Heart Attack - Heart Disorders

Heart Attack

A heart attack, or myocardial infarction, occurs when the blood supply to part of the heart muscle itself (the myocardium) is severely reduced or stopped. This occurs when one of the coronary arteries (that supply blood and nutrients to the heart) is blocked by an obstruction. A heart attack can also be caused by a blood clot lodged in a coronary artery, which is called coronary thrombosis or coronary occlusion. The underlying cause of most heart attacks suffered by Americans is arterial disease–atherosclerosis–which also accounts for 85% of all cardiovascular (CVD) deaths in the U.S.

If blood supply to the myocardium is cut off drastically or for a long time, muscle cells suffer irreversible injury and die. Depending on where the blockage occurs and the amount of heart muscle that is damaged, a heart attack can be extremely serious or relatively minor. Even after a heart attack, the heart can recover so long as the damaged area is not too extensive. This is because small blood vessels within the heart may gradually reroute blood around the blocked or clogged arteries, in a process called collateral circulation.

Symptoms of a Heart Attack.     According to the American Heart Association's Fact Sheet on Heart Attack, Stroke and Risk Factors , symptoms include uncomfortable pressure, fullness, squeezing, or pain in the center of the chest (which may spread to the shoulders, neck or arms) for more than a few minutes. Nausea, dizziness, sweating, fainting, a feeling of severe indigestion, and shortness of breath may also occur. Conversely, sharp, stabbing twinges generally are not signals of a heart attack. The importance of recognizing the symptoms of a heart attack and responding immediately cannot be overemphasized. More than 300,000 heart attack victims, the AHA warns, die before reaching the hospital each year, usually because they did not recognize the warning signals in time to receive emergency medical service.

Diagnosing Heart Disorders.     Heart disorders are diagnosed on the basis of symptoms, medical history, and tests–for instance, a treadmill exercise test or coronary angiograph–which allow the physician to examine the coronary arteries themselves to determine the nature and extent of narrowing or blockage. Blood tests may also be used to detect abnormal levels of certain enzymes in the bloodstream, which are thought to be precursors of a heart attack. Additional tests may be needed in certain cases to rule out other conditions such as muscle disorders, infection, structural abnormalities, anxiety, or indigestion. A doctor may also test for signs of fluid accumulation in the lungs and tissues, or use an electrocardiogram (ECG or EKG) to discover any abnormalities of heart rhythm, insufficient blood flow to the heart muscle, or other problems. Ultrasound, another noninvasive procedure, defines heart size and pumping ability, and can also be used to check for problems with the functioning of the heart valves. The key is to identify the symptoms of heart disease in time to implement holistic strategies to counteract their effects.

The importance of early detection and diagnosis is underscored by the fact that as many as 25% of Americans who die of sudden cardiac death no previous symptoms of a heart problem, according to the March 1994 issue of Graboys Heart Letter . Sudden cardiac death (SCD) occurs when an already damaged heart muscle (caused by hardening of the arteries, viruses, drugs, or valve disorders) leaves a person susceptible to irregularities in the electrical signals that govern the heart's beating. When an incident occurs, the heart rhythm deteriorates into a fibrillation or twitching, and blood flow stops. If blood flow is not restored quickly, death will result. SCD kills 300,000 Americans each year–or one victim every 90 seconds. The average age of victims is between 55 and 60. As noted, the great majority of those who die suddenly have cardiovascular disease, in particular coronary artery disease (CAD), also sometimes called coronary heart disease (CHD).

Coronary Artery Disease Risk Factors.     Unlike other organ systems of the body, most heart diseases are not caused by infection (although cardiac infections can occur), but rather by atherosclerosis of the coronary arteries. According to the American Heart Association, the major risk factors for coronary artery disease include heredity, increasing age, high blood cholesterol levels, high blood pressure, and cigarette smoking. Coronary artery disease can also result from other contributing risk factors such as diabetes, obesity, physical inactivity, and emotional stress.