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Vasovagal syncope

What is Vasovagal Syncope?

Syncope is a sudden loss of consciousness resulting from a transient decrease in the blood supply to the brain, leading to the loss of consciousness. Reflex syncope is the medical term for the type of syncope that occurs due to the vasovagal system reacting to something, such as the sight of blood or strong emotion. Most people who suffer from vasovagal syncope have a prodrome, a brief period of symptoms preceding their loss of consciousness. Some symptoms of the prodrome include dizziness, fainting or lightheadedness, a feeling of being hot or chilly, pallor and nausea, sweating; palpitations; hazy vision, as well as bad hearing or hearing weird sounds.

An episode of vasovagal syncope is characterized by a sharp drop in blood pressure and heart rate followed by passing out or fainting. It’s the most common sort of reflex syncope, which occurs for reasons that you can’t control. Because it’s caused by variables affecting the heart and the brain, it’s also known as neurocardiogenic syncope (NCS). When it comes to Vasovagal syncope, there is no need for treatment. You may, however, hurt yourself during a vasovagal syncope episode. Your doctor may conduct testing for more serious reasons for fainting, such as heart disease.

This article will cover the symptoms, causes, complications, diagnosis, and treatment for vasovagal syncope.

What causes vasovagal syncope?

Every part of your body has nerves that influence the rate at which your heart beats. They also help to keep your blood pressure in check by adjusting the diameter of your arteries and veins. They normally function together to ensure that your brain receives enough oxygen-rich blood at all times. When your blood vessels abruptly open wide and your blood pressure drops, your brain and body can get their messages mixed up. This is especially true if you are experiencing an allergic reaction. Slower heart rate and lower blood pressure work together to lessen blood flow to the brain. This is the reason you pass out.

Parasympathetic nervous system activity in response to specific emotional or environmental triggers causes benign vasovagal syncope(1). Typically, vasovagal syncope episodes occur after standing for a prolonged period of time; they can be triggered by fasting, dehydration, being in crowded or excessively warm environments, or following stressful events, like seeing blood and needles. Although it is not clear why, however exposure to these stimuli causes a vasovagal reflex, characterized by heart rate reduction and peripheral blood vessel dilation. As a result, the brain’s oxygen supply is reduced, leading to a loss of consciousness and a decrease in blood pressure.

Syncope can also be caused by orthostatic hypotension, which is a drop in blood pressure that occurs when someone stands up suddenly after lying down or sitting for a long time. If you’re standing up, your blood pressure will drop since your lower body veins aren’t constricting as quickly as they should be. When the delay occurs due to blood pooling in leg veins, less blood returns to the heart, causing a reduction in cardiac output and blood pressure.

The major causes of vasovagal syncope are these:

  • Standing up after sitting, bending, or lying down for a long time
  • A strong emotional response
  • Overheating
  • Strenuous physical exertion
  • Intense pain
  • A lot of coughing

Tpes of reflex syncope

Two major types of reflex syncope are similar to vasovagal syncope. The main difference is the causes are easier to identify.

  1. Carotid sinus syndrome: It’s more common in males who are 50 and older than in younger guys. When pressure is applied to the neck, this reaction causes you to pass out (2). It might happen while shaving, wearing a tight collar, or turning your neck in a certain way.
  2. Situational syncope: Syncope that is predictable and occurs during certain activities or circumstances falls under this category. passing out during a bowel movement, coughing, or swallowing are all examples of this type of syncope that can occur in the course of daily activities (3).

What are the symptoms of vasovagal syncope?

Whether you’re standing or sitting, vasovagal syncope is more likely to occur. If you’re lying down, it’s extremely uncommon. Having your blood drawn is one of the most typical triggers. You’re most likely to experience symptoms in the immediate aftermath of a vasovagal syncope. Prodrome (rhymes with “dome”) is a term for this time, which is more common in the elder people. Detecting the early signs of vasovagal syncope can be a powerful preventative measure.

