Symptoms and Causes of Heart Attacks
A heart attack (myocardial infarction) is the death of heart muscle due to the loss of blood supply. Usually, the loss of blood supply is caused by a complete blockage of a coronary artery by a blood clot. A coronary artery is an artery that supplies blood to the heart muscle. Death of the heart muscle causes chest pain and electrical instability of the heart muscle tissue. Electrical instability of the heart causes ventricular fibrillation (chaotic electrical disturbance). Orderly transmission of electrical signals in the heart is important for the regular beating (pumping) of the heart. A heart undergoing ventricular fibrillation quivers, and can not pump or deliver oxygenated blood to the brain. Permanent brain damage and death can occur unless oxygenated blood flow is restored within five minutes.
Approximately one million Americans suffer a heart attack annually. Four hundred thousand of these victims die as a result. Many of the heart attack deaths are due to ventricular fibrillation of the heart that occurs before the victim can reach any medical assistance or the emergency room. These electrical disturbances of the heart can be treated with medications once the patient reaches the hospital. Therefore, 90% to 95% of heart attack victims who make it to the hospital survive. The 5% to 10% who later die are those who have suffered major heart muscle damage.
Early heart attack deaths can be avoided if a bystander starts CPR (cardiopulmonary resuscitation) within five minutes of the onset of ventricular fibrillation.
CPR involves breathing for the victim and applying external chest compression to make the heart pump. When paramedics arrive, medications and/or electrical shock (cardioversion) to the heart can be administered to convert ventricular fibrillation to a normal heart rhythm. Therefore, prompt CPR and rapid paramedic response can improve the survival chances from a heart attack.
A heart attack is caused by the formation of a blood clot on a cholesterol plaque located on the inner wall of an artery to the heart (coronary artery). Cholesterol is a fatty chemical that is part of the outer lining of cells in the body. Cholesterol plaque is the formation of a hard, thick substance on the artery walls which is caused by deposits of cholesterol on the artery walls; a process that begins in the late teens. Over time, the accumulation of cholesterol plaque causes thickening of the artery walls and narrowing of the arteries; a...