Alternative names:
Fainting, loss of consciousness, "passing out"
What is syncope?
What are the signs of syncope?
What causes syncope?
How does my doctor tell
if I have syncope?
How is syncope treated?
What is syncope?
Syncope (SIN'ko-pe) is a brief loss of consciousness caused by a drop in blood flow to the brain. This is commonly known as fainting, or "passing out." Most syncope is fairly harmless, but when it is caused by a cardiac problem, it can be life-threatening.
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What are the signs of syncope?
People with syncope may:
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Faint or black out at any time, especially after a meal or exercise |
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Fall without a cause |
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Feel light-headed or dizzy |
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Feel "wobbly" or weak when standing |
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Feel nauseous |
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Have chest pain, or shortness of breath |
If you faint after exercise, faint frequently, and/or have a family history of sudden death, you should be examined by a doctor immediately.
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What causes syncope?
You faint from a sudden drop in blood pressure, and because your brain isn't getting enough blood. This can happen if you stand up very suddenly after lying down. Other reasons for syncope include hyperventilation, overheating, low blood sugar, dehydration, and the use of alcohol or drugs. It can be a side effect of medications for anxiety, high blood pressure, nasal congestion, and allergies.
Syncope can also be the symptom of a deeper problem with your nervous system, blood circulation, or heart. Cardiac syncope is most often caused by an abnormal heart rhythm (arrhythmia), which means the heart isn't pumping blood properly. It can also be a symptom of valvular disease, heart artery narrowing, and a heart attack.
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How does my doctor tell if I have syncope?
To find the root cause of your syncope, your doctor will first ask:
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When does your fainting occur? |
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How often do you faint? |
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Do you notice any symptoms—such as chest pain—before you faint? |
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Do you have a family history of fainting, seizures, or heart problems? |
If your doctor suspects that heart problems may be causing your syncope, he or she may use some of the following tests:
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An electrocardiogram (ECG or EKG) measures the electrical activity of your heart. It helps your doctor see how well your heart beats, and can tell if your heart muscle has been damaged in any way. A technician puts small metal disks—electrodes—on your skin to read the pattern of electrical impulses from your heart. The test only takes a few minutes, and is often used to diagnose a heart arrhythmia, or irregular heartbeat. |
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A chest X-ray |
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An echocardiogram uses sound waves to make a picture of your heart. Your doctor sees this image on a television monitor, and can examine how well your heart works. The test takes about 45 minutes, and is painless. |
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A Holter monitor provides a non-stop reading of your heart rate and rhythm as you go about your daily activities. You wear the small monitor at all times, and it makes a record of your heart's electrical activity, much like an electrocardiogram. This gives your doctor valuable information about what happens to your heart when you feel an arrhythmia (irregular hearbeat), or chest pain (angina). Holter monitors are most often used for a day or two. |
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In a treadmill stress test, a patient is first hooked up to monitoring equipment, which may include an electrocardiogram, and then told to walk slowly on a treadmill. A technician adjusts the speed and angle of the treadmill to make the patient's heart work harder. Afterwards, the technician may perform an echocardiogram. |
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A tilt-table exam shows how a patient's heart reacts to a quick change of position and prolonged standing. The patient lies flat on a table which is then rapidly tilted to 65 degrees. Sometime a doctor may give a patient various medications during the test to help find the best treatment for a patient's fainting episodes. |
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How is syncope treated?
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When syncope is thought to be a result of emotional stress (simple fainting), treatment is usually not required |
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When due to an underlying heart condition, such as heart valve disease, correcting the underlying problem is the best approach |
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When due to an abnormally slow heart rate, treatment with pacemaker placement may be necessary |
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