What Is Coronary Heart Disease?
Coronary heart disease (CHD)—also sometimes called coronary artery disease—is the most common form of cardiovascular disease, a group of disorders that involve the heart and blood vessels. CHD is a narrowing of the coronary arteries, the vessels that supply oxygenated blood (fuel) to the heart muscle.
Physical activity increases the oxygen needs of the body, and the heart responds to the greater demand by pumping blood more vigorously and more quickly, which in turn increases the oxygen needs of the heart muscle. In CHD, narrowed coronary arteries limit the supply of oxygenated blood to portions of the heart muscle. If narrowing is not extensive, difficulties may occur only during physical exertion, when the narrowed arteries are unable to meet the increased oxygen requirements of the heart. However, as the disease worsens, the narrowed arteries may starve the heart muscle of oxygen during periods of normal activity, or even at rest.
When portions of the heart muscle do not receive sufficient flow, symptoms such as shortness of breath, marked fatigue or chest pains may occur. Sometimes the symptoms are “atypical”, and these may include complaints such as shoulder or arm discomfort with increased exertion, discomfort in the upper abdomen of neck on exertion, or even passing out. Such symptoms should not be ignored, especially in people at risk of heart disease by virtue of strong family history, habitual use of certain drugs (such as cocaine), and age (all people over the age of 40).
Nor should symptoms, typical or atypical, be ignored in women. It is important to note that although younger women (under age 40) are generally at much lower risk for CHD than men, the presence of diabetes increases a woman's risk to the same level as a nondiabetic man of the same age—and young diabetic women can and do have heart attacks. Use of tobacco in young diabetic women increases the risk of CHD, stroke, and blood clots. A woman's risk for CHD also rises after her menstrual periods stop, such that by age 65 women develop CHD at the same rate as men.
Coronary heart disease is generally due to the buildup of plaques in the arterial walls, a process known as atherosclerosis. Plaques are composed of cholesterol-rich fatty deposits, collagen, other proteins, and excess smooth muscle cells. Atherosclerosis, which usually progresses very gradually over a lifetime, thickens and narrows the arterial walls, impeding the flow of blood. Blood clots form more easily on arterial walls roughened by plaque deposits. The clots may block the narrowed coronary artery completely and cause a heart attack. Arteries may also narrow suddenly as a result of an arterial spasm. (Spasms are most commonly triggered by smoking.)
Symptoms of CHD usually develop insidiously. In the early stages of the disease, there are generally no symptoms. As the disease progresses, chest pain (angina pectoris) may develop during periods of physical activity or emotional stress, because the narrowed arteries cannot supply the heart with the increased amount of blood and oxygen necessary at those times. Angina usually subsides quickly with rest, but over time, symptoms arise with less exertion, occur more frequently, have greater duration, and may eventually lead to a heart attack. However, in a third of CHD cases, angina never develops, and a heart attack can occur suddenly with no prior warning.
Although CHD can be a life-threatening condition, the outcome of the disease in many ways is up to the patient. The difference between survival and death is often dependent upon rapidly getting to the hospital if the frequency, duration, or severity of symptoms increases, or to a doctor so that a proper diagnosis can be made and treatment can be started. Damage to the arteries can be slowed or halted with lifestyle changes, including smoking cessation, dietary modifications, and regular exercise, or by medications to lower blood pressure and cholesterol levels. Additional goals of treatment, which may involve medication and sometimes surgery, are to relieve symptoms, improve the circulation, and prolong life.
Who Gets Coronary Heart Disease?
More than 16 million Americans suffer from CHD. Despite significant declines in the rate of CHD in recent decades, it remains the leading cause of death for both men and women in the United States. Each year about 785,000 Americans will have a first heart attack, once of the serious complications caused by CHD. Other complications, which affect millions of Americans, include angina (chest pain), heart failure, and arrhythmias, most especially atrial fibrillation.
About half of Americans have at least one of three key risk factors for CHD: high blood pressure, high cholesterol, and smoking.
