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STUDY OF CAVERNOSAL ARTERIAL ANATOMY USING COLOR AND POWER DOPPLER SONOGRAPHY: IMPACT ON HEMODYNAMIC PARAMETER MEASUREMENT
Vol. 162,358460, August 1999 Printed in U S A
STUDY OF CAVERNOSAL ARTERIAL ANATOMY USING COLOR AND POWER DOPPLER SONOGRAPHY: IMPACT ON HEMODYNAMIC PARAMETER MEASUREMENT RE1 K. CHIOU,* GREGORY L. ALBERTS, BRANDON D. POMEROY, JOSEPH C. ANDERSON, LYNETTE K. CARLSON, JAMES R. ANDERSON AND RANDY K. WOBIG h m the Departmentsof Radio-, and Preventive and Societal Medicine, and Section of Urologic Surgery, University of Nebraska Medical Center and Urnlogy Section, Omaha Veterans w a i r s Medical Center, Omaha, Nebraska
ABSTRACT
Purpose: We report on color and power Doppler ultrasound to study cavernosal arterial anatomy, and evaluate the impact of vascular anatomy on the measurement of hemodynamic parameters. Materials and Methods: Cavernosal arterial anatomy of 42 patients with erectile dysfunction was evaluated using color and power Doppler ultrasound. A computerized waveform analysis was used to measure peak systolic velocity, end diastolic velocity and resistive indexes at various sites, including the penile crura, and proximal mid and distal penile shaft. Hemodynamic parameters were measured in each artery in cases of bifurcated or multiple cavernosal arteries. Results: A total of 80 corpora were adequately evaluated. We observed a single artery without major proximal branches in 37 corpora, a single artery with major proximal branches in 17, bifurcated arteries in 15, 2 cavernosal arteries in 4 and marked arterial tortuosity in 1. In 6 corpora the main cavernosal artery arose from the superficial dorsal artery. The peak systolic velocity was highest a t the proximal and decreased progressively a t the distal site. The peak systolic velocity plus or minus standard deviation at the mid shaft averaged 69.3 2 30.0%of that a t the proximal penile shaft. Of the 15 corpora with bifurcated arteries 67%had a 40%or greater difference in peak systolic velocity between the branches. Complete or partial occlusion of the cavernosal artery was identified in 3 corpora, and a dramatic difference in peak systolic velocity proximal and distal to the stenotic area was demonstrated. Conclusions: Cavernosal arterial anatomy is variable and hemodynamic parameters differ a t various sites of measurement. Parameters should be measured at a consistent proximal site to obtain a reliable assessment. Variations in vascular anatomy and cavernosal artery pathology should be considered when interpreting color Doppler sonography and before penile vascular surgery. KEYWORDS:ultrasonography, Doppler, color; impotence; arteries; penis; hemodynamics Erection is achieved through hemodynamic mechanisms which involve the increase of cavernosal arterial flow, relaxation of corporeal smooth muscle and veno-occlusive function. Hemodynamic studies are important in the evaluation of patients with erectile dysfunction. Color Doppler sonography is currently the best method available to study penile hemodynamics, and power Doppler sonography has dramatically enhanced the capacity to study penile vascular anatomy.' Peak systolic velocity is commonly used to diagnose arterial insufficiency, and end diastolic velocity based criteria, such as the resistive index, are used to diagnose venoocclusive dysfunction. Current methods of Doppler hemodynamic studies vary and some disregard the impact of vascular anatomy. We previously reported our observations of hemodynamic patterns of pharmacologically induced erection using color Doppler sonography with a computerized waveform analysis.2 We report on color and power Doppler ultrasound to study cavernosal arterial anatomy, and its impact on the measurement of hemodynamic parameters.
