended from within a lumen of the introducer sheath230to enter the left atrium212L through mitral valve222.

Once introducer sheath230is in position within left atrium212L, steerable ablation balloon catheter231is advanced out a distal end of the introducer sheath and toward one of the pulmonary veins (e.g.,214,216,218, and220). InFIG.2, the target pulmonary vein is right superior pulmonary vein214. A guidewire232and a steerable portion234of the ablation balloon catheter are manipulated until the distal tip of the ablation balloon catheter is directed toward the ostium of the target pulmonary vein, after which the ablation balloon is extended at least partially into the pulmonary vein.

Carried near a distal end of ablation balloon catheter231, ablation balloon236remains in a collapsed condition so that it may pass through introducer sheath230, and enter target pulmonary vein214. Once in position, the ablation balloon236is deployed, so that it engages and secures the ablation balloon catheter231in a position axial to the target pulmonary vein214.

As optionally shown, the embodiment ofFIG.2may include mapping electrodes238and240. The mapping electrodes238and240may be ring electrodes that allow the clinician to perform a pre-deployment electrical mapping of the conduction potentials of the pulmonary vein214. Although shown as being carried on ablation balloon catheter231, mapping electrodes may alternatively be carried on-board a separate electrophysiology catheter (e.g., such as on-board a loop catheter).

To ablate the tissue, once deployed, ablation balloon236may electrically conduct a DC energy current into the targeted tissue of the pulmonary vein214. In other embodiments, the ablation balloon236may transmit radio-frequency energy to ablate the target tissue. In yet other embodiments, the ablation balloon236may deliver one or more of the following energies to the targeted tissue: cryoablation, laser, chemical, and high-intensity focused ultrasound, among others.

FIG.3shows an ablation balloon catheter331including an ablation balloon336advanced into the ostium of pulmonary vein314. As the ablation balloon catheter331enters the pulmonary vein314, mapping may be conducted using electrodes338(hidden from view) and340in order to verify proper location prior to deployment of the ablation balloon336.

It has been discovered that proper positioning of the ablation balloon within the pulmonary vein is critical to the efficacy of an ablation therapy. For example, if the ablation balloon is not centered axially within the pulmonary vein when inflated, a portion of the ablation balloon may not contact a portion of the pulmonary vein circumference. This portion of non-lesioned tissue will allow for the continued conduction of electrical signals through the pulmonary vein and into the left atrium312L of the heart310. Non-lesioned tissue greatly impedes the efficacy of the lesioned tissue to limit the flow of stray electrical signals that cause arrhythmias. Moreover, the ill-centered position and uneven pressure of the ablation balloon within the pulmonary vein314may overly-stress pulmonary vein tissue that is in contact with the ablation balloon336when inflated, and may also reposition the pulmonary vein closer to structures (e.g., phrenic and esophageal nerves) that can be damaged by a nominal lesion depth of the ablation therapy. The Applicant has discovered that overly-straining the pulmonary vein tissue results in thin tissue and a deeper lesion than desired; similarly, under-straining the pulmonary vein tissue results in thicker tissue and a shallower lesion than desired—all of which decreases ablation therapy efficacy. Specifically, stressed tissue is less likely to evenly ablate and may even exhibit increased thermal capacity capability, therefore being capable of absorbing increased ablation energy before necrosis. Accordingly, aspects of the present disclosure improve the fit of the ablation balloon336within the pulmonary vein314with an ablation balloon profile that betters conforms to the contours of the pulmonary vein between antral and ostial portions thereof. This improved conformance between the inflated ablation balloon336and pulmonary vein314results in improved ablation therapy efficacy, and the reduced likelihood that follow-up ablation procedures will be necessary.

