Penile erection is largely a vascular process, and the penile endothelium and smooth muscle tissue are very sensitive to functional and structural changes. Vasculogenic ED results from an impairment of endothelial dependent or independent smooth muscle relaxation (functional vascular ED, initial stages), occlusion of the cavernosal arteries by atherosclerosis (structural vascular ED, late stages), or a combination of these.3 Current data support a complex interplay between endothelial dysfunction, subclinical inflammation, and androgen deficiency (Figure 1). The relationship between ED and CAD at the clinical level is supported by this common pathophysiological basis. The ‘artery size’ hypothesis explains why patients with CAD frequently report ED before CAD detection.10 According to this hypothesis, for a given atherosclerotic burden, the smaller penile arteries suffer obstruction earlier than the larger coronary arteries (Figure 2). The same concept holds also true in the case of non-obstructing atherosclerosis: since the smaller penile artery have a greater endothelial surface and erection requires a large degree of vasodilation to occur when compared with arteries in other organs, the same degree of endothelial dysfunction will be symptomatic in these smaller vessels but subclinical in the larger ones (i.e. coronaries). In the same context, accelerated arterial ageing (as indicated by increased arterial stiffening that also affects large arteries of ED patients) may be a common background.11,12 Erectile dysfunction is associated with an incremental inflammatory and endothelial-pro-thrombotic activation.13 Interestingly, this activation is equal to that found in CAD patients with no ED, while when these two conditions are combined the burden is additive. Androgen deficiency may be also implicated in the common pathogenetic pathways of ED and CVD; however, this warrants further substantiation.2
Perk J,  De Backer G,  Gohlke H,  Graham I,  Reiner Z,  Verschuren WM,  Albus C,  Benlian P,  Boysen G,  Cifkova R,  Deaton C,  Ebrahim S,  Fisher M,  Germano G,  Hobbs R,  Hoes A,  Karadeniz S,  Mezzani A,  Prescott E,  Ryden L,  Scherer M,  Syvänne M,  Scholte Op Reimer WJ,  Vrints C,  Wood D,  Zamorano JL,  Zannad F. European Guidelines on cardiovascular disease prevention in clinical practice (version 2012). The Fifth Joint Task Force of the European Society of Cardiology and Other Societies on Cardiovascular Disease Prevention in Clinical Practice (constituted by representatives of nine societies and by invited experts). Developed with the special contribution of the European Association for Cardiovascular Prevention & Rehabilitation (EACPR), Eur Heart J , 2012, vol. 33 (pg. 1635-1701)https://doi.org/10.1093/eurheartj/ehs092
Three FDA-approved oral medications, sildenafil, tadalafil, and vardenafil are available. These drugs are phosphodiesterase type 5 (PDE-5) inhibitors that can prolong levels of cGMP in tissue allowing improved smooth muscle relaxation, thus facilitating an erection. PDE-5 inhibitor drugs are effective in 56-63% of diabetic men with ED. More stringent glycemic control can improve these results. Men with testosterone deficiency may benefit from a combination of oral ED medication and testosterone supplementation.
One study the authors reviewed measured these changes in middle-aged men with and without coronary artery disease. This study found that the peak heart rate during intercourse was lower than heart rates measured during the patients' normal daily activities. The study participants' peak oxygen consumption levels during intercourse were moderate -- comparable to their oxygen consumption levels during moderate activities such as walking on level ground at 3 to 4 miles per hour, climbing stairs slowly or doing general housework such as vacuuming.