All evaluations were performed in a "do not disturb" environment with only essential personnel, including a urologist (R. K. C.). Intracorporeal injection of a 0.4 cc mixture of 30 mg. papaverine, 0.5 mg. phentolamine and 20 pg. prostaglandin E l per cc was administered in the left corpora. A dynamic ultrasound study was performed as previously described, using a computerized waveform analysis to observe the hemodynamic pattern.* Cavernosal arterial anatomy was assessed using color and power Doppler sonography during the peak response. The cavernosal arteries were examined from the penoscrotal junction t o the distal penile shaft with the penis gently stretched toward the abdomen and the transducer placed at the ventral penile surface. The cavernosal arteries at the crura were also examined with the transducer pushing down the scrotum. After a peak response was reached peak systolic velocity, end diastolic velocity and resistive index were measured at various sites, including the penile crura, and proximal, mid and distal penile shaft. Measurements were obtained from each artery in cases of multiple or bifurcated cavernosal arteries.
MATERIALS AND METHODS
Cavernosal arterial anatomy of 42 patients 24 to 72 years old (mean age 48) with erectile dysfunction was evaluated.
RESULTS
Accepted for publication March 19, 1999. * Requests for reprints: Urolo 'c Surgery, Creighton University, 601 N. 30th St., Omaha, Nebrasfa 68131.
Cavernosal arterial anatomy. We observed a wide variation in cavernosal arterial anatomy (see figure). A total of 80 corpora were adequately studied. For analysis cases were
358
CAVERNOSAL ARTERIAL ANATOMY IMPACTS HEMODYNAMIC PARAMETER MEASUREMENTS
359
significant difference between crural and proximal shaft peak systolic velocity in patients with early branching. The peak systolic velocity at the proximal shaft and crura was 32.4 z 17.2 and 36.6 2 17.6 cm. per second, respectively, in corpora without major branches (p = 0.22), and 21.2 i 11.8 and 34.5 i 19.4 cm. per second, respectively, in those with major branches (p = 0.0005). Hemodynamic evaluation in 1patient was done elsewhere with a Doppler device that did not assess vascular anatomy. The patient was diagnosed with normal right but poor left cavernosal artery flow with a peak systolic velocity of 9 cm. per second. Color and power Doppler sonography with vascular anatomy assessment revealed a bifurcated left cavernosal artery with a peak systolic velocity of 40.8 cm. per second proximal, 34.1 in the main artery distal and 10.6 in the secondary artery distal to the bifurcation. End diastolic velocity also varied at different sites of measurement but we observed no consistent pattern of variation. When cases were categorized as end diastolic velocity 0 or Less, 0.1 to 5 and greater than 5 cm. per second, values for the proximal and mid penile shaft were the same in 60 (76%)and different in 19 (24%). DISCUSSION
Color and power Doppler ultrasound reveals cavernosal artery anatomy. A, single artery without major proximal branches. B , artery with major proximal branches. c, bifurcated cavernosal artery. D ,multiple cavernosal arteries. E , cavernosal artery arising from superficial dorsal artery. F , marked tortuosity of cavernosal artery. G, crossing artery between right and left corpora. H , cavernosal artery occlusion. Note no demonstrable blood flow in artery distal to occlusion (arrow).