FIG.4is a cross-sectional front-view of portions of a left atrium412L and a pulmonary vein414with an ablation balloon catheter431positioned therein, prior to deployment of the ablation balloon436, consistent with various aspects of the present disclosure. As shown inFIG.4, the ablation balloon436is in position within the pulmonary vein414prior to balloon deployment. In one embodiment of the present disclosure, the proper location of the ablation balloon may be determined/verified by mapping, prior to deployment of the ablation balloon. As shown inFIG.4, ostial and antral portions of the pulmonary vein,415and416respectively, are irregular and varying in shape along both a longitudinal length and a cross-section of the pulmonary vein. Importantly, it has been discovered that many pulmonary veins exhibit an oval cross-sectional shape, as opposed to circular. Where ablation balloons are substantially circular, during inflation certain portions of the oval cross-sectional shape of the pulmonary vein may be overly stressed, while other portions of the pulmonary vein do not contact the ablation balloon limiting efficacy of the ablation therapy. Accordingly, aspects of the present disclosure are directed to an ablation balloon with a substantially oval shape (e.g., as shown inFIGS.7A-C). Such embodiments minimize and unify wall stress along a circumference of the pulmonary veinous tissue.

FIG.5shows expanded ablation balloon536engaged between ostial portion515and antral portion516of target pulmonary vein514. The expanded shape of the ablation balloon536has three distinct portions, as further discussed in relation toFIGS.6A-B, and7A-C, designed to more precisely match the contours of the pulmonary vein. This distinct shape increases the surface area contact between the pulmonary vein and the expanded ablation balloon, which consequently greatly improves the efficacy of the ablation therapy (that relies on surface contact between the ablation balloon and pulmonary vein tissue). Without continuous contact along a circumference of the pulmonary vein, a continuous lesion along the circumference may not be formed. As a result, stray electrical signals (though likely decreased in strength) may still be able to travel between the pulmonary vein and left atrium512L. Accordingly, the patient may still experience cardiac arrhythmias. As such, continuous contact along a diameter of the pulmonary vein is necessary to completely ablate the pulmonary vein tissue and to mitigate all electrical signal communication between the pulmonary vein and the left atrium. To achieve such continuous contact, the present disclosure teaches a multi-contour ablation balloon with at least three distinct portions for more effective ablation therapies.

In its expanded state shown inFIG.5, ablation balloon536engages inner walls of target pulmonary vein514. Through one or more ablation processes mentioned above, the ablation balloon produces a circumferential zone of ablation550along the inner wall of the pulmonary vein between ostial515and antral516portions. The ablation zone electrically isolates the target pulmonary vein from left atrium512L. To the extent that arrhythmiatic foci were located within the ablation zone, the arrhythmiatic foci are destroyed. To the extent the arrhythmiatic foci are located in the target pulmonary vein on the opposite side of the ablation zone from the left atrium, the electrical impulses produced by those foci are blocked or inhibited by the ablation zone.

In a typical ablation therapy, pulmonary veins are treated in accordance to their likelihood of having an arrhythmiatic foci. Often, all pulmonary veins are treated. The processes as described for right superior pulmonary vein514are similar for each of the three other pulmonary veins516,518, and520.

Once ablation therapy is complete, ablation balloon536may be contracted and ablation balloon catheter531may be retracted back into introducer sheath330(as shown inFIG.3). An electrophysiology catheter, or electrodes proximal and distal to the ablation balloon, may be used to verify the efficacy of the therapy prior to removal of the ablation balloon catheter531. In various embodiments of the present disclosure, additional electrodes may also be positioned on a surface of the ablation balloon536, either alone, or in conjunction with the electrodes proximal and distal the ablation balloon.

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 a conductive or a nonconductive material and can be either self-erecting or mechanically erected, such as through the use of an internal balloon. In one example embodiment, a lumen extending through a length of a shaft534of the ablation balloon catheter531may inject a fluid into the ablation balloon which exerts a radial force on the ablation balloon and thereby expands the balloon into an erect configuration (as shown inFIG.5).

In certain specific embodiments, an ablation balloon may consist of non-compliant material. In such embodiments, over-expansion of a distal portion of the balloon near an ostial portion of the pulmonary vein tissue wall may be prevented where the proximal portion of the balloon has come into contact with an antral portion of the pulmonary vein tissue wall.

