This tracing demonstrate some aspects of the operating function of the AdaptivCRT algorithm. After programming, the AV delay is extended to 300 ms to allow for intrinsic AV conduction. The device then measures the atrioventricular conduction time and the width of the P wave and the QRS complex. The AV delay is measured by analyzing the timing between the bipolar atrial EGM and the bipolar ventricular EGM that are displayed on this tracing. The analysis of the P-wave and the QRS width includes the HV shock channel (not displayed on this tracing).

The first step of the optimization process consists in the assessment of the atrio-ventricular conduction. In this patient, the time between spontaneous atrial and spontaneous right ventricular EGMs is greater than 200 ms which is defined as prolonged by the device. The patient is therefore stimulated in biventricular with both the programming AdaptivCRT Auto BiV and LV or AdaptivCRT Auto BiV. The rationale for this choice is that left ventricular pacing alone is probably more risky in a patient with AV conduction disorders. It is probably better to choose a biventricular pacing in this context, the right ventricular stimulation being effective if the left lead moves or present an increased threshold.

The « response to a detected ventricular event » algorithm is disabled during the 5 cycles used for the analysis. The periodic detection required for this measure can reduce the percentage of total biventricular stimulation by 1 to 2%. If the recording of the episodes of ventricular sensing is programmed from 5 consecutive cycles, the episodes of ventricular sensing related to the use of the AdaptivCRT will be recorded every 16 hours (5 cycles are required for measuring the width of the P wave and the QRS).