categorized as single artery without major branches at the proximal penile shaft (37), single artery with major branches at the proximal penile shaft (17), artery that bifurcates into 2 parallel arteries (15), 2 cavernosal arteries (4,miscellaneous, including cavernosal arteries that arise from the SUperficial dorsal artery or accessory pudendal artery (6) and artery with marked tortuosity (1)(parts E and F of figure). In addition, crossing arteries between the corpora were identified in 5 cases (part G of figure). Hemodynamic parameter measurement. In general the peak systolic velocity value was highest at the proximal and decreased progressively at distal sites of measurement. A higher peak systolic velocity at the mid versus proximal shaft was noted in 1 patient. Vascular anatomy assessment revealed a communication between the 2 corpora at the mid shaft. After excluding that case from analysis, average peak systolic velocity was 69.3 i 30% at the mid shaft and 49.4 5 23.5% of that of the proximal shaft at the distal shaft. Of the 15 corpora with bifurcated arteries 67% had a 40% or greater difference in peak systolic velocity between the branches. Complete or partial occlusion of the cavernosal artery was identified in 3 corpora, and a dramatic difference in peak systolic velocity proximal and distal to the stenotic area was demonstrated as expected (part H of figure). There was a
Duplex sonography as a noninvasive tool to study penile hemodynamics was first introduced by Lue et a1 in 1985.3 Continuous improvements in ultrasound technology and the advent of color and power Doppler imaging have greatly enhanced the capacity to study hemodynamics and penile vascular anatomy.4-7 We previously reported our experience with dynamic color Doppler sonography, which showed that the commonly used intervals of 5 or 10 minutes for recording may not be reliable in detecting maximal peak systolic velocity.2 We also observed a significant number of patients with an end diastolic velocity of 0 who had only engorgement or partial erection at the time. In these patients the 0 end diastolic velocity and resistive index of 1 could not be explained by the intracorporeal pressure. We believe that end diastolic velocity can be affected by other factors, such as the status of the cavernosal artery, and one should be cautious in interpretation to avoid misdiagnosing veno-occlusive dysfunction. The pathophysiology of erectile dysfunction is no less complicated than that of urinary dysfunction, and hemodynamic studies should be performed with attention t o detail similar to that used in urodynamic studies. We interpret color Doppler studies by considering the hemodynamic patterns of the dynamic study, erectile response and the dose of pharmacological agent required.2 Intracorporeal injection may result in priapism, which must be managed promptly to avoid erectile tissue damage. In this study the peak systolic velocity was generally highest at the proximal cavernosal artery and decreased progressively at distal sites of measurement. Thus, it is preferable to measure hemodynamic parameters at a consistent proximal site and to note the presence of unusual anatomy. We measure at the penoscrotal junction and try to visualize the crural arteries, which is especially important when there is a n early major branch as the peak systolic velocity tends to decrease after major branching. We noted that about 75% of cavernosal arteries with major proximal branches had a 30% or greater difference in peak systolic velocity between the crura and proximal shaft. We attempt to measure parameters proximal to bifurcated or major branches and, if this is not feasible, we measure parameters from both branches. Simplified ultrasonic velocimetry devices avoid the pitfall of measuring heniodynamic parameters from the superficial dorsal penile artery.8 However, they do not have the capacity to assess cavernosal arterial anatomy nor to adjust the site of measurement according to variations in vascular anatomy. In this series 1 patient was previously diagnosed elsewhere
360
CAVERNOSAL ARTERIAL ANATOMYIMPACTS HEMODYNAMIC PARAMETER MEASUREMENTS
with poor left cavernosal artery flow using such a device. We noted a bifurcated left cavernosal artery with a normal peak systolic velocity at the main artery but a low peak systolic velocity in 1branch after the bifurcation. It is likely that the misdiagnosis resulted from measuring parameters at the secondary rather than main artery. With wide variations in cavernosal vascular anatomy it seems likely that this problem may be common when these devices are used. If they are used as the primary tool of hemodynamic evaluation, it is advisable to perform color and power Doppler sonography to evaluate patients with a n abnormal result more completely before proceeding to more invasive testing, such as pelvic angiography . It is not clear what constitutes normal hemodynamic parameters in patients with varied vascular anatomy. The criteria for normal based on individuals with a single artery probably need to be adjusted for those with bifurcated or multiple arteries. Arterial pathology can also occur in the helicine arterioles. Sarteschi7 and Montorsis et a1 used power Doppler sonography to study penile arteriolar circulation and suggested that arteriolar pathology may contribute to impotence. How useful and practical it is clinically to detect helicine artery pathology and arteriolar hemodynamic abnormalities requires further study. Our current practice is to examine the cavernosal artery from the base of the penis to the distal penile shaft with no attempt to identify helicine arteriolar hemodynamic abnormalities. Penile vascular anatomy is important when considering vascular surgery for impotence. We have noted cavernosal artery stenosis or occlusion in several patients. Early in our series we performed penile revascularization in 1 patient based on a traditional evaluation without a detailed study of cavernosal arterial anatomy. No improvement in erectile function was achieved after surgery. Subsequent color and power Doppler sonography revealed cavernosal artery stenosis at the mid penile shaft. With that experience we believe that a detailed assessment should be performed preoperatively when considering penile revascularization for erectile dysfunction. In a study of cadavers Martinez-Piiieiro et a1 noted that anatomical variations of the penile artery occur frequently.10 Color and power Doppler studies of cavernosal arterial anatomy may help delineate penile vascular anatomy and aid in selecting the appropriate penile revascularization procedure for an individual. For example, in this series the main cavernosal blood supply arose from the superficial dorsal artery or accessory pudendal artery in 6 corpora. If penile revascularization is performed in these patients, selection of the anastomotic site based on individual anatomy may be critical.
