Pacing lead with porous electrode for stable low threshold high impedance pacing

A cardiac pacing system, comprising:

• a pacemaker having pulse means for generating pacing pulses, and sense means for receiving sensed cardiac signals;
• a lead for delivering said pacing pulses to the patient's heart and for sensing cardiac signals and delivering said sensed cardiac signals to the pacemaker, said lead having a proximal end for connection to said pacemaker, a distal end, conductive means between said proximal and distal ends for conducting said pulses and said sensed cardiac signals, and a tip electrode at said distal end, said tip electrode having a surface for interfacing with the patient's heart wall, said tip surface having first and second surface areas, insulating means for electrically isolating said first and second surfaces, and connecting means for connecting said first surface to said conductive means;
• and
• said pacemaker further having selective connecting means for selectively connecting said pacemaker to said conductive means so that said first surface delivers said pacing pulses, and so that said sense means receives said sensed cardiac signals from said first surface.

A pacing lead for delivering pacing pulses from a cardiac pacemaker to a patient's heart, and for sensing patient cardiac signals and delivering said signals to the pacemaker, said lead having a proximal end, a distal end, and a length therebetween, and conductive means for conducting said pulses and said sensed signals respectively along said length, said lead further having a tip configuration at said distal end, said tip configuration comprising:

• a substantially hemispherical overall tip surface area, said tip surface area having a porous surface material;
• a first surface area within said overall tip area, centered substantially at the axial center of said tip area, a second surface area within said overall tip area and positioned around said first area, and insulating means for electrically insulating said first and second areas from each other;
• eluting means for eluting an eluant to one of said first and second surface areas and at least a portion of said other of said first and second surface areas;
• and
• connecting means for connecting only said one surface areas to said conductive means.