Abstract | Full Text | Full Text PDF | PubMed | Scopus (95) | Google ScholarSee all References When used in combination with NO-donor medications such as nitroglycerin, the modest blood pressure effects of sildenafil are potentiated, resulting in a significant decrease in systolic (21-55 mm Hg) and diastolic (up to 26 mm Hg) blood pressure levels, as well as vasodilatory symptoms such as headache, light-headedness, and nausea.10x10Kloner, RA and Zusman, RM. Cardiovascular effects of sildenafil citrate and recommendations for its use. Am J Cardiol. 1999; 84: 11N–17N
De Berardis et al.6 assessed general HRQOL in 1,460 men with type 2 diabetes in Italy. Within the cohort, 615 men reported that they never experienced ED, 346 stated that they occasionally had ED, and 449 stated that they frequently had ED. They then compared general HRQOL among these three groups. In the univariate analysis, they found that degree of ED negatively correlated with general HRQOL scores in all eight domains of the Short Form 36 (SF-36) health survey questionnaire. In the multivariate analysis, ED was not independently associated with physical function, bodily pain, or role limitations due to physical problem scores but was independently associated with general HRQOL outcomes in the domains of general health (P = 0.004), role limitations due to emotional problems (P = 0.001), vitality (P = 0.001), social functioning (P = 0.01), and overall mental health (P = 0.002). Another study examining the effect of ED on quality of life in hemodialysis patients, more than half of whom had diabetes, also noted an independent, negative effect of ED on the emotional domains of general HRQOL.39
Another oral treatment that has been used with very little success is yohimbine (Yocon, Yohimex). This is an alpha 2 adrenergic receptor blocker that increases cholinergic and decreases adrenergic tone. It stimulates the mid-brain and increases libido. Optimal results occur when used in men with psychogenic ED. Side effects include anxiety and insomnia.
Crossref | PubMed | Google ScholarSee all References These hormonal findings were supported by a study of 1132 men aged 30 to 79 years that found an inverse relationship between blood pressure and serum testosterone levels.32x32Khaw, KT and Barrett-Connor, E. Blood pressure and endogenous testosterone in men: an inverse relationship. J Hypertens. 1988; 6: 329–332
The initial step in evaluating ED is a thorough sexual history and physical exam. The history can help in distinguishing between the primary and psychogenic causes. It is important to explore the onset, progression, and duration of the problem. If a man gives a history of “no sexual problems until one night,” the problem is most likely related to performance anxiety, disaffection, or an emotional problem. Aside from these causes, only radical prostatectomy or other overt genital tract trauma causes a sudden loss of male sexual function.
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.
ED can be caused by many things. The most common causes in men with diabetes are problems related to blood vessel– and nerve-related complications. Sometimes, though rarely, ED can be caused by a hormonal imbalance. Depression can also cause ED, as can stress and excessive worrying about sexual performance. Certain medications can cause temporary ED.
Diabetes is known to sabotage two body parts that provide essential components of an erection: nerves and blood vessels. Studies suggest that diabetic nerve damage (neuropathy) is the most important risk factor for ED in people with diabetes. If pelvic nerves that trigger penis muscles to relax are impaired, there may be a break in the chain between brain and penis, disrupting erection. Some researchers suspect that an inadequate supply of oxygen to the nerves causes this damage.
However, population-based studies of ED in prostate cancer survivors also document that ED has a negative effect on general health. Penson, et al.36 studied HRQOL in 2,306 prostate cancer survivors 2 years after their diagnosis. They noted that men with ED (defined as erections that were insufficient for sexual intercourse) had significantly worse general HRQOL when compared to prostate cancer survivors who were potent. Importantly, this association remained in a multivariate analysis that controlled for 31 other potential confounding variables. Finally, this association was noted in both the physical and mental domains of general quality of life, indicating that ED has a much broader effect on quality of life than one might expect.
Abstract | Full Text | Full Text PDF | PubMed | Scopus (56) | Google ScholarSee all References Cardiologists use METs of oxygen consumption to compare the energy expenditure of different forms of activity.51x51DeBusk, R, Drory, Y, Goldstein, I et al. Management of sexual dysfunction in patients with cardiovascular disease: recommendations of the Princeton Consensus Panel. Am J Cardiol. 2000; 86: 62F–68F

Crossref | PubMed | Scopus (47) | Google ScholarSee all References Because of this perceived increase in risk, many couples are concerned about resuming sexual activity in the setting of cardiac disease. A study that monitored male patients after coronary artery bypass grafting found that 17% of patients and 35% of their partners were afraid of resuming sexual activity.1x1Muller, JE. Sexual activity as a trigger for cardiovascular events: what is the risk?. Am J Cardiol. 1999; 84: 2N–5N


Penile arterial supply (top) and venous drainage (middle), longitudinal views. Bottom, Transverse and longitudinal views of venous return. From Lue TF. Physiology of penile erection and pathophysiology of erectile dysfunction and priapism. In: Walsh PC, Retik AB, Vaughan ED Jr, Wein AJ, eds. Campbell's Urology. Vol 2. 7th ed. Philadelphia, Pa: WB Saunders Co; 1998:1157-1179. With permission from Elsevier.

