Characteristics and hemodynamic advantages of a new ventricular synchronized pacemaker

Numerous patients with pacemakers may exhibit periods of spontaneous sinus rhythm or, after some time of artificial pacing, may show a return to a normal A-V conduction. In these instances, pacing by fixed-rate pacemakers may give rise to competition with the spontaneous rhythm and prevent the heart from exploiting the physiological mechanism of adaption to increased effort. To overcome the difficulties a new pacemakers (1) has been designed which stimulates the heart at a fixed rate when the ventricoular rate flow and synchronizes on it when the spontaneous ventricular rate is higher than an established value.