Pathophysiology of erectile dysfunction

Given the complexity of the system, it is not surprising that a wide variety of diverse disorders may result in erectile dysfunction (Table 1). Often, the cause is multifactorial, but vasculogenic causes are the most commonly implicated.

Vasculogenic Causes of ED
Neurogenic Causes of ED
Endocrinological Causes of ED
Priapism and Postpriapism ED
Psychogenic Causes of ED

Vasculogenic Causes of erectile dysfunction

Arterial insufficiency

Because the development and maintenance of a rigid erection depend on achieving a high intracavernosal pressure, it is not surprising that disorders affecting the peripheral arterial blood flow are strongly associated with erectile dysfunction (Table 2).

The most common cause is atheroma involving either the common or internal iliac arteries or their more distal branches (Figure 28). The risk factors for this are similar to those for coronary artery disease (including smoking, hypertension, hyperlipidemia, diabetes mellitus and obesity). Narrowing or occlusion of the internal pudendal arteries reduces perfusion pressure to the corpora, resulting in a failure to achieve full rigidity. In the absence of such pressure, the normal veno-occlusive mechanisms cannot operate and, thus, the problem is compounded by secondary venous leakage. Obliterative disease of the aorta may also result in erectile dysfunction.

Venous leakage

In the presence of a normal arterial inflow, normal veno-occlusive mechanisms should slow egress of blood from the corpora to a virtual trickle during full erection. Failure to do so results in a flaccid erection and leakage of blood, either into the deep dorsal vein or the cavernosal venous system (Figure 29). The etiology of this is obscure, but is more likely to be a primary disorder of intracavernosal smooth muscle than a problem primarily related to the penile veins themselves.

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Table 1 Risk factors for erectile dysfunction

Vascular factors

myocardial infarctioncoronary artery bypass surgerycerebral vascular accidentperipheral vascular diseasehypertensionhyperlipidemiasmoking