Optimization of atrioventricular delay by surface electrocardiography during dual chamber pacing / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Nominal atrioventricular (AV) interval in dual chamber pacemaker (DDD) is not the best AV delay in the majority of patients with atrioventricular block. To find a simple method for optimizing AV delay adjustment, we assessed surface electrocardiography (ECG) for optimizing AV delay during dual chamber pacing.</p><p><b>METHODS</b>DDD pacemakers were implanted in 46 patients with complete, or almost complete, AV block. Optimal AV delay was achieved by programming an additional delay of 100 ms, to the width of intrinsic P wave or to the interval between pacing spike to the end of P wave on surface ECG. Left ventricular (LV) end diastolic and end systolic volumes, ejection fraction and diastolic parameters were measured by Doppler echocardiography during both nominal and optimal AV delay pacing.</p><p><b>RESULTS</b>Compared to nominal AV delay setting, LV end diastolic volume increased [to (53.2 +/- 11.3) ml from (50.2 +/- 10.2) ml, P < 0.05], end systolic volume decreased [to (26.1 +/- 9.0) ml from (27.9 +/- 8.2) ml, P < 0.05] during adjusted AV delay pacing, resulting in an increase in LV ejection fraction [to (68.2 +/- 5.3)% from (64.5 +/- 4.3)%, P < 0.05]. LV diastolic filling and isovolumic relaxation time were not significantly changed.</p><p><b>CONCLUSION</b>Optimization of AV delay by surface ECG is a simple method to improve LV systolic function during dual chamber pacing.</p>

Clinical application of low energy intracardiac cardioversion of atrial fibrillation / 介入放射学杂志

Objective To evaluate the efficacy and safety of low energy intracardiac cardioversion in persistent atrial fibrillation. Methods Low energy intracardiac cardioversion was performed by delivering R wave synchronized biphasic shocks in 7 patients(4 men, 3 women) with persistent atrial fibrillation. Prior to the procedure, all patients underwent transesophageal echocardiographic examinations to rule out the presence of intracardiac thrombus and received subcutaneous injection of low molecular weight heparin for 3 5 days. Two custom made 6 Fr catheters(Rhythm Technologies of Getz, USA) were used for de fibrillation shock delivery. One catheter was positioned in the lower right atrium so that the majority of the catheter electrodes had firm contact with the right atrial free wall. The second catheter was placed randomly either in coronary sinus through right internal jugular vein or in the left pulmonary artery through femoral vein. In addition, a standard diagnostic 6 F quadropolar catheter was placed at the right ventricular apex for ventricular synchronization and postshock ventricular pacing. Shocks were delivered by Implant Support Device(Model 4510, Teleceronics). After conversion, all patients were treated with intravenous amiodarone in the first 24 hours followed by oral administration. Results In all 7 patients cardioversion of atrial fibrillation to sinus rhythm was successfully obtained. A mean of 2?1 shocks per patient has been delivered with a total amount of 13 shocks. The average delivered energy was 7.8?2.2 Joules. No complication occurred. At a mean follow up of 18?9 months, 4 of the 7 patients treated successfully showed sinus rhythm there after. Atrial fibrillation recurred in 3 patients at the second, fifth day and eighth month after cardioversion. Conclusions Low energy intracardiac cardioversion is effective and safe, and can be easily performed in patients without geneal anesthesia. It offers a new option for restoring sinus rhythm in patients with persistent atrial fibrillation.