FIGS.6A and6Bare isometric side and top views, respectively, of an ablation balloon600, consistent with various aspects of the present disclosure. As shown inFIGS.6Aand6B, the ablation balloon includes three distinct portions that are designed to improve the amount of surface area of the ablation balloon contacting the interior of the pulmonary vein. A first portion605is designed to mate with an ostial portion of the pulmonary vein. An intermediary portion610similarly mates to a transitional portion of the pulmonary vein between the ostial and antral portions. A second portion615at a proximal end601of the ablation balloon mates to an antral portion of the pulmonary vein. By including three distinct contours along a length of the ablation balloon, the ablation balloon is better suited to conform to/with the contours of the pulmonary vein. As discussed above, contouring the length of the deployed ablation balloon to better contact the pulmonary vein is critical to the efficacy of the ablation therapy which requires contact between the pulmonary vein tissue and the ablation balloon600. To improve insertion and withdraw characteristics of the ablation balloon catheter, the proximal end601and distal end602of the ablation balloon600may also include chamfers or radiuses to minimize sharp corners on the ablation balloon which may catch on an antral portion of the pulmonary vein when being inserted or on the introducer sheath when being retracted into a lumen of the sheath.

In one example application of ablation balloon600ofFIGS.6A and6B, the shape of the ablation balloon may be tailor fit for a specific patient based on measurements (e.g., ultrasonic images, magnetic resonance images, etc.) of the patient's pulmonary vein and entrance thereto. Specifically, based on the measurements of the patient, a shape along the longitudinal axis of the ablation balloon600may be selected that mimics the shape of the pulmonary vein (and in some embodiments may vary along a length of the longitudinal axis). Similarly, the diameters of the various portions of the ablation balloon600, including a first portion605, and an intermediary portion610may vary over a length. For example, the intermediary portion610varies over a length to accommodate an antral portion of a target pulmonary vein as it intersects with the left atrium.

As shown inFIGS.6A-6C, and consistent with various embodiments of the present disclosure, a first portion605of ablation balloon600can be inserted into a pulmonary vein, and (when inflated therein) comes into contact with a length of an ostial portion of the vein. As shown inFIG.6A, the first portion605of the ablation balloon600can be of a substantially consistent diameter along a longitudinal axis as the pulmonary vein ostia often maintains a fairly consistent diameter. Intermediary portion610, when inflated within the pulmonary vein, can come into contact with a length of an antral portion of the pulmonary vein. Due to the antral portion of the pulmonary vein being located between a small diameter of the ostial portion of the pulmonary vein and a large diameter associated with an intersection between the pulmonary vein and left atrium, the antral portion often exhibits a varying diameter over a longitudinal axis of the vein. In some pulmonary veins, this varying diameter may be substantially linear as shown by the intermediary portion610, as shown inFIG.6B; in others, the intermediary portion may appear as a radius. The intermediary portion may also prevent over insertion of the ablation balloon600into the pulmonary vein. In one specific example, the ablation balloon600may be (partially) inflated before being inserted into the pulmonary vein. In such a case, the intermediary portion610(and/or second portion615) acts as a hard-stop upon contacting the antral portion of the pulmonary vein.

In further example embodiments, ablation balloon600may be specific to a particular pulmonary vein. For example, various studies have determined average, maximum, and minimum pulmonary vein diameters across various patient demographics (see Table 1 below). Using such data, ablation balloons for each of the pulmonary veins may be created and swapped out during a therapeutic procedure for atrial fibrillation patients, for example; increasing efficacy of the ablation procedure. Various other parameters of a pulmonary vein may also be considered to tailor custom therapeutic solutions, thereby improving contact between each pulmonary vein and ablation balloon600. In one specific example, where a range of diameters of a pulmonary vein ostia (e.g., right superior pulmonary vein) are between 15 and 20 millimeters, first portion605of the ablation balloon600may have a diameter around 19 millimeters to ensure contact (when inflated) between the pulmonary vein and the first portion605for most patients, while limiting the potential for damage to smaller diameter pulmonary veins which may be permanently damaged by excess wall stress on the pulmonary vein tissue. Moreover, when the tissue is experiencing an excess wall stress, the ablation therapy can suffer from decreased efficacy and consistency of ablation.

