Estella Pulse Generators - BIOTRONIK USA - News

74 Estella Pulse Generators Technical ManualAutomatic Threshold Measurement1. The Automatic Threshold Measurement is the component of theVCC feature that measures the ventricular pacing threshold bystepping down the output until non-capture occurs.2. The Automatic Threshold Measurement occurs over a series ofcardiac cycles and begins at the threshold test start that decreasesuntil capture is lost. AV delay is shortened to 50 ms after a pacedatrial event and to 15 ms after a sensed atrial event to ensureventricular pacing.3. The pacing amplitude decrements with every paced beat by 0.6V,until the first non-captured beat. The algorithm then decrementsby smaller increments of 0.1V until the first failed capture, atwhich point it determines that the capture threshold is precedingvalue. .4. If two out of three non-capture events are detected, the pacingamplitude is set to the sum of the pacing threshold voltage andthe programmed safety margin. If two non-captures are detectedwhen the voltage decrements are greater than 0.1 V, the pacingamplitude is set to the previous amplitude and then the amplitudedecrements by 0.1 V until the pacing threshold is determined.When another two non-capture are detected, the previous voltagesetting is the pacing threshold.5. The pacing amplitude is then set to the pacing threshold plus aprogrammable safety margin (0.5 V through 1.2 V in steps of 0.1 V).6. In addition to performing the threshold search after a loss ofcapture, the search is also conducted at a programmable intervalor a specific time during the day to provide an accurate safetymargin even with gradual changes in the pacing threshold. Notethat a CV initiated by spontaneous loss of capture will reset thetimer that triggers the next periodic measurement if the search isprogrammed to interval.Capture Verification (CV)The Capture Verification function is the component of the VCC featurethat provides beat-to-beat capture verification. (Not available in the ATMmode).1. If VCC determines that capture has been maintained, then thepulse amplitude remains at that current setting and no action isrequired.