Hemodynamics of Penile Erection: III. Measurement of Deep Intracavernosal and Subtunical Blood Flow and Oxygen Tension (original) (raw)
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Hypothesis of human penile anatomy, erection hemodynamics and their clinical applications
Asian Journal of Andrology, 2006
Aim: To summarize recent advances in human penile anatomy, hemodynamics and their clinical applications. Methods: Using dissecting, light, scanning and transmission electron microscopy the fibroskeleton structure, penile venous vasculature, the relationship of the architecture between the skeletal and smooth muscles, and erection hemodynamics were studied on human cadaveric penises and clinical patients over a period of 10 years. Results: The tunica albuginea of the corpora cavernosa is a bi-layered structure with inner circular and outer longitudinal collagen bundles. Although there is no bone in the human glans, a strong equivalent distal ligament acts as a trunk of the glans penis. A guaranteed method of local anesthesia for penile surgeries and a tunical surgery was developed accordingly. On the venous vasculature it is elucidated that a deep dorsal vein, a couple of cavernosal veins and two pairs of para-arterial veins are located between the Buck's fascia and the tunica albuginea. Furthermore, a hemodynamic study suggests that a fully rigid erection may depend upon the drainage veins as well, rather than just the intracavernosal smooth muscle. It is believed that penile venous surgery deserves another look, and that it may be meaningful if thoroughly and carefully performed. Accordingly, a penile venous surgery was developed. Conclusion: Using this new insight into penile anatomy and physiology, exact penile curvature correction, refined penile implants and promising penile venous surgery, as well as a venous patch, for treating Peyronie's deformity might be performed under pure local anesthesia on an outpatient basis.
The Scientific World JOURNAL, 2004
The penile erectile tissue, specifically the cavernous smooth musculature and the smooth muscles of the arteriolar and arterial walls, plays a key role in the erectile process. In the flaccid state, these muscles are tonically contracted by the sympathetic discharge, and vasoconstrictors secreted by endothelium allowing only a small amount of arterial flow for nutritional purposes.
Penile veins play a pivotal role in erection: the haemodynamic evidence
International Journal of Andrology, 2005
Although penile venous surgery has almost been abandoned and the venous factor eliminated as a contributing factor to erectile dysfunction, new concepts of erectionrelated veins has recently been described and reported in literature. We sought to conduct a haemodynamic study on human cadavers in order to elucidate to what extent penile veins act in erection, and to explore the possible role of erection-related veins as an important contributor to impotence. From November 2002 to December 2003, seven fresh human cadavers of men who had no sexual activity for at least 6 months prior to death, and in whom the penis was intact were used for this study. Infusion cavernosometry was carried out with an induction flow of 150 mL/min before and after the erection-related veins were removed. A rigid erection was attained in all subjects, lasting significantly longer (p ¼ 0.043) after removal of erection-related veins. Similarly, there were significant differences in the maintenance flow (p ¼ 0.043), T max (p ¼ 0.043), V max (p ¼ 0.043), and pressure loss (p ¼ 0.043). In cadaveric penises, a rigid erection could be maintained in spite of the fact that the low flow rate of 21 mL/min is much lower than the average arterial perfusion rate observed in cases of arterial insufficiency. We therefore concluded that penile veins may play a significant role in attaining sufficient erection, and further research is required to study this possible clinical implication.
