System and method for automatically compensating for latency conduction time in a programmable pacemaker
 An implantable pacemaker provides a paced AV delay that is automatically adjusted to include patient variations in latency conduction, that is, the time interval between a stimulus to the heart and an evoked potential, time due to lead position and specific patient latency. An AV timer, designed to provide a programmed AV interval, starts its timing operation at the generation of an atrial pulse, and restarts the timing operation again at the occurrence of the evoked atrial potential. The evoked atrial potential is typically monitored from a ring electrode of a bipolar lead relative to the pacemaker can (case), although other monitoring configurations are also possible. The length of the AV intrval is programmed to a desired value using conventional programming techniques. By starting the AV timer from the paced atrial stimulus, and restarting it from the evoked atrial potential, all variablility in nodal conduction time due to lead position and specific patient latency is removed, thereby obviating the need of having the pacemaker make adjustments to the AV interval. The paced AV delay (the time interval from the generation of an atrial stimulus to the generation of a ventricular stimulus) is automatically adjusted to compensate for these variations, while the AV interval (desired time from an atrial depolarization to a ventricular depolarization) remains at the desired value. In a rate-responsive packemaker, the programmed AV interval may still be shortened to mimic decreases in AV nodal conduction during periods of physical activity without affecting operation of the invention. 
Siemens-Pacesetter, Inc.
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A61N A61N A61N
inventional additional inventional
James L.
Duncan