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Biomedical subjects

T F Lue

Publications and source records attributed to T F Lue.

At least 217 records · Page 12Linked to original sources
PubMed1986

Priapism: a refined approach to diagnosis and treatment.

The recent introduction of intracorporeal injections of papaverine and phentolamine for the diagnosis and treatment of impotence has resulted in an increased incidence of iatrogenic priapism. Based on our research into penile hemodynamics we propose a refined approach to all types of priapism. Intracorporeal blood gas and pressure monitoring should be used to differentiate ischemic (low flow) from nonischemic (high flow) types. Most cases of papaverine-induced or phentolamine-induced priapism will respond to aspiration alone or in combination with intracorporeal instillation of a diluted alpha-adrenergic agent. In spontaneous priapism alpha-adrenergic agents can be tried first if patients have only mild or no ischemia. In patients with severe ischemia stagnant blood should be evacuated and a shunt procedure should be performed to allow metabolic replenishment of tissue. Intracorporeal pressure monitoring will help to determine the size and number of shunts needed to re-establish corporeal circulation.

Adult↗
PubMed1986

Hemodynamics of papaverine- and phentolamine-induced penile erection.

We investigated the hemodynamic changes induced in the canine corpora cavernosa by intracorporeal injection of papaverine or phentolamine. In six dogs studied, papaverine profoundly increased the resistance to venous outflow, whereas phentolamine (an alpha-adrenergic blocker) had little or no effect. In four other dogs, flow within the internal pudendal artery was measured with an ultrasonic flow probe placed directly on the artery. Papaverine increased arterial flow by 300 to 700 per cent over baseline levels, whereas the increase with phentolamine was only 50 to 100 per cent. We conclude that papaverine, by virtue of its direct smooth-muscle-relaxing properties, has a dual hemodynamic effect: it decreases the resistance to arterial inflow, thereby allowing large increases in the flow of blood into the penis during tumescence; and increases the resistance to venous outflow. Phentolamine only decreases the resistance to arterial inflow, more modestly than papaverine, and does not increase the resistance to venous outflow.

Animals↗
PubMed1986

Functional evaluation of penile veins by cavernosography in papaverine-induced erection.

Of 49 patients in whom cavernosography was performed after papaverine-induced erection 38 had abnormal venous leakage to various drainage systems (corpus spongiosum, cavernous vein or superficial and deep dorsal veins). Because the effect of papaverine on penile arteries, sinusoids and veins is similar to that caused by electrostimulation, we believe that this technique is better than other reported means of evaluating the functional status of the penile veins. However, we recommend that only patients with a normal arterial response but poor erection after papaverine injection be considered candidates for erection cavernosography, since they most likely will benefit.

Adult↗
PubMed1986

Diagnostic tests for impotence: a comparison of papaverine injection with the penile-brachial index and nocturnal penile tumescence monitoring.

The diagnostic usefulness of nocturnal penile tumescence monitoring, penile-brachial index and intracorporeal injection of papaverine (60 mg. in 20 ml. normal saline) was compared in 43 impotent men. Intracorporeal pressure was measured with a pressure transducer. Based on turgidity, and the time of onset and duration of erection, we classified the impotence as psychogenic/neurogenic (normal vascular competence), mild or severe arteriogenic, or venogenic. The intracorporeal injection of papaverine was useful as a functional diagnostic test for impotence. The penile-brachial index, an indirect measurement of the flaccid penis, did not correlate well with the results of the papaverine test. A poor response to papaverine injection documents organic impotence and, under these circumstances, nocturnal penile tumescence monitoring is not necessary. We conclude that the intracorporeal injection of papaverine currently is the best screening technique for the differential diagnosis of vasculogenic impotence.

Adult↗
PubMed1986

Further evidence of venous outflow restriction during erection.

To elucidate the effect of venous outflow restriction during erection, we studied eight dogs during artificial saline perfusion of the penis with and without neurostimulation to induce erection. With the infrarenal aorta clamped temporarily, saline infusion rates of 0.9 and 1.9 ml/min raised the mean intracorporeal pressure to 34 and 42 cm H2O, respectively, before stabilisation or return to baseline. When cavernous nerve stimulation was initiated, the mean intracorporeal pressure rose to 124 and 184 cm H2O (with infusion rates of 0.9 and 1.9 ml/min respectively) to induce full erection. Our results show that venous outflow restriction takes place during erection and that it is necessary not only to induce full erection but also to maintain it. Evaluation of venous competence is therefore essential during the investigation of impotence.

