Delivery system assemblies for implantable medical devices

#The present invention pertains to delivery system assemblies for implantable medical devices, and more particularly to delivery system assemblies configured to facilitate percutaneous transvenous deployment of relatively compact implantable medical devices.

#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, which are sometimes associated with elongate lead wires and well known to those skilled in the art, 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 the right ventricle (RV) of the heart. With reference to FIG. 1A, such a device 100 is illustrated, wherein pace/sense electrodes 111, 112 are formed on an exterior surface of an enclosure 101 that hermetically contains a pulse generator including pulse generator electronics and a power source. FIG. 1A further illustrates a fixation member 115 mounted to an end of enclosure 101, in proximity to electrode 111, in order to fix, or secure electrode 111 against the endocardial surface in the apex of the RV. Enclosure 101 is 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 electrode 112 is formed as an exposed portion of capsule 101. A hermetic feedthrough assembly (not shown), such as any known to those skilled in the art, couples electrode 111 to the pulse generator contained within enclosure 101.

#FIG. 1B illustrates a distal portion of a standard guiding catheter 150 having been maneuvered up through the inferior vena cava IVC and into the RV from the right atrium (RA), according to methods known in the art of interventional cardiology. Although device 100 may be delivered to the RV, for implant, through catheter 150, improved delivery means are desirable to deploy device 100 at the implant site.

#The following drawings are illustrative of particular embodiments of the present invention and therefore do not limit the scope of the invention. The drawings are not to scale (unless so stated) and are intended for use in conjunction with the explanations in the following detailed description. Embodiments will hereinafter be described in conjunction with the appended drawings wherein like numerals denote like elements, and

#FIG. 1A is a schematic showing an example of an implanted cardiac stimulation device;

#FIG. 1B is a schematic showing the implanted device along with a guiding catheter;

#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. 2A is a plan view of a delivery system assembly 200, according to some embodiments. FIG. 2A illustrates system assembly including a handle 210 from which an elongate outer subassembly extends; the outer subassembly, which is also shown in FIG. 2C, includes an elongate outer tube 230 and a stability sheath 250 surrounding a length L of outer tube 230. With reference to FIGS. 2A and 2C, outer tube 230 is coupled to a first control member 211 of handle 210, for example, by a UV cure adhesive, and a proximal end 251 of stability sheath 250 is fixed to handle 210, distal to control member 211. FIG. 2B is a plan view of an inner subassembly that extends within the outer subassembly. FIG. 2B illustrates the inner subassembly including an elongate inner member 220, which extends from a proximal end 221 thereof to a flared distal end 222 thereof; proximal end 221 of inner member 220 is fixed within handle 210 and may be coupled to a luer fitting (not shown) to which a stop cock 260 is shown coupled in FIG. 2A. With reference to the cut-away section shown in FIG. 3A, flared distal end 222 is contained within a distal-most portion of outer tube 230, just proximal to a distal end 232 of outer tube 230, according to some embodiments. According to the illustrated embodiment, first control member 211 is slidable along handle 210 to move/retract outer tube 230 longitudinally, relative to inner member 220, from a first position 31, which is illustrated in FIG. 3A, to a second position 32, for example, where distal end 232 of outer tube 230 is approximately aligned with flared distal end 222 of inner member 220, which is illustrated in FIG. 3B. Alternately, second position 32 may be located more proximally, such that more of inner member is exposed distal to distal end 232 of outer tube 230, or more distally, such that only fixation member 115 of device 100 is exposed. According to some embodiments, an O-ring type seal member (i.e. silicone; not shown), which may be lubricated, for example, with silicone oil, forms a dynamic sealing interface between outer tube 230 and inner member 220 within handle 210, in proximity to first control member 211.

#With further reference to FIG. 3A, device 100 is shown held within the distal-most portion of outer tube 230, just proximal to distal end 232. FIG. 3A further illustrates a proximal end 121 of device 100 abutting flared distal end 222 of inner member 220, which, preferably conforms to proximal end 121 of device 100. With reference back to FIG. 1B, it may be appreciated that delivery system assembly 200 is preferably employed in place of the illustrated guiding catheter 150, to deliver device 100 through the venous system and into proximity with a target implant site, for example, in the RV, when outer tube 230 is in first position 31 shown in FIG. 3A. According to an exemplary embodiment, a distal-most portion of outer tube 230, which contains device 100, has an inner diameter of approximately 0.275 inch (˜0.7 cm) and an outer diameter of approximately 0.3 inch (˜0.8 cm). Although FIG. 3A illustrates the distal-most portion of outer tube 230 being enlarged from a remainder of outer tube 230, for example, over a length of approximately 3.5 cm (˜1.4 inch), according to alternate embodiments, an outer diameter along a more significant length up to an entire length of outer tube 230 may be the same as that of the distal-most portion. With reference to FIG. 3B, once delivery system assembly 200, with device 100 held therein, is positioned with distal end 232 of outer tube 230 adjacent to the target implant site, outer tube 230 is retracted, per arrow R (FIG. 3A), by means of first control member 211, to second position 32 (FIG. 3B), so that fixation member 115 of device 100 is exposed to secure electrode 111 to tissue at the implant site. According to FIG. 3B, almost an entirety of device 100 exposed when outer 230 is in second position 32; thus, a distance between first position 31 and second position 32 may be as small as approximately 2 cm up to approximately 6 cm, depending on the length of device 100. Alternately, second position 32, as mentioned above, may be located to only expose enough of fixation member 115 to secure device 100 at the implant site, in which case, the distance between the first and second positions may be as small as approximately 0.5 cm to 1 cm. According to some preferred embodiments, flared distal end 222 of inner member 220 is radiopaque and distal end 232 of outer tube 230 is fitted with a radiopaque marker, so that the retraction of outer tube 230, relative to flared distal end 222, for the deployment of device 100, can be observed via fluoroscopy. According to an exemplary embodiment, flared distal end 222 is formed from a polyether block amide, for example, PEBAX® 7033, with a radiopaque Barium sulfate filler; and the distal-most portion of outer tube 230 is formed from a polyether block amide, for example, PEBAX® 7233, which, at distal end 232, includes a radiopaque band of 75% Tungsten and 25% PEBAX® 6033 sandwiched between layers of the PEBAX® 7233.