Optimized of AV interval (AVD) by the method using pulse oximetry signal amplitude changes: experience from years 1996-2002

Abstract

PURPOSE To optimize the AV delay in sequentially paced patients using a method with beat-to-beat amplitude changes in the pulse oximetry signal. PATIENTS and METHOD A total of 94 patients with dual chamber pacemakers (60 men) were studied. Patients with a pacemaker enabling to change AVD at constant RR intervals were included. The beat-to-beat changes in the pulse oximetry signal amplitude were produced by instantaneous change of DDI to VVI mode from various AVD (50-250 ms). These amplitude drops served to calculate atrial contribution (AC). The oAVD corresponded to the maximal AC obtained. RESULTS From the whole group, 58 patients had repeated examinations within a time range of an hour to a year to evaluate the stability of the oAVD and reproducibility of the relationship between individual ACs and AVDs. A total of 193 evaluations were performed.The curve illustrating the dependence of ACs on AVDs was stable with time. A total of 108 examinations produced clear results showing an oAVD to be within the AVDs 100 and 250 ms. The remaining investigations either showed that the patient did not exhibit any changes in AC with regard to AVD between 100 and 250 ms (47 cases) or that the optimal AVD was even beyond the maximal tested AVD (38 cases). AV delays below 100 ms were unexceptionally detrimental in all patients. In most (81) cases there was a rise in ACs in AVDs between 50 and 175 ms but additional increase in AVDs produced no significant change in ACs. In patients with heart failure the oAVD was longer than in healthy patients (36 cases). CONCLUSIONS The described method enables to identify the optimal AV interval in DDD paced patients non-invasively, rapidly and observer-independently. The optimal AVD is rather stable and does not seem to exhibit an intraindividual variation even within a long period of time.