Physiology of Penile Erection and Pathophysiology of Erectile Dysfunction
Urologic Clinics of North America, 2005
The molecular and clinical understanding of erectile function continues to gain ground at a particularly fast rate. Advances in gene discovery have aided greatly in working knowledge of smooth muscle relaxation/contraction pathways. Intensive research has yielded many advances. The understanding of the nitric oxide pathway has aided not only in the molecular understanding of the tumescence but also aided greatly in the therapy of erectile dysfunction. As a man ages or undergoes surgery, preventative therapies to preserve erectile dysfunction have begun. All clinical interventions derived their beginning in a full anatomical, molecular, and dynamic knowledge base of erectile function and dysfunction. In this chapter the components of erectile function will be explained. Hemodynamics and Mechanism of Erection and Detumescence Corpora Cavernosa The penile erectile tissue, specifically the cavernous smooth musculature and the smooth muscles of the arteriolar and arterial walls, plays a key role in the erectile process. In the flaccid state, these smooth muscles are tonically contracted, allowing only a small amount of arterial flow for nutritional purposes. The blood partial pressure of oxygen (PO2) is about 35mmHg range. 1 The flaccid penis is in a moderate state of contraction, as evidenced by further shrinkage in cold weather and after phenylephrine injection. Sexual stimulation triggers release of neurotransmitters from the cavernous nerve terminals. This results in relaxation of these smooth muscles and the following events: 1. Dilatation of the arterioles and arteries by increased blood flow in both the diastolic and the systolic phases 2. Trapping of the incoming blood by the expanding sinusoids 3. Compression of the subtunical venular plexuses between the tunica albuginea and the peripheral sinusoids, reducing the venous outflow 4. Stretching of the tunica to its capacity, which occludes the emissary veins between the inner circular and the outer longitudinal layers and further decreases the venous outflow to a minimum
J Urol, 1999
Purpose: The extent to which hemodynamic erectile responses predict penile buckling forces has not previously been analytically investigated. An engineering study was performed to compare hemodynamic data with penile buckling force values. Methods: Dynamic infusion pharmacocavernosometry studies in 21 impotent patients (age 43, range 24±62 y) were accomplished to obtain information during penile erection concerning hemodynamic values, penile buckling forces and their determinants: intracavernosal pressure, erectile tissue mechanical properties and penile geometry. Results: In the 21 patients, discrepancies existed in several patients who demonstrated normal hemodynamic values (low¯ow-to-maintain and high equilibrium intracavernosal pressures) but elevated cavernosal compliance values and diminished penile buckling forces. There was poor correlation between cavernosal compliance and equilibrium intracavernosal pressure (r 70.36); better correlation between compliance and expandability (r 70.72) and best correlation between dimensionless compliance and the dimensionless product of expandability with equilibrium pressure (r 70.88). These data implied that cavernosal compliance was dependent on multiple factors, not only equilibrium intracavernosal pressure. Conclusions: Hemodynamic indices which correlate with intracavernosal pressure alone do not predict penile buckling forces since the latter are dependent not only on intracavernosal pressure but also on penile geometry and erectile tissue properties. The most relevant tissue property in predicting adequate penile buckling forces is cavernosal expandability. A new impotence classi®cation system and diagnostic algorithm based on the determinants of penile rigidity and not exclusively on hemodynamic responses is proposed.
Cavernosal Arterial Anatomic Variations and Its Effect on Penile Hemodynamic Status
The Journal of Urology, 2002
Objecti6e: With continuous improvements in ultrasound technology, small vessels with remarkably slow blood flow that may not be assessed by color Doppler ultrasonography, can be evaluated using power Doppler ultrasonography. In the present study, penile arterial anatomic variations were determined with power Doppler ultrasonography and its impact on penile hemodynamic status. Methods: A total of 54 patients with erectile dysfunction were evaluated with power Doppler ultrasonography. The effects of vascular anatomic variations and the structure of the corpora cavernosa and tunica albuginea on vascular status were assessed on both sides. Results: A normal penile vascular system was observed in 35.2% and 25% of 54 patients (mean age: 46.6 911.5 years) at the radix and mid-shaft of the penis, respectively. Pure arterial component was observed in 40.7% (22/54) and 47.2% (17/36) of the patients at the base and mid-shaft of the penis, respectively. Penile arterial insufficiency was severe in 9.2 and 5.5% of the patients at the base and mid-shaft of the penis, respectively, whereas intrapenile truncus was found in six patients (5.5%), the ratio of single cavernosal artery, intrapenile and extrapenile bifurcations were 69.4, 7.4 and 12.0%, respectively. Twenty (18.5%) dorso-cavernosal perforators, 15 (13.9%) cavernoso-dorsal and 30 (27.8%) intercavernosal branches were found. Peak systolic blood flow velocity values were decreased in 12 of 36 patients (33.3%) distally, while increased blood flow was observed in 11 (30.5%). Conclusions: Hemodynamic parameters might be variable at either side of the penis and depend on intrapenile arterial anatomic variations. Parameters determined using power Doppler ultrasonography should be evaluated from the proximal to distal side of the penis to obtain reliable and standard results. However, variations of penile arterial anatomy and its effect on penile hemodynamic changes should not be overlooked especially in the patients who are candidates for penile reconstructive or vascular surgery.
