Delivery system assemblies for implantable medical devices

An inner member of an improved assembly for a delivery system includes a first segment formed by a multi-lumen tubing surrounded by a braided tubing, and a second segment formed by a single-lumen tubing that extends within a distal portion of the braided tubing. The single-lumen tubing accommodates an antenna of a medical device, is in fluid communication with three lumens of the multi-lumen tubing, and opens into a flared distal end of the inner member. A distal-most portion of an outer tube of the system contains the flared distal end and an enclosure of the medical device abutting the distal end. A pull wire of the assembly extends within another lumen of the multi-lumen tubing and between the single-lumen tubing and the distal extent of the braided tubing, and is coupled to a pull band mounted in a cone member that forms the flared distal end.

TECHNICAL FIELD

The present invention pertains to the delivery of implantable medical devices, and more particularly to improved assemblies for systems that facilitate percutaneous transvenous deployment of relatively compact implantable cardiac medical devices.

BACKGROUND

The traditional implantable cardiac pacemaker includes a pulse generator device to which one or more flexible elongate lead wires are coupled. The device is typically implanted in a subcutaneous pocket, remote from the heart, and each of the one or more lead wires extends therefrom to a corresponding electrode, coupled thereto and positioned at a pacing site, either endocardial or epicardial. Mechanical complications and/or MRI compatibility issues sometimes associated with elongate lead wires are well known to those skilled in the art and have motivated the development of cardiac pacing devices that are wholly contained within a relatively compact package for implant in close proximity to the pacing site, for example, within a right ventricle RV of the heart. With reference toFIG. 1, such a device100is shown, having been deployed by an exemplary delivery system200at an implant site in the right ventricular apex.

FIG. 1illustrates device100including a hermetically sealed enclosure105containing pulse generator electronics and a power source (not shown), pace/sense electrodes111,112formed on an exterior surface of enclosure105, and a fixation member115, which is mounted to a distal end of enclosure105, in proximity to electrode111, in order to fix, or secure electrode111against the endocardial surface at the implant site. Enclosure105is preferably formed from a biocompatible and biostable metal such as titanium overlaid with an insulative layer, for example, medical grade polyurethane or silicone, except where electrode112is formed as an exposed portion of the metal. A hermetic feedthrough assembly, such as any suitable type known to those skilled in the art, couples electrode111to the pulse generator contained within device enclosure105.FIG. 1further illustrates a proximal end121of device enclosure105configured for temporary attachment of a tether280, or some other type of retention member, that may be employed to test the engagement of fixation member115with tissue at the implant site, and/or to retain a temporary connection between the deployed medical device100and delivery system200, if repositioning of device100is necessary.

FIG. 2Ais a plan view of exemplary delivery system200; andFIGS. 2B-Care plan views of exemplary outer and inner assemblies, respectively, of system200.FIG. 2Aillustrates system200including a handle210from which the elongate outer assembly ofFIG. 2Bextends.FIGS. 2A-Billustrate the outer assembly including an elongate outer tube230, which has a proximal end231coupled to a first control member211of handle210, and a stability sheath250, which surrounds a limited length L of outer tube230and is fixed to handle210.FIG. 2Cillustrates the exemplary inner assembly, which extends within a lumen formed by outer tube230of the outer assembly in system200; the inner assembly includes an elongate inner member220, wherein inner member220includes a proximal end221, which is fixed within handle210, and a flared distal end222, which is configured to conform to proximal end121of device100. With reference toFIG. 2A, proximal end221of inner member220may be coupled to a stop cock260by a luer fitting (not shown), and distal end222of inner member220is contained in a distal-most portion232of outer tube230, just proximal to a distal opening203thereof. With reference toFIG. 2D, which is a plan view of the distal end of system200having a cut-away section of outer tube230, distal-most portion232is sized to contain device100therein, when proximal end121of device100abuts flared distal end222of inner member220.FIG. 2Cfurther illustrates the inner assembly including a pull wire225, which is coupled to a second control member212of handle210, at a proximal end51thereof, and which is anchored at a location52, in proximity to distal end222of inner member220, so that inner member220may be deflected, per arrow D (FIG. 2D), via movement of second control member212, per arrow B (FIG. 2A). The deflection per arrow D translates to outer tube230of delivery system200and helps to orient distal-most portion232thereof so an operator may maneuver system200within a patient's venous system for deployment of device100to a target implant site like that shown inFIG. 1. With reference toFIG. 2E, once distal-most portion232is positioned in proximity to the target implant site, the operator may withdraw outer tube230relative to inner member220and device100, per arrow W, via movement of first control member211per arrow A (FIG. 2A), in order to engage fixation members115of device100with tissue at the site.

