The initial event for normal erectile function is sexual stimulation. Subsequent to processing in the central nervous system neural impulses are conveyed along the spinal cord, exiting through the pelvic parasympathetic preganglionic nerves. These pelvic nerves form the pelvic plexus and send their message through first messenger, acetyl choline, to the cavernosal nerves. The cavernosal nerves enter erectile bodies (corpora cavernosa) (Figure 1). Here, their nerve endings release a second messenger, nitric oxide. Nitric oxide activates the enzyme guanylyl cyclase, which lyses guanosine triphosphate (GTP) to produce a third messenger, the intracellular cyclic guanosine monophosphate (cGMP). Ultimately, the result is a decrease of intracellular calcium and an opening of potassium channels with the resultant relaxation of vascular smooth muscle in the arteries, aterioles, and sinusoids of the corpora cavernosa. The sinusoids open and rapidly fill with blood. Finally, the distended sinusoids compress their drainage pathways (venules) against the fibroelastic covering of the cavernosal bodies (tunica albuginea) and trap the blood in cavernosal bodies. The combination of an increased inflow of blood into the penis and coincident markedly diminished outflow results in rapidly increasing intracavernosal pressure that ultimately approximates systolic pressure. At this pressure the penis has sufficient axial rigidity to permit vaginal penetration.
Viagra, Cialis, Levita, and Staxyn all work in a similar fashion and make it physically possible to get an erection when aroused. However, men whose blood pressure is poorly controlled and who take alpha-blockers for high blood pressure treatment should not take any of these treatments for erectile dysfunction as it may reduce blood pressure to critically low levels, causing fainting or sudden death. Also, you may be prohibited to use these drugs if you demonstrate any of the following:
PubMed | Google ScholarSee all References This prolonged excretion half-life produces enhanced erections up to 36 hours after oral dosing, thereby potentially allowing for more spontaneous engagement of intercourse. The efficacy of tadalafil in the treatment of ED has been proved in randomized double-blind, placebo-controlled trials.78x78Porst, H, Padma-Nathan, H, Giuliano, F, Anglin, G, Varanese, L, and Rosen, R. Efficacy of tadalafil for the treatment of erectile dysfunction at 24 and 36 hours after dosing: a randomized controlled trial. Urology. 2003; 62: 121–125
Crossref | Google ScholarSee all References Different classes of β-blockers have been postulated to have differential effects on erectile function, with the nonselective β-blockers (eg, propranolol) having more deleterious effects than the more cardioselective medications (eg, atenolol, metoprolol).42x42Weiss, RJ. Effects of antihypertensive agents on sexual function. Am Fam Physician. 1991; 44: 2075–2082

A recent systematic review and meta-analysis of relevant studies in this field confirmed that erectile dysfunction is associated with increased risk of CV events and all-cause mortality[89]. The pooled relative risks were 1.44 (95%CI: 1.27-1.63) for total CV events, 1.19 (95%CI: 0.97-1.46) for CV mortality, 1.62 (95%CI: 1.34-1.96) for myocardial infarction, 1.39 (95%CI: 1.23-1.57) for cerebrovascular events, and 1.25 (95%CI: 1.12-1.39) for all-cause mortality, for men with vs without erectile dysfunction. Of note, the relative risk was higher in intermediate-compared with high- or low-CV-risk populations and with younger age, with obvious clinical implications. Interestingly, the relative risks were higher when erectile dysfunction was diagnosed with the use of a questionnaire compared with a single question (RR = 1.61; 95%CI: 1.38-1.86 vs RR = 1.27; 95%CI: 1.18-1.37, respectively; P = 0.006).
For patients who failed oral medical therapy or unable to tolerate the side effects, intracavernosal injection of vasoactive agents can often provide effective alternative. Various vasoactive agents such as alprostadil, papaverine or phentolamine have been used either as single agent or combination agents to potentiate the NO release and cavernosal smooth muscle vasodilation. However, intracavernosal injection therapy has high attrition rate and can be associated pain especially with alprostadil injection (2). The practice of isolating compounds and understanding its pharmacological attributes before using it as a drug therapy has been a strength of Western medicine.

