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Cardiac Syndrome X
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Cardiac Syndrome X
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Related terms: angina, microvascular angina

Angina pectoris is a Latin phrase that means "strangling in the chest." Patients often say that angina is like a squeezing, suffocating, or burning feeling in their chest, but an episode of angina is not a heart attack. The pain often happens after exercise. Unlike a heart attack, the heart muscle is not damaged forever, and the pain usually goes away with rest.

Angina attacks are usually caused by coronary artery disease (CAD). Angina is the pain you feel when a clogged or diseased vessel in your heart (called a coronary artery) no longer delivers enough oxygen-rich blood to a part of your heart. The heart's lack of oxygen-rich blood is called ischemia.

Angina usually happens when your heart has an extra need for oxygen-rich blood, such as during exercise. Other causes of angina can be emotional stress, extreme cold or hot temperatures, heavy meals, alcohol, and smoking.

What is cardiac syndrome X?

Cardiac syndrome X is a condition where patients have the pain of angina, but they do not have CAD. So even though patients with cardiac syndrome X have symptoms of CAD, the coronary arteries are clear of blockages.

Cardiac syndrome X is more common in women, especially women who have gone through menopause. It is not life threatening and does not increase your risk of heart attack or CAD.

What are the symptoms?

Patients with cardiac syndrome X have the pain of angina, but they do not have CAD.

The pain of angina starts in the center of the chest, but the pain may spread to your left arm or your neck, back, throat, or jaw. You may have numbness or a loss of feeling in your arms, shoulders, or wrists. Patients with cardiac syndrome X often have chest pain after they exercise.

When patients with cardiac syndrome X have an exercise stress test, the results may look as though they have CAD. But when doctors use a test called coronary angiography to look for blockages in the coronary arteries, the arteries look clear and normal.

What causes cardiac syndrome X?

There are many theories about what causes cardiac syndrome X. Some doctors think it has to do with how patients feel pain, while others think it may be linked to low levels of the female hormone estrogen.

New research has shown that cardiac syndrome X is most likely caused by a form of angina called microvascular angina. In microvascular angina, the small blood vessels in the heart (called capillaries) tighten or constrict. This tightening reduces the blood flow in the heart and causes the pain of angina. But because these capillaries are so tiny, they do not increase the risk of heart attack. They are also too small to detect with the standard tests that doctors would normally use to see larger vessels.

How is cardiac syndrome X diagnosed?

Cardiac syndrome X is usually diagnosed by using many of the same tests used to diagnose CAD. These tests will help your doctor determine if you have cardiac syndrome X and not CAD.

  • A baseline electrocardiogram (ECG or EKG), which records your heart's electrical activity while you sit quietly. An exercise ECG, also known as a stress test, will show how your heart responds to increasing exercise. Both tests are designed to show if your heart is not working properly, most likely due to a lack of oxygen.
  • An exercise radioisotopic test, also called a nuclear stress test, which uses a radioactive substance that is injected into your bloodstream to show how blood flows through your arteries. Doctors can figure out if your heart muscle is damaged or dead, or if you have a serious narrowing in an artery. For people who cannot take an exercise test, medicines can be given that make your heart beat as if you were exercising.
  • Echocardiography, which uses sound waves to produce an image of the heart to see how it is working.
  • Coronary angiography, which is performed in the cardiac catheterization laboratory. After you are given medicine to relax you, dye is injected into your bloodstream to give doctors an x-ray "movie" of heart action and blood flow through your valves and arteries (called an angiogram). Doctors can see the number of blockages that you have and how serious those blockages are.

In patients with CAD, coronary angiography usually shows a blocked artery that slows blood flow to the heart. But in patients with cardiac syndrome X, the test results are completely normal. If you have an abnormal exercise stress test and a normal coronary angiogram, your doctor may suspect that you have cardiac syndrome X.

Before making a firm diagnosis, your doctor may check for other conditions that could be causing your symptoms, including high blood pressure or heart valve disease.

How is cardiac syndrome X treated?

A number of medicines can help relieve the angina pain that comes with cardiac syndrome X.

  • A medicine called nitroglycerin (nitro) can widen or dilate the arteries and improve blood flow to your heart. Nitro can be given through a skin patch, pills, an ointment, or a spray.
  • Beta-blockers "block" the chemical or hormonal messages sent to your heart. When you are under physical or emotional stress, your body sends signals to your heart to work harder. Beta-blockers block the effect these signals have on your heart, so they reduce the amount of oxygen your heart demands.
  • Calcium channel blockers can help to keep your arteries open and reduce your blood pressure by relaxing the smooth muscle that surrounds the arteries in your body. The oxygen demand of the heart is also reduced by these medicines.

You may need to try a number of these medicines before you find the one that works best for you.

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Updated October 2013
Texas Heart Institute Heart Information Center
Through this community outreach program, staff members of the Texas Heart Institute (THI) provide educational information related to the prevention, diagnosis, and treatment of cardiovascular disease. It is not the intention of THI to provide specific medical advice, but rather to provide users with information to better understand their health and their diagnosed disorders. Specific medical advice will not be provided and THI urges you to visit a qualified physician for diagnosis and for answers to your questions.
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