Implantable medical device lead assembly having high efficiency, flexible electrode head

An implantable medical device lead assembly has an electrode head including a flexible tip of elastomeric material embedding at least one rigid or flexible electrode. The at least one electrode and the elastomeric material define a curved tip surface adapted to contact the tissue to be stimulated. The compliance of the tip surface preferably approaches that of the body tissue to be stimulated so as to minimize the stress applied to the heart thereby reducing the adverse reaction of the heart to the presence of the electrode head. By way of example, the at least one electrode may take the form of a metallic or conductive polymer pin or may be made of wire. The elastomeric material may take the form of an envelope disposed about the electrode head and having formed integrally therewith anchoring means preferably comprising a plurality of pliant tines.