Methods of use and construction details for exemplary delivery system200are described in a commonly assigned United States Patent Application, which has the Pre-grant Publication Number 2013/0079798 (Ser. No. 13/239,990). Furthermore, an alternative exemplary delivery system, similar to a delivery system300shown in the plan view ofFIG. 3, is described in another commonly assigned United States Patent Application, which has the Ser. No. 14/039,937. In contrast to system200, outer tube230of system300is shown including a pre-formed bend236, and a handle310of system300, as described in the '937 application, contains a stop cock within a sidewall thereof, and further includes a flushing assembly315. System300may be employed to deploy medical device100in a similar fashion to that described for system200. Although delivery systems like systems200and300have been disclosed and are known in the art, there is still a need for improved assemblies thereof, for example, which accommodate new and improved forms of cardiac pacing devices that are wholly contained within a relatively compact package for implant in close proximity to the pacing site, for example, like medical device1200, which is described below in conjunction withFIGS. 4A-B.

SUMMARY

An improved assembly for a delivery system, according to some embodiments of the present invention, extends within an elongate outer tube of the system and includes an elongate inner member. The inner member includes a first segment, formed by a multi-lumen tubing, and a braided tubing that surrounds the multi-lumen tubing and extends distally from a distal end thereof, and a second segment, formed by a single-lumen tubing extending within the distal extent of the braided tubing and defining a lumen that opens into a flared distal end of the inner member. The lumen is sized to accommodate an antenna of a medical device and is in fluid communication with three lumens of the plurality of lumens defined by the multi-lumen tubing. The flared distal end, formed by a cone member of the assembly, is preferably configured to conform to a proximal end of a hermetic enclosure of the medical device, from which the antenna extends proximally, and a distal-most portion of the elongate outer tube of the system is configured to contain the flared distal end together with the medical device enclosure abutting the flared distal end. The inner assembly further includes a pull wire that has a proximal end coupled to a control member of a handle of the system, and a distal end coupled to a pull band mounted in the cone member. A first length of the pull wire extends distally from the proximal end thereof, within another lumen of the plurality of lumens defined by the multi-lumen tubing of the first segment of the inner member, and a second length of the pull wire extends from the first length to the distal end thereof, between the single-lumen tubing of the second segment of the inner member and the distal extent of the braided tubing of the first segment of the inner member.

DETAILED DESCRIPTION

The following detailed description is exemplary in nature and is not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the following description provides practical examples, and those skilled in the art will recognize that some of the examples may have suitable alternatives.

FIG. 4Ais a plan view of another exemplary cardiac stimulation device1200whose configuration has prompted the development of improved delivery system assemblies, according to embodiments described herein.FIG. 4Aillustrates device1200including a hermetically sealed enclosure1205, cardiac pacing and sensing electrodes111,1211, and fixation member115coupled to a distal end1252of device housing1205. Like the above described enclosure105of device100(FIG. 1), enclosure1205of device1200contains pulse generator electronics and a power source within a relatively compact form factor, wherein electrode111is coupled to the controller via an hermetically sealed feedthrough assembly known in the art. Fixation member115, like in device100, holds electrode111in intimate contact with tissue at an implant site, for example, as illustrated inFIG. 4B. With further reference toFIG. 2A, unlike device100, device1200includes an antenna1210on which sense electrode1211is mounted. Antenna1210, for example, being formed by an insulated conductor1213that electrically couples electrode1211to the pulse generator electronics, extends proximally from a proximal end1251of device enclosure1205, such that sense electrode1211is spaced a distance from proximal end1251of enclosure1205, for example, to be located for atrial sensing (P-waves) when device1200is implanted in the right ventricle RV, for example, as shown inFIG. 4B. The distance may be between approximately 6 cm and approximately 10 cm, such that electrode1211is located in the right ventricle RV, as shown; or, according to alternate embodiments, the distance may be between approximately 10 cm and approximately 15 cm, such that electrode is located in the right atrium RA, for example, as indicated with the dashed line inFIG. 4B. A co-pending and commonly assigned U.S. Patent Application having the Ser. No. 62/025,690 provides a detailed description of an implantable medical device similar to device1200, the description of which is hereby incorporated by reference.

FIG. 5Ais a longitudinal cross-section of a portion of an improved assembly5220, according to some embodiments, for an inner member of a delivery system, for example, inner member220of either system that is described above in conjunction withFIGS. 2A-3; andFIGS. 5B-Care cross-section views through section lines B-B and C-C, respectively ofFIG. 5A.FIGS. 5A-Cillustrate assembly5220including a multi-lumen tubing540and a single-lumen tubing510, wherein tubing510extends distally from a distal end503of multi-lumen tubing540to a cone member53of assembly5220. Cone member53is shown forming flared distal end222of the above-described inner member220, which conforms to a proximal end1251of device enclosure1251; and a single lumen511formed by single-lumen tubing510, which opens into flared distal end222, is shown being sized to contain antenna1210of device1200. According to an exemplary embodiment, a length of lumen511is between approximately 6 cm and approximately 16 cm, and a diameter D of lumen511is approximately 0.070 inch, minimum. With reference toFIGS. 5B-C, assembly5220further includes a braided tubing52, which surrounds multi-lumen tubing540and single lumen tubing510, and an optional sleeve56extending around braided tubing52. A length of multi-lumen tubing540is preferably at least 100 cm, and, with reference back toFIGS. 2A-3, it should be understood that, when assembly5220forms inner member220, multi-lumen tubing540extends proximally into handle210.