FIGS.7A-Cshow isometric, top, and front views, respectively, of an ablation balloon700, consistent with various aspects of the present disclosure. The ablation balloon consists of three distinct portions. A first portion705is designed to mate with an ostial portion of the pulmonary vein. An intermediary portion710includes a constantly varying outside diameter that mates to a transitional portion of the pulmonary vein between the ostial and antrum portions. A second portion715at a proximal end of the ablation balloon700includes a constantly varying outside diameter that mates to an antral portion of the pulmonary vein. By including three distinct contours along a length of the ablation balloon, the ablation balloon exhibits improved conformance to/with the contours of a target pulmonary vein. Importantly, as a further measure to improve the fit of the ablation balloon700within a pulmonary vein, a cross-sectional shape of the ablation balloon is substantially oval, which Applicant has discovered to more closely mimic the shape of a typical pulmonary vein. The substantially oval shape of the ablation balloon further facilitates uniform ablation therapy application within the pulmonary vein by improving the axial centering of the ablation balloon700within the pulmonary vein. Also, during inflation of the ablation balloon700, the oval shape of the ablation balloon700can self-adjust (e.g., rotate) to properly mate with the curvature of the pulmonary vein.

In various embodiments of the present disclosure, an ablation balloon700is capable of conducting ablation therapy at more than one location of the ablation balloon. For example, energy can be delivered to a first portion705, an intermediary portion710, and a second portion715of the ablation balloon700. In some embodiments, the first portion705, the intermediary portion710, the second portion715, or combinations thereof may simultaneously conduct ablation therapy. For example, ablation energy can be applied in series (or in parallel) to the first portion705and the intermediary portion710. In more specific embodiments, the amount of ablation therapy (e.g., energy transmitted to the tissue, and the length of therapy) conducted at a tissue location may be controlled individually.

In cryoablation specific applications of an ablation balloon catheter, a distal portion of the expanded ablation balloon centers the ablation balloon within a pulmonary vein and anchors it thereto. An intermediary portion and proximal portion are then cooled to deliver a cryoablation therapy to an antral portion of the pulmonary vein. Once the ablation therapy is complete, the ablation balloon is deflated and the ablation balloon is removed from the pulmonary vein.

In various embodiments of the present disclosure, an ablation balloon may include one or more (internal) balloons that may be independently inflated. In one exemplary embodiment, a first (internal) balloon positioned at a proximal end of the ablation balloon may be expanded to deliver ablation therapy circumferentially to the pulmonary vein antrum, and a second (internal) balloon positioned at a distal end of the ablation balloon may be expanded to deliver ablation therapy circumferentially to the pulmonary vein ostia. Such (internal) balloons can relate to portions of the ablation balloons inFIGS.6and7(e.g., first portion705, intermediary portion710, and second portion715). In one specific embodiment, the one or more internal balloons may be encompassed by an external balloon.

One important benefit of the present disclosure is that ablation balloons, consistent herewith, are associated with decreased esophageal and phrenic nerve interaction with the pulmonary vein. Oftentimes, such interaction is caused by wall distortion due to expansion of the balloon within the pulmonary vein to a diameter greater than an internal diameter of the pulmonary vein. Preventing interaction between the pulmonary veins and the esophageal and phrenic nerves greatly decreases complications related to nerve damage from the ablation therapy.

In one specific application of ablation balloon700ofFIGS.7A-C, a first portion705(also referred to as a plug) may be plugged into a pulmonary vein, while an intermediary portion710(also referred to as a flared end—which may or may not include the second portion715) conducts a cryoablation therapy. Such a design helps stabilize the balloon700within the pulmonary vein while improving contact around the pulmonary vein ostia.

FIGS.8A-Cshow isometric, top, and front views, respectively, of an ablation balloon800, consistent with various aspects of the present disclosure. The ablation balloon consists of five distinct portions. A distal portion802of the balloon800has a radial surface that extends into contact with a first longitudinally extending portion805designed to mate with an ostial portion of a pulmonary vein. The first longitudinally extending portion805may include one or more ablation elements820. An intermediary portion810includes a (constantly) varying outside diameter that mates to a transitional portion of the pulmonary vein between the ostial and antrum portions. A second longitudinally extending portion815may be substantially spherical and extend to a proximal end801of the ablation balloon800. The second longitudinally extending portion815may have a constantly varying outside diameter. In various embodiments, the second longitudinally extending portion815may mate with an antral portion of the pulmonary vein. The second longitudinally extending portion815may include one or more ablation elements820. By utilizing these distinct contours along a length of the ablation balloon800, the ablation balloon may exhibit improved conformance to/with the contours of a target pulmonary vein. In the present embodiment, the cross-sectional shape of the ablation balloon800is substantially peanut-shaped, which Applicant has discovered to more closely mimic the shape of a typical pulmonary vein.

