Syncope, or fainting, is a medical problem that can have many different causes. It may occur rarely or frequently. Causes of syncope may 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 dysfunction of the nerves controlling the heart and blood vessels.
Arrhythmia (or dysrhythmia). A heart rate that is too slow, too fast, or too irregular to maintain adequate blood flow to the body.
Structural heart disease (abnormalities of the heart muscle or valves). Enlargement of the heart muscle or malfunction of one or more of the heart valves may cause an obstruction of the blood flow within the heart.
When a doctor sees a child with a complaint of syncope, the doctor will carefully evaluate the child's past medical history and perform a physical exam as well as an electrocardiogram (ECG) and often an echocardiogram (ultrasound exam of the heart). If basic components of the exam or history do not reveal a potential cause for the syncope, and the child has no history of heart disease or a heart condition, then further diagnostic procedures, such as a tilt table procedure, may be scheduled.
The tilt table procedure attempts to identify the cause for the onset of syncope by making changes in posture from lying to standing. This is done by having the child lie flat on a special bed or table with safety belts and a footrest while connected to ECG and blood pressure monitors. The bed or table is then elevated to an almost standing position to simulate the child standing up from a lying position. The blood pressure and ECG are measured during the test to evaluate changes during the position changes. If the test causes an episode of syncope, then the probable cause of the syncope is vasovagal syndrome. The doctor can then prescribe specific treatment for the syncope once the cause is known. Sometimes medications are given through an IV or by mouth to increase the sensitivity of the test, and the procedure is repeated.
If the test does not cause an episode of syncope, and/or the ECG and blood pressure recordings do not detect an abnormality, then additional tests or procedures may be scheduled to gather further diagnostic information.