FIG. 6is an exploded plan view of assembly5220, wherein multi-lumen tubing540and braided tubing52are shown forming a first elongate segment601of the inner member, and wherein single-lumen tubing510is shown forming a second elongate segment602of the inner member.FIG. 6illustrates braided tubing52surrounding multi-lumen tubing540and extending distally from distal end503thereof, wherein the distal extent of braided tubing52defines a lumen to receive single-lumen tubing510for the integration of second elongate segment602together with first elongate segment601. Assembly5220may also include the aforementioned optional sleeve56configured to fit around braided tubing52for the reinforcement of a junction between multi-lumen tubing540and single-lumen tubing510, when segments601,602are integrated together.FIG. 6further illustrates assembly5220including pull wire225(i.e. 0.010″ stainless steel wire coated with PTFE) coupled to a pull band55, which is mounted in cone member53, wherein pull wire225extends proximally from the coupling to pull band55to the above described coupling between proximal end51of pull wire225and second control member212of handle210,310. The integration of pull wire225into assembly5220may be appreciated with reference back toFIGS. 5B-C.

FIGS. 5B-Cillustrate multi-lumen tubing540defining first, second, third, and fourth elongate lumens541,542,543,544, wherein fourth lumen544provides a passageway for a first length225-1of pull wire225.FIG. 5Cillustrates a second length225-2of pull wire225being sandwiched between single-lumen tubing510and braided tubing52. According to the illustrated embodiment, the remaining lumens541-543are in fluid communication with single lumen511of single-lumen tubing510and with one or more ports formed in handle210,310.FIG. 5Billustrates first lumen541being somewhat larger than lumens542-544, for example, to accommodate a snare tool (not shown), and second and third lumens542,543providing passageways for first and second lengths of tether280, which is shown looped through an eyelet structure terminating a distal end of antenna1210.

With further reference toFIGS. 5B-Cand6, according to an exemplary construction method, first length225-1of pull wire225is inserted into fourth lumen544of multi-lumen tubing540, for example, before coupling proximal end51of pull wire225to control member212and after coupling second length225-2of pull wire225to pull band55, so that second length225-2extends within the distal extent of braided tubing52, sandwiched between braided tubing52and single-lumen tubing510. Then first and second segments601,602are integrated together, for example, by reflowing a wall of the distal extent of braided tubing52, according to any suitable process known in the art, so that the wall of braided tubing52adheres to a wall of single-lumen tubing510. The wall of braided tubing52may have been reflowed together with a wall of multi-lumen tubing540either before or after inserting first length225-1of pull wire225therein, and either before or during the reflow of the distal extent of the wall of braided tubing52.FIG. 6illustrates a distal end513of single-lumen tubing510that extends distally beyond braided tubing52, when first and second segments601,602are integrated together, and which extends within pull band55when pull wire225and pull band55are in position, having cone member53assembled thereover, as shown inFIGS. 5A and 6. A proximal end531of cone member53overlaps braided tubing52and single-lumen tubing510for attachment thereto, preferably by reflowing proximal end531to create a bond between cone member53and braided tubing52and single-lumen tubing510. Optional sleeve56, when included in assembly5220, may be integrated together with segments601,602during the aforementioned re-flow process, according to some construction methods.

According to an exemplary embodiment: single-lumen tubing510is formed from a medical grade fluoropolymer liner, for example, polytetrafluoroethylene (PTFE); braided tubing52is formed by a 304 stainless steel braid (0.001″×0.005″; 65 pics per inch) set in a medical grade polymer, for example, a 63D durometer PEBAX®; optional sleeve56is formed from a medical grade polyether block amide, for example, a 35D durometer PEBAX®; multi-lumen tubing540is formed from a medical grade polymer, such as 55D durometer PEBAX®, preferably with a fluoropolymer lining each lumen541-544, for example, PTFE; cone member53, for example, an injection molded component, is formed from a medical grade polymer, such as 72D durometer PEBAX® loaded with 20% BaSO4(radiopacity for fluoroscopic visibility); and pull band55is formed from a medical grade stainless steel ring.

In the foregoing detailed description, the invention has been described with reference to specific embodiments. However, it may be appreciated that various modifications and changes can be made without departing from the scope of the invention as set forth in the appended claims.