Pacing system for termination of cardiac arrhythmias utilizing scanning techniques
 A system and method for terminating a cardiac arrhythmia includes pacing means for stimulating the heart with at least one stimulation pulse during a narrow region of susceptibility (termination window) of the arrhythmia cycle. The location of the region of susceptibility is initially found by delivering the stimulation pulse(s) to the heart in accordance with a prescribed scan pattern. The scan pattern delivers the stimulation pulse(s) at a time during the cardiac cycle such that each successive stimulation pulse is presented to the heart at a slightly different time than was a prior stimulation pulse, thereby assuring that the region of susceptibility or termination window is eventually located. When the arrhythmia is successfully terminated, the location of the successful stimulation pulse within the prescribed scan pattern is stored. Upon the next occurrence of a cardiac arrhythmia, the initial stimulation pulse is presented to the heart at a time within the prescribed scan pattern that is backed up from the location of the prior successful stimulation pulse by a prescribed amount. Thus, even though the region of susceptibility may have moved in either direction within the cardiac cycle, the initial stimulation pulse of the next scanning sequence is likely to be applied at a location within the cardiac cycle that is near and moving towards the region of susceptibility. 
Siemens-Pacesetter, Inc.
A
A61N
inventional
James L.
Duncan