Abstract: An implantable medical device (IMD) includes one or more semiconductor switches and one or more switch driver circuits. The semiconductor switches, in response to one or more switch-on and switch-off commands that each have a voltage magnitude, switch between a conductive state and a non-conductive state, respectively, to thereby selectively supply one or more therapy pulses using electrical energy from an electrical energy source. The switch driver circuits, in response to drive commands, selectively supply the switch-on and switch-off commands to the semiconductor switches. The switch driver circuits, using a portion of the supplied therapy pulses, increase the voltage magnitudes of the switch-on and switch-off commands to a magnitude that maintains the switch in the conductive state or the non-conductive state, respectively, while the therapy pulses are being supplied.

Abstract: An implantable medical device includes two or more pacing output channels coupled to a single unipolar electrode or bipolar electrode pair. The implantable medical device can control each pacing output channel to deliver pacing pulses via the single electrode or electrode pair at different times and with different amplitudes. In some embodiments, the implantable medical device is used to deliver extra-systolic stimulation therapy. In such embodiments, a first pacing output channel can be controlled to deliver pacing pulses via the electrode or electrode pair with an amplitude sufficient to depolarize a chamber of the heart. A second pacing output channel is controlled to deliver extra-systolic pulses, which can have a lower amplitude than the pacing pulses, via the electrode or electrode pair an extra-systolic interval after sensed or paced depolarizations of the chamber. In some embodiments, the implantable medical device delivers ESS therapy and cardiac resynchronization therapy (CRT).