Prevention and termination of pacemaker-mediated tachycardia in a new DDD pacing system (Siemens-Pacesetter model...

The clinical incidence of Pacemaker-Mediated Tachycardia (PMT) has been substantially reduced with the availability of wide range postventricular atrial refractory period (PVARP) programmability in most current technology DDD pacemakers. However, patients may still be at clinical risk for PMT if the PVARP must be reduced to allow higher atrial tracking capability or VA conduction (VAC) is not periodically assessed to ensure adequate PVARP selection. A new DDD pacer (Siemens-Pacesetter Model 2010T) incorporates programmable responses to a sensed PVC to prevent PMT induction due to VAC following a PVC. In each of these responses, the PVARP is automatically extended to prevent detection of the retrograde P wave, thus preventing the PMT. Additionally, should a PMT occur for reasons other than a PVC, the selected PVARP extension algorithm is periodically invoked to terminate the PMT. This study was conducted to evaluate the operation and clinical benefit of these PVC response functions and PMT termination capabilities. The exact timing operation of the pacer during these responses is also reviewed.