Patent Description:
Ablation of cardiac tissue has been used to treat cardiac arrhythmias. Ablative energies are typically provided to cardiac tissue by a tip portion, which can deliver ablative energy alongside the tissue to be ablated. Some of these catheters administer ablative energy from various electrodes disposed on or incorporated into three-dimensional structures, e.g., wire baskets and balloons.

An irrigated electrophysiology balloon catheter with flexible-circuit electrodes is disclosed. The catheter may include an outer tubular shaft having an outer surface, a first lumen disposed therethrough, and a second lumen disposed therethrough. It may also include an inner tubular shaft having an outer surface disposed in the first lumen of the outer tubular shaft and having a distal portion that extends out of a distal portion of the outer tubular shaft. A catheter balloon may also be provided. The catheter balloon may include a membrane having a first end and a second end, the first end connected to the outer surface of the outer tubular shaft about the distal portion of the outer tubular shaft, and the second end connected to the outer surface of the distal portion of the inner tubular shaft. As such, a distal segment of the inner tubular shaft may be disposed in the balloon.

To help prevent fluids, e.g., irrigation fluid or air, from passing between a space between the inner tubular shaft and the outer tubular shaft, a first seal and a second seal may also be provided about the locations where the inner tubular shaft emerges from the outer tubular shaft. The materials and dimensions of these seals are instrumental in ensuring that the seals are sufficiently robust such that they do not fail during use of the catheter.

The flexible-circuit electrodes may include substrates disposed on the balloon. Delamination of these substrates may be prevented by use of a reinforcement component, e.g., a Liquid Crystal Polymer (LCP) or Ultra High Molecular Weight Polyethylene (UHMWPE) yarn, that extends the length of the balloon. <CIT> describes an ablation balloon and catheter shaft that deflects to conform to a shape of a target pulmonary vein receiving ablation therapy for a cardiac arrhythmia. <CIT> describes an irrigated balloon catheter with support spines and variable shape. <CIT> describes a low profile electrode assembly. <CIT> describes a balloon catheter with a reduced distal length.

While the specification concludes with claims, which particularly point out and distinctly claim the subject matter described herein, it is believed the subject matter will be better understood from the following description of certain examples taken in conjunction with the accompanying drawings, in which like reference numerals identify the same elements and in which:.

Where values are provided in inches, <NUM> inch = <NUM>.

<FIG> is a schematic illustration of an invasive medical procedure using apparatus <NUM>, according to an embodiment. The procedure is performed by a medical professional <NUM>, and, by way of example, the procedure in the description hereinbelow is assumed to comprise ablation of a portion of a myocardium <NUM> of the heart of a human patient <NUM>. However, it is understood that embodiments disclosed herein are not merely applicable to this specific procedure and may include substantially any procedure on biological tissue or on non-biological materials.

To perform the ablation, medical professional <NUM> inserts a probe <NUM> into a sheath <NUM> that has been pre-positioned in a lumen of the patient. Sheath <NUM> is positioned so that a distal end of probe <NUM> enters the heart of the patient. A diagnostic/therapeutic catheter <NUM> (e.g., a balloon catheter), which is described in more detail below with reference to <FIG>, is deployed through a lumen of the probe <NUM>, and exits from a distal end of the probe <NUM>.

As shown in <FIG>, apparatus <NUM> is controlled by a system processor <NUM>, which is in an operating console <NUM> of the apparatus, also shown schematically at reference numeral <NUM>. Console <NUM> comprises controls <NUM> and screen <NUM>, which may be used by medical professional <NUM> to communicate with the processor. As such, screen <NUM> may comprise a touch screen and controls <NUM> may comprise, e.g., a mouse or trackball. During the procedure, processor <NUM> typically tracks a location and an orientation of the distal end of the probe <NUM>, using any method known in the art. For example, processor <NUM> may use a magnetic tracking method, wherein magnetic transmitters 25X, 25Y and 25Z external to the patient <NUM> generate signals in coils positioned in the distal end of the probe <NUM>. The CARTO® system (available from Biosense Webster, Inc. of Irvine, California) uses such a tracking method.

The software for the processor <NUM> may be downloaded to the processor in electronic form, over a network, for example. Alternatively, or additionally, the software may be provided on non-transitory tangible media, such as optical, magnetic, or electronic storage media. The tracking of the distal end of probe <NUM> may be displayed on a three-dimensional representation <NUM> of the heart of the patient <NUM> on screen <NUM>. However, it may be displayed two-dimensionally, e.g., by fluoroscopy or MRI.

