Assessment and modeling of the physical components of human corporo-venous function. Venegas, Jos[acute]e G., Maryrose P. Sullivan, Subbarao V. Yalla, Martyn A. Vickers, Jr. Division of Urology, West Roxbury Veterans Affairs Medical Center, Department of Anesthesia (Bio-engineering), Massachusetts General Hospital, Harvard Medical School
APStracts 2:0185H, 1995.
To understand the mechanisms that control cavernosal sinusoidal drainage during an erectile event and to develop an approach to separate and quantify specific causes of veno-occlusive dysfunction, a comprehensive hydrodynamic model was developed and a detailed analytical study was conducted in patients with erectile dysfunction. Using the analogy between electrical circuits and hydraulic systems, in which pressure is represented by voltage and flow rate by electrical current, we developed an electrical analog model of penile hemodynamics based on current anatomical and physiologic evidence and including a mechanism of flow limitation by the subtunical veins. This model was simulated by computer for steady state and transient intra-cavernosal conditions to predict the graded effect of changes in cavernosal smooth muscle tone, subtunical resistance and cavernosal and tunical compliances. The model primarily predicted that the steady state cavernosal pressure-infusion flow relationship has two phases. An initial phase was characterized by a gradual slope up to a critical flow, and a second phase bya much steeper slope occurring after subtunical venular flow limitation is reached. Predictions of this model were compared with clinical data obtained during incremental saline cavernosometry (SaC) and pharmacocavernosometry (PhC) in a group of 13 patients with erectile dysfunction. These studies were performed using a computer-controlled infusion system capable of generating a constant and stable infusion rate and delivered an uninterrupted supply of infusate while automatically changing from constant flow to constant pressure feedback control when cavernosal pressure reached the threshold of 80 mmHg. From these studies, steady state pressure-flow and pressure -circumference relationships of the penis were analyzed and interpreted in terms of the specific components of the electrical analog model. 

Received 15 December 1994; accepted in final form 21 April 1995.
APS Manuscript Number H1097-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on  9 May 1995.