Acute Coronary Syndrome and Heart Attack – Pathophysiology
Acute Coronary Syndrome and Heart Attack
By Mayo Clinic Staff
Acute coronary syndrome is a term used for any condition brought on by sudden, reduced blood flow to the heart. Acute coronary syndrome symptoms may include the type of chest pressure that you feel during a heart attack, or pressure in your chest while you’re at rest or doing light physical activity (unstable angina). The first sign of acute coronary syndrome can be sudden stopping of your heart (cardiac arrest). Acute coronary syndrome is often diagnosed in an emergency room or hospital.
Acute coronary syndrome is treatable if diagnosed quickly. Acute coronary syndrome treatments vary, depending on your signs, symptoms and overall health condition.
By Mayo Clinic Staff
Acute coronary syndrome symptoms are the same as those of a heart attack. And if acute coronary syndrome isn’t treated quickly, a heart attack will occur. It’s important to take acute coronary syndrome symptoms very seriously as this is a life-threatening condition. Call 911 or your local emergency number right away if you have these signs and symptoms and think you’re having a heart attack:
Chest pain (angina) that feels like burning, pressure or tightness
Pain elsewhere in the body, such as the left upper arm or jaw (referred pain)
Shortness of breath (dyspnea)
Sudden, heavy sweating (diaphoresis)
If you’re having a heart attack, the signs and symptoms may vary depending on your sex, age and whether you have an underlying medical condition, such as diabetes.
Some additional heart attack symptoms include:
Pain similar to heartburn
Lightheadedness, dizziness or fainting
Unusual or unexplained fatigue
Feeling restless or apprehensive
When to see a doctor
If you’re having chest pain and you believe it’s an emergency situation, call 911 or your local emergency number immediately. Whenever possible, get emergency medical assistance rather than driving yourself to the hospital. You could be having a heart attack.
If you have recurring chest pain, talk to your doctor. It could be a form of angina, and your doctor can help you choose the best treatment. Stable angina occurs predictably. For example, if you jog, you may experience chest pain that goes away when you rest. In unstable angina, chest pain isn’t predictable and often occurs at rest. It may also be more intense pain than stable angina.
By Mayo Clinic Staff
Acute coronary syndrome is most often a complication of plaque buildup in the arteries in your heart (coronary atherosclerosis) These plaques, made up of fatty deposits, cause the arteries to narrow and make it more difficult for blood to flow through them.
Eventually, this buildup means that your heart can’t pump enough oxygen-rich blood to the rest of your body, causing chest pain (angina) or a heart attack. Most cases of acute coronary syndrome occur when the surface of the plaque buildup in your heart arteries ruptures and causes a blood clot to form. The combination of the plaque buildup and the blood clot dramatically limits the amount of blood flowing to your heart muscle. If the blood flow is severely limited, a heart attack will occur.
By Mayo Clinic Staff
The risk factors for acute coronary syndrome are similar to those for other types of heart disease. Acute coronary syndrome risk factors include:
Older age (older than 45 for men and older than 55 for women)
High blood pressure
High blood cholesterol
Lack of physical activity
Type 2 diabetes
Family history of chest pain, heart disease or stroke. For women, a history of high blood pressure, preeclampsia or diabetes during pregnancy.
Tests and diagnosis
By Mayo Clinic Staff
If you have signs and symptoms of acute coronary syndrome, your doctor may run several tests to see if your symptoms are caused by a heart attack or another form of chest discomfort. If your doctor thinks you’re having a heart attack, the first two tests you have are:
Electrocardiogram (ECG). This is the first test done to diagnose a heart attack. It’s often done while you’re being asked questions about your symptoms. This test records the electrical activity of your heart via electrodes attached to your skin. Impulses are recorded as “waves” displayed on a monitor or printed on paper. Because injured heart muscle doesn’t conduct electrical impulses normally, the ECG may show that a heart attack has occurred or is in progress.
Blood tests. Certain heart enzymes slowly leak into your blood if your heart has been damaged by a heart attack. Emergency room staff will take samples of your blood to test for the presence of these enzymes.
Your doctor will look at these test results and determine the seriousness of your condition. If your blood tests show no markers of a heart attack and your chest pain has gone away, you’ll likely be given tests to check the blood flow through your heart. If your test results reveal that you’ve had a heart attack or that you may be at high risk to have a heart attack, you’ll likely be admitted to the hospital. You may then have more-invasive tests, such as a coronary angiogram.
Your doctor may also order additional tests, either to figure out if your heart’s been damaged by a heart attack, or if your symptoms have been brought on by another cause:
Echocardiogram. If your doctor decides you haven’t had a heart attack and your risk of having a heart attack is low, you’ll likely have an echocardiogram before you leave the hospital. This test uses sound waves to produce an image of your heart. During an echocardiogram, sound waves are directed at your heart from a transducer, a wand-like device, held on your chest. The sound waves bounce off your heart and are reflected back through your chest wall and processed electronically to provide video images of your heart. An echocardiogram can help identify whether an area of your heart has been damaged by a heart attack and isn’t pumping normally.
Chest X-ray. An X-ray image of your chest allows your doctor to check the size and shape of your heart and its blood vessels.
