[Deleterious effects of apical right ventricular stimulation. Should we change our standard method of pacemaker...

Up to now the apical right ventricle one is the best pacemaker implantation. As a matter of fact this site is easily reachable by catheter and dislocations are few. Nevertheless evidence from the literature demonstrates dyssynchrony in myocardial contraction pattern, diastolic dysfunction and mismatch in perfusion and innervation. For this reason alternative sites of stimulation have been tested. One of these is represented by the right ventricular outflow tract. Some studies have compared this site to the apical one, showing a better cardiac index in the former; moreover QRS was narrower and fewer perfusional defects have been found. On the contrary, other studies did not show any significant differences between these two sites of stimulation. In order to obtain cardiac resynchronization, biventricular pacing, has been introduced, consisting in the contemporary stimulation of the lateral wall of both ventricles from a cardiac vein, originating from the coronary sinus. It has been proposed a bifocal stimulation, in which we introduce one catheter into the apex and another one in the right ventricular outflow tract: in this case QRS complex is narrower but cardiac output is not increased. A newer pacing technique is represented by direct His bundle stimulation. We can obtain a narrow QRS complex, like the physiological one. So we might solve problems related to intraventricular dyssynchrony.