Patent ID: 8666490

Claim:
A medical device, comprising: implantable electrodes including at least a first electrode configured to be disposed at a first site of a heart chamber and a second electrode configured to be disposed at a second site of the heart chamber; pacing circuitry configured to deliver a first pacing pulse to the first site using the first electrode as a cathode electrode for the first pacing pulse and to deliver a second pacing pulse to the second site using the second electrode as a cathode electrode for the second pacing pulse, the first pacing pulse and the second pacing pulse delivered during a cardiac cycle; sensing circuitry configured to sense a cardiac response to the pacing pulses including sensing cardiac electrical activity using the implantable electrodes, the sensing circuitry further configured to generate a differential signal between sensed cardiac electrical activity at the first electrode and sensed cardiac electrical activity at the second electrode; and capture circuitry configured to discriminate between single site capture, comprising capture by one of the first pacing pulse or the second pacing pulse, and multi-site capture, comprising capture by both the first pacing pulse and the second pacing pulse, based on the differential signal.