Medical electrical lead with backfilled electrode sub-assembly

A method of manufacturing a medical electrical lead, the method comprising:

• manufacturing a tubular electrode sub-assembly by:
• positioning an electrode over an outer liner surface of a tubular liner, wherein the tubular liner is located on a mandrel and comprises a continuous, uninterrupted inner liner surface facing the mandrel;
• delivering a flowable interstitial liner material comprising a hardenable organic polymer onto the electrode and tubular liner such that the interstitial liner material fills interstices of the electrode and forms an outer liner surface proximate an outer surface of the electrode;
• hardening the flowable interstitial liner material to form hardened interstitial liner material within the interstices of the electrode;
• removing the mandrel from the tubular liner after hardening the interstitial liner material, wherein the tubular liner, the interstitial liner material and the electrode form the tubular electrode sub-assembly;
• positioning the tubular electrode sub-assembly over an external surface of a lead body after manufacturing the tubular electrode sub-assembly such that the inner liner surface faces the external surface of the lead body;
• wherein the lead body defines a longitudinal axis extending between a proximal end and a distal end of the lead body;
• wherein the longitudinal axis extends through the tubular electrode sub-assembly;
• attaching the tubular electrode sub-assembly to the external surface of the lead body at one or more selected attachment sites, wherein the one or more selected attachment sites occupy only a portion of an inner liner surface;
• and
• electrically connecting a conductive element located within an interior of the lead body to the electrode of the tubular electrode sub-assembly.