CONCLUSIONS
Penile arterial anatomy varies among individuals and hemodynamic parameters differ at various sites of measurement. Parameters should be measured at a consistent proximal site to obtain a reliable result. Variations in vascular anatomy and cavernosal arterial pathology should be considered when interpreting color Doppler studies and planning penile vascular surgery.
REFERENCES
1. Chiou, R. K. and Pomeroy, B. D.: Erectile dysfunction. Using color Doppler ultrasound hemodynamic studies for evaluation, Cont. Urol., 10 87, 1998. 2. Chiou, R. K.,Pomeroy, B. D., Chen, W. S., Anderson, J. C., Wobig, R. K. and Taylor, R. J.: Hemodynamic patterns of pharmacologically induced erection: evaluation by color Doppler sonography.J. Urol., 1 5 9 109, 1998. 3. Lue, T. F., Hricak, H., Marich, K. W. and Tanagho, E. A,: Vasculogenic impotence evaluated by high resolution ultrasonography and pulsed Doppler spectrum analysis. Radiology, 155: 777, 1985. 4. Schwartz, A. N.,Lowe, M., Berger, R. E., W a g , K. Y., Mack, L. A. and Richardson, M. L.: Assessment of normal and abnormal erectile function: color Doppler flow sonography versus conventional techniques. Radiology, 1 8 0 105, 1991. 5. Lee, B., Sikka, S. C., Randrup, E. R., Villemarette, P., Baum, N., Hower, J. F. and Hellstrom, W. J.: Standardization of penile blood flow parameters in normal men using intracavernous prostaglandin E l and visual sexual stimulation. J. Urol., 1 4 9 49, 1993. 6. Meuleman, E. J.,Bemelmans, B. L., van-Asten,W. N., Doesburg, W. H., Skotnicki, S. H. and Debruyne, F. M.: Assessment of penile blood flow by duplex ultrasonography in 44 men with normal erectile potency in different phases of erection.J. Urol., 147: 51, 1992. 7. Sarteschi, L. M., Montorsi, F., Fabris, F. M., Guazzoni, G., Lencioni, R. and Rigatti, P.: Cavernous arterial and arteriolar circulation in patients with erectile dysfunction: a power Doppler study. J. Urol., 1 5 9 428, 1998. 8. Knoll, L. D. and Abrams, J. H.: Evaluation of penile ultrasonic velocitometry versus penile duplex ultrasonography to assess penile arterial hemodynamics. Urology, 51: 89, 1998. 9. Montorsi, F., Sarteschi, M., Maga, T., Guazzoni, G., Fabris, G. F. M., Rigatti, P., Pizzini, G. and Miani, A,: Functional anatomy of cavernous helicine arterioles in potent subjects. J. Urol., 1 5 9 808, 1998. 10. Martinez-Piiieiro,L.,Julve, E. and Martinez-Piiieiro,J. A,: Topographical anatomy of the penile arteries. Brit. J. Urol., 80: 463, 1997.
