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Fainting (Vasodepressor Syncope) in Children


  • More than 20% of children will experience at least 1 fainting episode before the end of adolescence.
  • Over 75% of “passing out” is non-cardiac (vasovagal or neurocardiogenic syncope) and the result of our nervous system causing a sudden drop in blood pressure which results is a temporary lack of oxygen to the brain. (Figure 1 and 2)
  • More common in females than males
  • Incidence peaks in ages 15-19 years
  • Children <6 years of age most commonly faint from seizure, breath holding spells, or cardiac arrhythmia
  • Most patients will experience symptoms immediately before fainintg consisting of lightheadedness, vision changes (tunnel vision or blacking out), feeling hot, sweating, nausea, or turning pale
  • Most patients can be treated with aggresive hydration and NOT require medication

How Does Vasodepressor Syncope (Fainting) Occur?

I like to explain it like this:

Think of a water bottle (Figure 1).  When it is completely full, it doesn’t matter which way you turn the bottle (upright, on its side, upside down), there is always fluid in every space (Figure 2).


Now think of a bottle of water that is ½ or ¾ full, and try to turn it in different directions (Figures 3 and 4).

When it is on its side, there is an equal amount of fluid at each end.  But, when you flip the bottle upright, what happens?  GRAVITY pulls the water down to the bottom of the bottle, and there is a gap of air left at the top.


Our bodies are very similar to that bottle of water.  When we are lying flat on our back, there is an equal amount of fluid in our legs as in our head and neck.  However, when we stand up, gravity pulls the fluid down to our legs and feet and there is a temporary gap left at the top (OUR BRAIN!). This results is a brief loss of oxygen to the brain, which causes the sensation of lightheadedness and can cause someone to “pass out”.

Fainting is actually our body’s way of “re-setting” itself in some circumstances, whereby taking us to the ground ensures the fluid is again restored to the brain.

Other ways our bodies try to compensate is to increase the heart rate, beat more forcefully, or constrict the blood vessels in the lower part of our body as a way to force blood toward the top of our body.

Other causes of syncope (fainting) include Reflex Syncope (fainting at the site of blood or experiencing pain) or Convulsive Syncope (can mimic seizure activity).

Red Flags That Fainting Could Be Something More Serious

Fainting could indicate something more serious …

  • …if you experience no symptoms ahead of fainting
  • …if you faint during physical exertion (Note: lots of adolescents can faint with physical exertion but most of the time the fainting occurs just AFTER they have stopped the activity. An example is a child fainting mid stride while running vs. a child feeling lightheaded, nauseated, flushed and stops running then faints)
  • …if you experience racing heart beat or palpitations before fainting
  • …if you have a family history of sudden cardiac death, death at an early age for unexplained reasons, or have a family member who has an implantable defibrillator
  • …if you experience seizure-like activity during the episode
  • …if you wake up disoriented or extremely fatigued requiring you to immediately take a nap

A complete history and physical exam is enough to establish the diagnosis in the majority of cases.

Diagnosing Fainting Issues

The following are some of the ways in which we diagnose fainting in children:

  • A complete history and physical exam is enough to establish the diagnosis in the majority of cases.
  • Blood pressures taken lying, sitting, and standing
  • 12 lead Electrocardiogram
  • Exercise stress test if fainting occurs with exertion
  • Ambulatory ECG monitoring
  • Occasionally an echocardiogram to ensure there is normal heart function and no obstruction to blood flow out of the heart
  • Rarely a tilt table test

Possible Treatments for Fainting

The following are some of the ways in which we treat fainting:

  • Aggressive hydration – 60-80 ounces of non-caffeinated fluid per day, with at least 20 ounces of fluid containing electrolytes
  • Liberalizing salt intake with healthy salty snacks such as pretzels or peanut butter
  • Sitting with ankles crossed or frequently tensing the calf muscles or abdominal muscles
  • Other physical counter maneuvers
  • Moderate aerobic and isometric exercise
  • Paced breathing

Learn more about the complex conditions we treat at WakeMed Physician Practices – Pediatric Cardiology, including fainting/syncope, heart murmurs, palpitations and more.

About Jennifer Whitham, MD

Dr. Jennifer Whitham is a pediatric cardiologist at WakeMed with clinical interests in congenital heart disease, fetal cardiology, and functional cardiac assessment. She enjoys helping children with heart disease survive, thrive and live up to their fullest potential.

Request an appointment with Dr. Whitham today.