- No symptoms in the early stages of coronary heart disease.
- Chest pain (angina), or milder pressure, tightness, squeezing, burning, aching, or heaviness in the chest, lasting from 30 seconds to five minutes. The pain or discomfort is usually located in the center of the chest just under the breastbone, and may radiate down the arm (usually the left), up into the neck, or along the jaw line. The pain is generally brought on by exertion or stress and stops with rest. The amount of exertion required to produce angina is reproducible and predictable.
- A sudden increase in the severity of angina, or angina at rest, is a sign of unstable angina, which requires immediate medical attention because a heart attack may shortly occur.
- Crushing persistent chest pain—possibly with pain radiating to the arms, back, neck, or jaw— are common symptoms of a heart attack.
- Smoking promotes the development of plaque in the arteries. Also, by increasing the amount of carbon monoxide in the bloodstream and decreasing the amount of oxygen available to the heart, smoking increases the likelihood of angina.
- High blood cholesterol levels lead to coronary heart disease. LDL (low-density lipoprotein) enters the lining of the arterial walls where, after being chemically altered, its cholesterol can be incorporated into plaque.
- High blood pressure predisposes one to CHD.
- People with diabetes mellitus are at greater risk for atherosclerosis.
- Obesity may promote atherosclerosis.
- Lack of exercise (a sedentary lifestyle) may encourage atherosclerosis.
- Men are at greater risk than women for coronary heart disease, although the risk for postmenopausal women approaches that of men as estrogen production decreases with menopause.
- Women over age 35 who take oral contraceptives and smoke cigarettes have a higher risk of atherosclerosis.
- A family history of premature heart attacks (before age 55) is associated with greater CHD risk.
- A spasm of the muscular layer of the arterial walls may cause an artery to contract and produce angina. Spasms may be induced by smoking, extreme emotional stress, or exposure to cold air.
- In addition to patient history and physical examination, an electrocardiogram (ECG) may be performed to measure changes in the electrical activity of the heart resulting from abnormalities in the flow of blood or a prior heart attack.
- If you suffer a heart attack, diagnosis will often be made upon examination by a doctor or emergency medical technician.
- Chest x-rays.
- Blood tests.
- Exercise stress test. Blood pressure, heartbeat, and breathing rates are measured by electrocardiogram (ECG) while you walk on a treadmill. If you cannot exercise adequately, a medication may be injected instead.
- An injection of a radioisotope such as thallium may be given after an exercise test to gauge blood flow to the heart.
- An echocardiogram, which uses ultrasound waves to create moving images of the heart, may be performed.
- A coronary angiography is performed to determine the presence of narrowing of the coronary arteries. In this procedure a tiny catheter is inserted into an artery of a leg or arm and threaded up into the coronary arteries. A contrast material is then injected from the end of the catheter into the coronary arteries, and x-rays are taken.
- A less invasive alternative is computed tomography (CT) angiography. In this test, a CT scanner takes highly detailed computerized images of the moving heart and large blood vessels that clearly show the extent and nature of plaque formation.
- Magnetic resonance imaging (MRI) can also be used to show images of the heart and arteries. It is not invasive and, in contrast to CT angiography, it does not expose you to radiation.
- Emergency treatment and immediate hospitalization is necessary if unstable angina or a heart attack has occurred.
- For non-emergency treatment of CHD, you’ll need to adopt a heart-healthy lifestyle to manage your condition, in addition to any medication your doctor prescribes. Follow prevention tips for a heart-healthy lifestyle, including a low-fat diet and regular physical exercise. Avoid excessive alcohol consumption, nasal decongestants, and diet pills, all of which may raise blood pressure.
- Therapy with a cholesterol-lowering statin drug is recommended for anyone who has been diagnosed with CHD.
- Most people with CHD are prescribed a daily low-dose aspirin to help prevent blood clots. But daily aspirin can cause gastrointestinal bleeding and other side effects, so you will need to discuss this with your doctor.