ED can be caused by many things. The most common causes in men with diabetes are problems related to blood vessel– and nerve-related complications. Sometimes, though rarely, ED can be caused by a hormonal imbalance. Depression can also cause ED, as can stress and excessive worrying about sexual performance. Certain medications can cause temporary ED.
Abstract | Full Text | Full Text PDF | PubMed | Scopus (95) | Google ScholarSee all References Sildenafil is taken orally 1 hour before anticipated sexual intercourse and enhances the normal response to sexual stimulation; however, it has no effect on erections in the absence of stimulation.10x10Kloner, RA and Zusman, RM. Cardiovascular effects of sildenafil citrate and recommendations for its use. Am J Cardiol. 1999; 84: 11N–17N

Whereas management of sexual dysfunction in previously untreated hypertensive patients can be a challenging procedure, confronting the same clinical condition in individuals under antihypertensive regime can be even more demanding. In such cases there will always be a question hovering over physicians head. Is hypertension per se, antihypertensive medication or both, the causative factors provoking sexual dysfunction[15]?


After adjusting for cardiovascular risk factors including diabetes, heart failure and stroke, those taking PDE5 inhibitors were found to be markedly less likely to die than those taking alprostadil or no erectile dysfunction drugs. Filling more prescriptions for PDE5 inhibitors appeared to be associated with a greater benefit, although Andersson said that trend should be interpreted with caution because the study was not large enough for a definitive dose-response analysis.

PubMed | Google ScholarSee all References In a double-blind, placebo-controlled study, sildenafil was effective in patients with diabetes mellitus.58x58Rendell, MS, Rajfer, J, Wicker, PA, Smith, MD, and Sildenafil Diabetes Study Group. Sildenafil for treatment of erectile dysfunction in men with diabetes: a randomized controlled trial. JAMA. 1999; 281: 421–426
If your doctor says it's OK, you may be able to stop taking blood pressure medications temporarily to see if your sex life improves. To make sure your blood pressure remains within a safe range, you may need frequent blood pressure readings while you're not taking the blood pressure lowering medication that may be causing your sexual difficulties. This can be done with a home blood pressure monitoring device for convenience.
Despite physician’s inexperience and patient’s reluctance to disclose sexual dysfunction problems, attempts to estimate the magnitude of this clinical condition have predicted that over 150 million men worldwide experience some degree of erectile dysfunction. Several studies have demonstrated a wide range regarding the prevalence of erectile dysfunction, which is even higher in patients with essential hypertension where the relative risk is approximately two times higher than in normotensive individuals[6-11]. The etiology can be found in the structural and functional abnormalities of the penile arteries induced by high blood pressure. Smooth muscle hypertrophy, stenotic lesions due to atherosclerosis and impaired blood flow are among the prominent structural alterations whereas endothelial dysfunction and the defective nitric oxide-induced vasodilatory mechanism belong to the main functional abnormalities induced by increased blood pressure[12,13]. As a matter of fact, sexual dysfunction is encountered more frequently that it is indeed believed underlining the need for a more proper and concrete assessment.

