Pacemaker syndrome

Pacemaker syndrome

Mitsui et al was the first to describe pacemaker syndrome in 1969 as a symptom complex associated with right ventricular pacing [1]. In general it is due to loss of AV synchrony and it is relieved by AV sequential pacing. But of late, the role of V-V synchrony (loss of) has also been highlighted so that efforts to minimise right ventricular pacing have been promoted.

Patients with pacemaker syndrome may present with exertional dyspnoea, hypotension, near syncope or even syncope. Syncope occurs in the setting of a drop of systolic blood pressure more than 20 mm Hg at the onset of ventricular pacing. Easy fatigability, sensation of fullness and pulsations in the head and neck are also features of pacemaker syndrome. When an intact V-A conduction is present, the pacemaker syndrome may be more severe due to the reverse atrial kick associated with every cardiac cycle. Venous pressure elevation as a result of atrial contraction against a close A-V valve causes reflex peripheral vasodilation and hypotension by stimulating the vagal afferents.

The reported incidence of pacemaker syndrome varies widely. In those trials in which a dual chamber pacemaker was implanted and programmed to single chamber mode for the study purpose, the change over rates to dual chamber mode for suspected pacemaker syndrome was high. But in those trials in which a surgical revision was required for a mode change, the reported incidence was low. This may indicate a lower threshold for the diagnosis of pacemaker syndrome when surgical revision is not required.

Reference

1. Mitsui T, Hori M, Suma K, Wanibuchi Y, Saigusa M. The “pacemaking syndrome.” In: Jacobs JE, editor. Proceedings of the Eighth Annual International Conference on Medical and Biological Engineering. Chicago, Illinois: Association for the Advancement of Medical Instrumentation; 1969:29-33.