Assessment Of Cardiac Function In Different Atrio-Ventricular Delay In The Patients With Dual-Chamber Pacemakers Using Real-time Three-dimensional Echocardiography

Objective:To investigate the relationship between different atrioventricular delay (AVD) and cardiac hemodynamics and function in patients with dual chamber pacemaker implanted.Methods:Thirty five patients aged68.74±6.59were enrolled into the study., They suffered from atrioventricular conduction block or sick sinus syndrome and dual chamber pacemaker were planded in July2009to July2012, End-systolic volume (ESV), end-diastolic volume (EDV), ejection fraction (EF), peak filling velocity (PFR), peak systolic velocity (PER), rESV, rEDV, rEF, time to minimal segmental volume (Tmsv-16-SD, the SD of Tmsv in16of17segments, excluding the apical cap; Tmsv-12-SD, the SD of Tmsv of6basal and6middle segments and Tmsv-6-SD, the SD of Tmsv of6basal segments), left atrial maximal volume (LAVmax), left atrial minimal volume (LAVmin), left atrial presystolic volume (LAVpre), left atrial total volume (LAVt), left atrial total emptying fraction (LAVtEF), left atrial passive volume (LAVp), left atrial passive emptying fraction (LAVpEF), left atrial active volume (LAVa), left atrial active emptying fraction (LAVaEF) were measured and acquired using real-time three-dimensional echocardiography (RT-3DE). All the patients were paced for five successive continuous pacing periods of5minutes duration using five selective AV delays (140ms,170ms,200ms,225ms,250ms). The results were compared between the different AVDs.Results:1. When AVD increased from140ms to170ms, EF and PFR increased correspondingly and reached top at170ms, and then it started to decrease gradually. There was no difference between170ms and200ms for EF, but EF was higher when AVD was170ms than that was when AVD was140ms and225ms (p<0.05). When AVD was250ms, EF reached the bottom (p<0.05). When AVD was225ms and250ms, PFR was lower than that was when AVD was170ms (p<0.05). There was no change in EDV, ESV and PER (p>0.05).2. When AVD increased from140ms to250ms, there was no change in rEDV, rESV and rEF (p>0.05).3. When AVD increased from140ms to170ms, Tmsv-16-SD%, Tmsv-12-SD%, Tmsv-6-SD%, Tmsv-16-Dif%, Tmsv-12-Dif%, Tmsv-6-Dif%decreased corres-pondingly and reached bottom at170ms, and then it started to increase gradually (p<0.05).4. When AVD increased from140ms to170ms, LAVmax and LAVmin decreased correspondingly and reached bottom at170ms, and then it started to increase gradually(p<0.05).5. Taking EF as a standard, there were twenty four patients whose optimal AVDs were170ms, and the other eleven patients’optimal AVDs were200ms. For all patients the optimal AVDs were179.43±14.13ms.Conclusion:1. Cardiac function changed with different AVDs. When the optimal AVD was selected, the cardiac function could be significantly improved in patients with dual chamber pacemaker implanted.2.70%patients could get the best cardiac function when AVD was170ms, and the other was200ms. The optimal AVD was170-200ms in all patients.3. Taking EF as a standard, the patients’optimal AVDs were179.43±14.13ms.4. Though longer AVD could ensure the pacing tatio, it may be harmfull to the cardiac function in patients implanted dual chamber pacemaker.5. When the AVD was170ms, patients’ hearts could get the best systolic synchrony.6. RT-3DE was noninvasive, repeatable and easy approach for assessment of cardiac function. If we wanted to use RT-3DE for assessing optimal AVD in the patients with dual-chamber pacemakers, expanding the sample size were stilled needed.