Penile arterial supply (top) and venous drainage (middle), longitudinal views. Bottom, Transverse and longitudinal views of venous return. From Lue TF. Physiology of penile erection and pathophysiology of erectile dysfunction and priapism. In: Walsh PC, Retik AB, Vaughan ED Jr, Wein AJ, eds. Campbell's Urology. Vol 2. 7th ed. Philadelphia, Pa: WB Saunders Co; 1998:1157-1179. With permission from Elsevier.


Few simple laboratory tests can help identify obvious causes of organic ED. Initial labs should include HbA1c, free testosterone, thyroid function tests, and prolactin levels. However, patients who do not respond to pharmacological therapy or who may be candidates for surgical treatment may require more in-depth testing, including nocturnal penile tumescence testing, duplex Doppler imaging, somatosensory evoked potentials, or pudendal artery angiography.

Crossref | PubMed | Scopus (25) | Google ScholarSee all References In comparison, a randomized placebo-controlled trial of 65 patients given either placebo or 95 mg/d of sustained-release metoprolol for 4 months after percutaneous coronary angioplasty found no significant difference in sexual function between the 2 groups.44x44Franzen, D, Metha, A, Seifert, N, Braun, M, and Hopp, HW. Effects of beta-blockers on sexual performance in men with coronary heart disease: a prospective, randomized and double blinded study. Int J Impot Res. 2001; 13: 348–351
Abstract | Full Text | Full Text PDF | PubMed | Scopus (30) | Google ScholarSee all References Erections result from relaxation of the corpora cavernosa, which is mediated either by increasing intracellular cyclic guanosine monophosphate (cGMP) or cyclic adenosine monophosphate or by inhibition of their degradation. Increased parasympathetic tone results in a decrease in norepinephrine release and an increase in the release of acetylcholine; subsequently, NO synthase activity increases, which releases NO from both endothelial cells and nonadrenergic, noncholinergic neurons.10x10Kloner, RA and Zusman, RM. Cardiovascular effects of sildenafil citrate and recommendations for its use. Am J Cardiol. 1999; 84: 11N–17N

Ginseng. Korean red ginseng has long been used to stimulate male sexual function, but few studies have tried systematically to confirm its benefits. In one 2002 study involving 45 men with significant ED, the herb helped alleviate symptoms of erectile dysfunction and brought "enhanced penile tip rigidity." Experts aren't sure how ginseng might work, though it's thought to promote nitric oxide synthesis. "I would recommend ginseng [for men with ED]," says Espinosa. Discuss with your doctor before taking it since ginseng can interact with drugs you may already be taking and cause allergic reactions.

Crossref | PubMed | Scopus (443) | Google ScholarSee all References Nitroglycerin and other NO donors work through the same NO-cGMP pathway that sildenafil affects, thereby decreasing vascular resistance and blood pressure level.10x10Kloner, RA and Zusman, RM. Cardiovascular effects of sildenafil citrate and recommendations for its use. Am J Cardiol. 1999; 84: 11N–17N
Cardiovascular disease and erectile dysfunction (ED) are closely interrelated disease processes. Erectile dysfunction reportedly affects 10 million to 20 million men in the United States and more than 100 million men worldwide. Each year, about 500,000 persons in the United States survive a myocardial infarction, and an estimated 11 million have existing cardiovascular disease, making the issue of sexual function and cardiac disease relevant to many patients. We explore the relationship between ED and the presence of cardiovascular disease in the general population. We also review the prevalence and pathophysiological associations of ED and cardiovascular disease. The risks of sexual activity for patients with cardiovascular disease are discussed, as are prevention and treatment strategies for ED in this patient population.
A deficiency of L-arginine, however, does not generally disrupt nitric oxide synthesis because L-arginine availability is not the rate-limiting step in this process. In fact, research over the past five years has identified an endogenous (occurs in the body naturally) inhibitor called “asymmetric dimethylarginine” or ADMA, an amino acid which blocks the production of nitric oxide. By acting as an L-arginine mimic, this damaging look-alike effectively elbows out L-arginine and pushes it off to the side in the biochemical pathway leading to the synthesis of nitric oxide. ADMA is relatively elevated in patients with hypertension, high levels of cholesterol, triglycerides, homocysteine and low-density lipoprotein (LDL), and low levels of high-density lipoprotein (HDL), as well as with aging itself. This inhibitor of nitric oxide synthesis may very well be the common factor shared by all of these abnormal conditions. Increased levels of this detrimental inhibitor (ADMA) block nitric oxide production, leading to endothelial dysfunction.

In TCM, the meridian system is thought to represent a path through which the life energy qi flows and as discussed in earlier section, the “Jing” (kidney) qi plays an important role in penile erection. Acupuncture helps to correct the imbalances to relieve physical symptoms by stimulating various meridian points. The Shensu (BL23), Zusanli (ST36) and Neiguan (PC6) points represents important acupoints for penis stimulation and thus has a positive homeostatic effect on the autonomic nervous system, and potentially modulate NO release (55,56). While some studies have showed up to a third of patients reported improvement in penile erection and sexual activity, systematic review showed insufficient data to conclude that acupuncture is an effective intervention for treating ED (56,57). Therefore, further scientific research is required to investigate whether there are specific benefits of acupuncture for men with ED before acupuncture can be accepted as evidence-based practice.


In many of these cases, a discussion between the physician, the man with erectile dysfunction, and possibly his partner can help to resolve the issues leading to treatment failure. For men who experience severe side effects, can’t take the drugs for other reasons (such as taking medicines such as nitroglycerin), or don’t respond in spite of further education on the correct use of the drugs, there are other treatment options that can help most men remain sexually active.
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