Abstract
BACKGROUND: Pacemaker implantation involves intraoperative testing of ventricular sensing using a device called a pacing system analyzer (PSA). The value obtained is expected to correspond to those taken by the pacemaker after its implantation. This study determined the latency period for sensing intracardiac electrogram (EGM) by the right ventricular (RV) lead. METHODS: Patients without significant heart disease and underlying intrinsic atrioventricular (AV) conduction underwent Medtronic or Abbott dual-chamber pacemaker implantation with the RV lead positioned on the mid-septum. Real-time sensing data were obtained through PSA and after pacemaker implantation to evaluate latency as the time interval Q-VS between the onset of QRS on surface electrocardiogram and the sensed EGM by the RV lead. RESULTS: Of 157 patients, 105 had narrow QRS (<120 ms) and 52 had wide QRS of complete right bundle branch block (RBBB). Both narrow-QRS and RBBB patients had longer sensing latency through PSA (50.9 ± 24.2 and 67.8 ± 32.9 ms, respectively) than through pacemaker (18.2 ± 12.8 and 31.2 ± 14.8 ms, respectively, both p < 0.001). RBBB patients had longer sensing latency compared with narrow QRS patients, either through PSA or through pacemaker (p < 0.001). The sensing latency of Medtronic recipients was longer than those of Abbott in narrow-QRS (p < 0.05), but not in RBBB. CONCLUSION: We demonstrated longer RV lead sensing latency (1) through PSA than through pacemaker, (2) in RBBB than in narrow-QRS, and (3) in Medtronic pacemakers compared with Abbott pacemakers. Knowledge of sensing latency helps the optimization of the AV delay.