| Popis: |
Right ventricular apical pacing has been the standard for cardiac pacing in view of lead mechanical stability and low pacing thresholds. Patients receiving rate-adaptive dual chamber pacemakers because of high-degree atrioventricular (AV) block and/or severe chronotropic incompetence have thus obtained the benefits of rate control for many decades, without any appreciable hemodynamic adverse effects, for as long as the device was appropriately programmed. Dual-chamber pacing provides the AV-block patient with normal sinus function the benefit of physiological rate response and restoration of AV sequence. Thus, the improvement of quality-of-life of DDDR in patients with clear pacing indications is beyond question. Nonetheless, in recent years there have been numerous studies showing the deleterious effects of right ventricular apical pacing [1]–[5]. Some of these studies, however, are not in agreement with clinical observations, mostly because experience shows that, in prolonged follow-up, patients with DDD devices and permanent right ventricular apical pacing do not necessarily end up with cardiac dilatation and heart failure, even after decades of pacing. If the patients do not have a clear indication for pacing and left ventricular (LV) function is already impaired, such as was the case in the David study [6], it is likely that artificial pacing will cause only side effects and offer no clinical benefit. Therefore, it is apparent to us that many questions remain to be answered. |
