Interventional medical systems, catheters, and subassemblies

A catheter for retrieving an implantable medical device from an implant site, the medical device including a housing, the catheter comprising:

• an inner assembly comprising an elongate shaft and an engagement subassembly coupled to a distal end of the inner assembly shaft, and
• an outer assembly comprising a shaft, a device receptacle sized to contain the medical device therein joined to a distal end of the outer assembly shaft, the device receptacle being in fluid communication with a lumen of the outer assembly shaft and having a distal-most opening that allows passage of the medical device therethrough, wherein the inner assembly shaft is in sliding engagement with the lumen of the outer assembly shaft, and the engagement subassembly is in sliding engagement with the outer assembly receptacle and the engagement subassembly includes at least three capture members formed in a spring biased outward relationship to a longitudinal axis thereof, wherein each capture member comprises:
• an elongate spring-biased wire, and each wire includes a proximal portion and a distal portion,
• a grip located between the proximal and distal portions of the corresponding spring-biased wire, the grip being configured to interlock within a gap between an attachment feature of the device and a proximal end of the housing of the device, when the device receptacle of the catheter outer assembly forces the capture members, against the spring-bias thereof, toward the longitudinal axis of the engagement subassembly, and
• a length of the distal portion of each spring-biased wire being approximately equal to a length of the housing of the device, each distal portion being configured to extend alongside the device housing when the grip of each capture member interlocks within the gap between the device attachment feature and the proximal end of the device housing.

An engagement subassembly for an inner assembly of a catheter for retrieving an implanted medical device having an attachment feature and a housing, and the subassembly comprising:

• an inner assembly shaft;
• an elongate pull wire extending from a proximal end thereof to distal end thereof over a length approximately equal to a length of the inner assembly shaft;
• a pull band coupled to the distal end of the pull wire and configured for mounting in a distal end of the inner assembly shaft for deflection thereof;
• and
• at least three capture members arranged around a longitudinal axis of the engagement subassembly and being spring biased outward from the longitudinal axis, each capture member comprising:
• a spring-biased wire including a proximal portion and a distal portion;
• and
• a grip located between the proximal and distal portions of each spring-biased wire, each grip being configured to interlock within a gap between the attachment feature of the medical device and a proximal end of the housing of the medical device, when a device receptacle of an outer assembly of the catheter forces the capture members, against the spring-bias thereof, toward the longitudinal axis of the engagement subassembly.

An interventional medical system comprising an implantable medical device, comprising:

• a hermetically sealed housing,
• an attachment feature joined to a proximal end of the housing and protruding proximally therefrom, and
• a fixation member mounted to the distal end of the housing;
• and
• a catheter comprising:
• an inner assembly comprising an elongate shaft and an engagement subassembly coupled to a distal end of the inner assembly shaft, and
• an outer assembly comprising a shaft, a device receptacle sized to contain the medical device therein joined to a distal end of the outer assembly shaft, the device receptacle being in fluid communication with a lumen of the outer assembly shaft and having a distal-most opening that allows passage of the medical device therethrough, wherein the inner assembly shaft is in sliding engagement with the lumen of the outer assembly shaft, the engagement subassembly being in sliding engagement with the device receptacle of the outer assembly, and having a longitudinal axis approximately aligned with the longitudinal axis of the device receptacle, when contained therein, the engagement subassembly including at least three longitudinally extending segments arranged around, and being spring biased outward from, the longitudinal axis of the subassembly, the segments defining an interior of the engagement subassembly, the interior being sized to contain the attachment feature of the medical device, when the spring-biased segments are forced, against the spring bias thereof, toward the longitudinal axis of the subassembly by the device receptacle;
• wherein each spring-biased segment of the engagement subassembly comprises:
• a distal-facing surface tapering outward from the longitudinal axis of the engagement subassembly in a distal direction, the distal-facing surfaces of the segments, together, defining a distal-most opening into the interior of the engagement subassembly;
• and
• an interlocking edge terminating the distal-facing surface at a proximal end thereof;
• and
• wherein the distal-facing surface is oriented for confronting engagement with the proximal end of the housing of the medical device, when the device receptacle of the catheter outer assembly forces the segments, against the spring-bias thereof, toward the longitudinal axis of the engagement subassembly;
• and
• the interlocking edge of each segment is configured to interlock within a gap between the device attachment feature and the proximal end of the device housing, when the distal-facing surface of each segment is in confronting engagement with the proximal end of the device housing.