Conduction system pacing leads and methods of manufacturing

A distal assembly for an implantable lead, the distal assembly comprising:

• an outer shell having a proximal portion and a distal portion;
• a tubular inner preform disposed at least partially within the outer shell and comprising a proximal end, a distal end opposite the proximal end, a longitudinal slot extending from the distal end toward the proximal end, and a circumferential slot extending partially around a circumference of the inner preform;
• a coupler made of an electrically conductive material disposed within the shell and comprising a proximal portion having a proximal end and a channel extending distally from the proximal end, a distal portion opposite the proximal portion, and an intermediate portion between the proximal and distal portions, wherein the inner preform is mechanically coupled to the proximal portion of the coupler;
• a helical electrode having a proximal portion disposed about the distal portion of the coupler, and a distal portion extending distally from the distal portion of the shell;
• and
• a ring electrode disposed at a junction between the distal end of the lead body and the proximal portion of the outer shell,
• wherein one or both of the proximal and distal portions of the outer shell are formed by an overmolding process.

An implantable lead configured to be coupled to an implantable medical device (IMD), the implantable lead comprising:

• a tubular lead body having proximal end and a distal end opposite the proximal end;
• a distal assembly extending from the distal end of the lead body, the distal assembly comprising:
• an outer shell having a proximal portion and a distal portion;
• a tubular inner preform disposed at least partially within the outer shell and comprising a proximal end and a distal end opposite the proximal end;
• a coupler made of an electrically conductive material disposed within the shell and comprising a proximal portion having a proximal end and a channel extending distally from the proximal end, a distal portion opposite the proximal portion, and an intermediate portion between the proximal and distal portions, wherein the inner preform is disposed about and mechanically coupled to the proximal portion of the coupler;
• and
• a helical electrode having a proximal portion disposed about the distal portion of the coupler, and a distal portion extending distally from the distal portion of the shell;
• and
• a first electrical conductor extending through the lead body and mechanically and electrically coupled to the coupler within the channel.