Abstract: The present invention provides an improved extracardiac indifferent electrode configuration for implantable medical devices that overcomes the deficiencies of known unipolar and bipolar cardiac sensing and pacing systems. In particular, the present invention provides an indifferent electrode configuration wherein a subcutaneous extracardiac electrode is advantageously positioned so as to provide a truly indifferent return or reference electrode that does not inadvertently stimulate torso muscle and is not subject to detecting myopotentials generated by adjacent torso muscle. In addition, by being placed outside the heart, the indifferent electrode allows the intracardiac catheter to maintain a low profile, i.e., allows the catheter to be as small as possible, and does not generate metallic ions or cause degradation of catheter materials by generating such ions.

Abstract: A single preformed catheter configuration for a dual-chamber pacemaker system is provided. The catheter is formed of a heat-settable biocompatible material such as, for example, polyether polyurethane, and is formed in a predetermined shape to enhance and stabilize atrial electrode contact on the inner wall of the atrium, while also providing stress relief to absorb stresses occasioned by cardiac depolarization and respiration and modulation of the bulk cardiac complex. To this end, the catheter of the present invention includes a first section disposed in the superior vena cava to provide substantially stable support to the catheter, a second section disposed in the atrium and being preformed to substantially conform to the inner wall of the atrium, and a third section having a pliancy greater than that of the first two sections and being disposed distally of the second section.

Abstract: An electronic device for non-invasively communicating with an implanted device, such as, for example, a cardiac pacemaker. The electronic programming device includes a transceiver having an antenna, a transmitter portion and a receiver portion. The antenna portion is arranged to have two coils arranged in series phase opposition to suppress the effects of far-field interference signals on received near-field signals from the implanted device, when the transceiver is receiving data from the implanted device. The electronic device further includes means to isolate the transmit and receive functions thereof to prevent cancellation of the transmitted signal when the transceiver is in the transmit mode.

Abstract: A catheter lead for a cardiac pacemaker in which stimulating pulses are generated for delivery to the heart according to physiological need of the patient determined by signals obtained solely from the detection of naturally occurring P-waves propagating through the atrial myocardial tissue.

Abstract: An optimum placement, shape and orientation of catheter electrodes in a cardiac pacemaker system takes advantage of the peak-positive to peak-negative summative effect of a diphasic depolarization wave front of the P wave necessary to the beating of a heart. Electrode surface areas are maintained in the 4 to 6 mm.sup.2 range and disposed so as to minimize signal attenuation from gradient averaging of the depolarizing signature and also to minimize the effect of uncontrollable angular rotation of the cathether.

Abstract: A connector for connecting catheters to a body implantable device utilizes an insulating, highly viscous material behind a punched through solid material through which a set screw wrench can be inserted. The viscous material provides insulation after removal of the set screw wrench.

Abstract: A cardiac pacer uses switched capacitor circuits for maintaining isolation between an atrial channel subsystem and a ventricular channel subsystem. Cross-talk between the channels is prevented by the switched capacitor circuits which may include two sampling switches, a sampling capacitor, two transfer switches, and a filter. The switched capacitor circuits are disposed in series between the corresponding channel lead and the corresponding sensing circuit for that channel. An arrangement of switches and a corresponding controlling arrangement are used to change the mode of sensing and pacing of each channel independent of the mode used by the other channel. That is, each channel subsystem is independently operable for bipolar sensing, bipolar pacing, unipolar sensing, and unipolar pacing.

Abstract: A heart pacing and monitoring system includes a new lead system which, when used in conjunction with a telemetry-pacemaker system, permits the transmission of the complete intracardiac electrogram and is not adversely affected by pacemaker outputs or after potentials. Detecting ring electrodes are placed in both right atrium and ventricle in order to optimize electrogram (EGM) detection. Electrically separate from the pacing-sensing electrodes, the detecting electrodes are structurally part of a transvenously placed ventricular lead no larger than a conventional bipolar lead. The EGM telemetry system is also compatible with telephone monitoring systems. The present system is operative to detect and telemetrically record the entire normal and abnormal electrogram even in pacer dependent patients.