Vasovagal Syncope

Overview

Vasovagal syncope is a condition in which a sudden drop in blood pressure and slowing of the heart rate lead to a brief loss of consciousness. It is the most common type of fainting and is usually harmless. Blood flow to the brain is temporarily reduced and the person faints. Recovery happens on its own within a few seconds or minutes.

Vasovagal syncope develops when the vagus nerve overreacts. The vagus nerve controls heart rate and blood vessels. When certain triggers stimulate this nerve, the heart slows down and blood vessels dilate. Blood pressure drops rapidly and the brain does not receive enough blood. The result is fainting.

Vasovagal syncope can occur at any age but is more common in young adults and adolescents. In most people it happens once or a few times in life and is not a sign of a serious health problem. Repeated fainting, however, can affect daily life and should be investigated to determine whether it stems from another underlying cause.

There is a risk of falling during fainting. It is therefore important for people who experience vasovagal syncope to recognize warning signs and take precautions.

Symptoms

Vasovagal syncope usually begins with warning signs. These appear a few seconds or minutes before fainting and give the person an opportunity to sit or lie down.

Warning signs of vasovagal syncope include:

• Dizziness and lightheadedness. This is the most common warning sign. The person feels as though they are losing their balance.
• Hot flush and sweating. A sudden feeling of warmth and cold sweating may develop.
• Pale appearance. The skin becomes pale and loses color.
• Blurred vision or tunnel vision. The field of vision narrows or everything appears blurry.
• Nausea. A feeling of stomach nausea may accompany the other symptoms.
• Ringing in the ears. A ringing or buzzing sound may be heard in the ears.

During fainting, consciousness is lost completely. The person falls to the ground and usually comes to within a few seconds. Brief muscle twitching can sometimes occur during fainting — this can be confused with an epileptic seizure but is different.

After fainting, the person usually feels tired. Dizziness may continue for a while. It does not leave any serious lasting effects, however.

When to See a Doctor

• If you have fainted for the first time, see a doctor. It is important to determine whether the fainting was vasovagal syncope or something else.
• If you faint frequently or fainting is affecting your daily life, an evaluation should be done.
• If you sustained a serious injury during fainting, both the injury and the cause of fainting should be investigated.
• If chest pain, shortness of breath, irregular heartbeat, or palpitations accompany the fainting, go to the emergency room immediately. These may be signs of a heart problem.

Causes and Triggers

Vasovagal syncope develops as a result of overstimulation of the vagus nerve. Many different situations can trigger this stimulation.

The most common triggers are:

• Standing for a long time. Standing still without movement, particularly in hot and crowded environments, negatively affects circulation and can lead to fainting.
• Seeing blood, needles, or undergoing a medical procedure. The sight of blood, fear of needles, or stress during a medical procedure is a powerful trigger. This is especially common during blood draws, vaccinations, or minor medical procedures.
• Sudden severe pain. Unexpected and intense pain can trigger the vagus nerve.
• Excessively hot and airless environments. Being in hot, humid, and poorly ventilated places sets the stage for a drop in blood pressure.
• Prolonged coughing or sneezing. An increase in pressure inside the chest can affect the heart and vascular system.
• Straining excessively in the bathroom. Excessive straining, particularly during constipation, stimulates the vagus nerve.
• Dehydration and hunger. Insufficient fluid and food intake reduces blood volume and increases the risk of fainting.
• Alcohol use. Alcohol dilates blood vessels and contributes to a drop in blood pressure.
• Sudden emotional stress or fear. Intense fear, shocking news, or a traumatic event can trigger the vagus nerve.

In some people, vasovagal syncope can develop without any specific trigger. In most cases, however, a trigger can be identified.

Diagnosis

Vasovagal syncope is diagnosed through medical history, physical examination, and certain tests. The main aim is to confirm that the fainting is vasovagal and to rule out serious causes originating from the heart or nervous system.

