The pathogenesis of organic ED is related to dysfunction of the endothelium. Endothelial cells can become injured through a variety of mechanisms, most of which cause oxidative stress on the tissues. Many of these causes of oxidative stress are related to lifestyle issues which lead to hypertension, diabetes and dyslipidaemia (figure 1). Endothelial cell dysfunction results in reduction of endothelium-dependent vasorelaxation as well as increased adhesion of leukocytes to the endothelium. Endothelial cell injury then leads to a variety of sequelae, including ED, other types of vasoconstriction, atherosclerosis and thrombus formation.18
A duplex ultrasound is a diagnostic technique that uses painless, high frequency sound waves to visualize structures beneath the skin's surface. The principle is similar to the sonar used on submarines. Sound waves are reflected back when they contact relatively dense structures such as fibrous tissue or blood vessel walls. These reflected sound waves can be converted into pictures of the internal structures being studied.
The most common treatment for erectile dysfunction is drugs known as phosphodiesterase-5 (PDE-5) inhibitors. These include tadalafil (Cialis), vardenafil (Levitra), and sildenafil citrate (Viagra). These are effective for about 75% of men with erectile dysfunction. They are tablets that are taken around an hour before sex, and last between 4 and 36 hours. Sexual stimulation is required before an erection will occur. The PDE-5 inhibitors cause dilation of blood vessels in the penis to allow erection to occur, and help it to stay rigid. Men using nitrate medication (e.g. GTN spray or sublingual tablets for angina) should not use PDE-5 inhibitors.
Intraurethral therapy (Medicated Urethral System for Erections, or MUSE): Alprostadil (PGE1) has been formulated into a small suppository that can be inserted into the urethra (the canal through which urine and semen are excreted). The suppository is preloaded into a small applicator and by placing the applicator into the tip of the penis and compressing the button at the other end of the applicator and wiggling the applicator, the suppository is released into the urethra. Gentle rubbing/massaging of the penis will cause the suppository to dissolve and the medication is absorbed through the urethra and passes into the penis where it stimulates the relaxation of the muscle in the arteries and increases blood flow to the penis. It takes 15 to 30 minutes for this to occur. Success rates in the clinical studies were noted to be about 65%, however lower rates were noted when it started being used in the real world setting. This drug may be effective in men with vascular disease, diabetes, and following prostate surgery. This is a useful alternative for men who do not want to use self-injections or for men in whom oral medications have failed. Few side effects occur. The most common side effect is penile pain, which can vary from minor to uncomfortable. MUSE use has been associated with lowering of the blood pressure and thus it is recommended that the first time using the MUSE be in the physician's office so that you can be monitored. One cannot use lubricants of any type to help with the insertion of the applicator thus to make it easier to insert you should urinate immediately before using the MUSE system as this will lubricate the urethra. A temporary tourniquet is often helpful in allowing the medication to stay in the erectile tissue a little longer and seems to give a somewhat better response.