Hemodynamic characterization of a functional erection. Arterial and corporeal veno-occlusive function in patients with a positive intracavernosal injection test.

Objectives: To characterize hemodynamically a functional/rigid erection and study the hypothesis that a positive intracavernosal injection test indicates normal arterial and corporeal veno-occlusive function.

Methods: 33 patients (mean age 39.5 +/- 9 years), who developed rigid erection during pharmacocavernosometry, included in the present study. The presence of axial rigidity was determined at steady state equilibrium intracavernosal pressure, by absence of buckling to axial force of 1 kg, applied to the erect penis and sustained for >/=15 min. Arterial and veno-occlusive hemodynamic parameters were analyzed.

Results: Flow-to-maintain at intracavernosal pressure 150 mm Hg and mean pressure decay values ranged between 0.5-13 ml/min and 5-85 mm Hg, respectively. Flow-to-maintain values >5 ml/min were noticed in 8 patients (24. 24%), while pressure decay values >45 mm Hg in 13 patients (39.39%). Pharmacocavernosography revealed moderate opacification of venous structures in 7 cases (21.21%). Abnormal systemic-cavernosal systolic arterial pressure gradients in both cavernosal arteries were noticed in 9 patients (27.27%). All patients with flow-to-maintain values >5 ml/min had normal arterial function.

Conclusions: A functional/rigid erectile response may coexist with arterial insufficiency or corporeal veno-occlusive dysfunction. Presence of normal or borderline arterial inflow may compensate minimal or moderate veno-occlusive dysfunction, resulting in a functional - but not normal - erection. Such information is critical when the intracavernosal injection test is used for diagnostic purposes.