The pathophysiological basis for the predictive ability of ED has been discussed above. It should be emphasized, however, that ED should not only be viewed as a manifestation of obstructive CAD that could be identified by ischaemia revealing tests. Owing to the inflammatory and pro-thrombotic activation of the disease,13 it should also be regarded as an early warning sign of an imminent acute event (mainly acute myocardial infarction)22 due to the rupture of a subclinical plaque, and thus identification of the risk should ideally include plaque vulnerability tests. Finally, an issue that has important clinical implications is by how long the clinical manifestation of ED precedes the clinical manifestation of CAD. According to studies, men with ED and no cardiac symptoms have an increased incidence of experiencing a cardiac event, both acute and chronic, in the ensuing 2–5 years, thus providing a ‘window of opportunity’ for risk reduction management in these patients.2
Erectile dysfunction is frequent in patients with established CAD with prevalence rates ranging between 47 and 75% in studies.2,4,14 The AssoCiatiOn Between eRectile dysfunction and coronary Artery disease (COBRA) trial tested the hypothesis that the ED rate differs in CAD patients according to the clinical presentation (acute vs. chronic coronary syndromes) and the extent of vessel involvement (one vs. two to three vessel disease)15 (Figure 3). The overall ED prevalence in CAD patients was 47%, whereas in the normal coronary angiography group the ED rate was 24%. When separately considered, the ED rate was 22% in patients with acute coronary syndromes (ACS) and one-vessel disease and 55 and 65% in patients with ACS and multi-vessel disease and with chronic coronary syndrome, respectively. The study also showed that both severity (IIEF <10) and duration (>24 months) of ED were predictive of severe coronary involvement at angiography. This study offers pathophysiological and mechanistic explanations related to the clinical setting. In patients with multi-vessel disease, regardless of the clinical presentation, the advanced coronary and systemic atherosclerosis is the reason for the high rate of ED. However, in the setting of acute myocardial infarction with one-vessel disease, ED is far less frequent because the atherosclerotic burden is modest (i.e. abrupt occlusion of a single non-obstructing plaque in the absence of extensive atherosclerosis) in both the coronary and penile circulations.15,16
A sexually competent male must have a series of events occur and multiple mechanisms intact for normal erectile function. He must 1) have desire for his sexual partner (libido), 2) be able to divert blood from the iliac artery into the corpora cavernosae to achieve penile tumescence and rigidity (erection) adequate for penetration, 3) discharge sperm and prostatic/seminal fluid through his urethra (ejaculation), and 4) experience a sense of pleasure (orgasm). A man is considered to have ED if he cannot achieve or sustain an erection of sufficient rigidity for sexual intercourse. Most men, at one time or another during their life, experience periodic or isolated sexual failures. However, the term “impotent” is reserved for those men who experience erectile failure during attempted intercourse more than 75% of the time.

The primary complication of the surgical implantation is postoperative infection, which occurs in about 8% of cases involving diabetes. This infection can be difficult to treat and may require the removal of the device, although this occurs <3% of the time. The infection can also cause penile erosion, reduced penile sensation, and auto-inflation. Glycemic control should be optimized several weeks before surgery. Once a patient has surgery, none of the oral agents or vacuum devices will work because of the destroyed penile architecture.
4. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Erectile dysfunction (updated Nov 2015). https://www.niddk.nih.gov/health-information/health-topics/urologic-disease/erectile-dysfunction/Pages/facts.aspx (accessed Nov 2016). myDr myDr provides comprehensive Australian health and medical information, images and tools covering symptoms, diseases, tests, medicines and treatments, and nutrition and fitness.Related ArticlesImpotence causesFind out the physical and psychological causes of impotence, also called erectile dysfunction or ED.Erectile dysfunction: visiting your doctorFind out what questions a doctor may ask when discussing erectile dysfunction (ED, or impotence8 Surprising causes of erectile dysfunctionOccasional erectile dysfunction is not uncommon, but if it's persistent, erectile dysfunction caAdvertisement
Intracavernosal and intraurethral injections are second-line therapy for patients with ED. Alprostadil is the agent most commonly used for intracavernosal injections. The main adverse effects of intracavernosal injections are painful erection, priapism and development of scarring at the injection site.73 Alprostadil is also available as a topical cream in patients who cannot tolerate injections.75
Inflatable prostheses are complex mechanical devices that imitate the natural process of erection. Parts are inserted surgically into the penis and scrotum, and activated by squeezing. When erection is no longer desired, a valve on the pump is pressed, and the penis becomes flaccid. Self-contained single-unit prostheses are similar to the inflatable types, but more compact. The entire device is implanted into the penis. When erection is desired, the unit is activated by either squeezing or bending, depending on which of the two types of self-contained prostheses is used.
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