Evaluation of normal erectile function with color flow Doppler sonography.

To understand better the vascular events that occur during normal erection, we used color flow Doppler sonography to examine the erectile process in seven normal subjects. The relationship of systolic/diastolic velocities and spectral waveform changes in the penile arteries was studied in response to increasing pressure within the corpora cavernosa (tumescence) before and after the intracorporal administration of drugs to induce erection. A characteristic spectral waveform pattern was identified throughout the erectile cycle, and the pattern was correlated with increasing pressure. Both systolic and diastolic velocities were elevated during the initiation of erection, at which time the pressure within the corpora cavernosa was low (11-25 mm Hg). Systolic velocities remained elevated until the last phase of erection (83-106 mm Hg). Diastolic velocity decreased as the intracorporal pressure increased from 25 to 40 mm Hg. Between 40 and 63 mm Hg, diastolic velocity approximated zero. With increasing pressure (63-83 mm Hg), diastolic flow reversed. As the corpora cavernosa approached full erection (83-105 mm Hg), both the forward systolic and reverse diastolic flow components diminished. At approximately 106 mm Hg (systolic occlusion pressure), flow ceased. Systolic/diastolic velocity and waveform phase relationships could be used to define the integrity of both the cavernosal artery inflow and the venous sinusoidal outflow occlusion mechanisms. Color flow Doppler sonography enhanced our ability to observe and quantify dynamic erectile events and provided new insights into understanding normal erectile function.