What is vasovagal syncope?

Also known as the "common faint," vasovagal syncope (pronounced vay-zoh-Vay-gul Sing-kuh-pee) results from an abnormal circulatory reflex and could be caused by a number of factors.

In vasovagal syncope, the heart pumps more forcefully and the blood vessels relax. However, the heart rate does not compensate enough to maintain blood flow. In other words, the heart rate slows, and the blood vessels in the person's legs widen (dilate.) This allows blood to pool in the legs, which lowers blood pressure.

The combination of the drop in blood pressure and slowed heart rate quickly reduces blood flow to the brain, and the person faints.

Suspected causes include:

  • Environment — being in a hot and/or crowded setting
  • Emotional — high stress or feeling threatened
  • Physical — standing too long or getting up too quickly from a sitting position
  • Illness — fatigue, low blood sugar, dehydration or other illnesses

Unlike a seizure, the person who faints usually becomes alert soon after regaining consciousness. Three percent of adults ages 30 to 62 have had an episode of syncope, but 6 percent of those older than 75  faint.

Syncope accounts for 1 percent to 3 percent of emergency department visits and 1 percent to 6 percent of hospital admissions. The biggest risk is in people with heart disease, especially those with congestive heart failure or coronary heart disease.

Oftentimes, there's no real cause for vasovagal syncope, but common triggers could include standing for long periods of time, excessive heat exposure, dehydration, having blood drawn, or straining, such as to have a bowel movement.

For someone with Alzheimer's, it might be difficult to ascertain when they might faint. The caregiver can look for some signs if their loved one is experiencing the following: pale skin and lightheadedness, feeling warm, yawning a lot, having cold and clammy skin or becoming nauseous.

If it's believed someone is going to faint, they should lie down and lift their legs. When vasovagal syncope occurs, caregivers might observe a jerky, abnormal movement of their loved one and/or dilated pupils. The pulse will be slow and weak. Generally, recovery occurs in less than a minute.

Most diagnoses of vasovagal syncope are made through a thorough medical history and physical exam, along with ECG testing. Keep in mind that vasovagal syncope/fainting can also be a sign of a more serious condition, so a doctor should be kept abreast of an individual's history with the episodes.


Questions about Alzheimer's disease or a related disorder can be sent to Dana Territo, the Memory Whisperer, director of services at Alzheimer's Services of the Capital Area at advice@alzbr.org or visit the organization at 3772 North Blvd., Baton Rouge.