An Introduction to Coronary Heart Disease
Some 7 million Americans suffer from coronary heart disease (CHD), the most common form of heart disease. This type of heart disease is caused by a narrowing of the coronary arteries that feed the heart.
Many deaths caused by CHD could be prevented because CHD is related to certain aspects of lifestyle. Risk factors for CHD include high blood pressure, high blood cholesterol, smoking, obesity, and physical inactivity--all of which can be controlled. Although medical treatments for heart disease have come a long way, controlling risk factors remains the key to preventing illness and death from CHD.
Who is at risk for CHD?
Risk factors are conditions that increase your risk of developing heart disease. Some can be changed and some cannot. Although these factors each increase the risk of CHD, they do not describe all the causes of coronary heart disease; even with none of these risk factors, you might still develop CHD.
- High blood pressure
- High blood cholesterol
- Physical inactivity
- Heredity (family history of CHD)
What is Coronary Heart Disease
Like any muscle, the heart needs a constant supply of oxygen and nutrients that are carried to it by the blood in the coronary arteries. When the coronary arteries become narrowed or clogged and cannot supply enough blood to the heart, the result is CHD. If not enough oxygen-carrying blood reaches the heart, the heart may respond with pain called angina. The pain is usually felt in the chest or sometimes in the left arm and shoulder. (However, the same inadequate blood supply may cause no symptoms, a condition called silent angina.)
When the blood supply is cut off completely, the result is a heart attack. The part of the heart that does not receive oxygen begins to die, and some of the heart muscle may be permanently damaged.
What causes CHD?
CHD is caused by a thickening of the inside walls of the coronary arteries. This thickening, called atherosclerosis, narrows the space through which blood can flow, decreasing and sometimes completely cutting off the supply of oxygen and nutrients to the heart. Atherosclerosis usually occurs when a person has high levels of cholesterol, a fat-like substance, in the blood. Cholesterol and fat, circulating in the blood, build up on the walls of the arteries. The buildup narrows the arteries and can slow or block the flow of blood. When the level of cholesterol in the blood is high, there is a greater chance that it will be deposited onto the artery walls. This process begins in most people during childhood and the teenage years, and worsens as they get older.
In addition to high blood cholesterol, high blood pressure and smoking also contribute to CHD. On the average, each of these doubles your chance of developing heart disease. Therefore, a person who has all three risk factors is eight times more likely to develop heart disease than someone who has none. Obesity and physical inactivity are other factors that can lead to CHD. Overweight increases the likelihood of developing high blood cholesterol and high blood pressure, and physical inactivity increases the risk of heart attack. Regular exercise, good nutrition, and smoking cessation are key to controlling the risk factors for CHD.
What are the symptoms of CHD?
Chest pain (angina) or shortness of breath may be the earliest signs of CHD. A person may feel heaviness, tightness, pain, burning, pressure, or squeezing, usually behind the breastbone but sometimes also in the arms, neck, or jaws. These signs usually bring the patient to a doctor for the first time. Nevertheless, some people have heart attacks without ever having any of these symptoms.
It is important to know that there is a wide range of severity for CHD. Some people have no symptoms at all, some have mild intermittent chest pain, and some have more pronounced and steady pain. Still others have CHD that is severe enough to make normal everyday activities difficult.
Because CHD varies so much from one person to another, the way a doctor diagnoses and treats CHD will also vary a lot. The following descriptions are general guidelines to some tests and treatments that may or may not be used, depending on the individual case.
Treatment of Coronary Heart Disease
CHD is treated in a number of ways, depending on the seriousness of the disease. For many people, CHD is managed with lifestyle changes and medications. Others with severe CHD may need surgery. In any case, once CHD develops, it requires lifelong management.
What kind of lifestyle changes can help a person with CHD?
Although great advances have been made in treating CHD, changing one's habits remains the single most effective way to stop the disease from progressing.
If you know that you have CHD, changing your diet to one low in fat, especially saturated fat, and cholesterol will help reduce high blood cholesterol, a primary cause of atherosclerosis. In fact, it is even more important to keep your cholesterol low after a heart attack to help lower your risk of having another one. Eating less fat should also help you lose weight. If you are overweight, losing weight can help lower blood cholesterol and is the most effective lifestyle way to reduce high blood pressure, another risk factor for atherosclerosis and heart disease.
People with CHD can also benefit from exercise. Recent research has shown that even moderate amounts of physical activity are associated with lower death rates from CHD. However, people with severe CHD may have to restrict their exercise somewhat. If you have CHD, check with your doctor to find out what kinds of exercise are best for you.
Smoking is one of the three major risk factors for CHD. Quitting smoking dramatically lowers the risk of a heart attack and also reduces the risk of a second heart attack in people who have already had one.
What medications are used to treat coronary heart disease?
