Syncope is a brief loss of consciousness (fainting) that occurs most often when blood pressure and heart rate are too low and the heart doesn't pump enough blood to the brain. Syncope sometimes can be accompanied by nausea and vomiting, headache, confusion, lightheadedness, dizziness, and sweating. These symptoms are usually temporary. Syncope can be episodic or a sign of an underlying medical condition or neurologic disorder, such as postural orthostatic tachycardia syndrome, stroke, or Parkinson's disease.
There are different types of syncope. Vasovagal syncope, also called neurocardiogenic syncope, is the most common form and happens when blood pressure and heart rate drop suddenly, temporarily interrupting blood flow to the brain. This reaction may be triggered when the vagus nerve, a key nerve in the autonomic nervous system (which controls heartbeat and blood flow), becomes too active from, say, heat or hunger, causing the heart rate and blood pressure to drop too much or too fast (or both).
Situational syncope may be triggered by dehydration, emotional stress, anxiety, fear, or pain. It also may be brought on by alcohol or drug use or hyperventilation (breathing in too much air and getting rid of carbon dioxide too quickly). In some people, situational syncope can occur when they cough or urinate. In addition, certain medications, such as some blood pressure drugs, may cause syncope by lowering blood pressure too much, especially when people first begin taking them.
If you've had an episode of syncope and were not treated in an emergency department, alert your doctor, who will determine if tests or treatments are needed. Your doctor may want to conduct a physical exam and review your medical history. He or she also may record your heart rate and blood pressure while you're lying down and standing and order blood tests, an echocardiogram to check your heart's electrical activity, and a neurologic evaluation if necessary.
Treatment depends on what caused the syncope and may include changes to your diet or medication. If you and your doctor identify triggers such as dehydration, standing for long periods, heat, alcohol, skipping meals, or emotional stressors, you'll want to avoid those as much as possible.
If you feel faint, elevate your legs to help restore blood flow to the brain. If you can't lie down, sit down and put your head between your knees until you feel better.
If you see someone else faint, make sure they are horizontal and breathing. If they regain consciousness quickly, make sure they continue to lie down for at least 10 to 15 minutes. Offer them cold water to drink. If a person is not breathing or remains unresponsive for a minute or longer, call 911. If you know CPR, do it until paramedics arrive.
Dr. Blitshteyn is director and founder of Dysautonomia Clinic in Williamsville, NY, and associate professor of neurology at the University of Buffalo Jacobs School of Medicine and Biomedical Sciences.
