People sometimes refer to ED as "impotence," although the two aren't really the same condition. ED is the physical inability to develop or maintain an erection that is rigid enough for sex. Impotence is a broader term. While one cause of it is ED, impotence may also involve a lack of sexual desire, an inability to ejaculate, or problems with orgasm.
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.
Relaxation of erectile tissue requires nitric oxide from nonadrenergic-noncholinergic neurons and the endothelium.21 Penile tissue from diabetic men with ED demonstrates impaired neurogenic and endothelium-mediated relaxation of smooth muscle,22 increased accumulation of advanced glycation end products (AGEs),23 and upregulation arginase, a competitor with nitric oxide synthase for its substrate L-arginine.24 Normal responses to direct smooth muscle relaxants in most of these studies implies that the impairments are due to decreased synthesis, release, or activity of nitric oxide. The fundamental mechanisms mediating these changes are thought to be the same as for other diabetic complications: increased polyol pathway flux, intracellular accumulation of AGEs, activation of protein kinase C, and increased flux through the hexosamine pathway.25
Crossref | PubMed | Scopus (56) | Google ScholarSee all References When matched for age, hypertension, diabetes, and tobacco use, no significant difference was noted in the presence of ED (42% in the myocardial infarction group vs 48% in the control group). However, the presence of severe congestive heart failure has been associated with increased ED. A study of 80 patients with New York Heart Association class III/IV congestive heart failure found that 40% of these patients had complete ED, and another 40% had either mild or moderate ED.15x15Taylor, HA Jr. Sexual activity and the cardiovascular patient: guidelines. Am J Cardiol. 1999; 84: 6N–10N
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
Abstract | Full Text | Full Text PDF | PubMed | Scopus (25) | Google ScholarSee all References The Framingham Heart Study found a baseline risk of myocardial infarction in a healthy 50-year-old nonsmoking man to be approximately 1% per year, or 1 chance per million per hour.87x87Anderson, KM, Odell, PM, Wilson, PW, and Kannel, WB. Cardiovascular disease risk profiles. Am Heart J. 1991; 121: 293–298
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
As you get older, your risk of both ED and heart disease increases. But the connection between these conditions is stronger among younger men, according to the Mayo Clinic. If you experience ED under the age of 50, it’s more likely to be a sign of underlying heart problems. If you experience it after the age of 70, it’s much less likely to be linked to heart disease.
Treatments might be slightly different for different people, depending on their risk factors, but in general all treatment plans have similar elements: diet, exercise, and medications, if necessary (see the Table). Diet and exercise are the cornerstones of the treatment of atherosclerosis. Every diet should include low salt (especially for high blood pressure), low fat and cholesterol (especially for high cholesterol), and limited total calories (especially for patients who are overweight). People with diabetes mellitus should limit their intake of sugars and carbohydrates. Exercise helps to limit atherosclerosis. The more exercise, the better, but every little bit helps. The general recommendation is 30 minutes a day 5 days a week. Check with your doctor to be sure that an exercise program is safe for you. Cigarettes cause a variety of health problems, including atherosclerosis, so cigarette smoking should be stopped. If diet and exercise are not enough to control your atherosclerotic risk factors, then your doctor will prescribe medications. Heart attacks are prevented by controlling atherosclerotic risk factors, which means diet, exercise, and medications if necessary.
Sexual intercourse is an infrequent cause of myocardial infarction. In a study of 1774 patients after myocardial infarction, only 1.5% of these events occurred within 2 hours of sexual intercourse, and sexual activity was considered a direct contributing factor in 0.9%.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
The same device is considered a vacuum erectile device (VED), when it is used to increase inflow of the blood to the penis without a constriction band. Regular use of VED in post-prostatectomy patient increases penile oxygenation and is accepted as a valid option in penile rehabilitation. Recent study reported transient increase in oxygenation to the glans penis and corporal bodies were detected by oximetry after VED was applied, providing proof for possible role for VED to counter the early penile hypoxia, cavernosal fibrosis and long-term ED after radical prostatectomy (9).
Abstract | Full Text | Full Text PDF | PubMed | Scopus (95) | Google ScholarSee all References Sildenafil is absorbed rapidly, and peak plasma levels of 127 to 560 ng/mL are seen in a fasting state approximately 1 hour (range, 0.5-2 hours) after ingestion.3x3Zusman, RM, Morales, A, Glasser, DB, and Osterloh, IH. Overall cardiovascular profile of sildenafil citrate. Am J Cardiol. 1999; 83: 35C–44C
Erectile dysfunction is a common occurrence in men with diabetes. The incidence of erectile dysfunction increases progressively with age, from 5% in men age 20 to 75% in men over age 65. The cause of erectile dysfunction in men with diabetes is usually related to a decrease in the blood supply to the penis as well as to injury to the nerves that are responsible for the erection mechanism. A decrease in testosterone production has also been identified as the cause in some men with diabetes.