To operate apparatus <NUM>, processor <NUM> communicates with a memory <NUM>, which has many modules used by the processor to operate the apparatus. Thus, the memory <NUM> comprises a temperature module <NUM>, an ablation module <NUM>, and an electrocardiograph (ECG) module <NUM>. The memory <NUM> typically comprises other modules, such as a force module for measuring the force on the distal end of probe <NUM>, a tracking module for operating the tracking method used by the processor <NUM>, and an irrigation module <NUM> connected to a pump allowing the processor to control the pump, and thus irrigation provided to the catheter. For simplicity, such other modules are not illustrated in <FIG>. The modules may comprise hardware as well as software elements. For example, module <NUM> may include a radio-frequency generator with at least one output or output channel, e.g., ten outputs or ten output channels. Each of the outputs may be separately and selectively activated or deactivated by a switch. That is, each switch may be disposed between the signal generator and a respective output. Thus, a generator with ten outputs would include ten switches. These outputs may each be individually coupled to electrodes on an ablation catheter, e.g., the ten electrodes <NUM> on balloon <NUM>, described in further detail below. Such an electrical connection may be achieved by establishing an electrical path between each output and each electrode. For example, each output may be connected to a corresponding electrode by one or more wires or suitable electrical connectors. Thus, in some embodiments, an electrical path may include at least one wire. In some embodiments, the electrical path may further include an electrical connector and at least a second wire. Thus, electrodes <NUM> may be selectively activated and deactivated with the switches to receive radiofrequency energy separately from each of the other electrodes.

<FIG> is a schematic perspective view of the diagnostic/therapeutic catheter <NUM> in in which balloon <NUM> is in an expanded configuration. Catheter <NUM> may include a handle <NUM>, a knob <NUM>, a control <NUM>, and irrigation tubing <NUM>. Knob <NUM> may be used to advance and retract distal collar <NUM> to change the configuration of balloon <NUM> between an expanded configuration and a collapsed configuration, as further described below. An irrigation lumen (referred to below as second lumen <NUM> with reference to <FIG>) passes through catheter <NUM> and connects tubing <NUM> to balloon <NUM>, such that an irrigation fluid (e.g., saline) may be introduced or pumped through tubing <NUM> and ultimately into balloon <NUM> by a pump connected to a source of the irrigation fluid and irrigation module <NUM>. Control <NUM> may be used to further manipulate or steer portions of catheter <NUM>, such as by causing a deflection to a distal portion of catheter <NUM>.

With further reference to <FIG>, <FIG>, and <FIG> where the diagnostic/therapeutic catheter <NUM> is used to ablate an ostium <NUM> of a lumen, such as a pulmonary vein <NUM>, a proximal end (or first end) of balloon <NUM> may be supported on a distal end of an outer tubular shaft <NUM>, e.g., by being compressed thereon by collar <NUM>, which may also function as a ring electrode. Outer tubular shaft <NUM> terminates in the balloon at outer shaft opening <NUM>. An inner tubular shaft <NUM>, may be disposed through outer tubular shaft <NUM> such that it extends into balloon <NUM> via outer shaft opening <NUM>. A distal end (or second end) of balloon <NUM> may be attached to a distal end of inner tubular shaft <NUM> by being compressed thereon by collar <NUM>, which may function as a ring electrode. Another catheter, such as lasso catheter <NUM>, may pass through inner tubular shaft <NUM> to extend into collar <NUM>. Outer tubular shaft <NUM>, inner tubular shaft <NUM>, and lasso catheter <NUM> may be disposed with respect to each other in a telescoping relationship. However, the relative movement between outer tubular shaft <NUM> and inner tubular shaft <NUM> is limited by the fact that balloon <NUM> is connected on its proximal or first end to outer tubular shaft <NUM> and on its distal or second end to inner tubular shaft <NUM>. This relative movement permits for manipulating the shape of balloon <NUM>. Specifically, when the length of inner tubular shaft <NUM> that extends out of outer tubular shaft <NUM> is maximized, balloon <NUM> has an oblong shape, i.e., a collapsed configuration, whereas when the length of inner tubular shaft <NUM> that extends out of outer tubular shaft <NUM> is minimized, balloon <NUM> has a spherical shape, i.e., an expanded configuration, which is the configuration reflected in the figures. This relative movement may be effected by manipulation of knob <NUM> on handle <NUM>, to move inner tubular shaft <NUM> relative to outer tubular shaft <NUM>.