International Journal of Impotence Research, 1997
Radionuclide tracer techniques are intimately associated with some of the early ground-breaking investigations in erectile dysfunction and have evolved along with the ®eld. At the present time, the various investigations can be grouped into four categories: labeled blood-pool; tracer washout; tracer washin and combined blood-poolatracer and tracer washout examinations. Blood pool studies are most useful in assessing the integrity of arterial in¯ow, but may also be used to generate indices of venous leak. A non-imaging version of the blood-pool test may represent a simple and cost-effective alternative. Washout of intracavernosal xenon during erection seems the most rigorous method of testing venous integrity. Washout using 99m Tc-labeled substances may emerge as a convenient alternative to the more technically dif®cult xenon examinations. Dual-isotope blood pool and washout examinations, though complicated, represent an ideal method of analyzing penile hemodynamics, with potential to contribute signi®cantly to the understanding of penile physiology. Development of improved pharmacologic stimuli and augmentation of testing protocols by intracavernosal pressure monitoring may further improve the utility of quantitative and physiologic nuclear medicine examinations in erectile dysfunction.
Annals of the New York Academy of Sciences, 2007
A noninvasive diagnostic device was developed to assess the vascular origin and severity of penile dysfunction. It was designed and studied using both a mathematical model of penile hemodynamics and preliminary experiments on healthy young volunteers. The device is based on the application of an external pressure (or vacuum) perturbation to the penis following the induction of erection. The rate of volume change while the penis returns to its natural condition is measured using a noninvasive system that includes a volume measurement mechanism that has very low friction, thereby not affecting the measured system. The rate of volume change (net flow) is obtained and analyzed. Simulations using a mathematical model show that the device is capable of differentiating between arterial insufficiency and venous leak and indicate the severity of each. In preliminary measurements on young healthy volunteers, the feasibility of the measurement has been demonstrated. More studies are required to confirm the diagnostic value of the measurements.
A dual-radioisotope technique for the evaluation of penile blood flow during tumescence
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1992
A technique is described for concomitant study of both arterial and venous penile blood flow during tumescence. Dual-isotope acquisition is started after labeling red cells in vivo with 99mTc. Xenon-133 in saline is then injected into the corpus cavernosum followed with vasoactive drugs to induce an erection. The resulting xenon and technetium time-activity curves are inputs for a one-compartment model. In 14 subjects, the average peak arterial flow rate (PAF) for normal males was calculated as 13.0 +/- 1.28 ml/min (avg +/- s.d.) compared to 16.1 +/- 5.14 and 5.02 +/- 1.78 ml/min for patients with venous leak (VL) or arterial insufficiency (AI), respectively. Peak venous flows (PVF) were 4.25 +/- 1.17, 12.1 +/- 3.75, and 3.78 +/- 1.00 ml/min for normal, VL and AL respectively. Al patients have significantly lower PAF than normal (p = 0.002) or VL patients (p = 0.018), and VL patients had significantly higher PVF than normal (p = 0.012) or Al (p = 0.018). The technique may be helpful...