Attack (Myocardial Infarction)
Introduction to Heart Attack
Each year, about 1.1 million Americans suffer a heart attack. About 460,000 of those heart attacks are fatal. About half of those deaths occur within 1 hour of the start of symptoms and before the person reaches the hospital.
A heart attack (myocardial infarction) occurs when a coronary artery abruptly fails to deliver blood to a part of your heart. Coronary arteries are the blood vessels on the surface of your heart. They bring oxygen and nutrients to your heart muscle (myocardium).
Sometimes fat, circulating cholesterol and other substances combine to form a hard substance known as plaque. The plaques also attract blood components, which stick to the artery wall lining. The build up of plaque may clog the arteries and restrict blood flow to the heart. This is called coronary artery disease, atherosclerosis or hardening of the arteries. The process develops gradually, over many years. It often begins early in life, even in childhood.
The fatty buildup or plaque can break open and lead to the formation of a blood clot that seals the break. The clot reduces blood flow. The cycle of fatty buildup, plaque rupture, and blood clot formation causes the coronary arteries to narrow, reducing blood flow.
When too little blood reaches the heart, the condition is called ischemia. Chest pain, or angina, may occur. The pain can vary in occurrence. It may be mild and intermittent, or it may be more pronounced and steady. It can be severe enough to make normal everyday activities difficult. However, is some cases, it may cause no symptoms (a condition called silent
If a blood clot suddenly cuts off most or all blood supply to the heart, a heart attack results. The portion of the heart's muscle (myocardium) that is deprived of oxygen will be permanently destroyed. The more time that passes without treatment to restore blood flow, the greater the damage to the heart.
The heart muscle affected doesn't die all at once; rather a heart attack is a continuous process that may last from four to six hours. As time passes, without an intervention to improve blood flow, more heart muscle is deprived of oxygen and dies.
Although a part of your heart has died, the rest of your heart continues to work and pump blood throughout your body.