STUDY OF CAVERNOSAL ARTERIAL ANATOMY USING COLOR AND POWER DOPPLER SONOGRAPHY: IMPACT ON HEMODYNAMIC PARAMETER MEASUREMENT RE1 K. CHIOU,* GREGORY L. ALBERTS, BRANDON D. POMEROY, JOSEPH C. ANDERSON, LYNETTE K. CARLSON, JAMES R. ANDERSON AND RANDY K. WOBIG h m the Departmentsof Radio-, and Preventive and Societal Medicine, and Section of Urologic Surgery, University of Nebraska Medical Center and Urnlogy Section, Omaha Veterans w a i r s Medical Center, Omaha, Nebraska
ABSTRACT
Purpose: We report on color and power Doppler ultrasound to study cavernosal arterial anatomy, and evaluate the impact of vascular anatomy on the measurement of hemodynamic parameters. Materials and Methods: Cavernosal arterial anatomy of 42 patients with erectile dysfunction was evaluated using color and power Doppler ultrasound. A computerized waveform analysis was used to measure peak systolic velocity, end diastolic velocity and resistive indexes at various sites, including the penile crura, and proximal mid and distal penile shaft. Hemodynamic parameters were measured in each artery in cases of bifurcated or multiple cavernosal arteries. Results: A total of 80 corpora were adequately evaluated. We observed a single artery without major proximal branches in 37 corpora, a single artery with major proximal branches in 17, bifurcated arteries in 15, 2 cavernosal arteries in 4 and marked arterial tortuosity in 1. In 6 corpora the main cavernosal artery arose from the superficial dorsal artery. The peak systolic velocity was highest a t the proximal and decreased progressively a t the distal site. The peak systolic velocity plus or minus standard deviation at the mid shaft averaged 69.3 2 30.0%of that a t the proximal penile shaft. Of the 15 corpora with bifurcated arteries 67%had a 40%or greater difference in peak systolic velocity between the branches. Complete or partial occlusion of the cavernosal artery was identified in 3 corpora, and a dramatic difference in peak systolic velocity proximal and distal to the stenotic area was demonstrated. Conclusions: Cavernosal arterial anatomy is variable and hemodynamic parameters differ a t various sites of measurement. Parameters should be measured at a consistent proximal site to obtain a reliable assessment. Variations in vascular anatomy and cavernosal artery pathology should be considered when interpreting color Doppler sonography and before penile vascular surgery. KEYWORDS:ultrasonography, Doppler, color; impotence; arteries; penis; hemodynamics Erection is achieved through hemodynamic mechanisms which involve the increase of cavernosal arterial flow, relaxation of corporeal smooth muscle and veno-occlusive function. Hemodynamic studies are important in the evaluation of patients with erectile dysfunction. Color Doppler sonography is currently the best method available to study penile hemodynamics, and power Doppler sonography has dramatically enhanced the capacity to study penile vascular anatomy.' Peak systolic velocity is commonly used to diagnose arterial insufficiency, and end diastolic velocity based criteria, such as the resistive index, are used to diagnose venoocclusive dysfunction. Current methods of Doppler hemodynamic studies vary and some disregard the impact of vascular anatomy. We previously reported our observations of hemodynamic patterns of pharmacologically induced erection using color Doppler sonography with a computerized waveform analysis.2 We report on color and power Doppler ultrasound to study cavernosal arterial anatomy, and its impact on the measurement of hemodynamic parameters.
