Hemodynamic and symptomatic consequences of ventricular pacing.

After implantation of a ventricular demand pacemaker (VVI), occasional patients continue to have dizziness, syncope, or near syncope ("pacemaker syndrome"). To identify patients in whom VVI pacing may have deleterious effects, we compared cuff blood pressure responses to VVI pacing with blood pressure responses to atrioventricular sequential pacing (DVI) or sinus rhythm in 50 consecutive patients. Patients with intact ventriculoatrial conduction had a much greater decrease in systolic blood pressure with VVI pacing (24 +/- 11 mm Hg) than those with ventriculoatrial dissociation (-4 +/- 15 mm Hg) (P less than 0.005). Patients who were in heart failure had a lesser decrease in blood pressure with VVI pacing than did those without failure (P less than 0.05); 13 of the 14 heart failure patients lacked ventriculoatrial conduction. Ten patients had symptomatic dizziness after VVI pacing; the incidence of symptoms was higher in patients with ventriculoatrial conduction (9 of 23) than in those without ventriculoatrial conduction (1 of 27) (P less than 0.003). We conclude that the presence of intact ventriculoatrial conduction appears to be a crucial determinant of the hemodynamic response to VVI pacing, and its presence may identify patients who are at risk for "pacemaker syndrome."