Abstract: A lead assembly for a cardiac pacemaker is formed by an electrical conductor having one end connected to the pacemaker and a heart engaging electrode member attached to the opposite end. The electrode member has a profiled contact surface having at least one diametrically extending groove and a coating of iridium oxide thereon. The profiled electrode member offers at least a pair of edges to both grip the heart tissue to reduce relative movement of the electrode while focusing the discharge of the pulses thereby allowing reduction in the polarizing pacing voltage.

Abstract: A cardiac pacemaker lead has a structure which provides an enhanced sensitivity to atrial P-waves. The distal end of the lead has two sensing electrodes disposed thereon to contact atrial cardiac tissue and to detect near field P-waves with greater sensitivity than far field R-waves.