May 20, 2011
By Harvey B. Simon, M.D.
Harvard Medical School
Suppose for a moment that you're one of the millions of guys who develop a problem with erections. After putting it off, you finally go see your doctor. You expect to walk out with a prescription for Viagra, perhaps after your doctor checks your testosterone levels with a blood test.
Instead, though, your blood tests are for cholesterol and blood sugar, and the only prescription you're walking out with is for weight loss and exercise.
Time to find a new doctor? Not! In fact, your doc gets kudos for understanding that a man's ability to have an erection is often a barometer of his heart and blood vessel health.
Back to top
Not long ago, patients and their doctors called the problem "impotence." It was viewed as a psychological disorder. Now we know that only 15% of cases are caused by mental factors. So many men now think of erectile dysfunction (ED) as a urological or hormonal problem. It may be but often it's much more.
Even for men who have never had a twinge of chest pain, ED can mean a heart attack is in the wings. We know this from the results of a major American study of 8,063 men age 55 or older. When the study began in 1994, none of them had been diagnosed with heart disease, but 3,816 (47%) had ED and another 2,430 (30%) developed the problem over the next five years. During eight years of careful observation, the men with ED were 1.5 times more likely to develop signs of heart disease than were the men who had normal erectile function.
Back to top
Which Comes First?
Men who complain of ED have a substantial risk of developing heart disease. But are men with heart disease at risk for ED?
To find out, doctors in Italy studied 300 men with chest pain and known heart disease. They diagnosed ED in 47% of the heart patients; in most men, the ED was severe.
Interestingly, almost 70% of the men reported that they developed sexual difficulties an average of more than 3 years before they were diagnosed with heart disease. In fact, it's very common for ED to develop 2 to 4 years before heart trouble appears.
Back to top
Heart Trouble and ED Share Common Risks
ED and heart attacks are as different as night and day. Why, then, do they so often strike together?
The two conditions share common risk factors. For years, doctors have known that advancing age, smoking, abnormal cholesterol levels, hypertension, diabetes, physical inactivity and obesity are major heart disease risk factors. More recently, it's become clear that these same traits also contribute to ED:
Age. According to the Massachusetts Male Aging Study, age is the strongest risk factor for ED. Only 2% of 40-year-olds experience ED but the numbers rises to 25% at age 65, 55% at age 75, and 65% at age 80.
Smoking. Ever the villain, lighting up may prevent a man from "getting it up." According to a Mayo Clinic study, smokers are 1.4 times more likely to develop ED than nonsmokers; the more men smoke, the higher their risk.
Cholesterol. In the Massachusetts Male Aging Study, low levels of HDL ("good") cholesterol were linked to an increased risk of ED. In a California study, high total cholesterol levels predicted ED over 25 years of follow-up, and high cholesterol was the most common ED risk factor.
High blood pressure. A study by 51 health plans covering 28 million Americans reported that men with ED are 38% more likely to have high blood pressure than are men with normal sexual function, even after other chronic diseases are taken into account.
Diabetes. Diabetes can damage nerves and blood vessels. Both are essential for good erections. It's no surprise, then, that men with diabetes are about 3 times more likely to suffer ED than healthy men, and they develop it 10 to 15 years earlier. In all, men with longstanding diabetes severe enough to require treatment have a 50% risk of ED.
Lack of exercise. As exercise, sex is a flop, but regular exercise can help prevent sex from falling flat. According to Harvard's Health Professionals' Follow-up Study, men who exercise for 30 minutes a day are 41% less likely to develop ED than sedentary men.
Obesity. It's a growing problem in America; it's now recognized as an important contributor to many diseases. The Health Professionals' Study is among many that link overweight to ED. For example, a man with a 42-inch waist has a 50% higher risk of ED than a man with a 32-inch waist.
These major risk factors are enough to explain why so many men have both heart disease and ED. But there's more. Elevated levels of C-reactive protein and other inflammatory markers have been linked to heart disease, and new research shows they also predict ED.
Back to top
"NO" Explains It
Heart attacks and ED are both diseases of circulation. But heart patients have cholesterol-laden plaques blocking their coronary arteries. Men with ED don't have plaques in their penile arteries. Still, the two disorders share a common mechanism. The answer is NO not negative thinking but nitric oxide.
All arteries in the heart, the penis and the rest of the body have a thin inner lining of endothelial cells. These cells produce nitric oxide, a tiny chemical that helps keep the artery's lining smooth and healthy. Nitric oxide is important in other ways. It:
- Relaxes the muscle cells in an artery's middle layer, allowing it to widen and increase the flow of blood
- Permits the heart muscle to get more oxygen-rich blood when it's working hard
- Enables a good erection, which requires a six-fold increase in the amount of blood in the penis
- Allows nerve cells involved in desire to "talk" to the arteries of the penis
Doctors can't measure how much nitric oxide the body produces, but they can measure endothelial function with certain tests. Patients with heart disease often have impaired endothelial function and so do many men with ED. That's because the risk factors that contribute to both problems cause endothelial damage.
Back to top
Reducing Your Risk for ED
Men can protect themselves from heart disease by:
- Stopping smoking
- Improving their cholesterol levels
- Lowering high blood pressure
- Controling their diabetes
Will these actions also help reduce the risk for ED? The evidence suggests they may help. Separate studies report improved erectile function in obese men who exercise and lose weight, in diabetic men who achieve good blood sugar control, in smokers who quit, and in men who lower their elevated cholesterol levels. Needless to say, medications that improve cholesterol, blood pressure, and blood sugar are also extremely beneficial.
Back to top
Heart disease and ED are both distressingly common in 21st-century America. Although the two disorders seem worlds apart, they share many risk factors and often strike the same men.
Nearly 40% of all deaths in the United States are attributed to heart disease. And in half of all heart deaths in men there was no previously diagnosed heart disease. The disease was "silent."
Doctors are wrestling with ways to diagnose silent heart disease. For now, the best approach is to:
- Take a careful look at a man's risk factors
- Look for subtle or unusual symptoms of heart disease
- Consider test such as stress tests, nuclear scans, CT scans or even angiography, if problems seem likely.
That's where ED come in: Up to 40% of men who complain of ED have silent or undiagnosed heart disease. So every man with ED deserves a careful evaluation of his heart health, including heart disease risk factors.
The more severe the ED and the earlier it develops, the greater the risk of heart trouble. In addition, all patients should learn how to reduce their risks for heart disease and know what the warning signs are.
At one time, men with impotence were referred to psychologists, urologists and endocrinologists. In the Viagra era, primary care physicians provide most of the treatment, but as our understanding of ED increases, cardiologists are likely to get into the act.
ED stands for erectile dysfunction and endothelial dysfunction. It should also trigger careful medical and cardiac diagnosis and treatment so it won't also stand for early death.
Back to top
Harvey B. Simon, M.D. is an Associate Professor of Medicine at Harvard Medical School and a member of the Health Sciences Technology Faculty at Massachusetts Institute of Technology. He is the founding editor of the Harvard Men's Health Watch newsletter and author of six consumer health books, including The Harvard Medical School Guide to Men's Health (Simon and Schuster, 2002) and The No Sweat Exercise Plan, Lose Weight, Get Healthy and Live Longer (McGraw-Hill, 2006). Dr. Simon practices at the Massachusetts General Hospital; he received the London Prize for Excellence in Teaching from Harvard and MIT.