Anatomy of a Heart Attack

by Matt McMillen Health Writer

Heart attacks occur when something, usually a clot, blocks or reduces the flow of blood and oxygen to your ticker. Sometimes these myocardial infarctions (the official name for heart attacks) occur when the coronary arteries spasm. Even though everyone knows heart attacks are emergencies, it's sometimes easy to delay getting help, especially if symptoms are a little vague. Just to make sure you don't fall into that camp someday, get up to speed on what happens to the body during a heart attack and why there's no such thing as being too careful.

1. Plaque Builds Up

When you have too much fat and cholesterol in your bloodstream, a harmful substance called plaque builds up inside the blood vessel walls, narrowing them and reducing the blood flow that delivers oxygen to all parts of your body, including the heart. This condition is called atherosclerosis, says cardiologist Nicholas Ruthmann, M.D., of the Cleveland Clinic in Ohio.

blood clot

2. Blood Clots Form

Evenutally, that plaque buildup in the coronary arteries can rupture, triggering a similar response as a paper cut does on your finger, says Dr. Ruthmann: a clot forms in an attempt to fix the damage. But the body’s defense mechanism does more harm than good. “A clot that forms at the site of the plaque only makes the blockage worse,” he adds, either partially or completely arresting blood flow. This restriction of the blood supply, known as ischemia, is what causes heart attacks, which occur every 40 seconds to someone in the U.S., according to the American Heart Association.

2a. The Arteries Spasm

Coronary artery spasm doesn't always involve plaque buildup and it's not always serious, but it can sometimes lead to heart attack and even death, according to the Mayo Clinic in Rochester, MN. This occurs when the coronary arteries temporarily tighten and spasm, cutting off the oxygen supply to the heart. Unlike a “typical” heart attack, this type of attack usually occurs when people are at rest, often between midnight and early morning. Many people who have this condition don’t have common risk factors for heart attacks such as atherosclerosis—but many are smokers.

3. Blood Flow Is Blocked

No matter what type of heart attack you have, “damage to heart tissue occurs fairly quickly,” says David Friedman, M.D., a cardiologist at Northwell Health in Valley Stream, NY. When your heart doesn’t get the oxygen it needs to survive, it starts to die. The result: permanent scarring that can weaken your ticker and prevent it from working as well as it did before your heart attack happened. The amount of damage depends on the size of the blockage, where in the heart it occurs, and how quickly the blockage is opened. Together, these three factors determine the severity of your heart attack.

man having a heart attack

4. You Start Feeling Symptoms

Men and women can experience very different heart attack symptoms. Chest pain is the most common symptom for both, but women tend to be more likely to experience shortness of breath, nausea and vomiting, and pain that radiates in the back and jaw. “But, as far as what happens to the heart during a heart attack?” Dr. Ruthmann asks before answering his own question. “The heart muscle and heart cells are dying in the same way, whether you're a man or a woman.”

nurse testing patient's blood

5. Your Heart Releases Proteins

During a heart attack, the cells in your heart suffer damage, and this damage triggers your heart to release the proteins troponin T and troponin I into your bloodstream. Doctors in the emergency room (which is where you'll go ASAP but more on that in a few) will run blood tests to look for elevated levels of troponin, and if they find them, that will help them confirm that your chest pain is being caused by a heart attack. The results of such blood tests will also help identify the type of heart attack you are having—and the type of treatment you require.

6. Damage Begins to Accumulate

During a heart attack, your heart won’t be able to function normally. That’s bad news for your entire body. Your vital organs—meaning your brain, lungs, kidneys, and liver—depend on a steady diet of blood, oxygen, and nutrients, which the heart pumps to them. If your organs go without these essential supplies for too long, they too will become permanently damaged and begin to shut down. The more severe the heart attack—meaning the bigger the blockage and the more time it takes to treat it—the faster this occurs.

Close-up of medical oxygen flow meter shows low oxygen or an nearly empty tank

7. Blood Pressure Can Plummet

During a heart attack, blood pressure levels drop significantly. One result: The amount of blood and oxygen that reaches the brain drops significantly, too. Without oxygen, the brain cells begin to die, a process called cerebral infarction. The signs that this has begun to happen include vision loss, trouble moving, and impaired speech. It also may lead to unconsciousness, and it could cause the heart to stop beating altogether, a quickly fatal condition known as cardiac arrest.

Ambulance van on highway with flashing lights

There's No Such Thing as Overreacting

Because of all the reasons you just learned about, it's obvious why it's critical to get to the hospital as fast as possible. As Dr. Ruthmann says, “Time is tissue.” Seek help at the first sign of chest pain or other symptoms and you may limit the damage to your heart (and even save your life). STEMI heart attacks—when an artery is completely blocked, and no blood or oxygen can reach your heart—are particularly dangerous. “It’s the type of heart attack that can be rapidly fatal if not quickly treated.” Nearly two out of five heart attacks fall into this category. You won't know what type you're having, which is why it's important to get help ASAP.

Large red EMERGENCY sign on hospital entrance

What to Expect in the ER

If ER doctors suspect that you’re having a heart attack, they’ll order an electrocardiogram (ECG) to test your heartbeat for abnormalities. Bloodwork will be ordered to look for those tell-tale heart attack proteins. Immediate treatment will focus on clearing or opening the blockage that triggered the attack. This may include medications to dissolve the clot or relax constricting arteries, as well as surgical procedures to restore normal blood flow, such as percutaneous coronary intervention (PCI) or coronary bypass. It may sound scary, but here’s the good news: More than 90% of people who have a heart attack survive.

Matt McMillen
Meet Our Writer
Matt McMillen

Matt McMillen has been a freelance health reporter since 2002. In that time he’s written about everything from acupuncture to the Zika virus. He covers breaking medical news and the latest medical studies, profiles celebrities, and crafts easy to digest overviews of medical conditions. His work has appeared, both online and in print, in The Washington Post, WebMD Magazine, Diabetes Forecast, AARP, and elsewhere.