A pilot study of flaccid penile blood flow patterns in normal subjects and patients with erectile dysfunction

Dynamic penile scintigraphy was performed using 99Tcm-labelled autologous erythrocytes in five normally potent volunteers and 22 patients with erectile dysfunction including 11 patients with psychogenic and 11 patients with vasculogenic impotence (four arteriogenic, three venogenic, three arteriogenic and venogenic, one arteriogenic and neurogenic). Penile radioactivity changes in the flaccid state were monitored by a gamma camera for 60 min after injection of the radionuclide. The penile time-activity curves of the normal controls characteristically showed secondary pulses of increased activity of variable amplitude, duration and frequency, consistent with phasic increase in penile blood pool. This normal rhythmic pattern was impaired in patients with penile arterial insufficiency whereas a blunted pattern was seen in most patients with functional impotence as well as in patients with nonarteriogenic organic impotence with a psychological overlay. This study provides new insights into the flaccid penile circulatory physiology, which may contribute to our understanding of the pathophysiology of erectile dysfunction. In arteriogenic subjects, the impaired response may be attributable to an inadequacy of penile arterial inflow as well as secondarily due to the resultant sinusoidal dysfunction subsequent to penile ultrastructural damage due to an altered nutritive environment. Increased adrenergic activity in patients with psychogenic impotence may be responsible for the observed deviation from the normal pattern.