Estella Pulse Generators - BIOTRONIK USA - News

78 Estella Pulse Generators Technical ManualThe standard setting is one threshold measurement per day, but theuser may choose another frequency of measurement. The thresholdsearch is based on the presence or absence of atrial sensing markersgenerated by the device. The atrium is stimulated at a pacing rate higherthen the intrinsic rate to suppress atrial intrinsic events. As soon as thepacing output is lower then the atrial threshold, sensed atrial eventwill be detected either due to the emerging intrinsic rhythm or due toretrograde conducted events caused by ventricular paces. The detectionof sensed atrial activity is used to discriminate between atrial captureand non-capture. The atrial capture control is performed in four steps:1. Setup-Phase: The device monitors the rate and rhythm conditionand determines the actual rate in the atrium immediately before itstarts the threshold search. Automatic measurements are allowedif the atrial and ventricular rate is below 110 ppm and no modeswitching is active. If these conditions are met, the activation ofthe capture control algorithm causes a mode switch to DDI with anatrial overdrive pacing of +20 % of the actual determined rate. TheA p-V pinterval will be programmed to 50 ms, to avoid retrogradeconduction from the ventricle.2. Threshold search: The threshold is determined by decreasingthe amplitude stepwise at a programmed pulse duration untilloss of capture occurs. Loss of capture for one test amplitude isdeclared if in a test window of five cardiac cycles (5 A p-V pintervals)two or more intrinsic atrial events are sensed which indicatesunsuccessful pacing.3. Confirmation phase: The pacing threshold is considered to beconfirmed if capture is determined with the first step and loss ofcapture is confirmed with the second step.4. Amplitude adjustment: The pacing amplitude is defined by addingthe programmed safety margin to the determined threshold.7.15 Ventricular Pace Suppression (V p‐Suppression)7.15.1 Feature DescriptionV p-Suppression is a feature that is available in DDD(R)-ADI(R) mode.This feature promotes the intrinsic AV conduction by only pacing theventricle when intrinsic conduction becomes unstable or disappears.Depending on the presence or absence of AV conduction, the feature isimplemented either in the ventricular pacing suppression state ADI(R),which promotes the intrinsic conduction, or in the DDD(R) ventricularpacing state V pDDD(R), which provides ventricular pacing. Automaticswitching capabilities between those two states promote the intrinsicconduction as much as possible without harming the patient. Scheduled