Study Of Left Atrial Appendage Function In Patients With Permanent Ventricular Demand Pscing

Abstract

Previous studies have shown that the incidence of thromboembolism is higher in patients with single-chamber ventricular demand (VVI) pacemaker. However, data on left atrial appendage(LAA) function in pacing patients are limited. To investigate the influence of the pacing mode on the left atrial appendage function, we studied 30 patients with VVI pacemakers divided into two groups. Group I includes 10 patients studied within 1 week from date of implantation. Group II studied 3 or more years after implantation. The indication for pacemaker implantation was third degree atrioventricular block(AVB). All patients in both groups were totally dependant on the pacemaker. They all demonstrated sinus rhythm at time of study entry. None were hypertensive and were all• clinically free from organic heart diseases (valvular heart diseases, cardiomyopathies). We used transesophageal echocardiography to study LAA flow patterns, velocities, systolic pulmonary venous flow velocities, patency of LAA . and presence of SEC or LAA thrombi. • Comparing group 1 to group II patients, results revealed that mean values ofLAA emptying, filling velocities and systolic PVF velocities are higher in patients in group I than those of group II.(0.64:l:0.265m/s, 0.488±0.178mls& 0.542 ±P.205m/s versus 0.354±0.1258mls, 0.343cJ::0.1464m/s & 0.394 ±0.1125m/s respectively). SEC and LAA thrombi were completely absent in group I and present in 25 % and 15 % in patients in group II with chronic VVI pacing respectively. In conclusion, a decrease in LAA function in patients with chronic VVI pacing may account for an increased risk of thrombus formation in LAA (an increased thromboembolic risk in patients in sinus rhythm with VVI pacemakers).