Closed loop control of cardiac stimulator utilizing rate of change of impedance

摘要

A cardiac pacer of the type having an implantable pulse generator and electrical leads deployed in the right ventricular chamber of the heart. The lead has a stimulating electrode as well as a plurality of sensing electrodes coupled to the pulse generator. Certain control circuitry associated with the implantable pacer provides for measurement of the impedance variations occasioned by the pumping action of the heart and a differentiating circuit operatively coupled to the impedance sensing circuit for developing a control signal corresponding to the rate of change of the impedance with respect to time. This control signal may be coupled to the timing circuit of the implantable pulse generator, allowing the pacing rate to be altered in accordance with the level of physiologic activity of the person in whom the pacer is implanted.