US Patent 7460907 Pacing with hemodynamic enhancement

Apparatus (170) for heart pacing with hemodynamic improvement, including one or more electrodes (36), which convey electrical signals to respective cardiac muscle segments. Signal generation circuitry (50) applies an extended pacing signal (60, 61), having an overall duration greater than three times a chronaxie time, to the one or more electrodes so as to pace the heart. The signal preferably includes a train of a plurality of biphasic pulses, and has an amplitude at least three times as great as a threshold for pacing the heart, but not sufficient for cardioversion.