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Fainting (Syncope)

What is fainting?

It is a brief, sudden loss of consciousness. You become unresponsive, lose muscle tone, and may fall. Usually, there is complete recovery in a matter of seconds to a few minutes.

It is fairly common. The medical term for fainting is syncope.

How does it occur?

There are many different reasons for syncope. Usually it is not caused by a serious or life-threatening medical problem. However, if you are known to have heart disease, or you lose consciousness during even mild exercise, the cause may be serious and you may need prompt medical attention.

One of the most common and least worrisome reasons for syncope is anxiety or other emotional upset.

You may lose consciousness if you have not had enough liquids, especially if you stand up too quickly. This happens more often after illness or working in the hot sun.

As people age, the ability of the nervous system to control blood pressure becomes less sensitive. Rising from a lying to a standing position, or standing for a long time, may cause low blood pressure. This condition, called orthostatic hypotension, can cause loss of consciousness. This happens because not enough blood is pumped from the heart to the brain. It can be worse right after eating.

Low blood sugar from diabetic treatment or other causes can also cause fainting.

Some medicines, such as diuretics (water pills) and blood pressure-lowering medicines may cause fainting.

A common type of syncope is called vasovagal syncope. It can happen when you take a deep breath and push down but don't allow yourself to breathe out. You may do this, for example, when you urinate or have a bowel movement or when you cough hard or long. Vasovagal syncope can also occur if you stand in one place for too long.

Before you lose consciousness, you may feel giddy, lightheaded, or flushed. The syncope is caused by nerve impulses that slow the heart rate. As a result, the heart temporarily pumps less blood to the brain. This is the most common cause of fainting in healthy young adults.

Temporary pressure on a sensitive spot in the neck causes syncope in some people.

Sometimes heart problems cause syncope.

Irregular heart rhythms are the most common heart-related cause of syncope. The heart may beat so rapidly that too little blood gets to the brain. Or a very slow heart rate caused by heart block or pacemaker failure may cause syncope.

Some heart attacks immediately damage the pumping muscle and cause syncope.

Abnormal heart valves can cause drops in blood pressure that lead to syncope.

Loss of consciousness also occurs because not enough oxygen is getting to the brain.

What are the symptoms?

You may lose consciousness suddenly without any symptoms. Or at first you may feel nauseous or sweaty. If your fainting is caused by a heart problem, you may have a fast or irregular pulse. Sometimes people say they felt like their heart was jumping around in their chest. You may feel short of breath or pressure in your chest. If you have a heart valve problem, you may have some chest pain, especially with exertion, before you faint.

How is it diagnosed?

Your healthcare provider will ask about your medical history, particularly about the times you have fainted. How you felt before and after you lost consciousness are important facts that can help in making the diagnosis. Your provider will ask about the medicines you take and will examine you.

Depending on your age and health history, your healthcare provider may want to do some tests.

If your healthcare provider thinks a heart problem may be the cause of losing consciousness, you may have an electrocardiogram (ECG or EKG). The ECG records the electrical impulses from your heart. If the first ECG is normal, your provider may want to monitor your heart for a longer period of time. A special type of ECG called a Holter monitor can be worn for 1 to 3 days to make a recording of your heart rhythm, or another type of monitor called an event recorder can be used for several weeks at a time.

You may have an ultrasound test of the heart called an echocardiogram to see if there are any problems with the heart muscle or the heart valves.

You may have a stress test which will give information about the heart rhythm and the blood flow to the heart.

You may have a chest X-ray.

A tilt table test helps to diagnose syncope. In this test, your blood pressure is measured while the table on which you are lying is progressively tilted toward the head-up position.

Sometimes your healthcare provider may order a test of the electrical system of the heart called an electrophysiology study.

Even with all these tests, the exact cause for syncope may not be discovered.

How is it treated?

The treatment of syncope is based on the cause.

If vasovagal syncope is the problem, pay attention to what happens right before you faint. When you have these symptoms, take precautions to avoid losing consciousness, or to stop from getting hurt if you do faint. For example, try to lie down before you lose consciousness.

A careful review by your healthcare provider of the medicines and dosages you take can eliminate drugs as a cause for fainting.

Orthostatic hypotension, or a marked fall in blood pressure when you are standing up, can be helped by wearing support hose. Getting up slowly from lying or sitting also helps.

Heart-related problems can often be repaired. Heart valves causing blockage can be replaced. Pacemakers can be inserted to correct very slow heart rates.

How do I prevent syncope?

Follow your healthcare provider's instructions carefully.

Drink plenty of liquids, especially in hot weather.

Eat a healthy diet and eat at regular times throughout the day.

Let your healthcare provider know if your symptoms are getting worse or happening more often, and if you have had a recent change in medicines.

Published by McKesson Corporation.

This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.

SBI!