The vascular endothelium has an important role in angiogenesis and vascular repair by producing regulatory substances, including NO, prostaglandin, endothelins, prostacyclin and angiotensin II. These regulatory factors regulate the blood flow to the penis by controlling smooth muscle contractility and subsequent vasoconstriction and vasodilatation. Generally, in erectile tissue, increased blood flow through the cavernosal artery increases shear stress and produces NO, which further relaxes the vascular smooth muscles and increases blood flow in the corpora cavernosa.54 These events cause penile erection. However, in ED, endothelial NO synthesis is reduced and there is increased endothelial cell death (Figure 2).55
medicines called alpha-blockers such as Hytrin (terazosin
HCl), Flomax (tamsulosin HCl), Cardura (doxazosin
mesylate), Minipress (prazosin HCl), Uroxatral (alfuzosin HCl),
 Jalyn (dutasteride and tamsulosin HCl), or Rapaflo (silodosin).
Alpha-blockers are sometimes prescribed for prostate
problems or high blood pressure. In some patients, the use
of Sildenafil with alpha-blockers can lead to a drop in blood pressure or to fainting

A sexually competent male must have a series of events occur and multiple mechanisms intact for normal erectile function. He must 1) have desire for his sexual partner (libido), 2) be able to divert blood from the iliac artery into the corpora cavernosae to achieve penile tumescence and rigidity (erection) adequate for penetration, 3) discharge sperm and prostatic/seminal fluid through his urethra (ejaculation), and 4) experience a sense of pleasure (orgasm). A man is considered to have ED if he cannot achieve or sustain an erection of sufficient rigidity for sexual intercourse. Most men, at one time or another during their life, experience periodic or isolated sexual failures. However, the term “impotent” is reserved for those men who experience erectile failure during attempted intercourse more than 75% of the time.
Crossref | PubMed | Scopus (174) | Google ScholarSee all References This study concluded that patients who have stable coronary artery disease who can exercise to 4.5 metabolic equivalents (METs) with a negative or mildly positive stress test and without angina or hypotension can safely take sildenafil. Physicians who prescribe sildenafil should counsel their patients that, if they have chest pain or other cardiac symptoms with sexual intercourse, they should not take nitrates and should immediately call their physician.66x66Jackson, G. Sexual intercourse and stable angina pectoris. Am J Cardiol. 2000; 86: 35F–37F

Crossref | PubMed | Scopus (53) | Google ScholarSee all References This study found that, although hypertensive patients had more coronary artery disease, no direct evidence supported an association between hypertension and arteriogenic impotence, as measured by the PBI, peak systolic velocity, and resistive index, in patients with mild to moderate hypertension.

Crossref | PubMed | Scopus (23) | Google ScholarSee all References Similar to sildenafil, vardenafil produces a slight hypotensive effect with an average maximal decrease in blood pressure level of 5 to 10 mm Hg.74x74Gresser, U and Gleiter, CH. Erectile dysfunction: comparison of efficacy and side effects of the PDE-5 inhibitors sildenafil, vardenafil and tadalafil—review of the literature. Eur J Med Res. 2002; 7: 435–446

Erectile dysfunction (ED) is a common disorder that affects the quality of life of many patients. It is prevalent in more than half of males aged over 60 years. Increasing evidence suggests that ED is predominantly a vascular disorder. Endothelial dysfunction seems to be the common pathological process causing ED. Many common risk factors for atherosclerosis such as diabetes, hypertension, smoking, obesity and hyperlipidaemia are prevalent in patients with ED and so management of these common cardiovascular risk factors can potentially prevent ED. Phosphodiesterase type 5 inhibitors provide short-term change of haemodynamic factors to help initiate and maintain penile erection. They have been shown to be an effective and safe treatment strategy for ED in patients with heart disease, including those with ischaemic heart disease and hypertension.