• 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.
Towards this direction, several sufficiently powered studies have demonstrated a higher incidence of erectile dysfunction in patients with coronary artery disease, either asymptomatic or overt. At the same time, patients with erectile dysfunction are more prone to have established coronary artery stenosis of more than 50% and consequently evident CV disease[75]. This is in conformity with the “artery size hypothesis” according to which smaller arteries (e.g., penile arteries) are the first to undergo a vascular lesion prior to the larger ones (e.g., coronary arteries). Moreover, in such patients erectile dysfunction is connected to the number of occluded vessels and more interestingly occurs over three years before coronary artery disease becomes apparent[76-80].

The blood supply to your penis starts in your heart and flows through arteries in the belly to even smaller arteries that branch off to carry blood into the penis. With sexual stimulation, these blood vessels need to rapidly increase blood flow. If these blood vessels are blocked (atherosclerosis) by coronary artery disease, you may not be able to achieve or maintain an erection.11
Diabetes is known to sabotage two body parts that provide essential components of an erection: nerves and blood vessels. Studies suggest that diabetic nerve damage (neuropathy) is the most important risk factor for ED in people with diabetes. If pelvic nerves that trigger penis muscles to relax are impaired, there may be a break in the chain between brain and penis, disrupting erection. Some researchers suspect that an inadequate supply of oxygen to the nerves causes this damage.

Prescription drugs called “oral phosphodiesterase-5 (PDE5) inhibitors” are considered the “first-line non-invasive treatment” options for patients with ED. These include the drugs that go by brand names: Sildenafil, Vardenafil or Tadalafil. They work by helping the smooth muscle cells lining the blood vessels that supply the penis with blood to work properly. This allows a man to maintain an erection more easily.


Some commonly prescribed cardiovascular drugs (beta-blockers, diuretics, angiotensin-converting enzyme inhibitors, etc.) contribute to ED.18 Previous studies have shown a strong association between ED and diuretics in patients treated with hydrochlorothiazide or chlorthalidone.19,20 It has also been shown that patients treated with first-generation non-selective beta-blockers, such as propranolol, had more frequent ED than those treated with a placebo.21
Erectile dysfunction is common in the patient with cardiovascular disease. It is an important component of the quality of life and it also confers an independent risk for future cardiovascular events. The usual 3-year time period between the onset of erectile dysfunction symptoms and a cardiovascular event offers an opportunity for risk mitigation. Thus, sexual function should be incorporated into cardiovascular disease risk assessment for all men. A comprehensive approach to cardiovascular risk reduction (comprising of both lifestyle changes and pharmacological treatment) improves overall vascular health, including sexual function. Proper sexual counselling improves the quality of life and increases adherence to medication. This review explores the critical connection between erectile dysfunction and cardiovascular disease and evaluates how this relationship may influence clinical practice. Algorithms for the management of patient with erectile dysfunction according to the risk for sexual activity and future cardiovascular events are proposed.
At the same time, people with diabetes are susceptible to a type of blood vessel damage known as endothelial dysfunction. A recent study found that men with ED are at a greater risk of heart disease, which is also associated with endothelial dysfunction. If blood vessels aren't in good working order, the penis may not get enough blood for an erection.
The pilot study by Vardi et al. (18) showed that LIESWT was effective in treating men with ED, suggesting a physiologic impact of LIESWT on cavernosal hemodynamics. The LIESWT is an effective penile rehabilitation tool that improves erectile function and potentially reverses underlying ED. Recent meta-analysis (19) of 14 studies showed that LiESWT could significantly improve the International Index of Erectile Function (IIEF) [mean difference: 2.00; 95% confidence interval (CI), 0.99–3.00; P<0.0001] and Erection Hardness Score (EHS) (risk difference: 0.16; 95% CI, 0.04–0.29; P=0.01). In addition, the therapeutic efficacy was noted to last for at least 3 months. LiESWT has been cited to a potential cure for ED, unlike other well established non-surgical methods of treatment (i.e., PDE5i, ICI and VED) being on demand treatments.
Most studies into the effect of beta-blockers on ED point to negative effects of first- and second-generation beta-blockers, while beta-blockers with vasodilating effects can improve erectile function. Alpha-blockers, calcium channel blockers, and angiotensin-converting enzyme inhibitors seem to have a neutral effect on erectile function. Multiple previous studies have demonstrated a beneficial effect of angiotensin receptor blockers on erectile function and they should probably be the favoured antihypertensive agents in patients with ED.29
Perk J,  De Backer G,  Gohlke H,  Graham I,  Reiner Z,  Verschuren WM,  Albus C,  Benlian P,  Boysen G,  Cifkova R,  Deaton C,  Ebrahim S,  Fisher M,  Germano G,  Hobbs R,  Hoes A,  Karadeniz S,  Mezzani A,  Prescott E,  Ryden L,  Scherer M,  Syvänne M,  Scholte Op Reimer WJ,  Vrints C,  Wood D,  Zamorano JL,  Zannad F. European Guidelines on cardiovascular disease prevention in clinical practice (version 2012). The Fifth Joint Task Force of the European Society of Cardiology and Other Societies on Cardiovascular Disease Prevention in Clinical Practice (constituted by representatives of nine societies and by invited experts). Developed with the special contribution of the European Association for Cardiovascular Prevention & Rehabilitation (EACPR), Eur Heart J , 2012, vol. 33 (pg. 1635-1701)https://doi.org/10.1093/eurheartj/ehs092

