The vascular endothelium has an important role in angiogenesis and vascular repair by producing regulatory substances, including NO, prostaglandin, endothelins, prostacyclin and angiotensin II. These regulatory factors regulate the blood flow to the penis by controlling smooth muscle contractility and subsequent vasoconstriction and vasodilatation. Generally, in erectile tissue, increased blood flow through the cavernosal artery increases shear stress and produces NO, which further relaxes the vascular smooth muscles and increases blood flow in the corpora cavernosa.54 These events cause penile erection. However, in ED, endothelial NO synthesis is reduced and there is increased endothelial cell death (Figure 2).55
Erectile dysfunction is defined as the inability to attain or maintain a penile erection sufficient for satisfactory sexual performance. Cases of ED may be classified as predominantly organic in nature, predominantly psychogenic, or mixed. Usual organic aetiologies are vasculogenic, hormonal, and neurogenic. Owing to the relationship of vasculogenic ED with CVD, it is important to distinguish men with predominantly vasculogenic ED from those with predominantly psychogenic ED or non-vasculogenic organic ED.
Basaria S,  Coviello AD,  Travison TG,  Storer TW,  Farwell WR,  Jette AM,  Eder R,  Tennstedt S,  Ulloor J,  Zhang A,  Choong K,  Lakshman KM,  Mazer NA,  Miciek R,  Krasnoff J,  Elmi A,  Knapp PE,  Brooks B,  Appleman E,  Aggarwal S,  Bhasin G,  Hede-Brierley L,  Bhatia A,  Collins L,  LeBrasseur N,  Fiore LD,  Bhasin S. Adverse events associated with testosterone administration, N Engl J Med , 2010, vol. 36 (pg. 109-122)https://doi.org/10.1056/NEJMoa1000485
• Blood Vessels: Diabetes damages blood vessels, especially the smallest blood vessels such as those in the penis. Diabetes can also cause heart disease and other circulatory problems. Proper blood flow is absolutely crucial to achieving erection. “Erection is a hydraulic phenomenon that occurs involuntarily,” says Arturo Rolla, MD, of Harvard University School of Medicine. “Nobody can will an erection!” Anything that limits or impairs blood flow can interfere with the ability to achieve an erection, no matter how strong one’s sexual desire.
The drugs come in several strengths. Most men should start with a low to moderate dose. The dose can be adjusted depending on the results. Men with potential problems should always start with the lowest dose. Every man should avoid consuming alcohol before taking these drugs. Men who do not respond to a full dose on two or three different occasions should try other treatments.
Most of the time, ED is the first symptom of poor cardiovascular health. Hypertension oftentimes doesn’t manifest outward symptoms of heart disease.  Some men go undiagnosed with high blood pressure for a long time. It can be troublesome for many men who feel uncomfortable discussing ED with their health providers. Many fail to seek medical advice and suffer from progressive worsening of their cardiovascular problems before deciding to undergo treatment.

Evaluation of functional capacity is the mainstay for the management of patients with ED.30 However, it should be kept in mind that in men with heart failure sexual activity may affect the heart differently from physical activity of similar METS due to differences in psychological anticipation and sympathetic activation.30,49 Cardiac echocardiography may offer valuable information for left ventricular performance and valvular function. For risk categories of heart failure patients and their management, please refer to Table 3 and Figure 5.


How common is impotence? According to findings from several studies, including “The Massachusetts Male Aging Study,” overall prevalence for men between 40–70 years old is around 52 percent (or around 30 percent of all men between 18–60 years old). That’s right — nearly half of all men over 40 experience erectile dysfunction symptoms at some point. Not surprisingly, research demonstrates that impotence is increasingly prevalent with age. Around 40 percent of men in their 40s experience sexual dysfunction. Up to 70 percent of men in their 70s experience ED. (1) Every year more than 617,000 new cases of impotence occur in the United States alone.


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.
There are a number of reasons a man may not achieve the desired result from an oral erectile dysfunction drug. In some cases, a man may experience drug side effects severe enough to outweigh any potential benefit of taking the drug. Possible side effects of these drugs include headache, facial flushing, nasal congestion, and transient abnormal vision. (In October 2007, the FDA added a warning about sudden hearing loss to the package labels of oral erectile dysfunction drugs. While it’s not absolutely clear that the drugs can cause sudden hearing loss, a number of cases have been reported in men within hours or days of taking one of the drugs.)
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