Abstract: There is disclosed an implantable bone growth stimulator whose direct-current output can be monitored. Rather than to interrogate the device, e.g., by using a control magnet as in the heart pacer art, the device continuously transmits pulses of electromagnetic energy at a rate proportional to the current being delivered. The continuous transmission expends no more than about five percent of the total power. Instead of using an electrode lead as an antenna for radiating the pulses, a separate coil inside the device is utilized so that the therapeutic current itself is in no way affected by the pulse transmission. Effective transmission is achieved despite the fact that the device is hermetically sealed in a titanium case. Also included is an electronic switch for drastically limiting power drawn from the battery until implantation takes place, in order to provide an extended shelf life.

Abstract: A porous cardiac pacemaker electrode comprising a concavo-convex electrode cap having a plurality of apertures therethrough and an electrode shaft having a supporting edge formed thereon to which the concave surface of the electrode cap is joined. The porous cardiac pacemaker electrode is produced by deforming a platinum plate into a concavo-convex shaped cap member, forming a plurality of selectively spaced apertures through the electrode cap member to make the electrode cap substantially porous, forming an electrode shaft having a supporting edge, and joining the supporting edge of the electrode shaft to the concave surface of the electrode cap member.

Abstract: A cardiac pacemaker electrode including an electrode tip having an external surface with a concave region formed therein to increase the pacing impedance thereof. Further, the external surface of the electrode tip is roughened, for example by abrading with a jet of glass beads projected under pressure, to increase the microsurface area of the electrode tip and to reduce the sensing impedance thereof.

Abstract: A pacer which facilitates the measurements of both electrode impedance and stimulation threshold. When activated by an external magnet, a sequence of reducing-amplitude stimulating pulses is generated, with successive pulses in the sequence being separated by full-amplitude pulses. This pulse alternation scheme allows long test sequences, and therefore measurements with greater resolution, because full-amplitude pacing pulses are always present (even though at a slightly reduced rate). The reduction in amplitude of successive pulses is determined by the electrode impedance rather than being predetermined, and thus the examination of a skin potential recording allows electrode impedance to be determined along with the capture threshold.