The Effect Of Different Atrioventricular Delays On Left Atrial Function In The Third Degree AVB Patients With DDD Pacemaker Implanted

Objective To investigate the effects of different A-V delay (AVD) on left atrial function in the third degree AVB patients with dual-chamber pacemaker (DDD) implanted.Methods Seventy-six patients with DDD pacemaker were enrolled into the study. Patients were divided into two groups:one with normal cardiac function and another with diastolic dysfunction. Left atrial ejection fraction (LAEF) and Cardiac output (CO) were measured using real-time triplane volume analysis. Mean systolic peak strain rate(SR-s), mean early diastolic peak strain rate(SR-e)and mean late diastolic peak strain rate(SR-a)were measured using real-time triplane strain rate imaging. Patients were paced for five successive continuous pacing periods of10minutes duration using five selective AV delays (80ms,100ms,150ms,200ms and250ms). The results were compared between the different A-V delays.Results The group of diastolic dysfunction:①When A-V delay increased from80ms to200ms, LAEF、SR-a and CO gradually increased. When A-V delay increased to200ms, LAEF, CO, SR-a were reached to the highest level. Further increase in A-V delay to250ms resulted in decreased SR-a, LAEF and CO.②SR-s was increased while SR-e was decreased during DDD pacing under80ms and250ms A-V delays. Compared with200ms A-V delays, SR-s was increased significantly at80ms A-V delay (P<0.05). While in the group of normal cardiac function:Insignificant changes in LAEF、SR-s、SR-e and SR-a were detected by setting A-V delays.Conclusion Setting of AV delay has not significant effect on the left atrial function in patients with normal cardiac function, but moderate prolongation of AV delay has favorable effect on it in patients with diastolic dysfunction.