All evaluations were performed in a "do not disturb" environment with only essential personnel, including a urologist (R. K. C.). Intracorporeal injection of a 0.4 cc mixture of 30 mg. papaverine, 0.5 mg. phentolamine and 20 pg. prostaglandin E l per cc was administered in the left corpora. A dynamic ultrasound study was performed as previously described, using a computerized waveform analysis to observe the hemodynamic pattern.* Cavernosal arterial anatomy was assessed using color and power Doppler sonography during the peak response. The cavernosal arteries were examined from the penoscrotal junction t o the distal penile shaft with the penis gently stretched toward the abdomen and the transducer placed at the ventral penile surface. The cavernosal arteries at the crura were also examined with the transducer pushing down the scrotum. After a peak response was reached peak systolic velocity, end diastolic velocity and resistive index were measured at various sites, including the penile crura, and proximal, mid and distal penile shaft. Measurements were obtained from each artery in cases of multiple or bifurcated cavernosal arteries.
MATERIALS AND METHODS
Cavernosal arterial anatomy of 42 patients 24 to 72 years old (mean age 48) with erectile dysfunction was evaluated.
RESULTS
Accepted for publication March 19, 1999. * Requests for reprints: Urolo 'c Surgery, Creighton University, 601 N. 30th St., Omaha, Nebrasfa 68131.
Cavernosal arterial anatomy. We observed a wide variation in cavernosal arterial anatomy (see figure). A total of 80 corpora were adequately studied. For analysis cases were
358
CAVERNOSAL ARTERIAL ANATOMY IMPACTS HEMODYNAMIC PARAMETER MEASUREMENTS
359
significant difference between crural and proximal shaft peak systolic velocity in patients with early branching. The peak systolic velocity at the proximal shaft and crura was 32.4 z 17.2 and 36.6 2 17.6 cm. per second, respectively, in corpora without major branches (p = 0.22), and 21.2 i 11.8 and 34.5 i 19.4 cm. per second, respectively, in those with major branches (p = 0.0005). Hemodynamic evaluation in 1patient was done elsewhere with a Doppler device that did not assess vascular anatomy. The patient was diagnosed with normal right but poor left cavernosal artery flow with a peak systolic velocity of 9 cm. per second. Color and power Doppler sonography with vascular anatomy assessment revealed a bifurcated left cavernosal artery with a peak systolic velocity of 40.8 cm. per second proximal, 34.1 in the main artery distal and 10.6 in the secondary artery distal to the bifurcation. End diastolic velocity also varied at different sites of measurement but we observed no consistent pattern of variation. When cases were categorized as end diastolic velocity 0 or Less, 0.1 to 5 and greater than 5 cm. per second, values for the proximal and mid penile shaft were the same in 60 (76%)and different in 19 (24%). DISCUSSION
Color and power Doppler ultrasound reveals cavernosal artery anatomy. A, single artery without major proximal branches. B , artery with major proximal branches. c, bifurcated cavernosal artery. D ,multiple cavernosal arteries. E , cavernosal artery arising from superficial dorsal artery. F , marked tortuosity of cavernosal artery. G, crossing artery between right and left corpora. H , cavernosal artery occlusion. Note no demonstrable blood flow in artery distal to occlusion (arrow).