Animals↗
PubMed1986

Blood gas analysis in drug-induced penile erection.

To elucidate the hemodynamic changes during erection, we measured corporeal blood gases in 6 monkeys before, during, and after erection induced by either papaverine or phentolamine or a combination of the two. Papaverine alone caused a strong erection (maximal tumescence and rigidity) by means of a rapid, large increase in pO2 and pCO2 with a pH drop to the acidic range. Phentolamine alone caused 'delayed' tumescence with less rigidity; the intracorporeal pO2 level increased, but pCO2 and pH values did not change significantly. The combination of both drugs offered no advantage over papaverine alone. We conclude that papaverine is a potent erection-inducing drug that acts in a bimodal manner, namely, it increases the arterial inflow and, at the same time, decreases the venous outflow. Phentolamine affects the arterial component of erectile function only.

Animals↗
PubMed1986

The mechanism of penile erection in the monkey.

In conclusion, our studies in the monkey have settled some of the controversial issues surrounding penile physiology. We believe that, because of the monkey's anatomic similarity to man, results from simian studies can be extrapolated to human physiology.

Animals↗
PubMed1985

Urachal carcinoma.

Urachal carcinoma is a rare tumor that often does not manifest clinically until late in its course. Several radiographic features are helpful in suggesting the diagnosis preoperatively. We present a case of urachal carcinoma in which preoperative evaluation included magnetic resonance imaging. This technique was helpful not only in suggesting the diagnosis preoperatively, but also, and more importantly, in the preoperative staging of the neoplasm.

Carcinoma↗
PubMed1985

Penile replantation: current concepts.

We describe the microvascular repair of a traumatically lacerated penis (the fifth such case in the literature) and outline a uniform plan of management with which one can expect restoration of function and an adequate cosmetic appearance. Microvascular repair represents the most physiological method of reconstruction, with a lower incidence of urethral stricture disease, skin loss and sensory impairment.

Adult↗
PubMed1985

Vasculogenic impotence evaluated by high-resolution ultrasonography and pulsed Doppler spectrum analysis.

Vasculogenic impotence was evaluated by high-resolution sonography and quantitative Doppler spectrum analysis in 21 patients and two normal volunteers. Erection was induced by intracorporeal injection of papaverine, and B-scan imaging and Doppler analysis were performed with the penis flaccid and erect. The corpora cavernosa and its deep arteries, median septum, and corpus spongiosum were clearly displayed in every subject, with the dorsal vein and dorsal artery seen ventral to the corpora cavernosa. In the flaccid state, in all subjects, Doppler analysis demonstrated flow in the dorsal arteries but not in the deep arteries. During erection, the B-mode image showed varying degrees of enlargement of the corpora cavernosa, with increased tissue echogenicity, as well as a hypoechoic area in the peri-arterial region. The diameter of the penile arteries and flow within them also increased by varying degrees. Quantification of blood flow through all deep and dorsal arteries is feasible with this technique.

Adult↗
PubMed1985

Electrostimulation and penile erection.

Electrostimulation was used to study the neuroanatomy and physiology of penile erection in dogs and monkeys. The canine spinal nuclei responsible for penile erection, identified by the retrograde horseradish peroxidase transport technique after verification of the cavernous nerves with neurostimulation, were mediolateral autonomic neurons at T12-L3 and S1-S3. The erection induced by electrostimulation of the cavernous nerves is the result of increased arterial flow, relaxation of cavernous muscles, and venous outflow restriction. Study of electrostimulation in dogs and monkeys is invaluable for the understanding of the complex neurophysiology of human penile erection.

Animals↗
PubMed1984

Hemodynamics of canine corpora cavernosa during erection.

Being able to induce erection by electrical stimulation of the cavernous nerves, we studied the hemodynamics of canine penile erection. Simultaneous recording of flow and pressure of the internal pudendal artery as well as pressure within the corpus cavernosum clearly demonstrated that increase of arterial flow preceded corporeal pressure increase. When saline was infused directly into the corpus cavernosum, with the aorta clamped, decreasing venous flow during erection could be demonstrated. Tumescence of the corpus cavernosum was found to be a result of active relaxation of sinusoidal spaces, active arteriolar dilatation, and active venous constriction. At full erection, there was still flow into and out of the corpus cavernosum, although it was reduced to only a fraction of a milliliter per minute.

Animals↗
PubMed1984

Neuroanatomy of penile erection: its relevance to iatrogenic impotence.

