Syncope
Syncope
What is syncope? — "Syncope" is the medical term for fainting. After fainting, a person quickly "comes to" and is OK again. Syncope is very common. About 1 out of every 3 people has it at some point in life. In many cases, syncope is nothing to worry about.
What causes syncope? — Syncope happens when the brain temporarily doesn't get enough blood. One of the most common reasons this happens is called "vasovagal syncope." If you have vasovagal syncope, your body has a reaction in which your heart beats too slowly or your blood vessels expand (or both). This can happen for lots of different kinds of reasons. People can have vasovagal syncope if they:
Have stress from fear or pain (for example, because they are injured or have blood taken for tests)
Stand for too long or are over-tired or overheated
Have an unusual reaction to urinating, coughing, or other body functions
Sometimes vasovagal syncope happens with no clear cause.
People can also have syncope that is not vasovagal. This can happen due to the following problems:
The heart beats too quickly or too slowly because of problems with the heart's electrical system or because of side effects from some medicines.
Something blocks the flow of blood in the heart. This can happen in people who have conditions called "aortic stenosis" (a valve disease) or "hypertrophic cardiomyopathy" (a heart muscle disease).
Your blood pressure drops when you stand or sit up. That can happen if you:
•Do not drink enough water
•Take certain medicines that cause your blood pressure to drop
•Drink alcohol
•Lose a lot of blood (for example, if you get hurt)
•Have a medical condition that affects your blood pressure
Is syncope dangerous? — In many cases it is not dangerous. But it can be dangerous if you fall and hurt yourself when you faint. It can also be dangerous if you faint while driving. To be safe, check with your doctor or nurse before you start driving again after you faint.
Should I see a doctor or nurse? — Yes. Anyone who faints should see a doctor or nurse. Most cases of syncope are not serious. But people can get hurt when they faint. Plus, in some cases syncope is caused by a serious medical condition that should be treated. Knowing what caused you to faint can help you prevent it from happening again.
Tell your doctor or nurse what happened before, during, and after you fainted. If someone was with you when you fainted, that person might be able to tell you what happened. The following information is helpful:
What were you doing before you passed out?
How were you feeling before you passed out?
How long were you passed out?
How well did you recover?
Any past history of fainting?
A list of the medicines you take
Any medical conditions you might have
Your doctor or nurse will ask you a few questions and do an exam. During the exam, the doctor or nurse might:
Check your blood pressure and heart rate when you are lying down, sitting, or standing
Listen to your heart to check whether something might be wrong with your heart valves or heart muscle
Will I need tests? — Yes. Your doctor will do a test called an electrocardiogram (also called an "ECG"). For this test, the doctor will put sticky pads on your chest, belly, arms, and legs. Long, thin wires connect the pads to a machine (figure 1). The device records the electrical activity in your heart. This can show if the pattern of your heartbeats is abnormal.
You might get other tests, too. These could include 1 or more of the following:
Echocardiogram (also called an "echo") – This test uses sound waves to create an image of the heart (figure 2). It allows the doctors to measure the walls and chambers of the heart, see how the heart is pumping and check how the heart valves are working. Heart valves are flaps of tissue that open and close like swinging doors. They help keep blood moving in one direction.
Carotid sinus massage – For this test, a doctor presses on a blood vessel in your neck while watching your electrocardiogram. This can show if your blood vessel is too sensitive to pressure.
Home heart monitor – For home monitoring, you might wear or carry a device around at home. You will keep doing normal activities. One type of monitor records all your heart beats for 1 or 2 days (figure 3). With others, you push a button to record heart beats when you feel symptoms (figure 4).
Tilt table test – For this test, you lie flat on a table. Your doctor then monitors your heartbeats and blood pressure while your body is tilted with your head up (figure 5).
Can syncope be prevented? — You might be able to reduce your chances of fainting again if you:
Learn what causes your syncope:
•If an activity or condition causes your syncope, you can try to avoid it.
•If a medicine causes your syncope, your doctor can help you find an alternative.
•If a heart condition is causing your syncope, your doctor can suggest a treatment.
Lay down with your feet up when you feel like you might faint.
How is syncope treated? — That depends on what is causing your syncope. In many cases, the main treatment is to avoid the situations that cause syncope.
In less common cases, other treatment might be needed. For example, you might need a pacemaker if your heart beats too slowly and this causes syncope. A pacemaker is a device that is put under your skin. Thin wires attach them to your heart. They help the heart beat at a normal speed or in a regular pattern.
What if my child faints? — If your child faints, you should take him or her to see a doctor. Most cases of syncope in children are not serious. Often they are caused by vasovagal syncope. Syncope can also happen in children if:
They hold their breath for too long
Their blood pressure drops when they stand or sit up
They swallow medicines, drugs, or alcohol
They have carbon monoxide poisoning
In less common cases, syncope in children can be caused by a life-threatening condition, such as a serious heart condition, overheating, or a severe allergic reaction (called anaphylaxis).
All topics are updated as new evidence becomes available and our peer review process is complete.
This topic retrieved from UpToDate on: Mar 30, 2020.
Topic 15704 Version 10.0
Release: 28.2.2 - C28.105
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