ATRIAL SEPTAL PACING TO SYNCHRONIZE ATRIAL DEPOLARIZATION IN PATIENTSWITH DELAYED INTERATRIAL CONDUCTION

The current method of pacing the right atrium from the appendage or fr ee wall is often the source of delayed intraatrial conduction and disc oordinate left and right atrial mechanical function. Simultaneous acti vation of both atria with pacing techniques involving multisite and mu ltilead systems is associated with suppression of supraventricular tac hyarrhythmias and improved hemodynamics. in the present study we teste d the hypothesis that pacing from a single site of the atrial septum c an synchronize atrial depolarization. Five males and two females (mean age 58 +/- 6 years) with drug refractory paroxysmal atrial fibrillati on (AF) were studied who were candidates for AV junctional ablation. A ll patients had broad P waves (118 +/- 10 ms) on the surface EGG. Mult ipolar catheters were inserted and the electrograms from the high righ t atrium (HRA) and proximal, middle, and distal coronary sinus (CS) we re recorded. The atrial septum was paced from multiple sites. The site of atrial septum where the timing between NRA and distal CS (d-CS) wa s less than or equal to 10 ms was considered the most suitable for sim ultaneous atrial activation. An active fixation atrial lead was positi oned at this site and a standard lead was placed in the ventricle. The interatrial conduction time during sinus rhythm and AAT pacing and th e conduction time from the pacing site to the HRA and d-CS during sept al pacing were measured. Atrial septal pacing was successful in all pa tients at sites superior to the CS os near the fossa ovalis. During se ptal pacing the P waves were inverted in the inferior leads with short ened duration from 118 +/- 10 ms to 93 +/- 7 ms (P < 0.001), and the c onduction time from the pacing site to the HRA and d-CS was 54.3 +/- 6 .8 ms and 52.8 +/- 2.5 ms, respectively. The interatrial conduction ti me during AAT pacing was shortened in comparison to sinus rhythm (115 +/- 18.9 ms vs 97.8 +/- 20.3 ms, P < 0.05). In conclusion, simultaneou s activation of both atria in patients with prolonged interatrial cond uction time can be accomplished by pacing a single site in the atrial septum using a standard active fixation lead placed under electrophysi ological study guidance. Such a pacing system allows proper left AV ti ming and may prove efficacious in preventing various supraventricular tachyarrhythmias.