Various embodiments of the present disclosure are directed to pulmonary vein isolation balloon designs for optimum therapy delivery. Specifically, the balloon designs disclosed herein may be configured to facilitate improved energy delivery by better alignment between the balloon and the antral and/or proximal ostia portions of the pulmonary vein. The various embodiments disclosed herein may be applied to any of the various balloon-based energy delivery means (such as those discussed in more detail above).

Many cardiac catheter applications utilize the fossa ovalis to enter the heart. Due to the geometry between the fossa ovalis and an entrance to the pulmonary veins in the left atrium, the catheter shaft will naturally be biased towards a left side of the patient, putting pull/torque on the cardiac catheter as it locates (and is positioned in contact with) the pulmonary vein (e.g., for pulmonary vein isolation ablation therapy procedures). This biasing force pulls the catheter shaft off the natural centerline of the pulmonary vein being targeted, causing a variation in the forces and contact surface area experienced between the balloon and the pulmonary vein walls. As an example, when the biasing force pulls an ablation balloon off the natural centerline of a target pulmonary vein, the contact surface area and force exerted by the balloon on the side of the pulmonary vein which receives the additional biasing force will be greater than the other side(s) of the balloon. As a result, the energy delivery of the catheter is tied to catheter position, and may be one contributor to therapy variation.

Various embodiments of the present disclosure may be directed to multi-shape balloons for ostial and antral coverage of pulmonary vein geometry (e.g., two or more geometries). Such multi-shape balloons may facilitate centering of the balloon within a pulmonary vein for uniform ablation therapy applications, for example. Also, such multi-shape balloons may enable energy delivery to both antral and ostial portions of the pulmonary vein simultaneously (due to the increased contact area)—thereby targeting linear and circumferential conduction paths. In yet further embodiments, the multi-shape balloons may target energy delivery to distal, mid, or proximal balloon surfaces. The multi-shape balloon may also utilize a distal length of the balloon to contact an ostial portion of the pulmonary vein, facilitating proper centering of the balloon in the pulmonary vein, while a proximal length of the balloon in contact with an antrum of the pulmonary vein conducts the ablation therapy.

A multi-shape balloon, such as that shown inFIGS.5and6A-C, may be nested in a target pulmonary vein with a flare portion (also referred to as an intermediary portion610) that contacts all around the pulmonary vein ostia and antrum. When the balloon is plugged into a pulmonary vein, a flared portion of the balloon may be cooled. Such a design facilitates balloon stabilization within the pulmonary vein via a first portion605(as shown inFIGS.6A-C; also referred to as a plug) designed to mate with a circumference of the ostial portion of the pulmonary vein. In specific embodiments, a maximum flare of the balloon may be 23 millimeters in diameter with a 15 millimeter diameter distal end plug. In yet further more specific embodiments, the balloon may have an oval cross section to facilitate improved nesting in the pulmonary vein. It has been discovered that many pulmonary veins are oval (or at least the ostium/antral entrances of the pulmonary vein). Table 1 produced below shows the average pulmonary vein ostium diameters.

TABLE 1Average Pulmonary Vein Ostium DiametersnMaximum, mmMinimum, mmRatioRange, mmProjected, mmLeft superior3818.7 ± 2.913.9 ± 3.71.4 ± 0.41.0-3.017.5 ± 2.9Left inferior3815.9 ± 3.111.2 ± 3.11.5 ± 0.41.0-2.315.0 ± 2.7Both left761.5 ± 0.4*Right superior4218.8 ± 2.716.0 ± 2.01.2 ± 0.11.0-1.517.5 ± 2.1Righ inferior4217.9 ± 2.915.1 ± 3.01.2 ± 0.21.0-1.716.9 ± 3.1Both right841.2 ± 0.1*Left common427.3 ± 6.218.7 ± 6.71.6 ± 0.51.0-2.226.5 ± 4.8Right middle47.6 ± 3.15.6 ± 2.11.4 ± 0.41.0-2.07.0 ± 1.9Dimensions of pulmonary vein ostia measures with MRA. For each pulmonary vein, the maximal and minimal ostium diameters were measured together with the projected diameter by using a 45° RAO or LAO view angle for the MRA images. The ratio between maximal and minimal ostium diameters is a measure of the ovality of the PV ostia.*Differences in ovality were only significant between right and left pulmonary vein ostia (P <0.005). Table downloaded from http://circ.abajournals.org/ on Jun. 4, 2014

