The common reason behind each fainting episode is a temporary lack of oxygen-rich (red) blood getting to the brain. However, many different problems can cause a decrease in blood flow to the brain. Some causes of syncope include:
- Vasovagal syndrome (or neurocardiogenic syncope). A sudden drop in blood pressure with or without a decrease in heart rate. It is caused by a problem with the nerves controlling the heart and blood vessels. This is the most common cause of syncope and can follow periods of extreme emotion.
- Arrhythmia. A heart rate that is too slow, too fast, or too irregular to keep enough blood flow to the body, including the brain. This is a fairly rare cause of syncope.
- Structural heart disease (muscle or valve defects). There may be problems with the heart muscle or one or more of the heart valves. This may cause a decrease of blood flow to the body, including the brain. Inflammation of the heart muscle known as myocarditis can also cause fainting. The heart muscle becomes weak and is not able to pump as well as normal. The body again reacts to decreased blood flow to the brain by fainting.
- Orthostatic hypotension. This is a drop in blood pressure that occurs when a person has been standing for a while, or changes from a sitting to a standing position. Blood pools in the legs, preventing a normal amount of blood from being pumped to the brain. This brief drop in blood flow to the brain causes a person to faint. This more commonly occurs in senior adults.
Other situations or illnesses that can cause syncope include:
- Head injury
- Inner ear problems
- Low blood sugar
- Breath holding episodes
- Brain mass
- Aneurysm or abnormality of the blood vessels of the brain
- Having a bowel movement
Some children will have symptoms before they faint. A child may have:
- Changes in his or her vision
- Cold, damp skin
There may be enough warning signs that your child will have time to sit or lie down before fainting occurs. This can prevent injuries that may happen because of falling during syncope, such as head injury.
The healthcare provider will ask about your child’s symptoms and health history. He or she will give your child a physical exam. Helpful details you can provide include answers to these questions:
- How often does syncope occur?
- What your child was doing before the syncope?
- Did your child had any symptoms before the syncope?
- What did he or she ate before the syncope?
- What happened during and after the syncope?
- Was the syncope witnessed?
- How long did the period of loss of conscious persist after syncope?
The provider will check your child's blood pressure and heart. Your child’s blood pressure is usually checked more than once in different positions. It may be taken while your child is lying down sitting, and standing. The provider will look for changes in blood pressure that occur with orthostatic hypotension.
Often your child will not need any tests. If your child's provider thinks there may be a serious problem, he or she may refer you to a pediatric cardiologist. This is a doctor with special training to treat heart problems in children. He or she may order tests, such as:
- Electrocardiogram (ECG). This test records the electrical activity of the heart. It shows any abnormal rhythms (arrhythmias) and problems with heart function.
- Tilt table test. This test checks a child's blood pressure and heart rate while he or she is in different positions.
- Holter monitor. This test uses a portable monitor that your child wears for 24 hours or longer. It is used to evaluate irregular, fast, or slow heart rhythms while your child does his or her normal activities, even while away from the provider's office.
- Echocardiogram (echo). This test studies the heart's function. It uses sound waves (ultrasound) to make a moving picture of the heart and heart valves, pumping function, and blood flow through the heart.
After an episode of syncope, your child should lie down for 10 to 15 minutes. Or, your child can sit with his or her head between the knees. Give your child a drink of water.
Work with your child's healthcare provider to figure out the cause and ways to prevent further syncope.
If a heart problem is the cause of syncope, the pediatric cardiologist will figure out what treatment is needed.
Occasionally, the problem can also be due to a brain problem and may require consultation with a pediatric neurologist.
To prevent passing out caused by dehydration:
- Stay hydrated. Be sure your child stays well hydrated. Encourage him or her to drink plenty of water.
- Increase salt intake. Try non-fat salty snacks such as pretzels or crackers.
If passing occurs when standing too long:
- Advise your child not to lock his or her knees when standing.
- Advise your child to promote blood flow by relaxing and tightening the leg muscles.
If your child has passed out upon standing:
- Make sure your child sits up slowly, lets his or her legs hang off the bed, and tell him or her to wiggle the toes and take a few deep breaths before standing up.
If your child feels like he or she may pass out, advise him or her to sit or lie down quickly.
Call your child's provider if he or she has syncope, especially if:
- It continues even with preventive efforts
- It occurs with irregular heartbeats
- It occurs with exercise
- You have a family history of syncope
- There is no known cause
- It occurs unpredictably and in dangerous situations
- Injuries occur afterwards
- Syncope is a brief loss of consciousness and muscle tone. It’s caused when the brain doesn’t get enough blood.
- It is usually harmless, but in a small number of children, it is caused by a heart problem.
- Syncope is usually diagnosed with a health history and physical exam, including checking blood pressure and heart rate.
- If there is no serious cause, syncope is managed by finding the cause and learning ways to prevent it.
Tips to help you get the most from a visit to your child’s healthcare provider:
- Know the reason for the visit and what you want to happen.
- Before your visit, write down questions you want answered.
- At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you for your child.
- Know why a new medicine or treatment is prescribed and how it will help your child. Also know what the side effects are.
- Ask if your child’s condition can be treated in other ways.
- Know why a test or procedure is recommended and what the results could mean.
- Know what to expect if your child does not take the medicine or have the test or procedure.
- If your child has a follow-up appointment, write down the date, time, and purpose for that visit.
- Know how you can contact your child’s provider after office hours. This is important if your child becomes ill and you have questions or need advice.
January 16, 2018
causes of syncope in children and adolescents, Up To Date
Gandelman, Glenn, MD, MPH,Bass, Pat F., III, MD, MPH