There are a number of warning signs that appear 30-60 seconds before an attack, including the following:

  • Lightheadedness or nausea
  • A sudden “wave of heat,” or a tingling sensation
  • Pale skin
  • Exhaustion
  • Yawning
  • Profuse sweating
  • Slow pulse

Once an attack starts, the following symptoms can appear:

  • Loss of consciousness and falling to the ground, usually for no more than 15 seconds.
  • Eyes remain open but roll up and back into your head.
  • Twitching movements can sometimes be mistaken for a seizure.
  • Uncontrolled bladder

Once you come to, you’ll usually recover quickly (in about 20 to 30 seconds). Confusion or disorientation either doesn’t happen, or they don’t last longer than 30 seconds. The following may also occur:

  • Nervousness or depression
  • Dizziness
  • Headache
  • Nausea or vomiting
  • Paleness
  • Sweating
  • Urge to use the bathroom

How serious is vasovagal syncope?

Vasovagal syncope is rarely life-threatening on its own. Your body has a built-in reflex that causes this problem. It’s either too strong or occurring at the wrong time.
Accidents can occur if you fall or if you’re doing something dangerous at the time of passing out. Keep in mind that a wide range of life-threatening diseases can also cause fainting. You need to find out what caused you to faint or rule out a more serious issue if you don’t have a history of passing out.

Who is at risk for vasovagal syncope?

As many as one in three people will suffer from vasovagal syncope at some point in their lives. Vasovagal syncope is responsible for around 85% of all episodes of passing out or fainting in people under the age of 40 (4). It accounts for nearly half of all instances in the elderly. Vasovagal syncope is rare in those with autonomic nervous system abnormalities such as Parkinson’s disease. That’s because their nervous system isn’t working properly because of their condition.

What are the possible complications of vasovagal syncope?

While vasovagal syncope might be uncomfortable, it generally poses no health risks. Fainting can be dangerous, especially if it occurs while driving. The vast majority of people with occasional episodes of vasovagal syncope are able to drive safely. Your doctor may advise against driving if you have uncontrolled chronic syncope. For those who faint without warning signals, this is more likely to occur. Do what your doctor tells you to do.

How can it be diagnosed?

A physical examination is frequently the first step in making the diagnosis of vasovagal syncope. As part of the examination, your doctor will check your vital signs, including your heart rate and blood pressure. You may also be given a neck massage to check whether that causes you to faint.

In addition, your doctor may order a series of tests to rule out other possible causes of your fainting, including heart-related issues. These tests may include:

  • Electrocardiogram: This test measures the electrical activity in your heart. It has the ability to identify abnormal heartbeats and other cardiac issues (5). Depending on the severity of your condition, you may need to wear a portable monitor for several days or even weeks.
  • Echocardiogram: This test employs ultrasound imaging to examine the heart and look for disorders, such as heart valve issues, that might cause fainting.
  • Exercise stress test: This test examines the heart’s rhythms during activity. It’s commonly done on a treadmill as you walk or jog.
  • Blood tests: It’s possible that anemia could be the cause of or a contributing factor in your fainting spells. That is the reason doctors perform blood tests.
  • Tilt table test: A tilt table test may be recommended by your doctor if your fainting isn’t caused by any cardiac issues. During the exam, you lie on your back on a table that moves, tilting you upward at different degrees. Your pulse rate and blood pressure are monitored by a technician during the test to see if your posture affects them.

What are the treatment methods for vasovagal syncope?

Treatment is rarely essential in cases of vasovagal syncope. To avoid fainting, your doctor may be able to assist you in determining what causes you to faint and how to avoid it. Vasovagal syncope is a common occurrence, but if it disrupts your daily life, your doctor may recommend one or more of the following treatments:

  • Medications: Vasovagal syncope may necessitate the use of medication to control it. Researchers have studied the potential benefits of several drugs for vasovagal syncope (6). People with a history of frequent fainting are more likely to be evaluated for this type of condition. There are a variety of medications that your doctor may suggest you try, including the following:
  • Blood pressure-raising alpha-1 adrenergic agonists
  • Use of corticosteroids to aid in the elevation of sodium and fluid levels.
  • Inhibitors of the serotonin reuptake system (SSRIs) to control the neurological system

Doctors may try orthostatic training if these medications fail. A tilt table is used to progressively increase the amount of time spent upright.