categorized as single artery without major branches at the proximal penile shaft (37), single artery with major branches at the proximal penile shaft (17), artery that bifurcates into 2 parallel arteries (15), 2 cavernosal arteries (4,miscellaneous, including cavernosal arteries that arise from the SUperficial dorsal artery or accessory pudendal artery (6) and artery with marked tortuosity (1)(parts E and F of figure). In addition, crossing arteries between the corpora were identified in 5 cases (part G of figure). Hemodynamic parameter measurement. In general the peak systolic velocity value was highest at the proximal and decreased progressively at distal sites of measurement. A higher peak systolic velocity at the mid versus proximal shaft was noted in 1 patient. Vascular anatomy assessment revealed a communication between the 2 corpora at the mid shaft. After excluding that case from analysis, average peak systolic velocity was 69.3 i 30% at the mid shaft and 49.4 5 23.5% of that of the proximal shaft at the distal shaft. Of the 15 corpora with bifurcated arteries 67% had a 40% or greater difference in peak systolic velocity between the branches. Complete or partial occlusion of the cavernosal artery was identified in 3 corpora, and a dramatic difference in peak systolic velocity proximal and distal to the stenotic area was demonstrated as expected (part H of figure). There was a
Duplex sonography as a noninvasive tool to study penile hemodynamics was first introduced by Lue et a1 in 1985.3 Continuous improvements in ultrasound technology and the advent of color and power Doppler imaging have greatly enhanced the capacity to study hemodynamics and penile vascular anatomy.4-7 We previously reported our experience with dynamic color Doppler sonography, which showed that the commonly used intervals of 5 or 10 minutes for recording may not be reliable in detecting maximal peak systolic velocity.2 We also observed a significant number of patients with an end diastolic velocity of 0 who had only engorgement or partial erection at the time. In these patients the 0 end diastolic velocity and resistive index of 1 could not be explained by the intracorporeal pressure. We believe that end diastolic velocity can be affected by other factors, such as the status of the cavernosal artery, and one should be cautious in interpretation to avoid misdiagnosing veno-occlusive dysfunction. The pathophysiology of erectile dysfunction is no less complicated than that of urinary dysfunction, and hemodynamic studies should be performed with attention t o detail similar to that used in urodynamic studies. We interpret color Doppler studies by considering the hemodynamic patterns of the dynamic study, erectile response and the dose of pharmacological agent required.2 Intracorporeal injection may result in priapism, which must be managed promptly to avoid erectile tissue damage. In this study the peak systolic velocity was generally highest at the proximal cavernosal artery and decreased progressively at distal sites of measurement. Thus, it is preferable to measure hemodynamic parameters at a consistent proximal site and to note the presence of unusual anatomy. We measure at the penoscrotal junction and try to visualize the crural arteries, which is especially important when there is a n early major branch as the peak systolic velocity tends to decrease after major branching. We noted that about 75% of cavernosal arteries with major proximal branches had a 30% or greater difference in peak systolic velocity between the crura and proximal shaft. We attempt to measure parameters proximal to bifurcated or major branches and, if this is not feasible, we measure parameters from both branches. Simplified ultrasonic velocimetry devices avoid the pitfall of measuring heniodynamic parameters from the superficial dorsal penile artery.8 However, they do not have the capacity to assess cavernosal arterial anatomy nor to adjust the site of measurement according to variations in vascular anatomy. In this series 1 patient was previously diagnosed elsewhere
360
CAVERNOSAL ARTERIAL ANATOMYIMPACTS HEMODYNAMIC PARAMETER MEASUREMENTS
with poor left cavernosal artery flow using such a device. We noted a bifurcated left cavernosal artery with a normal peak systolic velocity at the main artery but a low peak systolic velocity in 1branch after the bifurcation. It is likely that the misdiagnosis resulted from measuring parameters at the secondary rather than main artery. With wide variations in cavernosal vascular anatomy it seems likely that this problem may be common when these devices are used. If they are used as the primary tool of hemodynamic evaluation, it is advisable to perform color and power Doppler sonography to evaluate patients with a n abnormal result more completely before proceeding to more invasive testing, such as pelvic angiography . It is not clear what constitutes normal hemodynamic parameters in patients with varied vascular anatomy. The criteria for normal based on individuals with a single artery probably need to be adjusted for those with bifurcated or multiple arteries. Arterial pathology can also occur in the helicine arterioles. Sarteschi7 and Montorsis et a1 used power Doppler sonography to study penile arteriolar circulation and suggested that arteriolar pathology may contribute to impotence. How useful and practical it is clinically to detect helicine artery pathology and arteriolar hemodynamic abnormalities requires further study. Our current practice is to examine the cavernosal artery from the base of the penis to the distal penile shaft with no attempt to identify helicine arteriolar hemodynamic abnormalities. Penile vascular anatomy is important when considering vascular surgery for impotence. We have noted cavernosal artery stenosis or occlusion in several patients. Early in our series we performed penile revascularization in 1 patient based on a traditional evaluation without a detailed study of cavernosal arterial anatomy. No improvement in erectile function was achieved after surgery. Subsequent color and power Doppler sonography revealed cavernosal artery stenosis at the mid penile shaft. With that experience we believe that a detailed assessment should be performed preoperatively when considering penile revascularization for erectile dysfunction. In a study of cadavers Martinez-Piiieiro et a1 noted that anatomical variations of the penile artery occur frequently.10 Color and power Doppler studies of cavernosal arterial anatomy may help delineate penile vascular anatomy and aid in selecting the appropriate penile revascularization procedure for an individual. For example, in this series the main cavernosal blood supply arose from the superficial dorsal artery or accessory pudendal artery in 6 corpora. If penile revascularization is performed in these patients, selection of the anastomotic site based on individual anatomy may be critical.
