Heart pacemaker electrode having two portions of different conductive properties for stimulating and sensing

Claim 1

An electrode head for a distal, heart-proximate end of a heart pacemaker lead comprising: a high conductivity tip portion of said electrode head and a low conductivity tail portion of said electrode head, said high and low conductivity portions being disposed adjacent to each other and being electrically connected, said high conductivity tip portion comprising a tip area of said electrode head that is substantially smaller in area than said low conductivity tail portion, said low conductivity portion including conductive flexible plastic projections that extend rearwardly from said tip area adapted for engaging heart trabeculae to retain said tip and tail portions in electrical contact with heart tissue, said high conductivity portion having a conductivity selected for applying stimulation pulses to said heart primarily only via said high conductivity tip portion, and said low conductivity tail portion having a conductivity selected such that both high conductivity and low conductivity portions of said electrode head are effective for sensing signals from said heart, said low conductivity tail portion being effective for sensing signals from a larger area within said heart than is said high conductivity tip portion.