Heart Attacks: What you need to Know
The heart’s job is to pump oxygen-rich blood to the entire body. But the heart itself also needs oxygen to survive. When blood flow to the heart muscle is severely reduced or cut off completely, the heart is unable to function properly. The part that is deprived of oxygen begins to die. That is a heart attack.
Cardiac Arrest vs. Heart Attack
Cardiac arrest is not the same as a heart attack, but the two are linked. A heart attack occurs when blood flow to the heart is blocked. In sudden cardiac arrest, the heart suddenly stops beating. As the AHA puts it, heart attack is a “circulation” problem, and sudden cardiac arrest is an “electrical” problem.
Sudden cardiac arrest occurs, as the name implies, suddenly and usually without any advanced warning. It is triggered by a disruption of the electrical currents that keep the heart beating. This disruption, called an arrhythmia, stops the heart from pumping blood to the brain, lungs and other organs. The person can lose consciousness within seconds and may have little or no pulse. If the person does not receive treatment within minutes, cardiac arrest will cause death.
A heart attack increases the risk of sudden cardiac arrest, which can occur after a heart attack or during recovery. However, most heart attacks do not lead to sudden cardiac arrest. Arrhythmia is also caused by cardiomyopathy (thickening of the heart muscle), heart failure and damage to the areas of the heart that control the electrical currents that keep the heart pumping rhythmically.
A heart in cardiac arrest can be restarted through CPR and the use of a defibrillator to shock the heart back into a normal beating rhythm.
Blood flow can be blocked when the coronary arteries that supply the heart muscle with blood become narrowed from plaque, which is a buildup of fat, cholesterol and other substances. This is known as atherosclerosis, sometimes called hardening of the arteries. The plaque can constrict the artery, slowing blood flow. Sometimes, the plaque breaks, forming a blood clot. The clot can completely block the blood flow through the artery to the heart muscle.
When the heart muscle is oxygen-deprived, the condition is called ischemia. If that leads to damage or death of part of the heart muscle, it is called an ischemic heart attack, or a myocardial infarction.
A blocked artery is not the only cause of heart attack. A coronary artery may contract or go into spasm, causing the artery to narrow and slow or stop blood flow to part of the heart. The AHA says the causes of spasms are not well known. They can occur in both seemingly normal vessels and in those with atherosclerosis. If the spasm is severe enough, it can cause a heart attack.
Another possible, though very rare, cause of heart attack is spontaneous coronary artery dissection. This is when the arterial wall rips or tears, causing loss of blood flow to the heart. It’s not clear what causes this, but the Mayo Clinic says there are a few risk factors, including genetic diseases that affect the body’s connective tissues, such as vascular Ehlers-Danlos syndrome and Marfan syndrome, extremely high blood pressure, illegal drug use and others.
Unfortunately, atherosclerosis has no symptoms of its own. The AHA explains that when a coronary artery afflicted with atherosclerosis narrows and blocks blood flow, other blood vessels that serve the same area of the heart can expand to compensate for the weaker artery. This network of expanded blood vessels is called collateral circulation. The AHA says it protects some people from heart attacks by delivering needed blood to the heart. It also may explain why those with atherosclerosis have no advanced warning. Collateral circulation can also help after a heart attack by bringing added blood to the heart muscle to help it recover.
The most common warning sign of a weakened heart is angina. This is defined as recurring chest discomfort that typically lasts only a few minutes. Angina is not the same as a heart attack, because angina attacks don’t cause permanent damage to the heart muscle. Still, any unexplained chest discomfort, such as angina, warrants a visit to the doctor.
There are different types of angina:
- Stable angina, or angina pectoris, occurs during exercise or emotional stress, as blood pressure and heart rate increase and the heart struggles to get adequate blood flow.
- Unstable angina, or acute coronary syndrome, can occur while resting or sleeping, and often is unexpected. The AHA says unstable angina can lead to a heart attack and should be treated as an emergency.
Many people envision a heart attack as it’s often shown in movies or on TV: chest-clutching pain followed by a collapse to the floor. While that can happen, it is far from typical. Most heart attacks begin with mild pain or discomfort. Heart attack symptoms can last for hours, days or weeks. And, unlike with sudden cardiac arrest, the heart usually keeps beating during a heart attack.
The AHA lists the following symptoms that can suggest a heart attack is happening:
- Discomfort in the center of the chest that lasts more than a few minutes or that goes away and comes back. It can feel like uncomfortable pressure, squeezing, fullness or pain.
- Pain or discomfort in other parts of the body, such as one or both arms, the back, neck, jaw or stomach.
- Shortness of breath, with or without chest discomfort.
- A cold sweat, nausea or lightheadedness.
Symptoms for Women
While women also experience chest pain or discomfort, they are more likely to notice some of the other symptoms, particularly shortness of breath, nausea and/or vomiting and back or jaw pain. Women often fail to recognize these as symptoms of a heart attack, thinking they are caused by less dangerous conditions, such as acid reflux, the normal aches and pains of aging or the flu and these symptoms must be taken seriously.
The best way to prevent a heart attack is to know your risk factors. Some, such as age (risk goes up as you age), gender (men are at higher risk than women), ethnicity (African-Americans, Mexican-Americans, American Indians, Native Hawaiians and some Asian-Americans have higher risk) and family history, you can’t do much about. Others, however, are directly under your control. To lower your risk of heart attack, the AHA recommends:
- Don’t smoke – and if you do, quit right away.
- Control blood pressure and cholesterol levels.
- Keep diabetes under control.
- Maintain a healthy body weight.
- Engage in physical activity.
- Eat a heart-healthy diet.
- Keep stress under control.