The diagnostic process typically includes:

• Detailed medical history. This is the most important step. Your doctor will ask what you were doing before you fainted, how you felt, whether there were warning signs, and how long the fainting lasted. Identifying trigger factors makes diagnosis much easier.
• Physical examination. Heart auscultation, blood pressure measurement, and a general examination are performed. Blood pressure may be measured while standing and lying down to rule out orthostatic hypotension.
• Electrocardiogram (ECG). This shows the electrical activity of the heart. It is used to investigate whether there is a heart rhythm disorder or structural problem.
• Echocardiography. This images the structure and function of the heart. It may be performed to rule out problems with the heart valves or pumping strength.
• Tilt table test. This is a special test used to trigger and confirm vasovagal syncope. The person is placed on a special table and the table is tilted to an angled position. Heart rate and blood pressure are monitored in this position. In some people, a vasovagal reaction is triggered during the test and the diagnosis is confirmed.
• Holter monitor or event recorder. In cases of repeated and frequent fainting, devices that record heart rhythm for days or weeks may be used.

Treatment

Vasovagal syncope often does not require any specific treatment. Avoiding triggers and recognizing warning signs to take precautions is usually sufficient. In people who faint frequently, however, certain approaches can be used.

Treatment and preventive approaches include:

• Avoiding triggers. Knowing which situations trigger fainting and staying away from them is the most effective approach. If there is a fear of blood or needles, lying down during a medical procedure can be helpful.
• Recognizing warning signs and sitting or lying down. If you feel dizzy, nauseous, or have a hot flush, sit or lie down right away. Lying down with your legs elevated increases blood flow to the brain and may prevent fainting.
• Physical maneuvers. When warning signs begin, tensing the leg muscles, crossing the legs, or interlocking the hands and pulling them apart can help raise blood pressure. These techniques have been found effective especially in people who develop a vasovagal reaction during a tilt table test.
• Drinking plenty of fluids. Drinking at least 2 liters of water a day maintains blood volume and prevents a drop in blood pressure. It is particularly important to increase fluid intake in hot weather and before physical activity.
• Increasing salt intake. With your doctor's recommendation, increasing salt consumption can help raise blood pressure. This recommendation is not appropriate for people with high blood pressure or heart disease, however.
• Compression stockings. Compression stockings that prevent blood from pooling in the legs can be helpful for some people.
• Medication. In cases of frequent and uncontrollable fainting, medication may rarely be considered. Medications such as fludrocortisone or beta blockers are used in some patients. These medications are not effective in every patient, however, and can have side effects.

Living with Vasovagal Syncope

Vasovagal syncope is mostly a harmless condition. Repeated fainting, however, can affect daily life and create a risk of injury from falls.

• Know your triggers. Note which situations cause you to faint. This information will help you take precautions in the future.
• Pay attention to warning signs. If you feel dizzy or have a hot flush, sit or lie down immediately. This simple step can prevent fainting.
• Drink plenty of water. Keep your daily fluid intake adequate. Dehydration can trigger vasovagal syncope.
• Move slowly. If you have been sitting or lying down for a long time, do not stand up suddenly. Straighten up slowly and wait a few seconds.
• Inform those close to you. Tell your family and those around you that you experience vasovagal syncope and what they should do when you faint. In most cases the person recovers on their own, but lying them down with their legs elevated speeds recovery.
• Be careful about driving. If you faint frequently, be careful when driving. In some countries, frequently recurring vasovagal syncope can be a barrier to holding a driver's license. Discuss this with your doctor.

Preparing for Your Appointment

What you can do:

• Note the fainting episode in detail: when, where, and what you were doing when it happened.
• Mention whether there were any warning signs.
• If you have a history of fainting, share how many times it has happened and under what circumstances.
• List all medications you are taking.
• Write your questions down in advance.

Questions you can ask your doctor:

• Is the cause of my fainting vasovagal syncope?
• Could there be a heart or nervous system problem?
• How can I take precautions?
• Is medication needed?
• Is it safe for me to drive?
• How often do I need to be monitored?

Your doctor may ask you:

• What were you doing before you fainted?
• Were there any warning signs?
• How long did you remain unconscious?
• Have you fainted before?
• Are there similar complaints in the family?
• Do you experience palpitations or chest pain?
• What medications are you taking?