Vasovagal (neurocardiogenic) syncope: causes and treatment


Fainting, also known as fainting , is the medical term for temporary loss of consciousness.

Fainting can lead to injury, so it's important to try to prevent it from happening again. Sometimes this can be a sign of a serious health problem that requires medical attention. Several medical conditions can cause syncope , and the most common type of syncope is vasovagal syncope.

Get Medication Information / Brooke Pelchinski


Vasovagal syncope (also called neurocardiogenic syncope) is a temporary loss of consciousness caused by a neurological vasovagal reflex that causes a sudden dilation of the blood vessels in the legs or a very slow heartbeat (bradycardia), or both.

Vasovagal syncope accounts for more than half of all syncope episodes. Although it is sometimes called "simple syncope," the mechanism of vasovagal syncope is actually not that simple.

Symptoms of vasovagal syncope

Loss of consciousness with vasovagal syncope may be sudden or may be preceded by several seconds to several minutes of warning symptoms.

  • The warning symptoms are sometimes called prodrome of syncope.
  • Those that arise after your resurrection are called postdromes .

Prodromal symptoms

Prodromal symptoms of syncope can include:

  • Daze
  • Ringing or buzzing in the ears.
  • Visual disturbances such as blinking vision or tunnel vision.
  • Sudden sweating
  • Sudden nausea

Prodromal symptoms are accompanied by a feeling of "graying" and then, finally, loss of consciousness. The time between the onset of prodromal symptoms and actual fainting can range from a few minutes to a second or two.

If you feel like you are about to pass out, you can stop the attack by lying down with your legs raised or by sitting in a chair with your head between your knees. Wait until you feel better before trying to get up.

Syncope features

An episode of vasovagal syncope has several characteristics:

  • They almost always occur when standing or sitting because the body's blood flows disproportionately to the legs and blood pressure drops. In a prone position, this almost never happens.
  • People with vasovagal syncope usually regain consciousness within seconds after falling or after being helped to the ground. This is because gravity no longer causes blood to pool in your legs when you are on the ground, and blood pressure rises almost immediately when you are lying down.
  • If someone tries to immobilize you during a vasovagal episode, your standing position can prolong the episode of unconsciousness. This is a potentially dangerous situation because it interferes with blood flow to the head.

If you see someone faint, put that person on their back and raise their legs above heart level. Loosen your belt, collar, or restrictive clothing and seek professional medical attention.

Postdromic symptoms

After an episode of vasovagal syncope, many people will feel very bad for hours, sometimes days or longer. The postdromal period is characterized by severe fatigue, nausea, dizziness, and loss of appetite.

It's especially important to note that until these persistent symptoms subside, people are especially prone to fainting again, so they should avoid driving, climbing stairs, or other dangerous activities and be alert to the warning signs of another episode of syncope.

Recurrent syncope

People who have had one or two episodes of vasovagal syncope often learn to recognize the warning signs. You can often prevent an attack by lying down and raising your legs.

On the other hand, attempts to "fight" an impending attack of vasovagal fainting by forcing yourself to stand or sit and "trying" not to faint almost never work.

Older adults with vasovagal syncope are more likely to experience atypical syncope, with no identifiable triggers or warning symptoms.

In general, vasovagal syncope is not life threatening, but injuries from falls can be dangerous. And if the episodes are frequent, this condition can seriously disrupt normal life.

When to contact a healthcare provider

You should see your doctor if you experience fainting for the first time. If you have already been diagnosed with vasovagal syncope, you should see your doctor if you are pregnant. have recurring episodes or blurred vision, chest pain, confusion, trouble speaking, shortness of breath, or irregular heartbeat before passing out.


Vasovagal syncope occurs when something triggers a vasovagal reflex , causing the blood vessels to suddenly dilate (dilate). The widening of the blood vessels causes a significant amount of blood volume to accumulate in the legs.

This union is usually accompanied by a slowing of the heart rate. As a result, blood pressure will drop dramatically. If the drop in blood pressure is enough to deprive the brain of the oxygen it needs, fainting occurs.

Common triggers for vasovagal syncope include:

  • Sudden severe pain
  • With your blood
  • Being exposed to a traumatic event or vision.
  • Extremely difficult urination or bowel movements
  • Cough
  • Hyperventilation
  • Stand still for a long period of time
  • Exercising in hot weather
  • Excessive use of alcohol or psychoactive substances.

