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.
For many men, stopping smoking is an erectile dysfunction remedy, particularly when ED is the result of vascular disease, which occurs when blood supply to the penis becomes restricted because of blockage or narrowing of the arteries. Smoking and even smokeless tobacco can also cause the narrowing of important blood vessels and have the same negative impact. 
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.
After adjusting for cardiovascular risk factors including diabetes, heart failure and stroke, those taking PDE5 inhibitors were found to be markedly less likely to die than those taking alprostadil or no erectile dysfunction drugs. Filling more prescriptions for PDE5 inhibitors appeared to be associated with a greater benefit, although Andersson said that trend should be interpreted with caution because the study was not large enough for a definitive dose-response analysis.
PubMed | Google ScholarSee all References Unlike sildenafil, vardenafil has been associated with a slight prolongation of the QT interval and thus should not be used by patients with a congenital QT prolongation or by any patient currently taking antiarrhythmic medications.67x67Vardenafil (levitra) for erectile dysfunction. Med Lett Drugs Ther. 2003; 45: 77–78

Third, men with Diabetes need to control their blood sugar levels. When your blood sugar is not under control, your body does not produce enough Nitric Oxide (NO) and vascular tissues don’t respond as effectively to NO. When enough blood flows into the penis, penile veins close off and block the blood from flowing out. This process results in an erection. If your body does not produce enough NO or if your penile tissues do not respond to NO, the pressure of the blood flowing into your penis is not sufficient to trap the blood, you penis will not get hard.
Erectile dysfunction becomes more common with age. However, the condition is even more common among men who have diabetes. Over time, diabetes can damage the blood vessels and nerves that control erections. In addition, some of the other conditions that often occur with diabetes, such as coronary artery disease, can also contribute to the development of erectile dysfunction.
Abstract | Full Text | Full Text PDF | PubMed | Scopus (395) | Google ScholarSee all References Phosphodiesterase type 5 is primarily responsible for the breakdown of cGMP in cavernosal tissues. The inhibition of PDE-5 by sildenafil therefore causes continued activation of the NO-cGMP pathway in the cavernosal tissue, thereby improving erectile function.10x10Kloner, RA and Zusman, RM. Cardiovascular effects of sildenafil citrate and recommendations for its use. Am J Cardiol. 1999; 84: 11N–17N
A disruption anywhere along the complex chain of events will impair the capacity to have an erection. Any man who has experienced the frustration of male impotence knows that the consequences extend beyond physical dissatisfaction to anxiety, tension, and embarrassment. A common reason for failure of the erectile apparatus is disruption of the path leading to nitric oxide production and blood flow control.
"Just because there is evidence doesn't mean it's good evidence," says Andrew McCullough, MD, associate professor of clinical urology at New York University Langone Medical Center in New York City, and one of the original clinical investigators for the ED drug Viagra (sildenafil). "And before men with ED start down the naturopathic route, it's smart to make sure that there isn't some underlying medical condition that needs to be corrected." Moreover, it is estimated that 30 million American men have erectile dysfunction, and 70% of cases are a result of a potentially deadly condition like atherosclerosis, kidney disease, vascular disease, neurological disease, or diabetes. Additionally, ED can also be caused by certain medications, surgical injury, and psychological problems.

When it comes to scientific development, in Western medicine, an analytic approach is often used to identify and resolve medical challenges. A hypothesis is first derived through general observations of a phenomenon. A research plan is then carefully designed and data collected. Once sufficient data is collected, critical statistical evaluations are done and conclusions are drawn (4). Every aspects of a disease entity are studied from macroscopic to microscopic views, down to the cellular and molecular levels. The deep understanding of the role of cGMP-specific phosphodiesterase type 5 enzymes in ED and the use of phosphodiesterase-5 inhibitors in treatment of ED exemplifies the success of this approach.
Your choice of blood pressure medications could make a difference in the bedroom (or wherever you like to have sex). Thiazides (diuretics or “water pills”) and beta blockers are the most likely to cause erectile dysfunction (ED), while alpha blockers the least likely. Alpha blockers work by reducing nerve impulses to blood vessels, allowing blood to pass more easily. Ask your doctor whether these or other blood pressure medications are best for you.

Luckily, awareness of ED as a significant and common complication of diabetes has increased in recent years, mainly because of increasing knowledge of male sexual function and the rapidly expanding armamentarium of novel treatments being developed for impotence. Studies of ED suggest that its prevalence in men with diabetes ranges from 35–75% versus 26% in general population. The onset of ED also occurs 10–15 years earlier in men with diabetes than it does in sex-matched counterparts without diabetes.

The body’s source for nitric oxide production is the amino acid L-arginine, which is naturally found in many foods. The average American ingests about 3,000–5,000 mg of L-arginine per day, as it is an amino acid naturally contained in many foods. Meats of all varieties, nuts, and dairy products are rich in L-arginine, so the body is accustomed to intake levels of several thousand milligrams every day.

A thorough history (including cardiovascular symptoms, age, presence of risk factors and comorbid conditions such as obesity, hypertension, dyslipidaemia, pre-diabetes, CAD, peripheral artery disease, symptoms suggestive of sleep apnoea, family history of premature atherothrombotic CVD and lifestyle factors), assessment of ED severity (according to SHIM) and duration, and physical examination (for both heart and peripheral circulation pathology) are mandatory first-line elements of investigation. A resting electrocardiogram, measurement of fasting plasma glucose, and estimation of glomerular filtration rate are desirable tests that may be used to further characterize cardiovascular status and risk and to identify men who require additional cardiologic workup. Owing to the accumulating evidence supporting the link with CVD, the measurement of testosterone is recommended in all men with a diagnosis of organic ED, especially in those for whom phosphodiesterase type 5 (PDE5) inhibitor therapy failed.
Combination therapy has proven effective for some men who don’t respond adequately to oral medicines. The idea is to use two drugs with different mechanisms of action for better results. Commonly, sildenafil is used in combination with pellets of alprostadil (synthetic prostaglandin E1) that are inserted into the urethra (the tube in the penis that carries urine from the bladder to the outside of the body). Alprostadil also increases the blood supply to the penis, but by different means.
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