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.
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.
Abstract | Full Text | Full Text PDF | PubMed | Scopus (46) | Google ScholarSee all References The significant sympathetic discharge associated with sexual intercourse may contribute to the development of arrythmias in susceptible patients.81x81Drory, Y, Fisman, EZ, Shapira, Y, and Pines, A. Ventricular arrhythmias during sexual activity in patients with coronary artery disease. Chest. 1996; 109: 922–924
Chlamydia and erectile dysfunction: What's the link? Some people who have chlamydia also experience erectile dysfunction (ED), which involves problems getting or maintaining an erection. Chlamydia can infect the prostate gland, leading to prostatitis, pain, and ED. In this article, learn more about the link between this common infection and ED, and treatments for both. Read now
Apostolo A,  Vignati C,  Brusoni D,  Cattadori G,  Contini M,  Veglia F,  Magrì D,  Palermo P,  Tedesco C,  Doria E,  Fiorentini C,  Montorsi P,  Agostoni P. Erectile dysfunction in heart failure: correlation with severity, exercise performance, comorbidities, and heart failure treatment, J Sex Med , 2009, vol. 6 (pg. 2795-2805)https://doi.org/10.1111/j.1743-6109.2009.01416.x

Table 3Metabolic Equivalent (MET) Values for Various Physical Activities56x56Wallis, RM, Corbin, JD, Francis, SH, and Ellis, P. Tissue distribution of phosphodiesterase families and the effects of sildenafil on tissue cyclic nucleotides, platelet function, and the contractile responses of trabeculae carneae and aortic rings in vitro. Am J Cardiol. 1999; 83: 3C–12C
• Medications: About 25 percent of ED cases are caused by drugs. Many medications, including common medicines prescribed for diabetes and its complications, can cause ED. The most common offenders are blood pressure drugs, antihistamines, antidepressants, tranquilizers, appetite suppressants, and cimetidine (an ulcer drug). In addition, over-the-counter medications, including certain eye drops and nose drops, have been associated with ED. That does not mean you should stop taking these medications! Rather, you should discuss them with your doctor to determine whether a different dosage, an alternate medicine, or additional treatments will resolve the ED.
27. Haahr MK, Jensen CH, Toyserkani NM, et al. Safety and Potential Effect of a Single Intracavernous Injection of Autologous Adipose-Derived Regenerative Cells in Patients with Erectile Dysfunction Following Radical Prostatectomy: An Open-Label Phase I Clinical Trial. EBioMedicine 2016;5:204-10. 10.1016/j.ebiom.2016.01.024 [PMC free article] [PubMed] [CrossRef]
Alcohol consumption, bad nutrition, a sedentary lifestyle, excessive stress, psychological issues, relationship issues, use of illegal drugs and overuse of prescribed drugs, poor sleep habits and excessive physical activity are all contributing factors to ED. Ailments like diabetes, as well as low and high blood pressure, in addition to prostate cancer, may also result in ED.
PubMed | Google ScholarSee all References In a double-blind, placebo-controlled study, sildenafil was effective in patients with diabetes mellitus.58x58Rendell, MS, Rajfer, J, Wicker, PA, Smith, MD, and Sildenafil Diabetes Study Group. Sildenafil for treatment of erectile dysfunction in men with diabetes: a randomized controlled trial. JAMA. 1999; 281: 421–426
Abstract | Full Text | Full Text PDF | PubMed | Scopus (46) | Google ScholarSee all References The Princeton Consensus Panel provided guidelines (Table 4) for physicians regarding patients who are being evaluated for their level of risk in resuming sexual activity.51x51DeBusk, R, Drory, Y, Goldstein, I et al. Management of sexual dysfunction in patients with cardiovascular disease: recommendations of the Princeton Consensus Panel. Am J Cardiol. 2000; 86: 62F–68F
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.