Nuclear scan. This test helps identify blood flow problems to your heart. Small amounts of radioactive material are injected into your bloodstream. Special cameras can detect the radioactive material as it is taken up by your heart muscle. Areas of reduced blood flow to the heart muscle — through which less of the radioactive material flows — appear as dark spots on the scan. Nuclear scans are occasionally done while you’re having chest pain to check the blood flow to your heart muscle, but more often, are done as part of a stress test.
Computerized tomography (CT) angiogram. A CT angiogram allows your doctor to check your arteries to see if they’re narrowed or blocked. In this minimally invasive test, you’ll change into a hospital gown and lie on a table that’s part of the CT scanning machine. You’ll receive an injection of a radioactive dye, and the doughnut-shaped CT scanner will be moved to take images of the arteries in your heart. The images are then sent to a computer screen for your doctor to view. This test is usually only done if your blood tests and electrocardiogram don’t reveal the cause of your symptoms.
Coronary angiogram (cardiac catheterization). This test can show if your coronary arteries are narrowed or blocked. A liquid dye is injected into the arteries of your heart through a long, thin tube (catheter) that’s fed through an artery, usually in your leg, to the arteries in your heart. As the dye fills your arteries, the arteries become visible on X-ray, revealing areas of blockage. Additionally, while the catheter is in position, your doctor may treat the blockage by performing an angioplasty. Angioplasty uses tiny balloons threaded through a blood vessel and into a coronary artery to widen the blocked area. Often, a mesh tube (stent) also is placed inside the artery to hold it open more widely and prevent re-narrowing in the future.
Exercise stress test. In the days or weeks following your heart symptoms, you may also undergo a stress test. Stress tests measure how your heart and blood vessels respond to exertion. You may walk on a treadmill or pedal a stationary bike while attached to an ECG machine. Or you may receive a drug intravenously that stimulates your heart in a manner that’s similar to the way you heart would be stimulated during exercise. Stress tests help doctors decide the best long-term treatment for you. Your doctor also may order a nuclear stress test, which is similar to an exercise stress test, but uses an injected dye and special imaging techniques to produce detailed images of your heart while you’re exercising.
Treatments and drugs
By Mayo Clinic Staff
Treatment for acute coronary syndrome varies, depending on your symptoms and how blocked your arteries are.
It’s likely that your doctor will recommend medications that can relieve chest pain and improve flow through the heart. These could include:
Aspirin. Aspirin decreases blood clotting, helping to keep blood flowing through narrowed heart arteries. Aspirin is one of the first things you may be given in the emergency room for suspected acute coronary syndrome. You may be asked to chew the aspirin so that it’s absorbed into your bloodstream more quickly. If your doctor diagnoses your symptoms as acute coronary syndrome, he or she may recommend taking an 81-milligram dose of aspirin daily.
Thrombolytics. These drugs, also called clotbusters, help dissolve a blood clot that’s blocking blood flow to your heart. If you’re having a heart attack, the earlier you receive a thrombolytic drug after a heart attack, the greater the chance you will survive and lessen the damage to your heart. However, if you are close to a hospital with a cardiac catheterization laboratory, you’ll usually be treated with emergency angioplasty and stenting instead of thrombolytics. Clotbuster medications are generally used when it will take too long to get to a cardiac catheterization laboratory, such as in rural communities.
Nitroglycerin. This medication for treating chest pain and angina temporarily widens narrowed blood vessels, improving blood flow to and from your heart.
Beta blockers. These drugs help relax your heart muscle, slow your heart rate and decrease your blood pressure, which decreases the demand on your heart. These medications can increase blood flow through your heart, decreasing chest pain and the potential for damage to your heart during a heart attack.
Angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs). These drugs allow blood to flow from your heart more easily. Your doctor may prescribe ACE inhibitors or ARBs if you’ve had a moderate to severe heart attack that has reduced your heart’s pumping capacity. These drugs also lower blood pressure and may prevent a second heart attack.
Calcium channel blockers. These medications relax the heart and allow more blood to flow to and from the heart. Calcium channel blockers are generally given if symptoms persist after you’ve taken nitroglycerin and beta blockers.
Cholesterol-lowering drugs. Commonly used drugs known as statins can lower your cholesterol levels, making plaque deposits less likely, and they can stabilize plaque, making it less likely to rupture.
Clot-preventing drugs. Medications such as clopidogrel (Plavix) and prasugrel (Effient) can help prevent blood clots from forming by making your blood platelets less likely to stick together. However, clopidogrel increases your risk of bleeding, so be sure to let everyone on your health care team know that you’re taking it, particularly if you need any type of surgery.
Surgery and other procedures
If medications aren’t enough to restore blood flow through your heart, your doctor may recommend one of these procedures:
Angioplasty and stenting. In this procedure, your doctor inserts a long, thin tube (catheter) into the blocked or narrowed part of your artery. A wire with a deflated balloon is passed through the catheter to the narrowed area. The balloon is then inflated, compressing the deposits against your artery walls. A mesh tube (stent) is usually left in the artery to help keep the artery open.
Coronary bypass surgery. This procedure creates an alternative route for blood to go around a blocked coronary artery.