Interventional medical systems and retrieval tools thereof

A tool for retrieving, in conjunction with a catheter, an implantable medical device from an implant site and into a receptacle of the catheter, the catheter comprising a distal-most catheter sidewall and the receptacle extending along a first central axis, the implantable medical device comprising a hermetically sealed housing extending along a longitudinal axis between a proximal end thereof and a distal end thereof, and an attachment feature joined to the proximal end of the housing, the attachment feature forming an annular recess where the attachment feature is joined to the proximal end of the housing, the tool being sized to fit in sliding engagement within the receptacle of the catheter, and the tool comprising:

• an elongate guide comprising:
• a guide sidewall defining a longitudinally extending guide lumen of the elongate guide extending along a second central axis, the guide lumen extending from a proximal opening thereof to a distal opening thereof, and the guide sidewall tapering from a first outer diameter to a smaller, second outer diameter at the distal opening of the guide lumen, the tapering extending over a length no greater than about 0.08 inch, and a ratio of the smaller, second outer diameter to the first outer diameter being no greater than about 60%;
• a rod extending proximally from the proximal opening of the guide lumen,
• wherein the tapering of the guide sidewall establishes, when the second central axis is radially offset from the first central axis, the distal opening of the guide lumen is axially proximate the distal opening of the receptacle and the guide sidewall is directly adjacent the distal-most catheter sidewall, a radial offset between the distal opening of the guide lumen and the distal-most catheter sidewall;
• and
• a lasso comprising:
• a first segment extending within the guide lumen and being fixedly attached to the elongate guide, the first segment having a distal end located in close proximity to the distal opening of the guide lumen;
• a second segment extending from the distal end of the first segment and looping back alongside the first segment within the guide lumen, the second segment being moveable relative to the first segment to increase and decrease a length of the second segment that protrudes distally from the distal opening of the guide lumen, and the second segment being configured to engage with the annular recess formed by the attachment feature of the implantable medical device;
• and
• an elongate tube coupled to a proximal end of the second segment of the lasso by an overlying layer of heat shrink tubing, wherein the elongate tube extends around the rod of the elongate guide, and wherein the elongate tube is in sliding engagement with the rod.

A tool for retrieving, in conjunction with a catheter, an implantable medical device from an implant site and into a receptacle of the catheter, the catheter comprising a distal-most catheter sidewall and the receptacle extending along a first central axis, the implantable medical device comprising a hermetically sealed housing extending along a longitudinal axis between a proximal end thereof and a distal end thereof, and an attachment feature joined to the proximal end of the housing, the attachment feature forming an annular recess where the attachment feature is joined to the proximal end of the housing, the tool being sized to fit in sliding engagement within the receptacle of the catheter, and the tool comprising:

• an elongate guide comprising a relatively straight rod portion and a coiled portion, the coiled portion forming a guide sidewall, the guide sidewall defining a longitudinally extending guide lumen of the elongate guide extending along a second central axis, the guide lumen extending from a proximal opening thereof to a distal opening thereof, the rod portion being integrally formed with the coiled portion and extending proximally from the proximal opening of the guide lumen, and the guide sidewall tapering from a first outer diameter to a smaller, second outer diameter at the distal opening of the guide lumen, wherein the tapering of the guide sidewall establishes, when the second central axis is radially offset from first central axis, the distal opening of the guide lumen is axially proximate a distal opening of the receptacle and the guide sidewall is directly adjacent the distal-most catheter sidewall, a radial offset between the distal opening of the guide lumen and the distal-most catheter sidewall;
• and
• a lasso comprising:
• a first segment extending within the guide lumen and being fixedly attached to the rod portion of the elongate guide, the first segment having a distal end located in close proximity to the distal opening of the guide lumen;
• a second segment extending from the distal end of the first segment and looping back alongside the first segment within the guide lumen, the second segment further extending proximally from the proximal opening of the guide lumen and alongside the rod portion of the elongate guide, the second segment being moveable relative to the first segment to increase and decrease a length of the second segment that protrudes distally from the distal opening of the guide lumen, and the second segment being configured to engage with the annular recess formed by the attachment feature of the implantable medical device;
• and
• an elongate tube coupled to a proximal end of the second segment of the lasso by an overlying layer of heat shrink tubing, wherein the elongate tube extends around the rod portion of the elongate guide, and wherein the elongate tube is in sliding engagement with the rod portion.