Myocardial ischemia occurs when blood flow to your heart muscle is decreased by a partial or complete blockage of your heart's arteries (coronary arteries). The decrease in blood flow reduces your heart's oxygen supply.
Myocardial ischemia, also called cardiac ischemia, can damage your heart muscle, reducing its ability to pump efficiently. A sudden, severe blockage of a coronary artery may lead to a heart attack. Myocardial ischemia may also cause serious abnormal heart rhythms.
Treatment for myocardial ischemia is directed at improving blood flow to the heart muscle and may include medications, a procedure to open blocked arteries or coronary artery bypass surgery. Making heart-healthy lifestyle choices is important in treating and preventing myocardial ischemia.
- Chest pressure or pain, typically on the left side of the body (angina pectoris)
- Neck or jaw pain
- Shoulder or arm pain
- A fast heartbeat
- Shortness of breath
- Nausea and vomiting
When to see a doctor
If you have chest discomfort, especially if it's accompanied by one or more of the other signs and symptoms listed above, seek medical care 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.
CMyocardial ischemia occurs when the blood flow through one or more of the blood vessels that lead to your heart (coronary arteries) is decreased. This decrease in blood flow leads to a decrease in the amount of oxygen your heart muscle (myocardium) receives. Myocardial ischemia may occur slowly as arteries become blocked over time, or it may occur quickly when an artery becomes blocked suddenly.
Conditions that may cause myocardial ischemia include:
- Coronary artery disease (atherosclerosis). Atherosclerosis occurs when plaques made of cholesterol and waste products build up on your artery walls and restrict blood flow. Atherosclerosis of the heart arteries is called coronary artery disease and is the most common cause of myocardial ischemia.
- Blood clot. The plaques that develop in atherosclerosis can rupture, causing a blood clot, which may lead to sudden, severe myocardial ischemia, resulting in a heart attack.
- Coronary artery spasm. A coronary artery spasm is a brief, temporary tightening (contraction) of the muscles in the artery wall. This can narrow and briefly decrease or even prevent blood flow to part of the heart muscle.
Things that may trigger chest pain associated with myocardial ischemia include:
- Physical exertion
- Emotional stress
- Cold temperatures
- Lying down
- Cocaine use
ausesFactors that may increase your risk of developing myocardial ischemia include:
- Tobacco. Both smoking and long-term exposure to secondhand smoke can damage the interior walls of arteries — including arteries in your heart — allowing deposits of cholesterol and other substances to collect and slow blood flow. Smoking also increases the risk of blood clots forming in the arteries that can cause myocardial ischemia.
- Diabetes. Diabetes is the inability of your body to adequately produce or respond to insulin properly. Insulin, a hormone secreted by your pancreas, allows your body to use glucose, which is a form of sugar from foods. Both type 1 and type 2 diabetes are linked to an increased risk of myocardial ischemia, heart attack and other heart problems.
- High blood pressure. Over time, high blood pressure can damage arteries that feed your heart by accelerating atherosclerosis. High blood pressure is more common in those who are obese. Eating a diet high in salt also may increase your risk of high blood pressure.
- 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 "bad" (low-density lipoprotein, or LDL) cholesterol in your blood is linked to an increased risk of atherosclerosis and myocardial ischemia. A high LDL level may be due to an inherited condition or a diet high in saturated fats and cholesterol. A high level of triglycerides, another type of blood fat, may also contribute to atherosclerosis. 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.
- Lack of physical activity. An inactive lifestyle contributes to obesity and is associated with higher cholesterol and triglycerides and an increased risk of atherosclerosis. People who get regular aerobic exercise have better cardiovascular fitness, which is associated with a decreased risk of myocardial ischemia and heart attack. Exercise also lowers high blood pressure.
- Obesity. Obese people have a high proportion of body fat, often with a body mass index of 30 or higher. Obesity raises the risk of myocardial ischemia because it's associated with high blood cholesterol levels, high blood pressure and diabetes.
- Waist circumference. A waist circumference of more than 35 inches (88 centimeters) for women and 40 inches (102 cm) or more in men increases the risk of heart disease.
- Family history. If you have a family history of heart attack or coronary artery disease, you may be at increased risk of myocardial ischemia.
Complications
Myocardial ischemia can lead to a number of serious complications, including:- Heart attack (myocardial infarction). If a coronary artery becomes completely blocked, the lack of blood and oxygen can lead to a heart attack that destroys part of the heart muscle, causing serious and in some cases fatal heart damage.
- Irregular heart rhythm (arrhythmia). Your heart muscle needs sufficient oxygen to beat properly. When your heart doesn't receive enough oxygen, the electrical impulses in your heart that coordinate your heartbeats may malfunction, causing your heart to beat too fast, too slow or irregularly. In some cases, arrhythmias can be life-threatening.
