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What is Syncope?

Syncope, also known as fainting or passing out, is the temporary loss of consciousness caused by insufficient blood flow to the brain. This often occurs due to low blood pressure, changes in heart rhythm, and pooling of blood in regions of the body.

Causes of Syncope

Syncope can have various triggers. Based on the causes, it can be classified as:

  • Vasovagal syncope: This type of syncope occurs due to temporary malfunctioning of the nervous system, which regulates blood pressure and heart rate. It is characterized by a sudden drop in blood pressure due to a trigger such as pain or emotional stress. Vasovagal syncope usually occurs while standing and mostly affects children and young adults.
  • Situational syncope: When vasovagal syncope is associated with certain situations that affect the nervous system, it is referred to as situational syncope. These situations can include:
    • Intense emotional stress
    • Pain
    • Hunger
    • Hyperventilation (breathing in too much oxygen and getting rid of too much carbon dioxide too quickly)
    • Forceful coughing
    • Urinating (micturition syncope)
    • Swallowing
    • Bowel movements
    • Dehydration
    • Wearing a tight collar
    • Exhaustion
    • Pregnancy
    • Use of alcohol or drugs
  • Neurologic syncope: This is caused by a neurological condition such as seizure, stroke, or transient ischemic attack (TIA). Other conditions that lead to neurologic syncope include migraines and normal-pressure hydrocephalus (NPH).
  • Postural syncope: This is caused by a drop in blood pressure due to a sudden change in body position, such as from lying down to standing. It can also be triggered by certain medications and dehydration and is more common in older people.
  • Cardiovascular syncope: This type of syncope is related to the underlying heart or vascular problems, some of which are serious and need medical attention. These include bradycardia (slow heart rate), tachycardia (fast heart rate), cardiac arrhythmias, atrial fibrillation, hypotension (low blood pressure), and heart valve problems such as aortic stenosis.

Symptoms Associated with Syncope

Common symptoms associated with syncope, which may serve as warning signs, include:

  • Nausea
  • Headache
  • Weak pulse
  • Blacking out (tunnel vision)
  • Blurry vision or seeing spots
  • Feeling warm
  • Slurred speech
  • Rapid heartbeat
  • Cold or clammy skin
  • Yawning or feeling tired
  • Feelings of weakness or unsteadiness
  • Vertigo, or a sensation that the room is moving

Diagnosis of Syncope

Most syncopal episodes do not last long. It is necessary to get a medical evaluation to understand the cause and determine whether treatment is necessary. Your doctor will review your medical history and ask questions about your symptoms. Your heart rate and blood pressure will be measured in different positions including lying down, sitting, and standing. Other tests may be performed, including:

  • Electrocardiogram: This test records the electrical activity of the heart and can detect an irregular heartbeat and other cardiac problems.
  • Tilt Test: This is a test where you are strapped to a bed which is then tilted to raise your head. Blood pressure and heart rate are measured at various tilt angles. This test can help identify vasovagal syncope and postural syncope.
  • Blood Tests: To check for metabolic changes or anemia
  • Echocardiogram: In this test, ultrasound waves are used to create an image of the heart structures.
  • Exercise stress test: This test determines how the heart responds to exercise.
  • Hemodynamic testing: This test uses a radioactive dye and imaging to check the blood flow and pressure inside your blood vessels when your heart muscle contracts and pumps blood throughout the body.
  • Imaging tests: These tests can include a CT or MRI scan.
  • Carotidsinusmassage: This test should only be done by a doctor, and involves palpating the carotid arteries to detect any carotid sinus hypersensitivity (CSH) - a common finding in the evaluation of syncope.

Treatments for Syncope

Depending on the diagnosis, syncope may be stopped or controlled with one or more of the following measures:

  • You should sit or lie down when you experience warning symptoms of syncope.
  • Making changes in your diet such as eating small, frequent meals and increasing salt and fluid intake.
  • Medications such as blood pressure medications or diuretics may need adjusting.
  • Exercising, wearing compression stockings, or occasionally tensing your legs muscles while standing can help to increase blood circulation.
  • Biofeedback training may be used to help you control increases in heart rate.
  • Treatment for structural heart disease may be recommended.
  • Implanting a pacemaker or cardiac defibrillator (ICD) to control heart rate and rhythm may be necessary.

Prevention of Syncope

Prevention is necessary to avoid complications of syncope and includes:

  • Remembering not to skip meals
  • Drinking plenty of fluids
  • Taking your time when standing up
  • Avoiding shirts with tight collars
  • Identifying the external factors or triggers that cause you to faint and trying to avoid them


Signet Heart Group
2800 North Highway 75
Sherman, Texas 75090


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Practice Hours: M-F 8am – 5pm

  • American Board of Internal Medicine
  • National Board of Echocardiography
  • Certification Board of Nuclear Cardiology
  • American Board of Vascular Medicine