Correlation between flow-mediated dilation and erectile dysfunction.

We hypothesized that there is a correlation between the magnitude of endothelial-mediated dilation of brachial artery and erectile function in patients. Thus, flow-mediated dilation of the brachial artery (FMD)-used to assess the function of endothelium-was measured in 56 patients (aged approximately 35 years) having erectile dysfunction for 6-12 months. The patients were grouped based on International Index of Erectile Dysfunction: severe (5-10), moderate (11-16), mild to moderate (17-21), and mild (22-25). As compared to the mild group (8.8 +/- 1.7%), FMD was significantly reduced in the mild-to-moderate group (5.7 +/- 1.1%), moderate group (5.3 +/- 0.8%), and severe group (4.4 +/- 0.6%). Also, there was a positive correlation between the magnitude of endothelial and erectile dysfunction. Patients were treated with the 5-phosphodiesterase inhibitor sildenafil, known to elevate vascular cGMP level and thus the vascular efficacy of internal nitric oxide, for 3 to 6 months prior to the study. The mean doses of sildenafil used were as follows: severe group, 100 mg/event; moderate group, 86.1 +/- 21.4 mg/event; mild-to-moderate group, 71.8 +/- 23.2 mg/event; mild group, 25 mg/event. We found a positive correlation between the sildenafil dose requirement and the severity of erectile dysfunction. On the bases on these findings, together with the known mechanism of action of sildenafil, we propose that vascular endothelial dysfunction could contribute to erectile dysfunction and that erectile dysfunction may be an early marker of peripheral vascular disease.