- Heart failure. Myocardial ischemia can damage the heart muscle itself, leading to a reduction in its ability to effectively pump blood to the rest of your body. Over time, this damage may lead to heart failure
Tests and diagnosis
Along with a review of your medical history and a thorough physical exam, the tests and procedures used to diagnose myocardial ischemia include:- Electrocardiogram (ECG).This test records the electrical activity of your heart via electrodes attached to your skin. Certain abnormalities in your heart's electrical activity may indicate myocardial ischemia.
- Echocardiogram. This test uses sound waves to produce an image of your heart. During an echocardiogram, sound waves are directed at your heart from a wand-like device (transducer) 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 and isn't pumping normally.
- 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 flows through your heart and lungs. Areas of reduced blood flow to the heart muscle — through which less of the radioactive material flows — appear as dark spots on the scan.
- Coronary angiography. Coronary angiography uses X-ray imaging to examine the inside of your heart's blood vessels. During coronary angiography, a type of dye that's visible by X-ray machine is injected into the blood vessels of your heart. The X-ray machine rapidly takes a series of images (angiograms), offering a detailed look at the inside of your blood vessels.
- Cardiac CT scan. CT scans can determine if you have coronary artery calcification — a sign of coronary atherosclerosis. The heart arteries also can be seen using CT scanning (coronary CT angiogram).
- Stress test. A stress test usually involves walking on a treadmill or riding a stationary bike while your heart rhythm, blood pressure and breathing are monitored. Because exercise makes your heart pump harder and faster than it does during most daily activities, a stress test can reveal problems within your heart that might not be noticeable otherwise. It can be particularly useful if your doctor suspects you may have myocardial ischemia but you don't have any signs or symptoms.
- Holter monitoring. A Holter monitor is a small, wearable device that records your heart rhythm. You usually wear a Holter monitor for one to two days. During that time, the device will record all of your heartbeats. A Holter monitor test is usually performed if an electrocardiogram isn't able to give your doctor enough information about your heart's condition or if your doctor suspects silent myocardial ischemia
Treatments and drugs
Treatment of myocardial ischemia is directed at improving blood flow to the heart muscle. Depending on the severity of your condition, you may be treated with medications, undergo a surgical procedure or both.
Medications
Medications that can be used to treat myocardial ischemia include:
- Aspirin. Your doctor may recommend taking a daily aspirin or other blood thinner. This can reduce the tendency of your blood to clot, which may help prevent obstruction of your coronary arteries. There are some cases where aspirin isn't appropriate, such as if you have a bleeding disorder or if you're already taking another blood thinner, so ask your doctor before starting to take aspirin.
- Nitroglycerin. This medication temporarily opens arterial blood vessels, improving blood flow to and from your heart.
- Beta blockers. These medications help relax your heart muscle, slow your heartbeat and decrease blood pressure so blood can flow to your heart more easily.
- Cholesterol-lowering medications. By decreasing the amount of cholesterol in your blood, especially low-density lipoprotein (LDL), or "bad," cholesterol, these drugs decrease the primary material that deposits on the coronary arteries.
- Calcium channel blockers. Calcium channel blockers, also called calcium antagonists, relax and widen blood vessels by affecting the muscle cells in the arterial walls. This increases blood flow in your heart. Calcium channel blockers also slow your pulse and reduce the workload on your heart.
- Angiotensin-converting enzyme (ACE) inhibitors. These drugs help relax blood vessels and lower blood pressure. ACE inhibitors prevent an enzyme in your body from producing angiotensin II, a substance in your body that affects your cardiovascular system in numerous ways, including constricting your blood vessels.
- Ranolazine (Ranexa). This medication helps relax your heart arteries. Ranolazine is an anti-angina medication that may be prescribed with other angina medications, such as calcium channel blockers, beta blockers or nitroglycerin.
Procedures to improve blood flow
Sometimes more aggressive treatment is needed to improve blood flow. Surgical procedures that may help include:
- Angioplasty and stenting. During angioplasty — also called a percutaneous coronary intervention (PCI) — your doctor inserts a long, thin tube (catheter) into the narrowed part of your artery. A wire with a tiny, deflated balloon is passed through the catheter to the narrowed area. The balloon is inflated to widen the artery, and then a small wire mesh coil (stent) is usually inserted to keep the artery open. Some stents slowly release medication to help keep the artery open. This procedure improves blood flow in your heart, reducing or eliminating myocardial ischemia.
- Coronary artery bypass surgery. During this procedure, a surgeon creates a graft to bypass blocked coronary arteries using a vessel from another part of your body. This allows blood to flow around the blocked or narrowed coronary artery. Because this requires open-heart surgery, it's typically reserved for cases of multiple narrowed coronary arteries.
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