Estella Pulse Generators - BIOTRONIK USA - News

7.11.2.1 PMT Detection and TerminationEstella Pulse Generators Technical Manual 69In addition to PMT prevention, Estella contains a programmable PMTdetection and termination algorithm. The termination feature will takeaction in case the prevention was not effective and a PMT is detected.The PMT detection constantly monitors for the presence of a PMT.The Estella PMT detection/termination algorithm consists of suspicion,confirmation and termination components and is described as follows.SuspicionA PMT is suspected when two criteria are met:• 8 successive V pace-A sense (V p-A s) sequences have occurredwith a length shorter than the VA criterion. This VA criterion isprogrammable between 250 and 500 ms.• The mean deviation of these 8 V p-A sintervals is less than the Stabilitycriterion parameter, defined as less than 25 ms.ConfirmationWhen the suspicion criterion has been met, the Estella slightly modifiesthe AV delay interval (+ or—50 ms) or the upper tracking rate (+50ms)for one cardiac cycle. If the V p-A sinterval remains stable, a PMT isconfirmed. Otherwise, a PMT is not confirmed and the algorithmrestarts. Once the PMT algorithm has confirmed a PMT, the cycle isbroken as follows:TerminationEstella extends PVARP (Post Ventricular Atrial Refractory Period) to theVA criterion value + 50 ms7.12 Adjustment of the PMT Protection WindowThe PMT protection window can be automatically adjusted. Thisautomatic adjustment functions in the following manner:When the PMT is detected and terminated, the PMT protection intervalis extended by 50 ms. If no additional PMTs arise within seven days, thelength of the PMT protection interval is reduced by 50 ms. The initialvalues of the PMT protection interval in the automatic setting at 250 msafter V pand 400 ms after a PVC.