Using the average diameters in Table 1, above, balloon dimensions may be optimized to improve fit for a large percentage of the potential patient population. Further, with proper fit between the balloon and the pulmonary vein, the balloon will engage with, and hold in position better, within a pulmonary vein with minimal force during an ablation therapy, for example. Proper fit may also minimize and unify wall stress/distortion—providing more uniform reaction to various ablation energy types. With lesser stretching/distortion of the pulmonary vein due to the native spacing dimensions between the balloon and a target pulmonary vein, the potential for esophageal and phrenic nerve interaction may be greatly reduced.

Aspects of the present disclosure are directed to a medical device balloon apparatus. The apparatus includes a distal portion with a first circumference, a proximal portion, and an intermediary portion. The proximal portion has a second circumference which is greater than the first circumference, and the intermediary portion has a varying circumference coupled between the proximal and distal portions of the ablation balloon. The distal portion includes a first circumferentially extending surface and the proximal portion includes a second circumferentially extending surface. Both of the first and second circumferentially extending surfaces extend ing tangential from a radial line extending off a longitudinal axis of the medical device balloon apparatus.

In one exemplary embodiment of the present disclosure, a system for treating atrial fibrillation is taught. The system includes a balloon delivery catheter with proximal and distal ends, and an ablation balloon coupled to the distal end of the balloon delivery catheter. The ablation balloon includes distal, proximal, and intermediary portions. The distal portion has a first circumference, and engages with an ostium of a pulmonary vein for aligning a longitudinal axis of the ablation balloon with a second longitudinal axis of the pulmonary vein. The proximal portion has a second circumference which is greater than the first circumference. The intermediary portion is coupled between the proximal and distal portions of the ablation balloon, and has a varying circumference. At least one of the proximal and intermediary portions of the ablation balloon engages with an antrum of the pulmonary vein along an uninterrupted length and circumference, and delivers a uniform ablation therapy to the pulmonary vein antrum.

In another embodiment of the present disclosure, a balloon catheter is disclosed for pulmonary vein isolation. The balloon catheter includes a catheter shaft, an ablation balloon, and tissue ablation means. The catheter shaft deploys an ablation balloon into a pulmonary vein, which is coupled to a distal end of the balloon delivery catheter. The ablation balloon deploys from an undeployed configuration and engages with a tissue wall of the pulmonary vein along an uninterrupted length and circumference of an antrum and ostia of the pulmonary vein. The tissue ablation means, in association with the ablation balloon, delivers a uniform ablation therapy around a circumference of the pulmonary vein antrum engaged by the ablation balloon. The ablation balloon also overcomes a biasing force exerted upon the ablation balloon by the catheter shaft by engaging with the ostia of the pulmonary vein to overcome the biasing force.

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. For example, a deployed ablation balloon, consistent with aspects of the present disclosure, may consist of a number of varying geometries based on imaging data indicative of the internal dimensions of a patient's targeted pulmonary vein. In such an embodiment, the deployed ablation balloon engages the targeted pulmonary vein along an uninterrupted length and circumference of the ablation balloon to maximize the efficacy of the ablation therapy. 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. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. 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.

It will be appreciated that the terms “proximal” and “distal” may be used throughout the specification with reference to a clinician manipulating one end of an instrument used to treat a patient. The term “proximal” refers to the portion of the instrument closest to the clinician and the term “distal” refers to the portion located furthest from the clinician. However, surgical instruments may be used in many orientations and positions, and these terms are not intended to be limiting and absolute. All other directional or spatial references (e.g., upper, lower, upward, downward, left, right, leftward, rightward, top, bottom, above, below, vertical, horizontal, clockwise, and counterclockwise) are only used for identification purposes to aid the reader's understanding of the present disclosure, and do not create limitations, particularly as to the position, orientation, or use of the disclosure. Joinder references (e.g., attached, coupled, connected, and the like) are to be construed broadly and may include intermediate members between a connection of elements and relative movement between elements. As such, joinder references do not necessarily infer that two elements are directly connected and in fixed relation to each other.

Any patent, publication, or other disclosure material, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated materials does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein will only be incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material.