Dr. Jeff Hersh: Dealing with a fainting spell

Dr. Jeff Hersh

Q: My wife and I were at the beach and she passed out. We went to the ER, but all they did was ask a bunch of questions, examine her and check an EKG. Then they sent us home. Does this sound right?

A: Probably.

Fainting/passing out (the medical word is syncope) is a temporary loss of consciousness and postural tone (going limp), usually lasting seconds to a minute or so. Since the brain is not able to store the high-energy phosphates it needs to function, a loss of adequate blood supply for even just three to five seconds is enough for it to temporarily shut down. Therefore, the typical cause of syncope is insufficient blood supply to the brain (cerebral hypoperfusion), with exceptions being when a toxic condition such as low blood sugar, drug abuse or others is implicated.

Syncope is very common; 30 percent to 50 percent of the population will have a fainting episode in their lifetime and it is responsible for 1 percent to 3 percent of all ER visits. It is much more common as we age, but does occur in kids; for example, breath-holding spells are an uncommon cause of childhood syncope.

Syncope is really a symptom, not a disease, so evaluation for the underlying cause is indicated. Since seizures, mini-strokes and other conditions can mimic syncope, the first step is to determine if the event was true syncope or something else.

Unknown causes account for more than 35 percent of true syncope episodes. When a cause is identified it is categorized as cardiac or non-cardiac.

Non-cardiac causes of syncope are most often benign; most people who have non-cardiac syncope have no change in their life expectancy.

There are many causes of non-cardiac syncope. The most common is vaso-vagal syncope, where stimulation of the nervous system causes blood pressure to drop and heart rate to decrease leading to cerebral hypoperfusion and syncope.

Other reflex mechanisms that, when inappropriately stimulated, cause cerebral hypoperfusion include an over-sensitive carotid sinus, micturition syncope (fainting from a reflex system activated during urination), emotionally triggered syncope (fainting when you get upset, see blood, etc.) and others.

Dehydration or a low blood count can also lead to syncope, since in either of these cases there may not be enough blood for the heart to pump, leading to cerebral hypoperfusion. Finally, pregnancy and certain other medical conditions can predispose one to fainting.

Cardiac syncope is a more ominous event and is responsible for about 10 percent of syncope cases. In these cases, the cerebral hypoperfusion is from a decrease in blood outflow from the heart. Causes can include an abnormal heart rhythm or mechanical obstruction of blood flow, such as from idiopathic hypertrophic subaortic stenosis or certain heart valve problems. Cardiac syncope is a marker of the severity of these underlying diseases, and the five-year mortality rate from the underlying heart condition after it occurs can be as high as 50 percent.

The most important evaluation of someone who has fainted is a good history and physical examination. The goal of this is to determine if the patient is at risk for cardiac issues or other serious causes of the syncope.

If there was a prodromal symptom (for example, feeling warm or lightheaded) or the fainting episode occurred during a position change, a non-cardiac cause is more likely. A history of heart rhythm problems or heart failure, as well as certain physical findings or an abnormal EKG, suggest an increased risk of cardiac syncope.

Older patients or those at risk for heart problems, aortic aneurysm, pulmonary emboli or other underlying serious conditions may require further evaluation. For example, patients at risk for heart rhythm problems may require heart monitoring, and those at risk for heart valve diseases may require an echocardiogram. Hospital admission may be indicated for some of these high-risk patients to expedite this evaluation. Low-risk patients are usually followed as outpatients.

Since syncope is really just a symptom, any necessary treatment is aimed at the underlying cause.

If you faint, you should seek medical care to be evaluated for possible high-risk underlying conditions that may have caused your episode. Thankfully, most cases of syncope are benign and not really a cause for concern.

Jeff Hersh, Ph.D., M.D., F.A.A.P., F.A.C.P., F.A.A.E.P., can be reached at