Estella Pulse Generators - BIOTRONIK USA - News

68 Estella Pulse Generators Technical ManualCautionOverdrive Pacing Mode—When programming the overdrivepacing mode, check whether the selected program can causePMT, and whether atrial over drive pacing would result.Corresponding to the measured retrograde conduction time, thePMT protection interval must be programmed to a correct value.7.11 Management of Specific Scenarios7.11.1 PMT ManagementA PMT is defined as a tachycardia caused by inadvertently trackingretrograde P‐waves. The PMT management feature includes PMTProtection/Termination and a programmable PMT detection andtermination algorithm.7.11.2 PMT ProtectionPacemaker‐mediated tachycardia (PMT) is normally triggered byventricular depolarizations that are not synchronized with atrialdepolarizations (e.g., VES). The tachycardia is maintained in a retrogradedirection by intrinsic VA conduction of the stimulated ventriculardepolarization and in an antegrade direction by ventricular pacing of thepacemaker that is triggered by P-waves. It is the objective of the atrialPMT protection interval to not use retrogradely conducted atrial sensedevents for pacemaker timing, but only to statistically evaluate them fordetection of atrial tachycardia incidents.To prevent occurrence of a PMT, Estella pacemakers start an atrial PMTprotection interval after each ventricular paced event. If an atrial eventis sensed within this PMT protection interval, this will neither start anAV delay nor a basic interval.The length of the PMT protection can be set to automatic (Auto). In thiscase, the PMT protection window can be automatically extended afterthe PMT is detected and terminated.NOTE:The initial values of the PMT protection interval in the automaticsetting at 250 ms after a V p, and 400 ms after PVC.