By Dr. Mukaila Kareem
Erectile dysfunction was once considered a mental issue with no effective medical treatment. This medical challenge began to unravel following a dramatic presentation often referred to as “a stiff moment in scientific history.” In 1983, at the American Urological Association Conference, an eye-witness account by Dr. Klotz reported about 30 slide-base presentation delivered by Prof Giles Brindley. The Professor, who was a trained psychiatrist but had a wide medical research interests, showed varying degrees of penile erections after injecting his penis with up to 17 different smooth muscle relaxing drugs.
To drive home his point, Prof Brindley informed his audience that he was wearing a pair of loose pants because he had injected his penis with papaverine in his hotel room before coming to the lecture hall. He reportedly pulled up his pants tight around his private area to show his erection but was dissatisfied as he thought that this did not reveal much of his firmness. He therefore proceeded to pull down his pants to demonstrate the greatest “show and tell” in scientific history.
With pants down, Brindley waddled off the podium with intent of having his audience touch the degree of his penile firmness but embarrassingly pulled up his pants and abruptly ended the lecture as spouses of the doctors in the audience screamed and some began to exit the lecture hall. As awkward as this was, it was the first time erectile dysfunction was linked with vascular origin. Literature records that by mid 1980s it became a routine intervention for men with erectile dysfunction to inject smooth muscle relaxing drugs to “get it back up”.
How Erection Works
The penis has a pair of spongy cigar-shaped erectile tissue called corpora cavernosa. The complex interactions of the brain, nerves, hormones, and arteries result in simple mechanical outcome of penile erection. In fact, erection can be likened to forcing air into a balloon! In limp or flaccid state, the corpora tissue is in a shrunken form or in contraction and its rich arteries are constricted with limited blood flow while the outflow venous vessels are dilated to keep the blood supply at basal level like a deflated balloon! However, upon sexual arousal via thoughts, imagery or physical stimulation, the cascade of neurovascular event cause the relaxation of both arterial vessels and the erectile tissue leading to onset of pressurized inflow of blood into the penis and simultaneous constriction of venous outflow. This results in blood entrapment and engorgement with consequent penile enlargement, rigidity and hardness.
At the cellular level, erection occurs because the inner lining of penile arteries and the nerves that supply the erectile tissue produce a potent gas called nitric oxide. This gas in turn diffuses into the smooth muscle cells of erectile tissue and penile arteries to produce a mouthful “second messenger” called cyclic guanosine monophosphate (cGMP). This second messenger plays the final part in relaxation cascade and its presence sustains pressurized blood engorgement into the penis until it is degraded by an enzyme called phosphodiesterase 5 (PDE5).
According to National Institute of Health, erectile dysfunction is defined as persistent failure to attain and/or maintain an erection sufficient for satisfactory sexual performance. In other words, erectile dysfunction fulfils three conditions: when a man can get erection sometimes, when an erection does not last long enough for sexual intercourse or when a guy is unable to get an erection at any time. The main cause of erectile dysfunction is vascular in origin due to inability of the inner lining of penile arteries to produce nitric oxide, a condition called endothelium dysfunction which may progress to stiffening, narrowing, and clogging of blood vessels called atherosclerosis. Atherosclerosis can occur at any vascular tree but according to “artery size” hypothesis, it occurs first in the smaller penile arteries leading to erectile dysfunction.
Therefore erectile dysfunction is sometimes referred to as “penile attack” similar to heart attack and it’s a predictor of impending heart attack in 3-5 years of onset of erectile dysfunction. This is because the blood flow impairment tends to show clinical event in 1-2mm penile artery diameter before this can develop significantly as heart attack in 3-4mm diameter in coronary artery or as stroke in 5-7mm in carotid artery. Beyond romance, erectile dysfunction has been literally regarded as a “matter of the heart” or impending “broken heart” as a way to demonstrate its link with heart attack.
The controllable risk factors of erectile dysfunction are therefore the same for heart attacks and strokes. These factors are chronic diseases such as hypertension, diabetes, and hyperlipidemia. The common lifestyle choices associated with erectile dysfunction and cardiovascular diseases are cigarette smoking, excess alcohol consumption, and lack of physical exercise. Erectile dysfunction is also linked with psychological stress of depression and anxiety. It should also be mentioned that low testosterone is also a factor in some erectile dysfunction cases.
Viagra, otherwise called “the blue pill” was an accidental discovery following a failed clinical trial for its use as heart conditions in early 1990s. The volunteers for the trial reportedly were experiencing increased erections days after taking Viagra. Following Brindley’s unusual lecture, there was increased understanding of physiology of penile erection and Pfizer took advantage of this to run pilot studies in patients with erectile dysfunction and was the first to bring to market oral medication for then challenging men’s problem.
The FDA approved Viagra in 1998 and this was followed by Levitra and Cialis in 2003. These three medications belong to a class of drugs called phosphodiesterase 5 inhibitors (PDE5i). Phosphodiesterase 5 (PDE5) is an enzyme that is mainly found in erectile tissue. This enzyme acts by quickly degrading the cGMP, a vasodilatory molecule that sustains pressurized blood flow to the penis. Low concentration of cGMP decreases the chance of obtaining and sustaining duration of an erection. The oral medications therefore target PDE5 by blocking its ability to degrade cGMP and consequently increases the concentration of cGMP thereby restore penile integrity on demand (Viagra and Levitra) or long term anticipation of sexual intercourse (Cialis).
As effective as these medications are, it should be noted that they do not reverse the atherosclerosis that cause the impair blood flow to the penis nor do they prevent the impending risk of heart attack. In other words, someone with erectile dysfunction would always have erectile dysfunction, the medications only help to manage but not cure it. Lifestyle measures such as smoking cessation, moderate alcohol consumption, weight loss and regular physical activity have been documented to improve and reverse erectile dysfunction of vascular origin. Regular physical activity is an enabler of healthy choices due to its positive carry over effect. For instance, a person who does not smoke or drink may not necessarily be physically active but a physically active person is not likely to smoke, drink or eat excessively.
Irrespective of atherosclerotic site, regularly physical activity augments the bioavailability of nitric oxide through mechanical forces called shear stress. This improves or maintains vascular health via relaxation of arterial blood vessels, decrease concentration of “bad” cholesterol and prevent the clogging or adhesion of a part of blood called platelets. A 2009 study carried out in Nigeria and led by a Physiotherapist colleague, Late Dr. Sikiru Lamina, found that 45 to 60mins of stationary bike at low intensity at the initial 2 weeks and then moderate intensity 3 times a week for next 5 weeks improved erectile function in hypertensive men. It has been documented in medical literature that sedentary men may reduce their risk of erectile dysfunction by adopting brisk walking 2 miles a day. This is within the physical activity guidelines for general health promotion of walking 30 minutes 5 days or more per week and safe for general population. However, those who intend to take up jogging, running or other high intensity activity must consult their health practitioners.
Dr. Kareem is a US based Physiotherapist and blogs on healthcrowonline.com. He can also be followed on twitter @MakPT1999