Vasovagal Attack

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What is a vasovagal attack?

A vasovagal attack is a disorder that causes a rapid drop in heart rate and blood pressure, resulting in decreased blood flow to the brain and fainting. Vasovagal attack is the most common cause of fainting. The disorder is also referred to as neurocardiogenic syncope. A vasovagal attack may occur in a person of any age, but the attacks are more common in children, young adults, and the elderly.

A vasovagal attack itself is not serious; however, injury is possible during a fainting episode. Prolonged standing is associated with vasovagal attacks because blood may pool in the legs, thus reducing blood flow to the brain. Heat exposure can also lead to a vasovagal attack. As blood flows to the body’s periphery to cool the body, this may result in decreased blood flow to the brain. Heightened emotions, such as panic or fright, including seeing blood, having blood drawn, or being fearful of your life, may cause a vasovagal attack. Straining to have a bowel movement can result in a vasovagal attack from stimulation of the vagus nerve, which lowers the heart rate in some people. Another cause of vasovagal attacks is the rapid pooling of blood to the leg muscles after running or other strenuous exercise.

The signs and symptoms of vasovagal attacks have a rapid onset and occur just once or periodically. The attacks vary among individuals. Some people with vasovagal attacks have mild symptoms, such as light-headedness, while others may have frequent fainting episodes. Lying down and elevating the feet if symptoms begin, therapy to treat feelings of fear or anxiety, and taking all medications as prescribed can all help prevent vasovagal attack.

A vasovagal attack by itself is not serious. However, fainting may be caused by a serious or life-threatening condition. Seek immediate medical care (call 911) if fainting is accompanied by serious symptoms, such as sweating, severe difficulty breathing, or chest pain or pressure, which may be combined with pale or blue lips and a fast heart rate. Also seek immediate care for injuries sustained during a fainting episode.

Seek prompt medical care if you are being treated for vasovagal attacks but mild symptoms recur or are persistent.

What are the symptoms of a vasovagal attack?

A vasovagal attack causes a rapid drop in blood pressure and heart rate, which may result in a number of symptoms. The symptoms can vary in intensity among individuals.

Common symptoms of a vasovagal attack

A vasovagal attack is associated with a number of common symptoms related to a lack of blood flow to the brain. Examples include:

  • Blurred or double vision
  • Cold skin
  • Difficulty breathing
  • Disorientation
  • Fainting, change in level of consciousness, or lethargy
  • Headache
  • Irregular heart beat
  • Nausea with or without vomiting
  • Pale skin or pallor
  • Pins-and-needles (prickling) sensation
  • Slow heart rate (bradycardia)
  • Sweating

Serious symptoms that might indicate a life-threatening condition

Vasovagal attacks by themselves are not serious; however, fainting may be caused by a serious or life-threatening condition. Seek immediate medical care (call 911) if you, or someone you are with, have any of these life-threatening symptoms including:

  • Abnormal pupil size or nonreactivity to light
  • Chest pain or pressure
  • Fast heart rate (tachycardia)
  • Injury from a fainting episode
  • Pale or blue lips (cyanosis)
  • Severe difficulty breathing

What causes a vasovagal attack?

A vasovagal attack is caused by a rapid drop in blood pressure and heart rate, resulting in a decrease in blood flow to the brain. Standing for a prolonged period of time, situations that induce panic or fear, and strenuous exercise can also cause a vasovagal attack.

A vasovagal attack may also happen as the result of heat exposure as your body attempts to cool itself by circulating blood to your body’s periphery. It can also occur in an individual straining to have a bowel movement, due to stimulation of the vagus nerve.

What are the risk factors for vasovagal attack?

A number of factors increase the risk of having a vasovagal attack. Not all people with risk factors will have vasovagal attacks. Risk factors for vasovagal attacks include:

  • Alcohol consumption

  • Blood pooling in the legs and away from the brain (standing for a long period of time or after strenuous exercise)

  • Exposure to blood or frightening stimuli (having blood drawn or seeing blood)

  • Fatigue

  • Heat exposure

  • Hunger (hypoglycemia)

  • Severe pain

  • Stress

  • Stimulation of the vagus nerve (while straining to have a bowel movement)

Reducing your risk of vasovagal attack

You may be able to lower your risk of vasovagal attacks by:

  • Lying down and elevating your feet if a vasovagal attack is beginning

  • Participating in stress reduction techniques or therapy to reduce your response to triggers

  • Understanding the potential triggers for vasovagal attacks

How are vasovagal attacks treated?

Treatment for vasovagal attacks begins with seeking medical care from your health care provider. To determine if you have vasovagal attacks, your health care provider will ask you questions and may ask you to undergo diagnostic tests.

The treatment approach for vasovagal attacks depends on treating the underlying cause of your vasovagal attacks. Treatment will include identifying your triggers for vasovagal attacks and discussing methods to prevent or avoid them. Other forms of treatment for vasovagal attacks are usually not necessary. However, if vasovagal attacks are frequent, your health care provider can prescribe several treatment options.

Treatment options for vasovagal attack

Several treatment options may be used for recurrent vasovagal attacks. These are dependent on the individual’s underlying medical condition and the exact cause of the vasovagal attacks. Examples include:

  • Medications (antidepressants and blood pressure drugs)

  • Methods to prevent pooling of blood in the legs (elastic stockings, contraction of the leg muscles while standing, walking in place to use the leg muscles, and consuming fluids)

  • Surgical procedures (insertion of a pacemaker)

What are the potential complications of a vasovagal attack?

You can help minimize your risk of serious complications by following the treatment plan you and your health care professional design specifically for you. Possible complications of vasovagal attacks include:

  • Disability from a fall during a fainting episode

  • Injury from falling

  • Poor quality of life

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Jan 20
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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