The balloon <NUM> of the diagnostic/therapeutic catheter <NUM> has an exterior wall, surface, or membrane <NUM> of a bio-compatible material, for example, formed from a plastic such as polyethylene terephthalate (PET), polyurethane, or PEBAX®. The outer tubular shaft <NUM> defines a longitudinal axis <NUM> of the balloon <NUM>. The balloon <NUM> is deployed, in a collapsed configuration, via the lumen <NUM> of the probe <NUM>, and may be expanded after exiting from the distal end as described above. The membrane <NUM> of the balloon <NUM> may be formed with irrigation pores or apertures <NUM> through which fluid (e.g., saline) can exit from the interior of the balloon <NUM> to outside the balloon for cooling the tissue ablation site at the ostium. While <FIG> and <FIG> show fluid exiting the balloon <NUM> as jet streams, the fluid may exit the balloon with any desired flow rate or pressure, including a rate where the fluid is seeping out of the balloon.

The membrane <NUM> supports and carries combined electrode and temperature sensing members which are each constructed as a multi-layer flexible circuit electrode assembly <NUM>. The "flex circuit electrode assembly" <NUM> may have many different geometric configurations. In the illustrated embodiment, the flex circuit electrode assembly <NUM> has a plurality of radiating substrates or strips <NUM>, upon which are disposed electrodes <NUM>. In the embodiments reflected in the figures, there is one electrode <NUM> disposed on each of the substrates <NUM>. Thus, for example, where balloon <NUM> includes ten substrates, it also includes ten electrodes. The substrates <NUM> are evenly distributed about the distal end <NUM> and the balloon <NUM>. Each substrate has wider proximal portion that gradually tapers to a narrower distal portion. Further each substrate extends from the first end of balloon <NUM> at collar <NUM> to the second end of balloon <NUM> at collar <NUM>.

Applicant has determined that various fluid-management considerations should be accounted for to avoid malfunction and to enable catheter <NUM> to be used in a clinical setting. For example, due to the telescoping relationship between outer tubular shaft <NUM> and inner tubular shaft <NUM>, there exists a space between outer tubular shaft <NUM> and inner tubular shaft <NUM>. Unaccounted for, air might enter this space through handle <NUM> and enter balloon <NUM>. Further, irrigation fluid in balloon <NUM> might enter this space via outer shaft opening <NUM> in balloon <NUM>, where inner tubular shaft <NUM> extends out of outer tubular shaft <NUM>. Accordingly, Applicant has devised seals that prevent fluids from entering the space between inner tubular shaft <NUM> and outer tubular shaft <NUM>, but that do not impede the telescopic functionality of inner tubular shaft <NUM> and outer tubular shaft <NUM>, and that are sufficiently robust to prevent fluid entry for at least five and up to twenty rounds of expanding and collapsing balloon <NUM> by the telescopic functionality provided by inner tubular shaft <NUM> and outer tubular shaft <NUM>. Applicant determined that the following characteristics might affect robustness of the seals: <NUM>) friction might cause a seal to bunch up around inner tubular shaft <NUM>, and thus fail, as it is moved back and forth inside outer tubular shaft <NUM>; <NUM>) repeated movement back and forth could cause wear on bearing surfaces of a seal, and this wear might lead to a leak; and <NUM>) the seal should withstand pressures generated inside balloon <NUM> by flowing irrigation fluid therein. Based on these characteristics and other features of catheter <NUM>, Applicant has devised two different seals, a first or distal seal <NUM> disposed in balloon <NUM> to prevent backwash of irrigation fluid, and a second or proximal seal <NUM> disposed in handle <NUM> to prevent entry of air.

First seal <NUM> is described with reference to <FIG> and <FIG>. First seal <NUM> is disposed about a distal segment <NUM> of inner tubular shaft <NUM>. Accordingly, first seal <NUM> may have a tubular configuration, or at least a round inner surface to encompass distal segment <NUM>.

