Hypertension can affect endothelial function in many ways. It can reduce endothelium-dependent vasodilatation by increasing the vasoconstrictor tone as a result of increased peripheral sympathetic activity.41–43 Another mechanism is hypertension-induced increase in cyclooxygenase activity that leads to an increase in reactive oxygen species; these in turn damage endothelial cells and disrupt their function.44–46 In some cases, endothelial NO synthase (eNOS) gene variations may relate to hypertension-associated endothelial dysfunction.6
PubMed | Google ScholarSee all References A dose-related phenomenon with propranolol use was suggested by another study, which showed that patients receiving propranolol dosages exceeding 120 mg/d developed ED at a higher rate than patients who received lower dosages of the same medication.43x43Warren, SC and Warren, SG. Propranolol and sexual impotence [letter]. Ann Intern Med. 1977; 86: 112
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.
PDE-5 inhibitors amplify the intacavernosal production of cGMP in response to nitric oxide. This is achieved through the inhibition of cGMP's breakdown by the enzyme, PDE-5. If the predominant abnormality in the individual EDDM patient is molecular, the higher tissue levels of cGMP will overcome these inhibitory factors and the patient will regain erectile function. If the physical structure (eg, the compliance) of the cavernosal tissue has been significantly compromised by apoptosis of smooth muscle or increased collagen deposits, restoration of erectile function will not be achieved. These structural changes explain the lower efficacy rates of PDE-5 inhibitors in EDDM than in the general population.
Although the results provide evidence that PDE5 inhibitors may benefit heart health, the retrospective study design makes it impossible to ascertain direct cause and effect, Andersson noted. It is possible that using erectile dysfunction drugs simply indicates a more active sex life, which could itself contribute to, or be a marker of, a heart-healthy lifestyle overall.
Powerful clinical and scientific experience suggests a close link between erectile dysfunction and heart disease. Studies like the Health Professionals Follow-up Study have revealed the risk factors for erectile dysfunction to be very similar to those for heart disease. Hypertension, smoking, diabetes, high cholesterol, obesity, and physical inactivity all strongly predict sexual dysfunction in men, as they do heart disease.1
Patients who use this therapy should be trained under the guidance of a urologist, and sterile technique must be used. The drugs must be injected into the shaft of the penis and into one of the penile erectile bodies (corpus cavernosum) 10–15 min before intercourse. Most patients do not complain of pain upon injection. Sexual stimulation is not required, and resulting erections may last for hours. Side effects include penile pain and priapism. The cost is about $12–20 per injection.
Another study showed a forty percent increase of blood flow to the heart within one year of starting a dietary program designed similar to the one described in my book, The End of Heart Disease. Of pertinent note is that, in the same study, the patients following a high-protein Atkins’ diet decreased blood flow to the heart by forty percent in one year.8 These dangerous high-protein diets are a certain path to erectile impotence and a premature cardiac death.
Abstract | Full Text PDF | PubMed | Scopus (19) | Google ScholarSee all References However, there has been disagreement regarding the effects of diuretics on erectile function; many studies found that only rarely have these medications been implicated convincingly as the cause of a patient's ED.36x36Wein, AJ and Van Arsdalen, KN. Drug-induced male sexual dysfunction. Urol Clin North Am. 1988; 15: 23–31
The safety of PDE5 inhibitors in patients with IHD has been shown in multiple trials. Arruda-Olson et al. investigated the safety of sildenafil during exercise stress tests in patients with IHD to ascertain whether the drug induces or exacerbates myocardial ischaemia. This was a prospective, randomised crossover study that demonstrated safety of sildenafil when given 1 hour before an exercise stress test.69 Another study that investigated 120 trials of sildenafil revealed that the rates of MI and cardiovascular death with sildenafil are as low as with placebo.70
There are two kinds of surgery for ED: one involves implantation of a penile prosthesis; the other attempts vascular reconstruction. Expert opinion about surgical implants has changed during recent years; today, surgery is no longer so widely recommended. There are many less-invasive and less-expensive options, and surgery should be considered only as a last resort.
To date, there are no studies directly comparing the effectiveness of these three agents among diabetic men with ED, so it is impossible to state that one agent is superior to another in terms of effectiveness in diabetic patients. However, there are an number of studies that compare the individual agents to placebo in diabetic men with ED. For example, Boulton et al.41 completed a 12-week double-blind, placebo-controlled randomized clinical trial of the effectiveness of sildenafil in 219 men with ED and type 2 diabetes. They found that sildenafil resulted in a significant improvement in the ability to both achieve and maintain an erection adequate for sexual intercourse in men with type 2 diabetes. In a similar study, Rendell et al.42 randomized 268 diabetic men with ED to receive either sildenafil in a dose-escalation manner or placebo. At the conclusion of the 12-week study, 56% of the patients in the sildenafil arm reported improved erections, compared to 10% in the placebo arm (P < 0.001). Additionally, 61% of patients in the diabetic arm reported at least one successful attempt at sexual intercourse in the final month of the study, compared to 22% in the control arm (P < 0.001). Similar randomized studies have documented the effectiveness of both tadalafil43 and vardenafil44 in the treatment of diabetes-related ED.
Abstract | Full Text | Full Text PDF | PubMed | Scopus (66) | Google ScholarSee all References However, some researchers have questioned whether the strain of sexual activity can be compared accurately with standard types of physical activity and whether sexual activity is more closely related to episodes of anger or fear.85x85DeBusk, RF. Evaluating the cardiovascular tolerance for sex. Am J Cardiol. 2000; 86: 51F–56F
Neurological (nerve and brain) diseases: The nervous system plays a vital part in achieving and maintaining an erection. It is common for men with conditions such as stroke, multiple sclerosis (MS), Alzheimer’s disease, Parkinson’s disease, and spinal cord injuries to experience ED. This is due to an interruption in the transmission of nerve impulses between the brain and the penis.
Before a man concludes that oral drugs don’t work for him, he should have his testosterone levels checked to rule out hormone deficiency as the cause of (or as a contributor to) his sexual dysfunction. Other symptoms of low testosterone include a low sex drive and infertility. Checking testosterone levels requires a blood test. If a man’s levels of testosterone are decreased or at the lower end of normal, his doctor may prescribe supplemental testosterone therapy, either as testosterone injections or testosterone gel, which is applied daily to the skin. In some cases, testosterone therapy alone can resolve sexual dysfunction, or it can be combined with the use of oral erectile dysfunction drugs.