Medications are prescribed according to the nature of the patient's CHD and other problems. The symptoms of angina can generally be controlled by "beta-blocker" drugs that decrease the workload on the heart, by nitroglycerine and other "nitrates" and by "calcium-channel blockers" that relax the arteries, and by other classes of drugs. The tendency to form clots is reduced by aspirin or by other platelet inhibitory and anticoagulant drugs. Beta-blockers are given to decrease the recurrence of heart attack. For those with elevated blood cholesterol that is unresponsive to dietary and weight loss measures, cholesterol-lowering drugs may be prescribed, such as lovastatin, colestipol, cholestyramine, gemfibrozil, and niacin. Impaired pumping function of the heart may be treated with digitalis drugs or ACE inhibitors. If there is high blood pressure or fluid retention, these conditions are also treated.
Ask your doctor which medication you are taking, what it does, and whether there are any side effects. Knowing more about this will help you stick to the schedule that has been prescribed for you.
What types of surgery are used to treat CHD?
Many patients can control CHD with lifestyle changes and medication. Surgery may be recommended for patients who continue to have frequent or disabling angina despite the use of medications, or people who are found to have severe blockages in their coronary arteries.
Coronary angioplasty or balloon angioplasty begins with a procedure similar to that described under angiography. However, the catheter positioned in the narrowed coronary artery has a tiny balloon at its tip. The balloon is inflated and deflated to stretch or break open the narrowing and improve the passage for blood flow. The balloon-tipped catheter is then removed.
Strictly speaking, angioplasty is not surgery. It is done while the patient is awake and may last 1 to 2 hours. If angioplasty does not widen the artery or if complications occur, bypass surgery may be needed.
In a coronary artery bypass operation, a blood vessel, usually taken from the leg or chest, is grafted onto the blocked artery, bypassing the blocked area. If more than one artery is blocked, a bypass can be done on each. The blood can then go around the obstruction to supply the heart with enough blood to relieve chest pain.
Bypass surgery relieves symptoms of heart disease but does not cure it. Usually you will need to make a number of changes in your lifestyle after the operation. If your normal lifestyle includes smoking, a high-fat diet, or no exercise, changes are advised.
Several experimental catheter-surgical procedures for unblocking coronary arteries are under study; their safety and effectiveness have not yet been established. They include:
- Atherectomy, a procedure in which surgeons shave off thin strips of the plaque blocking the artery and remove these strips.
- Laser angioplasty; instead of using a balloon to open up the blocked artery, doctors insert a catheter with a laser tip that burns or breaks down the plaque.
- Insertion of a stent, a metal coil that can be permanently implanted in a narrowed part of an artery to keep it propped open.
What is Congestive Heart Failure?
Heart failure occurs when the heart loses its ability to pump enough blood through the body. Usually, the loss in pumping action is a symptom of an underlying heart problem, such as coronary artery disease.
The term heart failure suggests a sudden and complete stop of heart activity. But, actually, the heart does not suddenly stop. Rather, heart failure usually develops slowly, often over years, as the heart gradually loses its pumping ability and works less efficiently. Some people may not become aware of their condition until symptoms appear years after their heart began its decline.
How serious the condition is depends on how much pumping capacity the heart has lost. Nearly everyone loses some pumping capacity as he or she ages. But the loss is significantly more in heart failure and often results from a heart attack or other disease that damages the heart.
The severity of the condition determines the impact it has on a person's life. At one end of the spectrum, the mild form of heart failure may have little effect on a person's life; at the other end, severe heart failure can interfere with even simple activities and prove fatal. Between those extremes, treatment often helps people lead full lives.
But all forms of heart failure, even the mildest, are a serious health problem, which must be treated. To improve their chance of living longer, patients must take care of themselves, see their physician regularly, and closely follow treatments.
Questions about Diet and Cholesterol
What is a heart-healthy diet?
A heart-healthy diet emphasizes foods low in saturated fat, total fat, and cholesterol to help lower blood cholesterol. This is the recommended eating pattern for Americans older than 2:
- Less than 10 percent of calories from saturated fat;
- An average of 30 percent of calories or less from total fat; and
- Less than 300 mg a day of dietary cholesterol.
Saturated fat increases blood cholesterol more than anything else you eat, so choose foods low in saturated fat to reduce blood cholesterol. If you are overweight, losing weight is important for lowering blood cholesterol. Being physically active also helps improve blood cholesterol levels because it can raise HDL ("good") cholesterol and lower LDL ("bad") cholesterol, as well as help you lose weight, lower your blood pressure, and improve the fitness of your heart and blood vessels.
Is margarine better than butter in a cholesterol-lowering eating pattern?
Yes. Butter is high in saturated fat, which raises blood cholesterol more than anything else you eat. Most margarines are made from vegetable oils that are hardened through a process called "hydrogenation." Hydrogenation forms a type of unsaturated fat called "trans" fat that appears to raise blood cholesterol more than other unsaturated fats but not as much as saturated fats. There are now margarines available that contain no "trans fats." You can also read food labels and choose margarines that contain liquid vegetable oil as the first ingredient (rather than hydrogenated or partially hydrogenated oil) and the least amount of saturated fat.
My last cholesterol level was within my goal. Does that mean I do not have to worry about my cholesterol any more?
High cholesterol and heart disease are not cured but are only controlled by diet and drug therapy. Stopping your treatment quickly returns your cholesterol to the level that existed before therapy was started.