The neuroanatomy of erection in men is not well defined. Recently, we isolated successfully the cavernous nerves for acute and chronic neurostimulation to induce penile erection in dogs and monkeys. We then investigated the anatomy of these nerves in humans by cadaveric dissection and serial histologic sectioning. Our experience in tracing the spinal nuclei responsible for vesical and urethral function by transportation of horseradish peroxidase enabled us to explore the location and organization of the spinal center for erection. Thus, systemic knowledge of the neuroanatomy of erection was accumulated. The spinal nuclei for control of erection are located in the intermediolateral gray matter at the S1 to S3 and T12 to L3 levels in dogs, and the S2 to S4 and T10 to L2 levels in humans. From these sacral nuclei axons issue ventrally and join the axons of the nuclei for the bladder and rectum to form the sacral visceral efferent fibers. These fibers emerge from the anterior root of S2 to S4, and join the sympathetic fibers to form the pelvic plexus, which then branches out to innervate the bladder, rectum and penis. The fibers innervating the penis (cavernous nerves) travel along the posterolateral aspect of the seminal vesicle and prostate, and then accompany the membranous urethra through the genitourinary diaphragm. These fibers are located on the lateral aspect of the membranous urethra and ascend gradually to the 1 and 11 o'clock positions in the proximal bulbous urethra. Some of the fibers penetrate the tunica albuginea of the corpus spongiosum, while others spread to the trifurcation of the terminal internal pudendal artery and innervate the dorsal, deep and urethral arteries. Shortly before the 2 corpora cavernosa merge the cavernous nerves penetrate the tunica albuginea along with the deep artery and cavernous vein. The terminal branches of these nerves innervate the helicine arteries and the erectile tissue within the corpora cavernosa. Because of the intimate relationship of the cavernous nerves to the rectum, prostate and urethra, they can be damaged easily during urological and pelvic procedures. This systemic knowledge of the human cavernous nerves from the spinal center to the erectile tissue should permit a better understanding of erection and impotence. Furthermore, with the aid of intraoperative neurostimulation, the cavernous nerves may be identified and preserved, thereby preventing iatrogenic impotence.

Animals↗
PubMed1984

Sonographic evaluation of experimental acute renal arterial occlusion in dogs.

Eleven segmental and eight total renal artery occlusions were evaluated by sonography in transplanted kidneys of 19 adult mongrel dogs. The segmental occlusions were serially scanned daily or every other day for up to 35 days. The total occlusions were scanned daily for up to 10 days. Each occlusion was confirmed angiographically, and kidneys were examined pathologically. Acute segmental renal artery occlusion produces a sequence of sonographic changes, beginning with a focal hypoechoic mass at 24 hr, which stays unchanged for 5-7 days. At 7 days, internal echoes appear, and the infarct slowly consolidates to an echogenic, slightly depressed focus at 17 days. Total renal artery occlusion produced no appreciable change in cortical echogenicity and only slight increase in size. Acute segmental renal infarction can be detected early in its course and demonstrates a sequence of changes that may aid in dating the infarct. Total renal infarction may appear normal sonographically, and further studies are needed to confirm that diagnosis.

Animals↗
PubMed1983

Potential preservation of potency after radical prostatectomy.

Radical prostatectomy often is followed by erectile dysfunction. Various etiologies have been postulated--vascular, psychologic, or neurologic. Recently, we were able to isolate the cavernous nerves of the prostatic plexus, which innervate the erectile tissue of the corpora cavernosa, for electroerection in dogs. Acute and chronic experiments were then performed to examine the relationship between erectile impotence and radical prostatectomy. We conclude that erectile impotence after total prostatectomy is a result of injury to the cavernous nerves and that potency can be preserved if these nerves are identified and salvaged during surgery.

Animals↗
PubMed1983

Hemodynamics of erection in the monkey.

Being able to induce controlled erection in dogs and monkeys, we investigated the hemodynamics and mechanism of penile erection. 'Chronic' monkey models, having had electrodes implanted around the cavernous nerves for electroerection, were studied to evaluate the details of the hemodynamic changes. The studies included: 1) arterial blood flow, 2) corporeal pressure, 3) blood gases, 4) venous flow and 5) radiography. Tumescence of the corpora cavernosa was found to be a result of: 1) active relaxation of the sinusoidal spaces, 2) active arteriolar dilatation and 3) active venous outflow constriction. At full erection there is adequate but reduced blood flow into and out of the corpora cavernosa for metabolic exchange.

Animals↗