Causes of Heart Attack

A heart attack occurs when one or more of the arteries supplying your heart with oxygen-rich blood (coronary arteries) become blocked. Over time, a coronary artery can become narrowed from the buildup of cholesterol. This buildup — collectively known as plaques — in arteries throughout the body is called atherosclerosis.

During a heart attack, one of these plaques can rupture and a blood clot forms on the site of the rupture. If the clot is large enough, it can completely block the flow of blood through the artery. When your coronary arteries have narrowed due to atherosclerosis, the condition is known as coronary artery disease. Coronary artery disease is the underlying cause of most heart attacks.

An uncommon cause of a heart attack is a spasm of a coronary artery that shuts down blood flow to part of the heart muscle. Drugs, such as cocaine, can cause such a life-threatening spasm. A heart attack can also occur due to a tear in the heart artery (coronary artery dissection). Other uncommon causes of heart attack include small blood clots or tumors that have traveled from other parts of the body (coronary embolism).

A heart attack is the end of a process that typically evolves over several hours. With each passing minute, more heart tissue is deprived of blood and deteriorates or dies. However, if blood flow can be restored in time, damage to the heart can be limited or prevented.

Symptoms

Common heart attack symptoms include:

• Pressure, a feeling of fullness or a squeezing pain in the center of your chest that lasts for more than a few minutes
• Pain extending beyond your chest to your shoulder, arm, back, or even to your teeth and jaw
• Increasing episodes of chest pain
• Prolonged pain in the upper abdomen
•  Shortness of breath
• Sweating
• Impending sense of doom
• Fainting
• Nausea and vomiting

Additional, or different, heart attack signs and symptoms in women may include:

• Heartburn or abdominal pain
• Clammy skin
• Lightheadedness or dizziness
• Unusual or unexplained fatigue

Heart attack symptoms vary


Not all people who have heart attacks experience the same symptoms or experience them to the same degree. Many heart attacks aren't as dramatic as the ones you've seen on TV. Some people have no symptoms at all. Still, the more signs and symptoms you have, the greater the likelihood that you may be having a heart attack.

A heart attack can occur anytime — at work or play, while you're resting, or while you're in motion. Some heart attacks strike suddenly, but many people who experience a heart attack have warning signs and symptoms hours, days or weeks in advance. The earliest warning of a heart attack may be recurrent chest pain (angina) that's triggered by exertion and relieved by rest. Angina is caused by a temporary decrease in blood flow to the heart.

Many people confuse a heart attack with a condition in which your heart suddenly stops (sudden cardiac arrest). Sudden cardiac arrest occurs when an electrical disturbance in your heart disrupts its pumping action and causes blood to stop flowing to the rest of your body. Heart attack is the most common cause, but not the only cause, of cardiac arrest.

When to see a doctor


During a heart attack, act immediately. Many people wait too long because they don't recognize the important signs and symptoms. Take these steps:

Call for emergency medical help. 

If you suspect you're having a heart attack, don't hesitate. Immediately call 911 or your local emergency number. If you don't have access to emergency medical services, have someone drive you to the nearest hospital. Drive yourself only as a last resort, if there are absolutely no other options. Driving yourself puts you and others at risk if your condition suddenly worsens.

Take nitroglycerin, if prescribed. 

If your doctor has prescribed nitroglycerin, take it as instructed while awaiting the arrival of emergency medical personnel.

Take aspirin, if recommended. 

If you're concerned about your heart attack risk, ask your doctor if chewing an aspirin tablet if you have heart attack symptoms is a good idea. Taking aspirin during a heart attack could reduce the damage to your heart by making your blood less likely to clot. Aspirin can interact with other medications, however, so don't take an aspirin unless your doctor or emergency medical personnel recommend it. Don't delay calling 911, though.

What to do if you see someone having a heart attack


If you encounter someone who is unconscious from a presumed heart attack, call for emergency medical help. If you have received training in emergency procedures, begin cardiopulmonary resuscitation (CPR). This helps deliver oxygen to the body and brain.

According to guidelines by the American Heart Association, regardless of whether you've been trained, you should begin CPR with chest compressions. Press down about two inches (about five centimeters) on the person's chest for each compression at a rate of about 100 a minute. If you've been trained in CPR, check the person's airway and deliver rescue breaths after every 30 compressions. If you haven't been trained, continue doing compressions only.

In the initial minutes, a heart attack can also trigger ventricular fibrillation, a condition in which the heart quivers uselessly. Without immediate treatment, ventricular fibrillation leads to sudden death. The timely use of an automatic external defibrillator (AED), which shocks the heart back into a normal rhythm, can provide emergency treatment before a person having a heart attack reaches the hospital.

Risk factors

Certain factors contribute to the unwanted buildup of fatty deposits (atherosclerosis) that narrows arteries throughout your body, including arteries to your heart. You can improve or eliminate many of these risk factors to reduce your chances of having a first or subsequent heart attack.

Heart attack risk factors include:

•  Age. Men who are 45 or older and women who are 55 or older are more likely to have a heart attack than are younger men and women.
• Tobacco. Smoking and long-term exposure to secondhand smoke damage the interior walls of arteries — including arteries to your heart — allowing deposits of cholesterol and other substances to collect and slow blood flow. Smoking also increases the risk of deadly blood clots forming and causing a heart attack.
• Diabetes. Diabetes is the inability of your body to adequately produce insulin or respond to insulin need properly. Insulin, a hormone secreted by your pancreas, allows your body to use glucose, which is a form of sugar from foods. Diabetes can occur in childhood, but it appears more often in middle age and among overweight people. Diabetes greatly increases your risk of a heart attack.
• High blood pressure. Over time, high blood pressure can damage arteries that feed your heart by accelerating atherosclerosis. The risk of high blood pressure increases as you age, but the main culprits for most people are eating a diet too high in salt and being overweight. High blood pressure can also be an inherited problem.
• High blood cholesterol or triglyceride levels. Cholesterol is a major part of the deposits that can narrow arteries throughout your body, including those that supply your heart. A high level of the wrong kind of cholesterol in your blood increases your risk of a heart attack. Low-density lipoprotein (LDL) cholesterol (the "bad" cholesterol) is most likely to narrow arteries. A high LDL level is undesirable and is often a result of a diet high in saturated fats and cholesterol. A high level of triglycerides, a type of blood fat related to your diet, also is undesirable. However, a high level of high-density lipoprotein (HDL) cholesterol (the "good" cholesterol), which helps the body clean up excess cholesterol, is desirable and lowers your risk of heart attack.
• Family history of heart attack. If your siblings, parents or grandparents have had heart attacks, you may be at increased risk. Your family may have a genetic condition that raises unwanted blood cholesterol levels. High blood pressure also can run in families.
• Lack of physical activity. An inactive lifestyle contributes to high blood cholesterol levels and obesity. People who get regular aerobic exercise have better cardiovascular fitness, which decreases their overall risk of heart attack. Exercise is also beneficial in lowering high blood pressure.
• Obesity. Obese people have a high proportion of body fat (a body mass index of 30 or higher). Obesity raises the risk of heart disease because it's associated with high blood cholesterol levels, high blood pressure and diabetes.
• Stress. You may respond to stress in ways that can increase your risk of a heart attack. If you're under stress, you may overeat or smoke from nervous tension. Too much stress, as well as anger, can also raise your blood pressure.
• Illegal drug use. Using stimulant drugs, such as cocaine or amphetamines, can trigger a spasm of your coronary arteries that can cause a heart attack.

Mayo Clinic