Crossref | PubMed | Scopus (35) | Google ScholarSee all References Also, if lower blood pressure level was the primary etiology of ED, all classes of antihypertensive agents should be expected to have relatively similar effects on erectile function because of their efficacy in lowering pressure, which has not been seen.6x6Kloner, RA. Erectile dysfunction and cardiovascular risk factors. Hosp Pract (Off Ed). 2001; 36: 41–44 (49-51.)
The causes of ED are numerous but generally fall into two categories: organic or psychogenic. The organic causes can be subdivied into five categories: vascular, traumatic/postsurgical, neurological, endocrine-induced, and drug-induced. Examples of the psychogenic causes are depression, performance anxiety, and relationship problems. In people with diabetes, the main risk factors are neuropathy, vascular insufficiency, poor glycemic control, hypertension, low testosterone levels, and possibly a history of smoking.
Crossref | PubMed | Scopus (697) | Google ScholarSee all References Subsequent in vitro electrical stimulation of these tissue samples showed decreased neurogenic and endothelium-dependent smooth muscle relaxation in the tissue from the patients with diabetes. These effects persisted even after controlling for smoking and hypertension. Other studies have shown a heightened smooth muscle tone in patients with diabetes mellitus.24x24Christ, GJ, Stone, B, and Melman, A. Age-dependent alterations in the efficacy of phenylephrine-induced contractions in vascular smooth muscle isolated from the corpus cavernosum of impotent men. Can J Physiol Pharmacol. 1991; 69: 909–913
Artery size also explains the onset of ED before occurrence of CAD. Coronary arteries are 3–4 mm in diameter, while the penile artery is 1–2 mm in diameter.17 Endothelial dysfunction and plaque burden in the small arteries may cause symptoms of ED before they affect blood flow in large arteries. Also, an asymptomatic lipid-rich plaque in the coronary arteries carries the risk of rupture that leads to acute coronary syndrome or death, so ED may be predictive of these serious events without warning cardiac symptoms.17
As a primary care doctor, my most important job is to tailor treatment for my patients while still making decisions based on the medical literature. So when patients tell me their treatment is causing undesired side effects—like ED—I work with them to create a plan to treat the condition while also finding a way to relieve those side effects. Fortunately, there are ways to deal with medically induced ED.
Gene therapy has the potential to become a future management option for patients with CAD and ED. Animal studies have been conducted to evaluate the effects of gene therapy. A rat model was studied by Bivalacqua et al. to evaluate the effect of the combination of eNOS gene therapy and sildenafil. This research suggested that erectile response was greater in male rats with diabetes treated with combination eNOS gene therapy and sildenafil, compared with male rats with diabetes treated with eNOS gene therapy or sildenafil alone.76–78
When it comes to scientific development, in Western medicine, an analytic approach is often used to identify and resolve medical challenges. A hypothesis is first derived through general observations of a phenomenon. A research plan is then carefully designed and data collected. Once sufficient data is collected, critical statistical evaluations are done and conclusions are drawn (4). Every aspects of a disease entity are studied from macroscopic to microscopic views, down to the cellular and molecular levels. The deep understanding of the role of cGMP-specific phosphodiesterase type 5 enzymes in ED and the use of phosphodiesterase-5 inhibitors in treatment of ED exemplifies the success of this approach.
Obesity is a strong predictor of ED as it is associated with other risk factors, such as diabetes, hyperlipidaemia and hypertension.4 Obesity increases the risk of ED by 30–90 % and acts as an independent risk factor for CVD. Obese men with ED have greater impairment in endothelial function than non-obese men with ED.5 Moreover, high BMI causes low testosterone levels, which in turn leads to ED, as observed in a prospective trial involving 7,446 participants.50
Physical and emotional stress — whether over-exercising, under-sleeping or just dealing with everyday stressors like work and a busy schedule — causes an increase in “stress hormones,” including cortisol and adrenaline. Stress can lower desire for sex. This is because stress can contribute to fatigue or preoccupation with other tasks. It can also significantly affect blood flow by increasing inflammation.
Age is a critical risk factor for the development of ED and endothelial dysfunction.4,5 ED is the most common condition occurring in middle-aged and older men.5 Kinsey et al. reported that 25 % of 65-year-old men and 75 % of ≥80-year-old men have ED.39 Moreover, ageing also decreases endothelial function, which is responsible for IHD.5 The incidence and severity of ED increases with age (a man aged 70 years is three-times more likely to have ED than a man aged 40 years).40
Since time immemorial, TCM has been adopted by many cultures and is widely practiced in Asian countries despite paucity of level 1 clinical evidence and limited published safety records. TCM is more congruent with Asian values, beliefs and philosophical orientation to health, simple administration, readily available and ease of access or procurement, and general belief that TCM is safer. While Asian males are clearly different from their Western counterparts with respect to biology, culture and beliefs, the practice of TCM appears to be adopted by many Western nations lately. Many men seek TCM to avoid embarrassing visits to physicians and potential side effects of pharmaceutical drugs, or after becoming frustrated with the outcome of modern medicine. Patients are choosing to take more responsibility for their health by exploring a variety of non-pharmaceutical drugs and wellness practices. Furthermore, TCM such as herbal medicine does not address a specific organ system only and is meant to restore and realign the vital energy within the body, which is responsible for ageing, clinical diseases and the deterioration of bodily function; while in Western medicine, each pill is intended for a specific organ/system and that a patient may need a collection of pills to treat multiple comorbidities, rendering modern medicine less attractive to TCM.
Adequate cavernosal arterial inflow is necessary for penile erection. Arterial morphology,28 flow,29 and diameter30 differ between diabetic and nondiabetic populations with ED. BB and STZ-induced diabetic rats exhibit impairment of endothelium-mediated vascular smooth muscle relaxation, and proposed mechanisms include changes in the expression, activity, or post-translational modification of endothelial NOS.31
The authors observe that multiple factors may be involved. In addition to decreased exercise capacity, patients with chronic heart failure have blood vessel and circulation abnormalities that can reduce blood flow into the penis and interfere with the ability to maintain an erection. And erectile dysfunction can be caused or worsened by many of the medications that are commonly prescribed to treat chronic heart failure.
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
Crossref | PubMed | Scopus (174) | Google ScholarSee all References All these men had ED and twice underwent symptom-limited supine bicycle exercise echocardiography 1 hour after taking either sildenafil (50 mg or 100 mg) or placebo. This study found no significant changes in resting heart rate, diastolic blood pressure level, or wall motion score index, and the exercise capacity of the 2 groups was similar. Both groups had similar numbers of patients who experienced dyspnea and/or chest pain, had a positive exercise echocardiographic test, and had exercise-induced wall motion abnormalities. Sildenafil caused a mean decrease of 7 mm Hg in the resting systolic blood pressure level compared with the placebo group. In conclusion, this study showed that in patients with stable coronary artery disease, sildenafil caused no change in symptoms, exercise endurance, or presence/extent of exercise-induced ischemia as measured by exercise echocardiography.
Oral medicines: The best known ED medications are the Big Three: Viagra (sildenafil citrate, made by Pfizer, Inc.), Levitra (vardenafil HCl, made by Bayer and GlaxoSmithKline), and Cialis (tadalafil, made by Eli Lilly). The three are chemically very similar, and all have proven very effective. Because they are effective, convenient, and relatively inexpensive (about nine dollars per pill), these medicines have become the treatment of choice for most men experiencing ED.