What is a heart attack?
A heart attack (also known as a myocardial infarction or MI) is the death of heart muscle from the sudden blockage by a blood clot in a coronary artery that supplies blood to the heart. Blockage of a coronary artery deprives the heart muscle of blood and oxygen, causing injury to the heart muscle. Injury to the heart muscle causes chest pain and pressure. If blood flow is not restored within 20 to 40 minutes, irreversible death of the heart muscle will begin to occur. Muscle continues to die for 6 to 8 hours at which time the heart attack usually is "complete." The dead heart muscle is replaced by scar tissue.
Click here to view interactive photos of hearts that have suffered a heart attack.
How is a heart attack treated?
Treatment of heart attacks includes:
- Antiplatelet medications to prevent formation of blood clots in the arteries
- Anticoagulant medications to prevent growth of blood clots in the arteries
- Coronary angiography with either percutaneous transluminal coronary angioplasty (PTCA) with or without stenting to open blocked coronary arteries
- Clot-dissolving medications to open blocked arteries
- Supplemental oxygen to increase the supply of oxygen to the heart's muscle
- Medications to decrease the need for oxygen by the heart's muscle
- Medications to prevent abnormal heart rhythms
- Cardiac surgery
The primary goal of treatment is to quickly open the blocked artery and restore blood flow to the heart muscle, a process called reperfusion. Once the artery is open, damage to heart muscle ceases, and pain improves. By minimizing the extent of heart muscle damage, early reperfusion preserves the pumping function of the heart. Optimal benefit is obtained if reperfusion can be established within the first 4 to 6 hours of a heart attack. Delay in establishing reperfusion can result in more widespread damage to heart muscle and a greater reduction in the ability of the heart to pump blood. Patients with hearts that are unable to pump sufficient blood develop heart failure, decreased ability to exercise, and abnormal heart rhythms. Thus, the amount of healthy heart muscle remaining after a heart attack is the most important determinant of the future quality of life and longevity.