Abstract | Full Text | Full Text PDF | PubMed | Scopus (95) | Google ScholarSee all References Sildenafil is taken orally 1 hour before anticipated sexual intercourse and enhances the normal response to sexual stimulation; however, it has no effect on erections in the absence of stimulation.10x10Kloner, 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 (37) | Google ScholarSee all References It has been postulated that regular exercise can decrease or possibly eliminate the small risk of myocardial infarction associated with sexual intercourse in most patients.8x8Muller, JE, Mittleman, A, Maclure, M, Sherwood, JB, Tofler, GH, and Determinants of Myocardial Infarction Onset Study Investigators. Triggering myocardial infarction by sexual activity: low absolute risk and prevention by regular physical exertion. JAMA. 1996; 275: 1405–1409
Crossref | PubMed | Scopus (1) | Google ScholarSee all References Angiotensin-converting enzyme inhibitors also have low rates of secondary ED associated with their use in both animal and human studies.45x45Srilatha, B, Adaikan, PG, Arulkumaran, S, and Ng, SC. Sexual dysfunction related to antihypertensive agents: results from the animal model. Int J Impot Res. 1999; 11: 107–113
Many products contain undocumented “fillers” that can cause allergic reactions.  In recent years, the FDA has found over 300 herbal products that contain hidden, deceptively labeled, or dangerous ingredients4. And since 2015, the FDA has released public warnings on more than 160 ED supplements and “male enhancement” products found to contain dangerous ingredients and contaminants5 .   An independent study of FDA data, conducted in 2018, found almost 800 herbal supplements that contained unlisted ingredients6.

Yohimbe. Before Viagra and the other prescription erectile dysfunction drugs became available, doctors sometimes prescribed a derivative of the herb yohimbe (yohimbine hydrochloride) to their patients suffering from ED. But experts say the medication is not particularly effective, and it can cause jitteriness and other problems. "It's not a great drug," says McCullough. "And I suspect the herb is not as potent as the pharmaceutical version." What's more, evidence shows that yohimbe is associated with high blood pressure, anxiety, headache, and other health problems. Experts discourage its use.
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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