If any of these events is followed by an episode of syncope, vasovagal syncope is usually the cause.

Risk factor's

The vasovagal syncope reflex can affect anyone, so almost anyone can have a vasovagal episode if a strong enough triggering event occurs. In fact, it is likely that most people will pass out at some point in their lives.

Vasovagal syncope can occur at any age and is much more common in adolescents and young adults than in older adults.

Some people are particularly prone to vasovagal episodes and can pass out even with relatively mild trigger events. These people tend to have recurring bouts of fainting from adolescence, and they often experience fainting after several different triggering events.

Rarely do some people experience frequent vasovagal syncope, which is so difficult to treat that they are effectively disabled. This may be due to a form of dysautonomia (an imbalance in the autonomic nervous system) that makes a person very prone to a vasovagal reflex that causes fainting. It is often accompanied by other symptoms of dysautonomia, such as bloating or cramps, diarrhea, constipation, extreme fatigue, and various pains.


Vasovagal syncope most often occurs after a viral illness, after exercise, after a warm shower, or early in the morning, at any time when a person is dehydrated.

Your healthcare provider will look at your symptoms, medical history, family history, and the sequence of events that led to the fainting episode.

The physical examination of people with vasovagal syncope is usually completely normal. Evaluation often helps identify similar conditions, including orthostatic hypotension or postural orthostatic tachycardia syndrome (POTS) .

Sometimes a diagnostic test is required.

You may need a tilt table test to distinguish between vasovagal syncope and orthostatic hypotension.

Watch out

People with a single isolated episode of vasovagal syncope generally do not require any medication. But if you have had recurring episodes, you are likely to have even more episodes if you do not receive effective treatment.

Anyone who suffers from vasovagal faints knows that these faints often occur at the most uncomfortable or impractical times and can be life-altering. Fortunately, treatment often helps. There are several treatments for vasovagal syncope: medications, exercise, and pacemakers. Finding the right combination of treatments often takes time.


Medicines can help regulate blood pressure and heart rate.

Medications that have been shown to help treat vasovagal syncope include:

  • Midodrin, a vasoconstrictor drug that dilates blood vessels.
  • Norpece (disopyramide), an antiarrhythmic drug
  • Serotonin reuptake inhibitors
  • Theophylline , which is commonly used to treat asthma.

The exercise

Exercise is likely to have the same benefit for people with vasovagal syncope.

If you have recurring fainting spells, be sure to speak with your doctor before moving on to any fitness plan. Depending on the underlying cause, you may need to have a stress test and other tests to determine how much exercise you can safely tolerate.

Interestingly, some people have been able to alleviate an episode of vasovagal syncope by immediately doing muscle tension exercises. These exercises can reduce the dilation of the blood vessels and increase the amount of blood that returns to the heart.

Examples include

  • Cross the leg with tension in the legs, abdomen and buttocks.
  • Clenching hands with clenched fists
  • Tension of the leg muscles
  • Squeezing a rubber ball


Several years ago there was a lot of enthusiasm for the use of pacemakers to treat vasovagal syncope, as vasovagal syncope is often accompanied by a sudden drop in heart rate.

However, the enthusiasm for the pacemaker declined rapidly after it was noted that many patients with vasovagal syncope who received pacemakers continued to faint, they simply did so without lowering their heart rate.

The use of a pacemaker should only be considered if the syncope is severe or recurrent, conservative measures do not work, and there is a significant slowdown in cardiac activity, as evidenced by a table tilt test or ambulatory ECG monitoring.

Frequently asked questions

What can I do to prevent vasovagal syncope?

If you know you are prone to fainting, avoid possible triggers such as excessive heat, stressful and highly emotional situations, dehydration, severe pain, and prolonged exercise.

Can certain foods affect the symptoms of vasovagal syncope?

For some people, a slightly higher salt diet can help prevent fainting symptoms by keeping blood pressure high. Check with your doctor before adding salt to your diet because it can have other adverse health effects.

Get the word of drug information

Vasovagal syncope is a very common condition. Most people who have episodes of vasovagal syncope lead fairly normal lives.

If you've had vasovagal syncope, especially more than one episode, you should learn as much as possible about the condition, including what triggers it, how to recognize warning symptoms, and how to stop the attack.

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