Impotence, or erectile dysfunction (ED), is the inability for a man to sustain an erection long enough for normal, satisfying sexual intercourse. To understand the underlying causes of impotence, it helps to know the basics about how an erection develops, along with potential problems that get in the way. Erections begin in the brain with a thought related to sexual desire. Then a chemical message travels from the brain to the penis. Blood flow to the penis increases as blood vessels leading to the reproductive system relax and allow for increased circulation.
Erectile dysfunction (ED), or impotence, is when a man has difficulty getting or maintaining a strong enough erection for sexual intercourse or other sexual activity. It can be caused by stress, anxiety or excessive alcohol consumption. But it can also be a symptom of an underlying condition such as atherosclerosis (narrowing of the arteries), diabetes or high blood pressure. Some medications can cause erectile dysfunction, for example beta-blockers and diuretics (commonly used to treat a variety of heart-related conditions such as high blood pressure and heart failure).
Figure. Progression of atherosclerosis. Endothelial dysfunction occurs early in atherosclerosis and prevents blood vessels from dilating properly. When the blood vessels that supply the penis are not able to dilate during sexual stimulation because of endothelial dysfunction, the penis cannot fill with blood, and the man develops erectile dysfunction. As atherosclerosis progresses, plaques build up in blood vessels and blood flow is slowed, further worsening erectile function. A heart attack occurs when an atherosclerotic plaque in a coronary artery ruptures, a blood clot forms over the plaque, and blood flow to the heart muscle is completely blocked. Atherosclerotic risk factors (black arrows) worsen cardiovascular health; modification of these risk factors (red arrows) improves cardiovascular health.
De Berardis et al.6 assessed general HRQOL in 1,460 men with type 2 diabetes in Italy. Within the cohort, 615 men reported that they never experienced ED, 346 stated that they occasionally had ED, and 449 stated that they frequently had ED. They then compared general HRQOL among these three groups. In the univariate analysis, they found that degree of ED negatively correlated with general HRQOL scores in all eight domains of the Short Form 36 (SF-36) health survey questionnaire. In the multivariate analysis, ED was not independently associated with physical function, bodily pain, or role limitations due to physical problem scores but was independently associated with general HRQOL outcomes in the domains of general health (P = 0.004), role limitations due to emotional problems (P = 0.001), vitality (P = 0.001), social functioning (P = 0.01), and overall mental health (P = 0.002). Another study examining the effect of ED on quality of life in hemodialysis patients, more than half of whom had diabetes, also noted an independent, negative effect of ED on the emotional domains of general HRQOL.39
Gene therapy has the potential to become a future management option for patients with CAD and ED. Animal studies have been conducted to evaluate the effects of gene therapy. A rat model was studied by Bivalacqua et al. to evaluate the effect of the combination of eNOS gene therapy and sildenafil. This research suggested that erectile response was greater in male rats with diabetes treated with combination eNOS gene therapy and sildenafil, compared with male rats with diabetes treated with eNOS gene therapy or sildenafil alone.76–78
Whereas lifestyle modification is a reasonable initial step when approaching a hypertensive patient with sexual dysfunction, finding the appropriate antihypertensive treatment is usually the next “complicated” move to care for. Several observational and clinical studieshave consistently associated antihypertensive medication with sexual dysfunction. Whether one class of antihypertensive agents is associated exclusively or more with erectile dysfunction compared to another, however, is a difficult puzzle to solve as there are many other factors (comorbid conditions, concomitant medications, personal characteristics) to be taken into account at the same time. In addition, erectile dysfunction has never been studied as the primary end-point before and as a result a definite causative relationship between antihypertensive medication and sexual dysfunction has never been proven.
For oral erectile dysfunction medicines to work as desired, they must be used properly in the first place. This means taking the medicine 30–45 minutes before engaging in sexual intimacy; taking the drug on an empty stomach or at least avoiding a heavy or high-fat meal before taking the drug (this is especially important when using sildenafil); and engaging in adequate genital stimulation before attempting intercourse. Drinking small amounts of alcohol (one to two drinks) should not compromise the effectiveness of erectile dysfunction medicines, but larger amounts of alcohol can diminish a man’s ability to have an erection.