Doppler Evaluation of Erectile Dysfunction - Part 1

D Golijanin; E Singer; R Davis; S Bhatt; A Seftel; V Dogra

Disclosures

Int J Impot Res. 2007;19(1):37-42. 

In This Article

Specific evaluation

Vascular evaluation and imaging may be indicated in patients with (a) arterial/arteriolar arteriogenic dysfunction, (b) veno-occlusive disorder, (c) Peyronie's disease, (d) high-flow priapism, (e) penile trauma (fracture) and (f) in patients without symptomatic peripheral vascular disease presenting with ED where penile Doppler is used to assess the risk of cardiovascular disease and need for further cardiac or peripheral vascular assessment. In the last group, significant risk factors such as hypertension, smoking, trauma, hyperlipidemia, diabetes mellitus, obesity and inactivity are closely related to ED and decrease in sexual ability is regarded as one of the first clinical parameters of increased risk of significant CAD or peripheral vascular disease.[13,14,15] Erectile dysfunction is now being recognized as one of the earliest manifestations of endothelial dysfunction and peripheral vascular disease. Montorsi et al.[16] have demonstrated that ED presents about 39 months before CAD possibly because the smaller penile arteries reach critical narrowing and decreasing blood flow earlier than larger vessels. He has demonstrated that a normal penile Doppler test virtually excludes CAD with a 98% negative predictive value, whereas an abnormal penile Doppler test had a 30% positive predictive value for CAD – a value many times higher than 4% found in the general population.[17] El-Sakka and Morsy[18] in evaluation of men with ED found that 77% of those with high-grade ischemic heart disease had an abnormal penile Doppler test with peak systolic velocity (PSV) of less than 25 cm/s. Gazzaruso et al.[19] demonstrated in asymptomatic type II diabetics that those with angiographically confirmed silent CAD had over seven times the rate of ED (33.8% vs 4.7%) than control type II diabetics without CAD. As more information accrues confirming ED as an early manifestation of peripheral vascular disease, penile Doppler testing may play a key role in selecting those who do or do not need further coronary artery vascular assessment.

Vasculogenic imaging is usually reserved for men with ED who have a potentially surgically treatable cause. These patients are frequently young, have often suffered traumatic straddle injuries to the penis and may be unresponsive to oral and intracavernosal therapy. In this group of men, the mainstay of investigation is color Doppler ultrasound of the penile vasculature.[20] In addition to penile color Doppler ultrasound evaluation, several other tests of penile function and anatomy are available, including, dynamic infusion cavernosometry, cavernosography, selective penile angiography, penile nuclear magnetic resonance and near-infrared spectrophotometry.[21]

The use of Doppler ultrasound in the assessment of the penile vasculature was first described in 1985.[22] Advantages of penile Doppler and pharmacologic duplex ultrasonography include objective, minimally invasive evaluation of penile hemodynamics at a relatively low cost. Intracavernosal injection of vasoactive substances including prostaglandin E1, papaverine and phentolamine permits testing penile circulation not only at rest when the flow is minimal but also under maximal direct pharmacologic stimulation, when arterial insufficiency may be observed.[23,24,25] These substances may be administrated as a single drug or in combination,[23,24] with reported efficacy rates of up to 94%. Intracavernosal injections are routinely given with color Doppler ultrasound, but despite this the tests have been less than completely reliable possibly owing to the negative effects of anxiety and adrenergic output on the testing results. A variety of techniques has been used to minimize anxiety and maximize the reproducibility of the investigations, including a quiet and private environment, manual stimulation and visual sexual stimulation.[26] Others have used avoidance of injection giving high doses of PDE5 inhibitors and visual stimulation to promote blood flow and erection during testing, gaining from a less invasive procedure but losing on the certainty of maximal vascular relaxation stimulation.[27,28,29,30,31,32,33,34,35,36,37,38,39] In addition to various techniques employed to stimulate penile blood flow and an erection during testing, in order to increase observer ability to precisely assess vasculogenic causes of ED, interpretation of penile Doppler ultrasound findings remain very difficult in some cases. First, there is a gray area in the criteria for identifying arteriogenic ED. The parameter that is most commonly used to define arteriogenic ED is peak systolic blood flow in the penile arteries. Peak flow rates less than 25 cm/s are abnormally low and peak flow rates greater than 35 cm/s are normal, but the range of 25–35 cm/s is equivocal. Recently, Speel et al.[40] reported that acceleration time was the most valid parameter to detect cavernous atherosclerotic pathology. Blood flow velocity in the cavernous artery following pharmacostimulation was determined with duplex ultrasonography in 106 patients with ED. The cutoff point for acceleration time to discriminate between atherosclerotic and non-atherosclerotic ED was determined at acceleration time 100 ms or greater. Sensitivity was 66% and specificity was 71%.

Secondly, the criteria for diagnosing veno-occlusive dysfunction are also not very convincing. During a complete erection, the end-diastolic velocity (EDV) of the cavernosal arteries should be zero, or reverse flow may also be observed as a result of the increased intracavernosal pressure in the rigid stage of erection. In men with veno-occlusive disorder, the usual criterion for diagnosing veno-occlusive dysfunction has been an EDV greater than 5 cm/s.[41,42] This observation was not confirmed in all studies and there is a poor correlation of color Doppler ultrasound findings and veno-occlusive dysfunction when diagnosis was made using gold standard method, which is cavernosogram with infusion cavernosometry.[39]. Although the accurate diagnostic procedure for venous leak diagnosis is infusion cavernosometry after maximal vasodilatation, this is rarely employed owing to poor surgical results of venous leak repair.

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