- To relieve or prevent symptoms of angina, rapidly acting nitrates, such as nitroglycerin, or longer-acting nitrates like isosorbide dinitrate may be prescribed to dilate blood vessels. A fast-acting nitroglycerin tablet placed under the tongue (sublingually) at the onset of an angina attack usually relieves the pain within minutes. Sublingual nitroglycerin may also be taken just prior to activities that commonly provoke angina. However, for any given angina attack, you should not take more than three nitroglycerin tablets at five-minute intervals—pain lasting longer than this may signal a heart attack. Fast-acting nitrolygcerin is also available in spray form, which is sprayed on or under the tongue.
- Longer-acting nitrates provide protection against angina symptoms for longer periods. It can be supplied in controlled-release capsules, skin patches, and ointments. In patients with unstable angina, intravenous nitrates may be administered in patients with unstable angina.
- Beta-blockers such as propranolol or metoprolol are prescribed to reduce the heart’s oxygen demand by slowing the heart rate and lowering blood pressure.
- ACE inhibitors such as enalapril may be prescribed to reduce blood pressure and dilate blood vessels.
- Calcium channel blockers such as verapamil, diltiazem, or nifedipine may be prescribed to reduce the heart’s oxygen demands and to increase coronary blood flow.
- Anticoagulants such as heparin or warfarin will be administered to reduce the risk of blood clots in patients with unstable angina.
- Vasodilators such as captopril, enalapril, or hydralazine may be prescribed to expand blood vessels, thus reducing blood pressure and facilitating blood flow.
- An obstructed coronary artery may be opened with percutaneous transluminal coronary angioplasty (PTCA), also called an angioplasty. In this procedure a small balloon is inserted into the circulatory system via a catheter and guided to the site of an arterial blockage. The balloon is then inflated, compressing the plaque, widening the passageway, and improving blood flow. Often, a stent is then placed in the artery to help keep it open. PTCA usually requires a hospital stay of only a few days.
- Coronary bypass surgery may be performed to improve blood flow to the heart. A mammary artery or a vein taken from the leg is grafted onto the damaged coronary artery to circumvent a narrowed or blocked portion.
- A heart transplant may be advised in severe cases in which the heart muscle has been badly damaged. The survival rate for heart transplant is 80% after one year and 63% after four years.
- Don’t smoke.
- Eat a diet low in saturated fat, dietary cholesterol, and salt—and that contains plenty of fruits, vegetables, and whole grains.
- Pursue a program of moderate, aerobic exercise for a minimum of 30 minutes, at least three days a week. People over age 50 who have led a sedentary lifestyle should check with a doctor before beginning an exercise program.
- Lose weight if you are overweight.
- See your doctor regularly to evaluate your CHD risk factors—including blood pressure, cholesterol, diabetes, and family history of CHD. If you are considered at sufficiently high risk for CHD, current guidelines recommend that you begin statin therapy. Your doctor will also address the need for treating any other risk factors.
- Your doctor may advise you to take a low dose of aspirin every day if you are at high risk for CHD. Aspirin reduces the tendency for the blood to clot, thereby decreasing the risk of heart attack. However, such a regimen should only be initiated under a doctor’s recommendation.
When To Call Your Doctor
- Emergency: Call an ambulance if you experience crushing chest pain, with or without nausea, vomiting, profuse sweating, shortness of breath, weakness, or intense feelings of dread.
- Emergency: Call an ambulance if chest pain from previously diagnosed angina does not subside after 10 to 15 minutes.
- Emergency: Call an ambulance the first time you experience intense chest pain.
- See your doctor if attacks of previously diagnosed angina become more frequent or more severe or occur at rest.
Reviewed by Larry A. Weinrauch, M.D., Assistant Professor of Medicine, Harvard Medical School, Cardiovascular Disease and Clinical Outcomes Research, Watertown, MA. Review provided by VeriMed Healthcare Network.