A heart attack occurs when one or more of the coronary arteries are blocked, depriving heart muscle of oxygen-rich blood. A blockage usually occurs when a plaque inside the coronary artery breaks open (ruptures) and a blood clot forms around it. Without blood supply, the heart muscle cells die. If a large area of the heart is damaged by a heart attack (the medical term is myocardial infarction, or Ml), it can cause sudden death. Heart attack is a serious condition that requires immediate treatment to restore blood flow. Angina is a type of chest pain that occurs when there is not enough blood flow to the heart muscle, often the result of narrowing of blood vessels that supply blood to the heart muscle.
Angina is termed either stable or unstable:
- Stable angina occurs at predictable times with a specific amount of exertion or activity. Rest usually relieves this type of angina within one to five minutes. Stable angina may continue without much change for years.
- Unstable angina is a change in the usual pattern of stable angina caused by reduced blood flow to the heart. In unstable angina, chest pain occurs at rest or with less and less exertion. Unstable angina is a warning sign that a heart attack may soon occur.
The most common symptom of a heart attack is severe chest pain, also described as discomfort, pressure, squeezing, or heaviness. Many people also have at least one of the following:
- Pain or discomfort that radiates to the back, jaw, throat. or arm
- Discomfort in the upper abdomen, often mistaken for “heartburn”
- Sweating, nausea, and vomiting
- Difficult breathing, palpitations, dizziness, and fainting
- Weakness, numbness, and anxiety
Chest pain is not always present during a heart attack. Many people have symptoms such as shortness of breath, dizziness, weakness or fainting, and abdominal pain without having chest pain. Women, older adults, and people with diabetes are more likely to have atypical symptoms and less likely to have chest pain during a heart attack. It is possible to have a “silent heart attack without any symptoms, although this is rare.
The major underlying cause of unstable angina and heart attack is coronary artery disease (CAD). Coronary artery disease occurs when plaque builds up over years inside your coronary arteries and reduces blood flow to the heart muscle. High cholesterol, high blood pressure, and smoking damage your arteries and contribute to plaque buildup.
The process of plaque buildup in the arteries is called atherosclerosis. It was previously thought that heart attacks occurred when plaque accumulated inside a heart artery until it completely blocked the blood flow. Now we know that most heart attacks occur when plaque ruptures. A blood clot formed over a ruptured plaque may not completely block the artery but may block blood flow enough to cause unstable angina. Unstable angina is a sign that a heart attack may soon follow, since the blood clot can quickly grow and block the artery. Sudden intense exercise, sudden strong emotion, or drug use can trigger a heart attack by causing a rapid rise in blood pressure, a surge in certain hormones, and other physical reactions. However, in most cases, there is no clear reason why heart attacks occur.
Exams & Tests When you arrive at the hospital, the emergency room doctor will perform a history and physical examination, and an electrocardiogram (ECG) will be done. An ECG can detect sighs of insufficient blood flow, heart muscle damage, abnormal heartbeats, and other heart problems. Several blood tests will be done, including tests to see whether cardiac enzymes are elevated, on indication of heart muscle damage.
Quick treatment for a heart attack or unstable angina is critical. If blood supply can be rapidly restored to the heart, more heart tissue can be saved from permanent damage. On the way to the hospital or in the emergency room, you probably will be given an aspirin. In addition to aspirin, other medications that prevent blood clots from forming or that break up blood clots may be given through a needle in your vein. These medications must be given within a few hours of the start of your heart attack to be effective. Other medications to help decrease your heart’s workload, ease your pain, and prevent any life-threatening abnormal heart rhythms are often also given.
If your doctor thinks you may need angioplasty, you may be taken directly to the cardiac catheterization lab for evaluation of your coronary arteries. A cardiac catheterization can indicate whether you need further therapy. During the catheterization procedure, your doctor may decide to reopen a blocked artery by performing angioplasty and inserting a stent, which is a small, coiled wire-mesh tube, inside the artery’s blocked area. If necessary, emergency coronary artery bypass surgery may be done.
You will probably be started on medications, such as ACE inhibitors, beta-blockers, and cholesterol-lowering medications called statins, to prevent another heart attack or heart failure. Usually, you continue to take these and possibly other medications after you leave the hospital.
If you have unstable angina, you will be treated with medications to reduce your heart’s workload and to prevent blood clot from growing larger. Depending upon your symptoms and the results of your tests, your doctor may recommend medications and/or angioplasty.