A coupler component <NUM> may also be provided. The coupler component <NUM> is also tubular in nature such that it may be attached to the distal portion of outer tubular shaft <NUM>, and such that coupler <NUM> may be considered a feature of outer tubular shaft <NUM>. As such the proximal or first end of balloon <NUM> may be attached to outer tubular shaft <NUM> by or in conjunction with coupler <NUM> using, e.g., the techniques described above. Accordingly, inner tubular shaft <NUM> extends into balloon <NUM>, through outer tubular shaft <NUM> and coupler <NUM>, in region <NUM> of balloon <NUM>.

Between region <NUM> and collar <NUM>, i.e., just proximal of region <NUM>, irrigation lumen or second lumen <NUM> of outer tubular shaft <NUM> terminates at termination point <NUM>, either at the distal tip of outer tubular shaft <NUM> or through a sidewall thereof proximate to the distal tip, or a combination thereof. As such, coupler <NUM> may be provided with at least one port or window <NUM> through a sidewall <NUM>, with window <NUM> disposed adjacent to termination point <NUM> to thus expose termination point <NUM> to the inside of balloon <NUM>. This enables irrigation fluid pumped through second lumen <NUM> to flow into balloon <NUM> via window <NUM>. As shown in <FIG>, there are two instances of window <NUM>.

Irrigation fluid that enters balloon <NUM> via window <NUM> pressurizes balloon <NUM>, thus causing its exterior surface <NUM> to become taut. As such, the pressure in balloon <NUM> is greater than the pressure in the space between outer tubular shaft <NUM> and inner tubular shaft <NUM>, giving rise to the need for first seal <NUM>.

First seal <NUM> may be mated to coupler <NUM> at the region <NUM> where inner tubular shaft <NUM> emerges therefrom. Applicant determined the following characteristics are important to fabricating a robust first seal <NUM>.

First seal <NUM> preferably includes a distal first-seal portion <NUM> made from a first material and a proximal first-seal portion <NUM> made from a second material. The first material and the second material may be different from each other. The first material may comprise: <NUM>) PEBAXTM, a thermoplastic elastomer that consists of polyamide and polyether backbone blocks, manufactured by Arkema; <NUM>) barium sulfate; <NUM>) PROPELLTM low friction compounds manufactured by Foster; or <NUM>) any combination thereof. In a preferred embodiment, the first material may comprise about <NUM>% PEBAX <NUM> SA <NUM> MED, about <NUM>% barium sulfate, and about <NUM>% PROPELL. The second material may comprise VESTAMID®, a polyamide manufactured by Evonik, such as VESTAMID CARE ML21.

With reference to <FIG>, distal first-seal portion <NUM> has: <NUM>) a pre-assembly wall thickness F of between about <NUM> inches and about <NUM> inches, e.g., about <NUM> inches; <NUM>) a pre-assembly inner diameter E of between about <NUM> inches and about <NUM> inches, e.g., about <NUM> inches. The proximal first-seal portion <NUM> has: <NUM>) a pre-assembly wall thickness C of between about <NUM> inches and about <NUM> inches, e.g., about <NUM> inches; and <NUM>) a pre-assembly inner-diameter B of between about <NUM> inches and about <NUM> inches, e.g., about <NUM> inches. As used herein, the term "pre-assembly" indicates characteristics of a component before it has been assembled into the catheter inasmuch as pre-assembly characteristics, particularly pre-assembly dimensions, are used to order materials and determine that they are being provided in compliance with a corresponding product specification.

The above material choices and dimensions enable a friction fit between first seal <NUM> and inner tubular shaft <NUM> that does not impede telescopic movement of inner tubular shaft <NUM> in outer tubular shaft <NUM>, such that distal segment <NUM> of the inner tubular shaft <NUM> has an outer diameter greater than or equal to the pre-assembly inner diameter E of the distal first-seal portion. Depending on pressures generated in balloon <NUM>, it may sometimes also be advisable for distal segment <NUM> of the inner tubular shaft <NUM> to have an outer diameter greater than or equal to the pre-assembly inner diameter B of the proximal first-seal portion.

To substantially cover distal segment <NUM>, first seal <NUM> may be between about <NUM> millimeters and about <NUM> millimeters long, e.g., about <NUM> millimeters long. Further, first seal <NUM> should be shorter than distal segment <NUM> to avoid interference that might otherwise be caused between, e.g., first seal <NUM> and collar <NUM> during assembly of catheter <NUM>. However, the lengths of distal first-seal portion <NUM> and proximal first-seal portion <NUM> are different based on the interplay between the dimensions and materials set forth above, and the various properties (e.g., friction) they impart to seal <NUM> on distal segment <NUM>. Thus, the distal first-seal portion may have a length G of between about <NUM> and about <NUM> inches long, e.g., <NUM> inches long.

