Patent ID: 6895274

Claim:
A method of operating an implantable cardiac stimulator to perform cardioverting, the cardiac stimulator having output means for delivering electrical stimulation of a predetermined polarity, amplitude, shape and duration, the method comprising: sensing the onset of tachycardia; applying pulses of biphasic pacing stimulation at a first intensity level selected from the group consisting of at the diastolic depolarization threshold, below the diastolic depolarization threshold or above the diastolic depolarization threshold, wherein each pulse of biphasic pacing stimulation comprises: a first stimulation phase with a first phase polarity, a first phase amplitude, a first phase shape and a first phase duration; and a second stimulation phase with a second phase polarity, a second phase amplitude, a second phase shape and a second phase duration; and determining whether pacing capture has occurred; wherein the first phase polarity is positive and the first phase amplitude is at a maximum subthreshold amplitude.