What Happens During a Heart Attack?
The heart muscle requires a constant supply of oxygen-rich blood to nourish it. The coronary arteries provide the heart with this critical blood supply. If you have coronary artery disease, those arteries become narrow and blood cannot flow as well as they should. Fatty matter, calcium, proteins, and inflammatory cells build up within the arteries to form plaques of different sizes. The plaque deposits are hard on the outside and soft and mushy on the inside.
When the plaque is hard, the outer shell cracks (plaque rupture), 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 artery, the heart muscle becomes “starved” for oxygen. Within a short time, death of heart muscle cells occurs, causing permanent damage. This is a heart attack.
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While it is unusual, a heart attack can also be caused by a spasm of a coronary artery. During a coronary spasm, the coronary arteries restrict or spasm on and off, reducing blood supply to the heart muscle (ischemia). It may occur at rest, and can even occur in people without significant coronary artery disease.
Each coronary artery supplies blood to a region of heart muscle. 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.
Healing of the heart muscle begins soon after a heart attack and takes about eight weeks. Just like a skin wound, the heart’s wound heals and a scar will form in the damaged area. But, the new scar tissue does not contract. So, the heart’s pumping ability is lessened after a heart attack. The amount of lost pumping ability depends on the size and location of the scar.
What Is a Heart Attack?
A heart attack happens when the flow of oxygen-rich blood to a section of heart muscle suddenly becomes blocked and the heart can’t get oxygen. If blood flow isn’t restored quickly, the section of heart muscle begins to die.
Heart attacks are a leading killer of both men and women in the United States. The good news is that excellent treatments are available for heart attacks. These treatments can save lives and prevent disabilities.
Heart attack treatment works best when it’s given right after symptoms occur. If you think you or someone else is having a heart attack (even if you’re not fully sure), call9–1–1 right away.
Heart attacks most often occur as a result of coronary heart disease (CHD), also called coronary artery disease. CHD is a condition in which a waxy substance called plaque (plak) builds up inside the coronary arteries. These arteries supply oxygen-rich blood to your heart.
When plaque builds up in the arteries, the condition is called atherosclerosis (ath-er-o-skler-O-sis). The buildup of plaque occurs over many years.
Eventually, an area of plaque can rupture (break open) inside of an artery. This causes a blood clot to form on the plaque’s surface. If the clot becomes large enough, it can mostly or completely block blood flow through a coronary artery.
If the blockage isn’t treated quickly, the portion of heart muscle fed by the artery begins to die. Healthy heart tissue is replaced with scar tissue. This heart damage may not be obvious, or it may cause severe or long-lasting problems.
Heart With Muscle Damage and a Blocked Artery
Figure A shows a heart with dead heart muscle caused by a heart attack. Figure B is a cross-section of a coronary artery with plaque buildup and a blood clot.
A less common cause of heart attack is a severe spasm (tightening) of a coronary artery. The spasm cuts off blood flow through the artery. Spasms can occur in coronary arteries that aren’t affected by atherosclerosis.
Heart attacks can be associated with or lead to severe health problems, such as heart failure and life-threatening arrhythmias (ah-RITH-me-ahs).
Heart failure is a condition in which the heart can’t pump enough blood to meet the body’s needs. Arrhythmias are irregular heartbeats. Ventricular fibrillation is a life-threatening arrhythmia that can cause death if not treated right away.
Don’t Wait–Get Help Quickly
Acting fast at the first sign of heart attack symptoms can save your life and limit damage to your heart. Treatment works best when it’s given right after symptoms occur.
Many people aren’t sure what’s wrong when they are having symptoms of a heart attack. Some of the most common warning symptoms of a heart attack for both men and women are:
Chest pain or discomfort. Most heart attacks involve discomfort in the center or left side of the chest. The discomfort usually lasts more than a few minutes or goes away and comes back. It can feel like pressure, squeezing, fullness, or pain. It also can feel like heartburn or indigestion.Upper body discomfort. You may feel pain or discomfort in one or both arms, the back, shoulders, neck, jaw, or upper part of the stomach (above the belly button).Shortness of breath. This may be your only symptom, or it may occur before or along with chest pain or discomfort. It can occur when you are resting or doing a little bit of physical activity.
Other possible symptoms of a heart attack include:
Breaking out in a cold sweatFeeling unusually tired for no reason, sometimes for days (especially if you are a woman)Nausea (feeling sick to the stomach) and vomitingLight-headedness or sudden dizzinessAny sudden, new symptom or a change in the pattern of symptoms you already have (for example, if your symptoms become stronger or last longer than usual)
Not all heart attacks begin with the sudden, crushing chest pain that often is shown on TV or in the movies, or other common symptoms such as chest discomfort. The symptoms of a heart attack can vary from person to person. Some people can have few symptoms and are surprised to learn they’ve had a heart attack. If you’ve already had a heart attack, your symptoms may not be the same for another one.
Quick Action Can Save Your Life: Call 9–1–1
If you think you or someone else may be having heart attack symptoms or a heart attack, don’t ignore it or feel embarrassed to call for help. Call 9–1–1 for emergency medical care. Acting fast can save your life.
Do not drive to the hospital or let someone else drive you. Call an ambulance so that medical personnel can begin life-saving treatment on the way to the emergency room. Take a nitroglycerin pill if your doctor has prescribed this type of treatment.
Each year, close to 1 million people in the United States have heart attacks, and many of them die. CHD, which often results in heart attacks, is the leading killer of both men and women in the United States.
Many more people could survive or recover better from heart attacks if they got help faster. Of the people who die from heart attacks, about half die within an hour of the first symptoms and before they reach the hospital.