Immediate Electrophysiological Effects of Different Atrial Pacing Sites on P-Wave Characteristics

This is a prospective, single-center, non-randomized, within-subject interventional study. The purpose is to compare the immediate effects of different atrial pacing sites on atrial electrical activation, as reflected by P-wave characteristics on surface electrocardiography (ECG). During pacemaker implantation, short-term pacing will be performed sequentially at multiple predefined atrial sites, including the right atrial appendage (RAA), atrial septum, Bachmann's bundle (BB) area, and posterosuperior bundle (PSB) regions. ECG parameters will be recorded at each site to evaluate differences in P-wave duration and morphology.