| BackgroundIn comparing with VVI and DDD pacemaker, single chamber atrial pacing (AAI) pacemaker not only remain the normal atrial-ventricular contraction sequence, but also preserved the synchronization of inter-ventricular activation; Atrial pacing mode is more physiological than any other pacing mode. In patients with sick sinus syndrome (SSS), the superiority of AAI pacing versus VVI had been definitely stated by several retrospective and prospective studies, as far as quality of life, exercise tolerance, congestive heart failure, pacemaker syndrome, stroke and atrial fibrillation were taken into account. In spite of that, only a small part of patients actually received AAI pacemaker and AAI pacemaker were underutilized in clinic. Objectives In order to improve the knowledge of AAI pacemaker and use the AAI pacemaker reasonably in clinic, we investigated the effects of AAI pacing on the hemodynamics and cardiac function in the patients with SSS and the prognosis of the patients with SSS receiving AAI pacemaker; the clinical applicant status of AAI pacemaker in our practice was investigated as well. Methods1. Echocardiography of 18 patients with SSS was performed when the implanted DDD pacemakers were programmed to AAI, DDD (AVD 120-150ms) or VVI pacing mode respectively. We measured the mitral blood stream (E peak, A peak), aortic flow velocity (AFV), aortic flow velocity time integral (AFVTI), stroke volume (SV), cardiac output (CO), left ventricular end-systolic/left ventricular end-diastolic diameter (LVESd/LVEDd) and left ventricular ejection fraction (LVEF) in each patient and compared all the measured parameter according to different pacing mode.2. 132 SSS patients received AAI, DDD or VVI mode pacemakers werefollowed-up in out-patient clinic. The incidence or prevalence of pacemaker syndrome, congestive heart failure, stroke, atrial fibrillation, the dislocation of electrode leads as well as operation complication, the parameters of echocardiogram and the changes of quality of life were compared in each group. The data of the new occurring AVB during follow-up in AAI group were collected in meantime.3. In order to get more information of the clinical applicant status of AAI pacemaker, we retrospectively analyzed the data of 175 patients with SSS received pacing therapy in ChangZheng hospital in the near five years. Results1. The effects of different pacing mode on hemodynamics and cardiac function. The value of A peak, AFV, AEVTI, LVEF, CO and SV were higher in AAI pacing mode than ODD or VVI pacing modes (p<0.05). During VVI pacing, the E peak of mitral blood steam was unstable in size and A peak showed intermittent and irregular. In comparing with AAI and DDD pacing mode, the value of A peak, AFV, AEVTI, LVEF, CO and SV of VVI pacing mode was the lowest. In other words, the negative effects of AAI pacing on hemodynamics and cardiac function were the least because both the normal atrial-ventricular contraction sequence and the synchronization of ventricular activation were remained in AAI pacing mode. The negative effects of DDD pacing mode were less than VVI pacing mode because the normal atrial-ventricular contraction sequence was preserved in DDD pacing mode2. The follow-up results of 132 patients with SSS receiving different pacing mode pacemakers. 18(23%) patients in VVI group suffered from the atrial fibrillation events, and no in AAI group(vs VVI group, P=0.049) ,one in DDD group (vs VVI group, P=0.009). 17(20%) patients in VVI group suffered from the stroke events, no in AAI group (vs VVI group, P=0.049), no in DDD group (vs VVI group, P=0.003). 17(20%) patients in VVI group suffered from congestive heart failure, no in AAI group(vs VVI group, P=0.049) and 4 in DDD group (vs VVI group, P>0.05). There were no significant differences between AAI and DDD group in all followed-up subjects. There were no significant differences in the incidence of pacemakersyndrome, operation compli... |
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