Your heart needs oxygen to survive. A heart attack occurs when the blood flow that brings oxygen to the heart muscle is severely reduced or cut off completely.
This happens when the coronary arteries that supply the heart with blood flow become narrowed from a build-up of fat, cholesterol, and other substances called plaque.
When plaque within a heart artery breaks, a blood clot forms around the plaque. This blood clot can block the blood flow through the artery to the heart muscle.
Ischemia is a condition in which blood flow and oxygen are restricted or reduced in a part of the body. Cardiac ischemia is decreased blood flow and oxygen to the heart muscle. When damage or death to part of the heart muscle occurs due to ischemia, it’s called a heart attack or myocardial infarction. About every 40 seconds, someone in the United States has a heart attack.
How is a heart attack different from cardiac arrest?
People often use these terms to mean the same thing, but they describe different events.
A heart attack is when blood flow to the heart is blocked. It’s a circulation problem.
With sudden cardiac arrest, the heart malfunctions and suddenly stops beating. It is an electrical problem caused by irregular heart rhythms called arrhythmias. A common and potentially deadly arrhythmia is ventricular fibrillation, which happens when the heart’s lower chambers suddenly start beating chaotically and stop pumping blood.
A heart attack can cause ventricular fibrillation, which in turn can cause sudden cardiac arrest. Death can occur within minutes after the heart stops.
Cardiac arrest may be reversed if CPR is performed and a defibrillator is used within minutes to shock the heart and restore a normal heart rhythm.
Catch the signs early
Don’t wait to get help if you experience any heart attack warning signs. Some heart attacks are sudden and intense, but others start slowly, with mild pain or discomfort. Pay attention to your body and call 911 if you experience any of the following:
Chest discomfort
Most heart attacks involve discomfort in the center of the chest that lasts more than a few minutes — or it may go away and then return. It can feel like uncomfortable pressure, squeezing, fullness, or pain.
Discomfort in other upper body areas
Symptoms can include pain or discomfort in one or both arms, the back, neck, jaw, or stomach.
Shortness of breath
This can occur with or without chest discomfort.
Other signs
Other possible signs include breaking out in a cold sweat, nausea, or lightheadedness.