Syncope (pronounced “sin ko pea”) is the medical term for fainting or passing out. It is caused by a temporary drop in the amount of blood that flows to the brain.
Syncope can happen if you have a sudden drop in blood pressure, a drop in heart rate, or changes in the amount of blood in areas of your body. If you pass out, you will likely become conscious and alert right away, but you may be feel confused for a bit.
Autonomic Nervous System (ANS)
The ANS automatically controls many functions of the body, such as breathing, blood pressure, heart rate and bladder control. Most times, these things happen without us noticing.
Syncope is a common condition. It affects 3% of men and 3.5% of women at some point in life. Syncope is more common as you get older and affects up to 6% of people over age 75. The condition can occur at any age and happens in people with and without other medical problems.
There are several different types of syncope. The type you have depends on what causes the problem.
Vasovagal syncope (also called cardio-neurogenic syncope)
Vasovagal syncope is the most common type of syncope. It is caused by a sudden drop in blood pressure, which causes a drop in blood flow to the brain. When you stand up, gravity causes blood to settle in the lower part of your body, below your diaphragm. When that happens, the heart and autonomic nervous system (ANS) work to keep your blood pressure stable.
Some patients with vasovagal syncope have a condition called orthostatic hypotension. This condition keeps the blood vessels from getting smaller (as they should) when the patient stands. This causes blood to collect in the legs and leads to a quick drop in blood pressure.
Situational syncope is a type of vasovagal syncope. It happens only during certain situations that affect the nervous system and lead to syncope. Some of these situations are:
Postural syncope (also called postural hypotension)
Postural syncope is caused by a sudden drop in blood pressure due to a quick change in position, such as from lying down to standing. Certain medications and dehydration can lead to this condition. Patients with this type of syncope usually have changes in their blood pressure that cause it to drop by at least 20 mmHg (systolic/top number) and at least 10 mmHg (diastolic/bottom number) when they stand.
Cardiac syncope is caused by a heart or blood vessel condition that affects blood flow to the brain. These conditions can include an abnormal heart rhythm (arrhythmia), obstructed blood flow in the heart due to structural heart disease (the way the heart is formed), blockage in the cardiac blood vessels (myocardial ischemia), valve disease, aortic stenosis, blood clot, or heart failure. If you have cardiac syncope, it is important to see a cardiologist for proper treatment.
Neurologic syncope is caused by a neurological condition such as seizure, stroke or transient ischemic attack (TIA). Other less common conditions that lead to neurologic syncope include migraines and normal pressure hydrocephalus
Postural Orthostatic Tachycardia Syndrome (POTS)
Postural-Orthostatic Tachycardia Syndrome is caused by a very fast heart rate (tachycardia) that happens when a person stands after sitting or lying down. The heart rate can speed up by 30 beats per minute or more. The increase usually happens within 10 minutes of standing. The condition is most common in women, but it can also occur in men.
Unknown Causes of Syncope
The cause of syncope is unknown In about one-third of patients. However, an increased risk of syncope is a side effect for some medications.
The most common symptoms of syncope include:
Many times, patients feel an episode of syncope coming on. They have what are called “premonitory symptoms,” such as feeling lightheaded, nauseous, and heart palpitations (irregular heartbeats that feel like “fluttering” in the chest). If you have syncope, you will likely be able to keep from fainting if you sit or lie down and put your legs up if you feel these symptoms.
Syncope can be a sign of a more serious condition. So, it is important to get treatment right away after you have an episode of syncope. Most patients can prevent problems with syncope once they get an accurate diagnosis and proper treatment.
Syncope can be caused by many things. Many patients have a medical condition they may or may not know about that affects the nervous system or heart. You may also have a condition that affects blood flow through your body and causes your blood pressure to drop when you change positions (for example, going from lying down to standing).
If you have syncope, you should see your doctor, who can refer you to a syncope specialist for a complete evaluation.
The evaluation begins with a careful review of your medical history and a physical exam. Your doctor will ask you detailed questions about your symptoms and syncope episodes, including whether you have any symptoms before you faint and when and where the episodes happen.
You may then have one or more tests to help your doctor determine the cause of your syncope. These tests check things like the condition of your heart, how fast your heart is beating (heart rate), the amount of blood in your body (blood volume), and blood flow in different positions.
Your heart rate and blood pressure will be measured and recorded while you are in different positions including lying down, sitting and standing.
Tests to determine causes of syncope include:
The test results will help your doctor determine what is causing you to have syncope. You may need other tests, including electrophysiology studies, autonomic nervous system testing, neurological evaluation, and computed tomography (CT) scan. Vestibular function testing may be done to rule-out problems in the inner ear. If you need any additional testing, your doctor will explain them and why they are needed.
Your referring physician will receive a complete report of test results and treatment recommendations. Your referring physician will share this information with you.
Your treatment options will depend on what is causing your syncope and the results of your evaluation and testing. The goal of treatment is to keep you from having episodes of syncope.
Treatment options include:
Your doctor and other members of your healthcare team will develop a treatment plan that is right for you and talk to you about your treatment options.
If you are diagnosed with syncope, check your state laws. Some states require drivers with syncope to contact the license bureau.
With the proper diagnosis and treatment, syncope can be managed and controlled. If you have had an episode of syncope, there is about a 30% chance you will have another episode. Your risk of another episode and how the condition affects you depends on several factors, including the cause and your age, gender and other medical problems you have. If you have questions about your risks, please talk to your doctor.
With the proper diagnosis and treatment, syncope can be managed and controlled.
Cleveland Clinic’s Center for Syncope and Autonomic Disorders combines experience, expertise and a team approach to diagnosing syncope. For patients beginning diagnosis of syncope, or those who have been told they have “autonomic dysfunction or neurologic causes for their syncope: make an appointment with a Neuromuscular Center staff member please call 216.636.5860 or toll free 866.588.2264.For patients who have POTs, underlying cardiac disease, or cardiac symptoms along with their syncope: contact the cardiology appointment line at 1.800.223.2273, ext 4-6697.
Doctors vary in quality due to differences in training and experience; hospitals differ in the number of services available. The more complex your medical problem, the greater these differences in quality become and the more they matter.
Clearly, the doctor and hospital that you choose for complex, specialized medical care will have a direct impact on how well you do. To help you make this choice, please review our Miller Family Heart, Vascular & Thoracic Institute Outcomes.
Choosing a doctor to treat your abnormal heart rhythm depends on where you are in your diagnosis and treatment. The following Heart, Vascular & Thoracic Institute Sections and Departments treat patients with Arrhythmias:
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For younger patients with abnormal heart rhythms:
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Syncope, Fouad-Tarazi, F, Laura Shoemaker L, Mayuga K, Jaeger F http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/cardiology/syncope/ Accessed September 4, 2014
Mayuga KA1, Butters KB, Fouad-Tarazi F.Early versus late postural tachycardia: a re-evaluation of a syndrome. Clinical Autonomic Research. 2008 Jun;18(3):155-7. doi: 10.1007/s10286-008-0472-1. Epub 2008 May 9.http://link.springer.com/article/10.1007/s10286-008-0472-1/fulltext.html Accessed 9/8/2014
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or healthcare provider. Please consult your healthcare provider for advice about a specific medical condition. This document was last reviewed on: 05/14/2019