A heart attack, or myocardial infarction (MI), is permanent damage to the heart muscle. "Myo" means muscle, "cardial" refers to the heart, and "infarction" means death of tissue due to lack of blood supply.
A closer look inside your coronary arteries
Your heart muscle needs to receive a good supply of blood at all times to function properly. Your heart muscle gets the blood it needs to do its job from the coronary arteries.
What is coronary artery disease?
Coronary artery disease is the narrowing or blockage of the coronary arteries caused by atherosclerosis. Atherosclerosis (sometimes called “hardening” or “clogging” of the arteries) is the buildup of cholesterol and fatty deposits (called plaque) on the inner walls of the arteries that restricts blood flow to the heart.
Without adequate blood, the heart becomes starved of oxygen and the vital nutrients it needs to work properly. This can cause chest pain called angina. When one or more of the coronary arteries are completely blocked, a heart attack (injury to the heart muscle) may occur.
What happens during a heart attack?
A network of blood vessels known as coronary arteries surround the heart muscle and supply it with blood that is rich in oxygen. The heart muscle needs this oxygen to function.
A heart attack occurs when a coronary artery becomes suddenly blocked, stopping the flow of blood to the heart muscle and damaging it. All or part of the heart muscle becomes cut off from its oxygen supply. Left without oxygen, the heart muscle is injured.
Let's take a closer look
When fat builds up inside your arteries it causes slight injury to your blood vessel walls. In an attempt to heal the blood vessel walls, the cells release chemicals that make the blood vessel walls stickier. Other substances traveling through your blood stream, such as inflammatory cells, cellular waste products, proteins and calcium, begin to stick to the vessel walls. The fat and other substances combine to form a material called plaque.
Over time, the inside of the arteries develop plaques of different sizes. Many of the plaque deposits are soft on the inside with a hard fibrous “cap” covering the outside. If the hard surface cracks or tears, the soft, fatty inside is exposed. Platelets (disc-shaped particles in the blood that aid clotting) come to the area, and blood clots form around the plaque.
If a blood clot totally blocks the blood supply to the heart muscle, called a coronary thrombus or coronary occlusion , the heart muscle becomes "starved" for oxygen and nutrients (called ischemia) in the region below the blockage. Within a short time, an acute coronary syndrome can occur.
Acute Coronary Syndrome is a name given to three types of coronary artery disease that are associated with sudden rupture of plaque inside the coronary artery: unstable angina, Non-ST segment elevation myocardial infarction or heart attack (NSTEMI), or ST segment elevation myocardial infarction or heart attack (STEMI).
Dark red = artery
Blue = outlines region of heart affected by blockage
Each coronary artery supplies blood to a region of the heart muscle. If an artery is occluded (blocked) there is no blood supply to that region.
The amount of damage to the heart muscle depends on the size of the area supplied by the blocked artery and the time between injury and treatment.
What is a coronary spasm?
A heart attack can also occur less frequently by a spasm of a coronary artery. During coronary spasm, the coronary arteries constrict or spasm on and off, causing lack of blood supply to the heart muscle (ischemia). It may occur at rest and can even occur in people without significant coronary artery disease. If coronary artery spasm occurs for a long period of time, a heart attack can occur.
What are the symptoms of a heart attack?
If you are having any one of the symptoms described below that lasts for more than 5 minutes, SEEK EMERGENCY TREATMENT (CALL 911) WITHOUT DELAY. These symptoms could be the signs of a heart attack (also called myocardial infarction or MI) and immediate treatment is essential.
Symptoms of a heart attack include:
- Angina: Chest pain or discomfort in the center of the chest; also described as a heaviness, tightness, pressure, aching, burning, numbness, fullness or squeezing feeling that lasts for more than a few minutes or goes away and comes back. It is sometimes mistakenly thought to be indigestion or heartburn.
- Pain or discomfort in other areas of the upper body including the arms, left shoulder, back, neck, jaw, or stomach
- Difficulty breathing or shortness of breath
- Sweating or “cold sweat”
- Fullness, indigestion, or choking feeling (may feel like “heartburn”)
- Nausea or vomiting
- Light-headedness, dizziness, extreme weakness or anxiety
- Rapid or irregular heart beats
Learn more about the symptoms of a heart attack and what to do if they occur.
What is the treatment of a heart attack?
Quick treatment via mediations, angioplasty or other means to open the blocked artery is essential to lessen the amount of damage. Learn more about treatment of a heart attack.
Healing of the heart muscle begins soon after a heart attack and takes about 8 weeks. Just like a skin wound, the heart’s wound heals and a scar will form in the damaged area. The new scar tissue does not contract or pump as well as healthy heart muscle tissue. So, the heart’s pumping ability is lessened. The amount of lost pumping ability depends on the size and location of the scar.
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