Vasovagal syncope (vay-zo-VAY-gul SING-cuh-pee) is the most common cause of fainting. Vasovagal syncope occurs when your body overreacts to triggers, such as the sight of blood or extreme emotional distress. The trigger results in vasovagal syncope — a brief loss of consciousness caused by a sudden drop in your heart rate and blood pressure, which reduces blood flow to your brain.
Vasovagal syncope is usually harmless and requires no treatment. However, you can injure yourself during a vasovagal syncope episode. Also, your doctor may recommend tests to rule out more serious causes of fainting, such as heart disorders.
Before a faint due to vasovagal syncope, you may experience some of the following:
When to see a doctor
Vasovagal syncope occurs when the part of your nervous system that regulates heart rate and blood pressure malfunctions in response to a trigger, such as the sight of blood. Your heart rate slows, and the blood vessels in your legs widen. This allows blood to pool in your legs, which lowers your blood pressure. This drop in blood pressure and slowed heart rate quickly diminish blood flow to your brain, and you faint.
Although vasovagal syncope can occur at any age, it's being recognized as an increasingly important cause of fainting in the elderly.
Common triggers for vasovagal syncope include:
Preparing for your appointment
It's a good idea to prepare for your appointment to make the most of your time with your doctor.
What you can do
What to expect from your doctor
During the physical exam, your doctor will listen to your heart and take your blood pressure. He or she may also massage the main arteries in your neck to see if that causes you to feel faint.
Tests and diagnosis
The diagnosis of vasovagal syncope often involves ruling out other possible causes of your fainting — particularly heart-related problems. These tests may include:
Tilt table test
Treatments and drugs
In most cases of vasovagal syncope, treatment is unnecessary. Your doctor may help you identify your fainting triggers and discuss ways you can avoid them. However, if you experience vasovagal syncope often enough to interfere with your quality of life, your doctor may suggest trying one or more of the following remedies.
If you feel like you might faint, lie down and lift your legs. This allows gravity to keep blood flowing to your brain. If you can't lie down, sit down and put your head between your knees until you feel better.
Last Updated: 2010-08-07
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