Cardiovascular effects of sildenafil citrate (Viagra): a naturalistic cross-over study

In a cross-over study we investigated the effects of sildenafil (single doses of 25- or 50mg) on cardiovascular autonomic nervous system (ANS) function assessed by serial recordings of blood pressure, conventional 12-lead electrocardiograms and standardized, time-and frequency domain indices of heart rate variability (HRV) in 21 men with erectile dysfunction. More than half of these patients had multiple comorbidities. Sildenafil induced significant mean reductions from baseline in resting blood pressure, accompanied by a reflex increase in heart rate. There were no significant changes after administration of sildenafil in any other of the ANS function indices. These preliminary findings suggest that sildenafil does not significantly affect cardiac ANS function in patients with erectile dysfunction.