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Syncope or Fainting Spells

What is syncope?

Syncope (pronounced “sin-cope–ee”) is the medical term for a fainting spell. It refers to a transient loss of consciousness due to a problem with the blood circulation.


Why does syncope occur?

There are 2 reasons why syncope occurs.

Abnormally low blood pressure
  • Syncope may result from an abnormally low BP due to inappropriate blood vessel relaxation triggered by the involuntary nervous system. This fall in BP causes low blood flow to the brain resulting in dizziness and fainting. Falling to the ground improves blood flow to the brain which returns you to consciousness, as the nervous system corrects itself.
  • The involuntary nervous system is responsible for tightly regulating the blood supply to the body’s peripheries and vital organs. It does so by co-ordinating nerve signals between the blood vessels, organs and the brain. It is not fully understood why it sometimes lowers the BP inappropriately, though there are often identifiable triggers such as infection, dehydration and the sight of blood.
  • This form of syncope is called neutrally mediated syncope, or a simple faint. It may also be referred to as neurocardiogenic, vasovagal, or vasodepressor syncope. All these names refer to the same problem, which is both common and can occur in otherwise perfectly healthy individuals.
Abnormal heart rate
  • Syncope may result from an arrhythmia with an abnormally fast or slow heart rate.
  • Abnormally fast heart rates are called tachyarrhythmias. These may arise from the upper or lower chambers of the heart. Excessively fast heart rates leave the heart with insufficient time to fill and pump effectively, resulting in syncope.
  • Abnormally slow heart rates are called bradyarrhythmias. These most commonly relate to aging of the heart’s normal electrical system which causes intermittent electrical failure of the sinus node, the AV node, or both. Medications, especially some used for tachyarrhythmias or for high BP, may interfere with normal electrical function by slowing down the heart’s circuitry.


What tests do I require for syncope?

You may require the following initial tests.

  • Blood tests – To determine if there is an underlying condition that has provoked your syncope.
  • ECG – To evaluate your heart rhythm.
  • Holter monitor – To evaluate your heart rhythm over a 24 h period for arrhythmias.
  • Echocardiogram – To evaluate the structure and function of your heart.

A holter monitor will often be normal when there is an electrical problem because the problem only occurs infrequently. If an arrhythmia is strongly suspected, it may be necessary to repeat the holter monitor or perform an extended holter monitor to identify the problem.

Learn more about the different Heart Tests here.


Implantable loop recorder

Implantation of a cardiac device called a loop recorder (ILR) may also be useful. This is a small recording device about the size of a computer USB stick that is implanted just underneath the skin over the chest. This is done in a simple day procedure taking 20 to 30 minutes. The loop recorder continuously monitors your heart rhythm 2 years and can provide diagnostic tracings of your rhythm during episodes.


What treatments are available for syncope?

  • Simple fainting spells. This is normally treated very effectively with simple measures. These include hydration, recognition, and antigravity measures. Medications are rarely necessary and are useful in only a small number of cases. Learn more about preventing simple faints here.
  • Tachyarrhythmias. Treatment depends on the type of arrhythmia and typically involves medications and/or catheter ablation. For individuals at high risk for dangerous tachyarrhythmias, an implantable cardioverter-defibrillator or ICD may be required to monitor the heart for arrhythmias and deliver a life-saving electrical shock when necessary.
  • Bradyarrhythmias. The first step is to stop unnecessary medications that may be slowing the heart rate down. If bradyarrhythmia remains a risk, treatment involves implantation of a cardiac device called a pacemaker to serve as a backup signal generator for the heart.