The pacemaker syndrome: a haemodynamic complication of ventricular pacing.

To investigate the pacemaker syndrome (PS) presenting a mixture of signs and symptoms (syncope, presyncope, nausea, dyspnoea, vertigo, loss of physical fitness, congestive heart failure) and related to ventricular pacing, the authors measured cardiac output (CO), peripheral blood pressure (PAP) and peripheral resistance (PR) during continuous atrial and/or ventricular pacing in two groups: patients with and without PS. In both groups a significant decrease in CO was found between atrial and ventricular pacing. A significant difference between the two groups was found in the degree of PAP drop which was significant in the PS group, in the group without PS insignificant. On the other hand, the PR increase at ventricular pacing was in the PS group insignificant, in the symptomless group significant. It is concluded that ventricular pacing causes a CO decrease due to loss of normal atrial transmission. Hypotension in PS patients is connected with an atrial reflex that inhibits normal vascular tone.