CONCLUSIONS
Penile arterial anatomy varies among individuals and hemodynamic parameters differ at various sites of measurement. Parameters should be measured at a consistent proximal site to obtain a reliable result. Variations in vascular anatomy and cavernosal arterial pathology should be considered when interpreting color Doppler studies and planning penile vascular surgery.
REFERENCES
1. Chiou, R. K. and Pomeroy, B. D.: Erectile dysfunction. Using color Doppler ultrasound hemodynamic studies for evaluation, Cont. Urol., 10 87, 1998. 2. Chiou, R. K.,Pomeroy, B. D., Chen, W. S., Anderson, J. C., Wobig, R. K. and Taylor, R. J.: Hemodynamic patterns of pharmacologically induced erection: evaluation by color Doppler sonography.J. Urol., 1 5 9 109, 1998. 3. Lue, T. F., Hricak, H., Marich, K. W. and Tanagho, E. A,: Vasculogenic impotence evaluated by high resolution ultrasonography and pulsed Doppler spectrum analysis. Radiology, 155: 777, 1985. 4. Schwartz, A. N.,Lowe, M., Berger, R. E., W a g , K. Y., Mack, L. A. and Richardson, M. L.: Assessment of normal and abnormal erectile function: color Doppler flow sonography versus conventional techniques. Radiology, 1 8 0 105, 1991. 5. Lee, B., Sikka, S. C., Randrup, E. R., Villemarette, P., Baum, N., Hower, J. F. and Hellstrom, W. J.: Standardization of penile blood flow parameters in normal men using intracavernous prostaglandin E l and visual sexual stimulation. J. Urol., 1 4 9 49, 1993. 6. Meuleman, E. J.,Bemelmans, B. L., van-Asten,W. N., Doesburg, W. H., Skotnicki, S. H. and Debruyne, F. M.: Assessment of penile blood flow by duplex ultrasonography in 44 men with normal erectile potency in different phases of erection.J. Urol., 147: 51, 1992. 7. Sarteschi, L. M., Montorsi, F., Fabris, F. M., Guazzoni, G., Lencioni, R. and Rigatti, P.: Cavernous arterial and arteriolar circulation in patients with erectile dysfunction: a power Doppler study. J. Urol., 1 5 9 428, 1998. 8. Knoll, L. D. and Abrams, J. H.: Evaluation of penile ultrasonic velocitometry versus penile duplex ultrasonography to assess penile arterial hemodynamics. Urology, 51: 89, 1998. 9. Montorsi, F., Sarteschi, M., Maga, T., Guazzoni, G., Fabris, G. F. M., Rigatti, P., Pizzini, G. and Miani, A,: Functional anatomy of cavernous helicine arterioles in potent subjects. J. Urol., 1 5 9 808, 1998. 10. Martinez-Piiieiro,L.,Julve, E. and Martinez-Piiieiro,J. A,: Topographical anatomy of the penile arteries. Brit. J. Urol., 80: 463, 1997.