Syncope

Syncope, also known as fainting, or a sudden and brief loss of consciousness, occurs when the brain does not get enough blood flow and oxygen.

There are many causes of syncope. A common type of syncope — vasovagal syncope or neurocardiogenic syncope — is caused by a malfunction of the nerves that control the action of the heart and blood vessels, called the autonomic nervous system. This type of syncope may be triggered by fear, severe pain, emotional distress or standing for a long time. Dehydration and low salt intake may also contribute to the condition.

Syncope may also be caused by very fast heart rhythms or arrhythmias called tachycardias, as in supraventricular tachycardia (SVT) or ventricular tachycardia. In some cases, syncope is caused by very slow heart rhythms, called bradycardias, as in sinus node dysfunction or heart block.

The hallmark symptom of syncope is fainting, or near fainting. The condition may also cause the following symptoms:

  • Chest pressure or pain
  • Fatigue
  • Lightheadedness or dizziness
  • Palpitations, which can be skipping, fluttering or pounding in the chest
  • Shortness of breath

Syncope or near syncope may occur spontaneously with unpredictable timing. Therefore, in many cases, specialized tests are needed to make an accurate diagnosis. Your child's doctor may order one or more of the following diagnostic tests to determine the source of your child's symptoms.

  • Electrocardiogram (ECG or EKG) — An electrocardiogram records the heart's electrical activity. Small patches called electrodes are placed on your child's chest, arms and legs, and are connected by wires to the ECG machine. The electrical impulses of your child's heart are translated into a graph or chart, enabling doctors to determine the pattern of electrical current flow in the heart and to diagnose arrhythmias.
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Because there are various reasons for syncope, the treatment for your child's syncope will depend on the cause. Syncope may be caused by very fast heart rhythms — tachycardias — such as in supraventricular tachycardia (SVT) or ventricular tachycardia. In other cases, syncope may be caused by very slow heart rhythms — bradycardias — such as in sinus node dysfunction or heart block.

If your child's syncope is due to a blood pressure problem, medications, extra fluid intake and salt may be recommended.

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Reviewed by health care specialists at UCSF Benioff Children's Hospital.

Related Information

UCSF Clinics & Centers

Heart Center

Arrhythmia Center
1825 Fourth St., Sixth Floor
San Francisco, CA 94158
Phone: (415) 514-2783
Fax: (415) 353-4144
Appointment information

Pediatric Heart Center Clinic at Mission Bay
1825 Fourth St., Sixth Floor
San Francisco, CA 94158
Phone: (415) 353-2008
Fax: (415) 353-4144
Appointment information

Cardiac Intensive Care Unit
1975 Fourth St., Fourth Floor
San Francisco, CA 94158
Phone: (415) 353-1955
Fax: (415) 353-9144