Second seal <NUM> is now described with reference to <FIG>. Inner tubular shaft <NUM> may move telescopically inside outer tubular shaft <NUM>. Further a proximal portion <NUM> of inner tubular shaft <NUM> extends out of proximal portion <NUM> of outer tubular shaft <NUM>. Second seal <NUM> may be disposed about the location at which proximal portion <NUM> of inner tubular shaft <NUM> extends out of proximal portion <NUM> of outer tubular shaft <NUM>.

Second seal <NUM> may have a tubular form, including a proximal section <NUM> and a distal section <NUM>. Distal section <NUM> may be secured to an outer surface <NUM> of outer tubular shaft <NUM>. Further, proximal section <NUM> may be placed into contact with an outer surface <NUM> of inner tubular shaft <NUM>. The outer diameter N of the proximal section <NUM> of the second seal <NUM> is about equal to an outer diameter of the distal section <NUM> of the second seal <NUM>. Further, a pre-assembly inner diameter I of the proximal section <NUM> may be less than a pre-assembly inner diameter H of the distal section <NUM> of the second seal to allow for a seal to be formed about the location where inner tubular shaft <NUM> enters outer tubular shaft <NUM> while leaving clearance in distal section <NUM> for securing distal seal <NUM> to outer tubular shaft <NUM>. As such, the pre-assembly inner diameter I of the proximal section <NUM> may be less than or equal to an outer diameter of a segment of the inner tubular shaft <NUM> disposed through proximal section <NUM>. More specifically: <NUM>) the pre-assembly inner diameter I of proximal section <NUM> may be between about <NUM> inches and about <NUM> inches, e.g., about <NUM> inches; <NUM>) the pre-assembly inner diameter H of distal section <NUM> may be between about <NUM> inches and about <NUM> inches, e.g., <NUM> inches; <NUM>) a wall thickness K of proximal section <NUM> may be between about <NUM> inches and about <NUM> inches, e.g., about <NUM> inches; and <NUM>) a wall thickness J of distal section <NUM> may be between about <NUM> inches and about <NUM> inches, e.g., about <NUM> inches.

Second seal <NUM> may be fabricated from silicone, e.g., Dow Corning's SILASTIC® Q7-<NUM>. A tube <NUM> comprised of, e.g., a polyimide, may be used to secure outer surface <NUM> of outer tubular shaft <NUM> to distal section <NUM> of seal <NUM>. As such, tube <NUM> may be disposed at least partially in the distal section of the second seal and about the outer tubular shaft.

Through ongoing research and product development efforts concerning the subject matter described above, Applicant has determined that balloon <NUM> must be able to withstand multiple cycles of being deployed from lumen <NUM> of probe <NUM> in the collapsed configuration, expanded to the expanded configuration, returned to the collapsed configuration and withdrawn into lumen <NUM> of probe <NUM>. The number of cycles may be from about five to about twenty. That is, the connection between substrate <NUM> and outer surface <NUM> of balloon <NUM>, as well as the overall integrity of the assembled balloon, must withstand at least about five to about twenty fatigue cycles and any additional frictional stresses experienced during five to twenty deployments from and five to twenty withdrawals into lumen <NUM>. To assist in preventing potential delamination of substrates <NUM> from outer surface <NUM>, which could arise from repeated fatiguing, Applicant has thus implemented a solution that would prevent, or at least significantly further lower the likelihood of, any such delamination. Applicant further determined that any such solution would need to accommodate for various design constraints, such as: <NUM>) minimizing concomitant safety concerns caused by any solution; <NUM>) minimizing any increase to diameter of the portions of balloon <NUM> upon which substrates <NUM> are adhered such that balloon <NUM> in the collapsed configuration may be readily deployed from and withdrawn into lumen <NUM> with little or no increase in friction therebetween (or especially, in the extreme, avoiding a need to increase the diameter of lumen <NUM>); <NUM>) minimizing any increase to the stiffness of balloon <NUM>, which could interfere with establishing contact between electrode <NUM> and tissue during a procedure; <NUM>) not impeding electrical contact between electrodes <NUM> and tissue during a procedure; and <NUM>) minimizing an increase to the number of assembly steps.

