Syncope (fainting)

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Syncope, commonly known as fainting, happens if you have a sudden, temporary drop in blood pressure or heart rate. People who have a syncopal episode temporarily lose consciousness but become conscious and alert again after a few seconds or minutes.

Many factors, such as strong emotions, heavy sweating, exhaustion or pooling of blood in the legs can trigger syncope. But sometimes syncope can be a sign of a more serious condition.

That’s why it’s important to get treatment right away to determine the cause of your syncopal episode. Most people can prevent problems with syncope once they get an accurate diagnosis and proper treatment.

Syncope definition

Syncope is the medical term for passing out temporarily or fainting. It’s a common condition, accounting for approximately 1%-3% of all emergency room visits and up to 6% of hospital admissions nationwide each year.

The definition of syncope is a temporary drop in blood flow to your brain from a sudden change in your blood pressure or heart rate. You lose consciousness and collapse, which lets normal blood flow come back. A syncopal episode usually lasts less than two minutes, and you might feel confused for a short time afterward.

A syncopal episode can be triggered by something simple, like forgetting to eat or drink, or it can be a symptom of a serious heart condition.

What causes syncope?

A syncopal episode is often caused by something that’s easily treatable, like dehydration. Sometimes syncope is caused by a life-threatening condition, like a dangerous, irregular heart rhythm. Common causes of syncope include:

  • Abrupt change in physical posture, such as standing up too quickly
  • Being under the influence of drugs or alcohol
  • Dehydration or low blood sugar from going without food for a long time
  • Emotional response to a traumatic event or an extremely happy event
  • Hard coughing
  • Intense pain
  • Neurological disorders such as:
  • Cardiovascular conditions such as:

Syncope signs & symptoms

If you have syncope, the main symptom is occasionally fainting or passing out. Before you faint in a syncopal episode, you may also experience other symptoms. These syncope signs and symptoms may include:

  • Blacking out
  • Cold, clammy sweating
  • Falling for no reason
  • Feeling dizzy
  • Heart palpitations or irregularities with your heart rhythm
  • Lightheadedness or feeling like you might fall
  • Nausea
  • Pale skin
  • Vision changes where everything seems blurred, you see spots or you have tunnel vision and see only what is directly in front of you
  • Yawning or feeling drowsy for no reason

Types of syncope

There are several different types of syncope. It can be related to underlying cardiac or neurological conditions. Other cases of syncope have no known cause.

Cardiac syncope is more common in men and those over age 60. People with known heart disease or a family history of premature sudden cardiac death are also at greater risk for cardiac syncope. If you faint frequently, and it’s not caused by dehydration or a sudden change in position, you may need to be tested for cardiac syncope.

Common causes of cardiac syncope include:

  • Arrhythmia: During episodes of arrhythmia (an irregular heart rhythm), the heart works inefficiently, and not enough oxygenated blood circulates to the brain.
  • Aortic dissection: This is a tear in the aorta, the large artery that carries blood from the heart to the rest of the body. It’s a rare but life-threatening condition.
  • Aortic valve stenosis: This is a narrowing of the valve between the heart and the aorta. Aortic valve stenosis can be present from birth or develop in old age.

Postural orthostatic tachycardia syndrome (POTS), also known as postural syncope, is a condition that causes your heart to beat faster when you go from sitting or lying down to standing up. If you have POTS, your body can’t keep your blood pressure steady and stable.

You’re at higher risk of developing POTS after serious infections such as mononucleosis, pregnancy or head injury. People with autoimmune conditions including Sjogren’s syndrome, lupus and celiac disease are also more likely to develop POTS.

Most people with POTS are women between 15 and 50 years old. Symptoms can come and go over a period of years. In most cases, adjustments in diet, medications and physical activity will improve quality of life for people with POTS.

Some people with POTS require medications, but most will improve by consuming more sodium (salt) and wearing compression garments on their legs.

Vasovagal syncope (also called neurocardiogenic syncope) is usually harmless and requires no treatment. It’s the most common type of syncope, and nearly half of all syncope cases are vasovagal syncope.

Vasovagal syncope causes you to faint when you see blood or experience other emotional distress. Your heart rate and blood pressure drop suddenly, leading to reduced blood flow to your brain, which causes you to lose consciousness.

Treatment is usually unnecessary. Your doctor might help you identify what causes your syncope and explain ways you can avoid those situations. Sometimes a medication to raise your blood pressure may be prescribed.

Neurologic syncope is much less common than other types of syncope. It can happen when you have a neurological condition such as a seizure, stroke or transient ischemic attack (TIA), also known as a ministroke.

Other less common conditions that lead to neurologic syncope include migraines and normal pressure hydrocephalus.

How syncope is diagnosed

Because a serious, underlying medical condition may have caused your syncope, we take extra steps to precisely identify what caused your syncopal episode.

If your syncope is not easily explained, we may order some diagnostic tests to gather more information. Common tests your doctor may order include:

  • Blood-volume determination to measure the amount of blood in your body and the amount of plasma and red blood cells in your blood
  • Electrophysiology study, where we use a thin, flexible tube called a catheter to stimulate your heart’s electrical system and record your heart rhythm
  • Hemodynamic testing to measure how well your body carries oxygen through your blood
  • Tilt-table test, which moves you from lying down to almost standing and monitors your heart’s electrical activity, blood pressure and nervous system reaction

Syncope treatment

Depending on what caused your syncopal episode, your personalized treatment plan may include:

  • Dietary changes such as eating more often, drinking more fluids, consuming more potassium or sodium, or avoiding caffeine or alcohol
  • Medication to treat an underlying disorder that is causing you to faint
  • Lifestyle changes as syncope treatment include raising the head of your bed while asleep or wearing compression stockings to improve your blood circulation

If you have cardiac syncope, your doctor may recommend:

  • Procedures to restore heart rhythm, such as a pacemaker implant, implantable cardioverter defibrillator or cardiac ablation
  • Treatment for heart or blood vessel disorders

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