[Pacemaker syndromes]

The pacemaker syndrome refers to symptoms and signs in pacemaker patients caused by inadequate timing of atrial and ventricular contractions. The lack of normal atrioventricular synchrony may result in decreased cardiac output and increased in atrial pressure which elicits a systemic hypotensive reflex response. These hemodynamic disturbances mostly occur in the presence of retrograde VA conduction is present. The incidence of pacemaker syndrome is uncertain, and varies from 7% to 20% of all ventricular paced patients. Neurologic symptoms or symptoms suggesting low cardiac output or congestive heart failure are indicative of the pacemaker syndrome. These symptoms may vary from mild to severe, they are nonspecific and very common among cardiac patients with or without pacemaker. In many patients they are not even noted until AV synchrony is restored. The pacemaker syndrome is not restricted to the VVI stimulation mode. It can be seen, though rarely, in atrial and even dual-chamber pacing (VDD, DDI, DDD). In these cases it is usually occasional and may be due to inappropriate programming or selection of the pacing mode.