RESUMO
BACKGROUND: Since the introduction of the dual chamber pacemaker (DDDR) in the early 1980s, researchers have repeatedly discussed and attempted to optimize the atrioventricular (AV) interval, in order to increase the cardiac performance of pacemaker patients. Nominal AV delay in a DDDR is not, by hemodynamics, the best option for the majority of patients with AV conduction disorders. Our research is suggesting a simplified approach to define an optimal AV delay in a DDDR pacemaker population on the use of the programming electrocardiogram (ECG) at follow-up. METHODS: The study enrolled 55 consecutive patients (67.28 ± 1.03 years, 36 male) with an initial dual chamber pacemaker implanted for complete and second degree AV block between 2005-2010. Optimal AV delay was achieved by programming an additional delay of 95 ms, to the medium value of the interval between atrial pacing spike to the end of P wave or to the width of intrinsic P wave, on the ECG of the programming device. At discharge, shortly after the implant procedure, the patients were examined by Doppler echocardiography, during nominal and optimal AV delay pacing measuring systolic and diastolic left ventricular function parameters. RESULTS: Compared with the nominal AV delay settings, the left ventricular end diastolic volume did not changed (from 112.3 ± 2.3 ml to 112.9 ± 2.3 ml), the end systolic volume decreased (from 59.8 ± 1.7 ml to 50.9 ± 1.3 ml, p<0.01) after adjusted the AV delay, followed by an increased left ventricle ejection fraction (from 61.07 ± 0.18 % to 65.46 ± 0.13 %, p<0.001) and isovolumic relaxation time decreased (from 102.7 ± 1.9 ms to 97 ± 2 ms, p<0.05). E wave velocity, A wave velocity and E/A ratio were not significantly changed. CONCLUSION: AV delay adjusted by programmer ECG in a follow-up session of an implantable device is a simple and useful method used in our laboratory as a resource for ventricular pacing optimization and hemodynamic improvement in patients with a dual chamber pacemaker (DDDR).
