Presented by: Bryant Lin, MD
Clinical Assistant Professor of Medicine
Stanford University Medical Center
Paul Wang, MD
Director, Stanford Cardiac Arrhythmia Service
April 8, 2010
- Syncope is a sudden and temporary loss of consciousness, commonly referred to as fainting or passing out.
- It can be caused by emotional stress, pain, sudden changes in body position, overheating, dehydration, low blood sugar, or exhaustion.
- It can also be a symptom of a serious heart condition that needs to be be carefully diagnosed with cardiac tests.
- The Stanford Syncope Center was established to improve diagnostic services and patient outcomes.
Syncope is a sudden and temporary loss of consciousness and erect posture, commonly referred to as fainting or passing out. It’s often related to temporary, insufficient blood flow to the brain and occurs when blood pressure is too low and the heart is unable to provide a normal supply of oxygen to the brain.
It’s a relatively common occurrence, said Bryant Lin, MD, a clinical assistant professor of medicine, who explained the causes and treatments of syncope at a presentation sponsored by the Stanford Health Library. One study showed that out of 7,000 people over 17 years old, more than 800 had experienced an episode; another study showed that about half the people polled went to a doctor about syncope, and about 7 percent went to the emergency room. Syncope becomes more prevalent with age, occurring in as many as 6 percent of people over age 75.
Syncope can be caused by emotional stress, pain, sudden changes in body position, overheating, dehydration, low blood sugar, or exhaustion. It can also be associated with psychiatric conditions, such as migraines, mini-strokes, or narcolepsy, or with neurological conditions, like Parkinson’s disease.
For the majority or people experiencing syncope-more than a third-the cause remains unknown. For others, the cause may result from several heart, neurologic, and metabolic disorders. Syncope can be broken into three broad categories:
- Vasovagal syncope is a neurological reaction caused by a sudden upset, such as the sight of blood or extreme distress, or physical exertion. The result is a sudden drop in heart rate and blood pressure, which reduces blood flow to the brain and brief loss of consciousness. Most people have a sense of being faint beforehand or of feeling nauseous.
- Orthostatic syncope, caused by abrupt changes in blood pressure, affects almost 10 percent of cases. It can be a result of a rapid change of position, dehydration, a reaction to medication, or as a symptom of a nervous system disorder.
- Cardiac syncope is associated with a serious cardiac disorder, including such structural problems as narrowing of the aortic valve, thickening of the heart muscle, a clot in the lungs, or an abnormal heart rhythm. Key features behind cardiac causes of syncope include family history, an abnormal EKG, and sudden onset.
“Syncope is a confusing situation so it’s often difficult to get an accurate description of the episode. However, cardiac and unknown causes of syncope affect survival, so it’s important to know the cause of the syncope,” said Dr. Lin.
There are several tests that can be performed to find the underlying cause of syncope. The evaluation begins with a careful review of your medical history and a physical exam. Cardiac syncope, the most serious genre of causes, is identified through electrophysiologic (EP) testing to assess the heart’s electrical system. Physicians will also use a cardiac stress test, electrocardiogram (EKG), and electroencephalogram (EEG) to identify indications of heart trouble.
“There’s a long list of possibilities behind syncope, but it’s important to determine whether it’s a cardiac cause,” said Paul Wang, MD, director of the Stanford Cardiac Arrhythmia Service and Cardiac Electrophysiology Laboratory. “It can be a symptom of a serious heart condition.”
An abnormality in heart rhythm, called bradycardia, becomes more common as we age and increases as a cause of fainting because the heart suddenly starts to beat too slowly. In some advanced cases, a pacemaker may be required to maintain a steady rhythm, said Dr. Wang.
“In general a pacemaker is not the first choice for treatment because the difference in survival rates is not that large,” he added.
Syncope can also be caused by a condition known as ventricular tachycardia-rapid heartbeat that originates in one of the heart’s chambers, causing life-threatening arrhythmia-or hypertrophic cardiomyopathy, a thickening of the heart muscle that often requires an implantable cardioverter defibrillator, a kind of pacemaker.
Because the cause of syncope can be difficult to diagnose, Stanford recently established the first specialty center in the western United States to improve diagnostic services and patient outcomes. The Stanford Syncope Center streamlines the full battery of available tests and treatments, and coordinates referrals to specialists when required
“Diagnosis is costly if not done in a logical manner,” said Dr. Wang. “We established this center to streamline care, educate the public, and coordinate research to improve outcomes.”
About the Speakers
Bryant Lin, MD, is a clinical assistant professor of medicine who specializes in primary care medicine, cardiac electrophysiology research, and biodesign He did his residency and internship at Tufts-New England Medical Center in Massachusetts and competed his fellowships at Stanford. He is Board Certification by the American Board of Internal Medicine. E joined Stanford in 2008.
Paul Wang, MD, is director of the Stanford Cardiac Arrhythmia Service and Cardiac Electrophysiology Laboratory. He received his medical education at the College of Physicians & Surgeons at Columbia University in New York, did his internship at New York Presbyterian Medical Center, and did his fellowship at Brigham and Women’s Hospital at Harvard Medical School.
For More Information:
About Dr. Wang
About the Stanford Syncope Center
American Heart Association