Erectile dysfunction is a common disorder defined as “the persistent inability to achieve and then maintain an erection to permit satisfactory sexual intercourse.”1 An estimated 18 million men in the United States (18%) have ED.2 In a cross-sectional analysis, the prevalence of ED differed markedly by age, ranging from 5.1% in men aged 20 to 39 years to 70.2% in men older than 70 years of age.2 However, a recent study found that the incidence of ED in younger men is increasing, estimating the prevalence of ED in younger men (<40 years) to be as high as 30%.3
Although it can be distressing for patients to discuss ED, proper evaluation and treatment of the condition can significantly improve quality of life.4 The growing acknowledgement that ED is a harbinger of cardiovascular disease (CVD), for example, has made the early diagnosis of ED associated with vascular risk factors a priority for many primary care clinicians. Proper evaluation and treatment of ED has been shown to decrease the risk for CVD morbidity.1,5-9
Causes of Erectile Dysfunction
Erectile dysfunction is caused by a variety of factors such as vascular, endocrinologic, neurologic, psychogenic, and anatomic abnormalities. It also can be caused by a combination of factors, which can make determining the cause of ED more difficult. Psychogenic etiologies of ED include depression, anxiety, and interpersonal partner-related conflicts.3 Men with ED related to psychogenic factors tend to experience a sudden onset of symptoms, decreased libido and normal androgen status, nocturnal or self-stimulated erections, and normal findings on penile duplex Doppler ultrasonography.3,10 Patients with ED related to vascular, endocrinologic, or neurologic factors usually experience a gradual onset of symptoms and a low to normal libido, weak noncoital erections, inconsistent early morning erections, and abnormal Doppler ultrasound findings.11,12
Cardiovascular Health and Erectile Dysfunction
Erectile dysfunction may be one of the first physical manifestations of atherosclerosis in men. Patients with ED of vascular etiology are at a higher risk for coronary artery disease (CAD) and should be screened for CVD and educated about lifestyle management options. Similarly, men with known risk factors for CVD — smoking, hyperlipidemia, hypertension, and diabetes — should be screened for ED.6 The coexistence of these diseases often is overlooked by providers and can lead to adverse health effects as both conditions worsen.8
There is a clear link between increasing severity of ED and poor cardiovascular health. Sufficient blood flow and nitric oxide levels are required for successful erections.13 Interference with blood flow greatly affects the ability to maintain an erection.13,14 When more than 50% of the lumen of the deep penile (cavernosal) and common penile arteries are narrowed, ED will occur.13
It also is important to evaluate the elasticity of the endothelium in patients with CVD and those with ED. Pohjantähti-Maaroos et al reported that men with ED had a significantly lower arterial elasticity index than those without ED after adjustment for age, diabetes, family history of CVD, smoking, physical activity, use of statins or β-blockers, waist circumference, blood pressure, and lipids.15 This study confirms that atherosclerotic damage physiologically affects the systemic elasticity of arteries, including the penile artery.
Dzenkeviciute et al evaluated subclinical vascular disease in relation to ED severity and found that men with ED had significantly higher CVD risk than controls.7 The severity of ED also was associated with left ventricular hypertrophy, left ventricular diastolic dysfunction, and impaired renal function. The changes they found in the endothelium were the same changes that occur in patients with chronic kidney disease and chronic myocardial injury.
Inman et al found new-onset CAD in more than 10% of men with ED during a 10-year follow-up period.6 Banks et al found that men with worsening ED and CVD have increasing hospitalizations related to myocardial infarction, ischemic heart disease, and heart failure. Vascular ED also is associated with increased overall mortality.9
Patients without CAD who have ED symptoms likely are experiencing mild endothelial changes beginning in arteries such as the penile artery and should be counseled about measures to prevent CAD.6