Adverse effects of atrioventricular synchronous right ventricular pacing on left ventricular sympathetic activity, efficiency, and hemodynamic status.

Right ventricular (RV) pacing is now recognized to play a role in the development of heart failure in patients with and without underlying left ventricular (LV) dysfunction. We used the cardiac norepinephrine spillover method to test the hypothesis that RV pacing is associated with cardiac sympathetic activation. We studied 8 patients with normal LV function using temporary right atrial and ventricular pacing wires. All measurements were carried out during a fixed atrial pacing rate. The radiotracer norepinephrine spillover technique was employed to measure total body and cardiac sympathetic activity while changes in LV performance were evaluated with a high-fidelity manometer catheter. Atrioventricular synchronous RV pacing, compared with atrial pacing alone, was associated with a 65% increase in cardiac norepinephrine spillover, an increase in LV end-diastolic pressure, and a reduction in myocardial efficiency. These responses may play a role in the development of heart failure and poor outcomes that are associated with chronic RV pacing.