With reference to <FIG> and <FIG>, a reinforcement component <NUM> is disclosed that assists in preventing delamination without violating these design constraints. At least one reinforcement component may be disposed along each of substrates <NUM>, extending from the first end of balloon <NUM>, i.e., from collar <NUM>, to the second end of balloon <NUM>, i.e., to collar <NUM>. As such, where balloon <NUM> includes ten substrates <NUM>, ten reinforcement components <NUM> may also be provided, one on each of the ten substrates. However, more than one reinforcement component <NUM> may be provided on each substrate <NUM>. The reinforcement components <NUM> may be attached to substrates <NUM> by any suitable method, e.g., with an adhesive.

Preferably, each reinforcement component <NUM> may have a form of a yarn, and when assembled take the shape of a roughly rectangular cross section having a thickness between about <NUM> inches and <NUM> inches. The yarn may be fabricated from an ultra-high molecular weight polymer or a liquid-crystal polymer, e.g., VECTRAN™, manufactured by Kuraray. So long as the thickness of the yarn is less than the thickness of electrode <NUM>, it may be disposed on a top surface of substrate <NUM>, i.e., adjacent to electrode <NUM>, such that it would not contact exterior surface <NUM> of balloon <NUM>. However, if the thickness of the yarn is greater than the thickness of electrode <NUM>, such that the yarn might interfere with the electrode's ability to conform to patient tissue, the yarn should be disposed on a bottom surface of the substrate, such that it would also be disposed directly against exterior surface <NUM> of balloon <NUM>. Such is the embodiment reflected in <FIG> and <FIG>.

By virtue of the embodiments illustrated and described herein, Applicant has devised a non-claimed method and variations thereof for using the catheter described herein. In a first variation, the method may include steps of flowing an irrigating fluid through the second lumen and into the balloon, and preventing the irrigation fluid from entering the outer tubular shaft via the distal portion of the outer tubular shaft. In a second variation, the method may include preventing air from entering the outer tubular shaft via the proximal portion of the outer tubular shaft. In a third variation, the method may include steps of extending the balloon out of a probe, expanding the balloon, collapsing the balloon, withdrawing the balloon into the probe, and repeating the steps of extending, expanding, collapsing, and withdrawing between five to twenty times. In a fourth variation, the method may include the steps of the first variation and the second variation. In a fifth variation, the method may include the steps of the first variation and the third variation. In a sixth variation, the method may include the steps of the second variation and the third variation. In a seventh variation, the method may include the steps of the first variation, the second variation, and the third variation.

Any of the examples or embodiments described herein may include various other features in addition to or in lieu of those described above. The teachings, expressions, embodiments, examples, etc., described herein should not be viewed in isolation relative to each other. Various suitable ways in which the teachings herein may be combined should be clear to those skilled in the art in view of the teachings herein.

Claim 1:
A catheter (<NUM>), comprising:
an outer tubular shaft (<NUM>) having an outer surface, a first lumen disposed therethrough, and a second lumen disposed therethrough;
an inner tubular shaft (<NUM>) having an outer surface disposed in the first lumen of the outer tubular shaft and having a distal portion that extends out of a distal portion of the outer tubular shaft (<NUM>), wherein the inner tubular shaft is translatable relative to the outer tubular shaft;
a catheter balloon (<NUM>) having a membrane including a first end and a second end, the first end connected to the outer surface of the outer tubular shaft (<NUM>) about the distal portion of the outer tubular shaft (<NUM>), and the second end connected to the outer surface of the distal portion of the inner tubular shaft, such that a distal segment of the inner tubular shaft is disposed in the balloon, the second lumen for introducing irrigation fluid into the catheter balloon;
a coupler component (<NUM>), the coupler component (<NUM>) being attached to the distal portion of the outer tubular shaft (<NUM>) at a location distal of the first end of the balloon (<NUM>) such that the inner tubular shaft (<NUM>) extends into the balloon through the coupler component; and
a first distal seal (<NUM>) disposed about the distal segment of the inner tubular shaft, the first distal seal comprising a distal seal portion (<NUM>) and a proximal seal portion (<NUM>), wherein the proximal seal portion (<NUM>) mates to the coupler component (<NUM>).