  • Therapies: It’s possible that a doctor will propose strategies to reduce the pooling of blood in your lower extremities. Wearing compression stockings or tensing your leg muscles when standing are some examples of this. Your blood pressure may need to be increased if you don’t normally have it. Standing for lengthy periods of time should be avoided, especially in hot, busy settings, and lots of fluids should be consumed.
  • Surgery: Patients with vasovagal syncope who haven’t responded to prior therapies may benefit from having an electronic pacemaker implanted.

Can vasovagal syncope be prevented?

When attempting to avoid a vasovagal syncope, it is important to avoid any potential triggers, such as standing for a long time or seeing blood, as well as consuming plenty of fluids to maintain an acceptable blood volume. Vasovagal syncope may not be entirely preventable, but you may be able to reduce the number of times you faint. In order to avoid a full-blown fainting spell, it is possible to recognize the prodrome of syncope and lay down on the floor. Last but not least, people who have had many episodes of syncope may be helped by taking medicine such as mineralocorticoids (such as fludrocortisone) and vasoconstrictors (such as disopyramide or midodrine), or selective serotonin reuptake inhibitors (e.g., fluoxetine). However, the effectiveness of these drugs differs from person to person.


Vasovagal syncope is a non-life-threatening condition that occurs when the heart rate and blood pressure fall as a result of specific stimuli (e.g., the sight of blood). Vasovagal syncope is diagnosed by conducting a medical history and physical examination and an ECG to rule out cardiogenic syncope. Positioning a person on the ground with their legs slightly elevated ensures that blood returns to the brain in the event of an acute syncope episode. In order to avoid the onset of vasovagal syncope, it is important to avoid any potential trigger factors as well as drink lots of fluids.

Vasovagal syncope is the most prevalent reason for fainting. In most cases, fainting isn’t an indication of an underlying health issue, but it’s always a good idea to see your doctor to rule out any possible causes. You may be able to prevent fainting spells and avoid injury if you learn to identify your triggers. If you’ve never experienced a fainting episode before or haven’t had one in the past and you suddenly experience one, you should contact your doctor right once. Get emergency medical attention if you pass out and injure your head, if you have problems breathing or chest pains, or if you have trouble speaking before or after you pass out.



KOCHIADAKIS, GEORGE E., et al. “Autonomic Nervous System Changes in Vasovagal Syncope”: Pacing and Clinical Electrophysiology, vol. 27, no. 10, Oct. 2004, pp. 1371–1377, 10.1111/j.1540-8159.2004.00641.x. Accessed 19 July 2022.
Amin, Vaibhav, and Behzad B. Pavri. “Carotid Sinus Syndrome.” Cardiology in Review, Sept. 2014, p. 1, 10.1097/crd.0000000000000041.
LIVANIS, EFTHIMIOS G., et al. “Situational Syncope:. Response to Head-up Tilt Testing and Follow-Up: Comparison with Vasovagal Syncope.” Pacing and Clinical Electrophysiology, vol. 27, no. 7, July 2004, pp. 918–923, 10.1111/j.1540-8159.2004.00559.x. Accessed 19 July 2022.
Connolly, Stuart J., et al. “Pacemaker Therapy for Prevention of Syncope in Patients with Recurrent Severe Vasovagal Syncope.” JAMA, vol. 289, no. 17, 7 May 2003, p. 2224, 10.1001/jama.289.17.2224. Accessed 4 Mar. 2022.
YOKOKAWA, MIKI, et al. “Neurally Mediated Syncope as a Cause of Syncope in Patients with Brugada Electrocardiogram.” Journal of Cardiovascular Electrophysiology, vol. 21, no. 2, Feb. 2010, pp. 186–192, 10.1111/j.1540-8167.2009.01599.x. Accessed 19 July 2022.
“January-February 2008 – Volume 16 – Issue 1 : Cardiology in Review.”, Accessed 19 July 2022.

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