Usually patients will try less invasive alternatives to treat impotence before opting for surgery. These alternatives may include supplements, herbs, lifestyle changes and even medications. In cases where other treatments do not work to resolve ED, surgery might be a last-resort option. Surgery involves implanting a penile prosthesis. This is a saline-filled silicone device or a malleable device. Although the likelihood of serious side effects is considered to be low, certain risks are associated with surgery to correct erectile dysfunction. These side effects may include: anesthetic risk, device infection, and device malfunction or mechanical failure. Some studies have found that five years following surgery around 10–20 percent of men experience device malfunction and failure. Infection rates are low. Around one percent of men who opt for this type of surgery get an infection.
In subsequent clinical studies, a surprisingly high percentage of EDDM patients–10% to 20%–claimed that the placebo "improved my erections," thus indicating a psychological basis for their ED. In the latter half of the 1980s, objective means were developed that could help determine if a EDDM patient had organic or psychogenic ED. The absence of rigid sleep erections confirmed by penile monitors was one criterion for organic ED. The failure of vasoactive agents (papaverine, Trimix, or prostaglandin E-1 [PGE-1]) injected into the corpora cavernosa to induce penile rigidity was another criterion for organic disease. Intracavernosal maintenance flow rates during pharmacocavernosometry and maximum cavernosal arterial flow during penile Doppler ultrasonography were additional determinants.
PubMed | Google ScholarSee all References They evaluated 40 patients with coronary artery disease who underwent coronary artery catheterization and whose penile brachial index (PBI) was measured by Doppler ultrasonography. Although a positive correlation was noted between the PBI and the severity of coronary artery obstruction, the relationship was not strong. Also, the degree of PBI abnormality did not effectively stratify the patients according to the severity of their coronary artery blockage. This study concluded that the PBI used alone would not be an effective predictor of ischemic heart disease.
The cardiovascular adverse effects of sildenafil use have been studied extensively. Phosphodiesterase type 5, although located primarily in the genitalia, also can be found throughout the systemic vasculature, although other PDEs predominate there10x10Kloner, RA and Zusman, RM. Cardiovascular effects of sildenafil citrate and recommendations for its use. Am J Cardiol. 1999; 84: 11N–17N
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
Crossref | Google ScholarSee all References A 1985 study found that ED accounted for 400,000 outpatient visits and 30,000 hospital admissions per year in the United States, with a direct total cost of $146 million.4x4Feldman, HA, Goldstein, I, Hatzichristou, DG, Krane, RJ, and McKinlay, JB. Impotence and its medical and psychosocial correlates: results of the Massachusetts Male Aging Study. J Urol. 1994; 151: 54–61
Crossref | PubMed | Scopus (174) | Google ScholarSee all References This study concluded that patients who have stable coronary artery disease who can exercise to 4.5 metabolic equivalents (METs) with a negative or mildly positive stress test and without angina or hypotension can safely take sildenafil. Physicians who prescribe sildenafil should counsel their patients that, if they have chest pain or other cardiac symptoms with sexual intercourse, they should not take nitrates and should immediately call their physician.66x66Jackson, G. Sexual intercourse and stable angina pectoris. Am J Cardiol. 2000; 86: 35F–37F

The views expressed in this article intend to highlight alternative studies and induce conversation. They are the views of the author and do not necessarily represent the views of hims, and are for informational purposes only, even if and to the extent that this article features the advice of physicians and medical practitioners. This article is not, nor is it intended to be, a substitute for professional medical advice, diagnosis, or treatment, and should never be relied upon for specific medical advice.


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.
The use of shock wave therapy has revolutionized the treatment of many aspects of medicine. High intensity extracorporeal shockwave therapy has been used for the treatment of nephro-urolithiasis while medium intensity shockwave therapy is used by orthopaedic surgeons to treat joint pain as well as tendinitis. Low intensity shockwaves therapy was first noted to improve ischaemia-induced myocardial dysfunction in animal studies when low intensity shockwaves were applied to porcine myocardium (13). Shockwaves induces a localized stress on cell membranes in the same way that shear stress affects endothelial cell membranes (14) and this triggers the release of angiogenic factors, such as increased NO production through increased activity of endothelial NO synthase (eNOS) and neuronal NO synthase (nNOS), platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF) (15). These shockwaves also cause membrane hyperpolarization (16), activation of the Ras signaling pathway, non-enzymatic synthesis of NO and induction of stress fibers and intercellular gaps (17).
Crossref | PubMed | Scopus (42) | Google ScholarSee all References Apomorphine does not appear to have any notable cardiovascular adverse effects and has been used successfully in Europe. However, apomorphine use has been associated with other unpleasant adverse effects such as nausea and emesis, and the drug has not been approved by the US Food and Drug Administration (FDA) for use in the United States.
There are a number of reasons a man may not achieve the desired result from an oral erectile dysfunction drug. In some cases, a man may experience drug side effects severe enough to outweigh any potential benefit of taking the drug. Possible side effects of these drugs include headache, facial flushing, nasal congestion, and transient abnormal vision. (In October 2007, the FDA added a warning about sudden hearing loss to the package labels of oral erectile dysfunction drugs. While it’s not absolutely clear that the drugs can cause sudden hearing loss, a number of cases have been reported in men within hours or days of taking one of the drugs.)
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