In Vivo Assessment of Trabecular Smooth Muscle Tone, its Application in Pharmaco-Cavernosometry and Analysis of Intracavernous Pressure Determinants

Abstract

A pharmaco-cavernosometry based clinical study was designed to define hemodynamic parameters consistent with complete trabecular smooth muscle relaxation, establish a methodology for overcoming incomplete trabecular smooth muscle relaxation, and determine under controlled conditions the contribution of venous outflow and arterial inflow to the steady-state equilibrium intracavernous pressure. Flow-pressure relationships were analyzed in 21 patients each of whom was assumed to have complete smooth muscle relaxation by virtue of the full, rigid and maintained erectile response following intracavernous vasodilator administration, which required intracavernous adrenergic agonists to achieve detumescence. Flow-to-maintain values increased linearly with intracavernous pressure while venous outflow resistance values were high and constant. Based on these relationships, trabecular smooth muscle tone was assessed in 123 impotent patients. In 14%, 63% and 14% of the patients (112 of 123 overall), respectively, 1, 2 and 3 doses of vasoactive agents were required to achieve hemodynamic relationships consistent with complete trabecular smooth muscle relaxation. In 9% of the patients such hemodynamic relationships were unable to be reached. In the 112 patients the influence of different engineering based measures of corporeal veno-occlusive function, including flow-to-maintain, pressure decay, venous outflow resistance and corporeal capacitance, was analyzed against the spectrum of equilibrium steady-state intracavernous pressures. Two distinct equilibrium pressure groups were identified reflecting different capacitance states: pressures greater than 60 mm. Hg (associated with low capacitance values) and pressures less than 50 mm. Hg (associated with high capacitance values), with pressures 50 to 59 mm. Hg representing a hemodynamic transition zone. When analyzed during complete trabecular smooth muscle relaxation, corporeal veno-occlusive hemodynamic variables in conjunction with cavernous arterial perfusion pressure determine the steady-state equilibrium intracavernous pressure. Failure to assess corporeal veno-occlusive function under such conditions will overestimate the degree of suspected corporeal structural disease.

The value of a second injection on the pharmaco induced erection test

“…Our results clearly show that improvement is often achieved. As much as 77% of the patients had improvement on rigidity with reinjection, what agrees with the results of Hatzichristou et al 4 Thirty per cent of the patients with incomplete erectile response to a single dose of drugs achieved a rigid erection after reinjection, demonstrating normality of veno occlusive mechanism. At least in these cases the diagnosis of venous leak if based only on a single injection could be mistaken.…”

“…1±3 However, it is liable to many false negative results attributed to incomplete relaxation of corporal smooth muscle, related to anxiety and absence of sexual arousal. Recently a new hydrodynamic method was introduced 4 to access the contractile status of the corpora cavernosa smooth muscle. The authors stressed the importance of doing more than one intracavernous injection to achieve complete relaxation in some patients.…”

Engineering analysis of penile hemodynamic and structural-dynamic relationships: Part III—Clinical considerations of penile hemodynamic and rigidity erectile responses

“…4 Hemodynamic data obtained included equilibrium pressure P eq ,¯ow-to-maintain and venous out¯ow resistance for various intracavernosal pressures, pressure decay from an initial pressure of 150 mmHg over 30 s cavernosal artery systolic occlusion pressure and gradients to the brachial artery systolic occlusion blood pressure (P brach ±P cav ). In all cases, complete smooth muscle relaxation was felt to exist on the basis of pressure±¯ow-to-maintain and pressure±venous out¯ow resistance relationships.…”

“…2 In such cases, patients may possess the ability to have satisfactory intercourse despite the recording of abnormal hemodynamic integrity by such studies as duplex Doppler ultrasonography 3 or dynamic pharmacocavernosometry. 4 On the other hand, penile rigidity may be inadequate despite the observation of normal physiologic hemodynamic erectile responses by erectile function testing. Such patients have often been classi®ed as having psychogenic impotence but physical factors other than hemodynamic variables have been shown to affect the magnitude of penile buckling forces.…”

Is there a role of hypoxemia in penile fibrosis

“…7±11 In a prospective study of men undergoing penile prosthesis insertion, we have found a direct correlation between erectile function and the ratio of trabecular smooth muscle to total erectile tissue. 2 Erectile function was de®ned by experimentally determined parameters of¯ow to maintain erection, resistance to ®lling, and pressure decay using dynamic infusion corpus cavernosography/cavernosometry (DICC) 12 ow-to-maintain values (50 ±120 ml/min) and substantial cavernous leakage. Similar relationships were found when out¯ow resistance and pressure decay were correlated with percent trabecular smooth muscle.…”