Normal hemodynamic parameters do not always predict the presence of a rigid erection: a quantitative assessment of functional erectile impairment

Abstract

The purpose was to assess objectively and quantitatively the hemodynamic status and the degree of functional erectile impairment in a group of impotent patients. A clinical study was designed, incorporating pharmacocavernosometry (to evaluate arterial and veno-occlusive function) with axial buckling forces and penile geometry measurements in a group of impotent patients. The pressure gradient between the intracavernosal pressure associated with the presence of penile axial rigidity and the equilibrium intracavernosal pressure was calculated (axial rigidity gradient, ARG); such methodology allowed a quantitative characterization of functional impairment, as ARG expresses the intracavernosal pressure increase necessary to achieve axial rigidity and therefore potency. Penile geometry characteristics were also expressed by calculating the penile aspect ratio (diameter/length, D/L). In 83 consecutive patients tested (mean age 42.89±9.96), rigidity occurred at intracavernosal pressures between 50 and 100 mm Hg. A conversely proportional relation was noticed between penile aspect ratio values and the intracavernosal pressure associated with rigidity values, clearly demonstrating the important functional role of penile geometry. ARG demonstrated a wide range of values (3–69 mm Hg), reflective of the severity of the erectile dysfunction on each patient. Half (50.6%) of the patients had ARG values ≤20 mm Hg, indicative of minimal and minimal-to-moderate erectile impairment, while 20.48% had ARG between 21–30 and 28.92% >30 mm Hg, indicative of moderate and severe erectile dysfunction (ED) respectively. In all, 6% of the study group, all of them with primary ED, ARG <20 mm Hg had normal hemodynamics, but low penile aspect ratio values indicating that penile geometry may be the cause of insufficient rigidity. Hemodynamic integrity is the most critical, but not the only determinant of penile rigidity, as erectile impairment may be noticed in patients with normal arterial inflow and corporal veno-occlusive function. In such cases, unfavorable penile geometry should be considered as the possible etiological factor of impotence.