What Is Vasovagal Syncope

Introduction

Vasovagal syncope is the medical term for when a person temporarily loses consciousness for a short period of time. This normally causes a person to fall over or collapse into a chair and is most commonly known as fainting.¹ It is a very common phenomenon, with thousands of people across the UK affected. It is the most common cause of loss of consciousness in young people and in people presenting to their GP or the Emergency Department.²

This article will discuss the meaning of vasovagal syncope, how it happens, common triggers for fainting, symptoms, diagnosis and the ways it can be managed.

What is vasovagal syncope?

A syncope is when a person briefly loses consciousness and rapidly recovers afterwards. There are many causes of syncope, with vasovagal syncope (fainting) being a common one. More concerning causes of syncope include abnormal heart rhythms, heart attacks and sudden drops in blood pressure due to diseases such as Parkinson's disease.¹ Due to the fact there are so many types of syncope, it is important to distinguish between them and ensure what appears to be a simple 'faint' is not due to an underlying medical problem.

Vasovagal syncope, or fainting, is classified as a type of reflex syncope. This is because it occurs as a reflex in response to a trigger, for example, emotional stress or standing for long periods of time.¹ Sometimes, people are aware of their triggers, and sometimes they are not. We will discuss triggers in more detail later in the article.

A trigger for vasovagal syncope will incorrectly cause our heart to beat slower and/or our blood pressure to reduce. This means that oxygen cannot get around our body as fast as it normally does, and our brain doesn't get the amount of oxygen it needs.² This causes loss of consciousness, meaning that the individual experiencing vasovagal syncope suddenly collapses. Once a patient has fallen, as their body is flat on the ground, blood will freely flow back to the brain and allow them to quickly recover.

Common triggers for vasovagal syncope

As stated earlier, some patients can identify what caused them to faint, and some can't. There is a wide range of common triggers for vasovagal syncope, and many patients experience a combination of them.

Vasovagal syncope can occur due to emotional stress, 'orthostatic' stress and a number of other specific triggers. Orthostatic stress refers to the causes of fainting related to standing up for a long time and maintaining our blood pressure throughout this.²

Some specific examples of triggers for vasovagal syncope are listed below.^2,3

• Standing up too quickly
• Not eating or drinking enough
• Drinking alcohol
• Hot showers or baths
• Queueing 
• Anxiety or nervousness
• Fear, including the sight of blood or medical procedures
• Being too hot
• Being upset or angry
• Severe pain

Symptoms of Vasovagal Syncope

Before a person faints, it is normal for them to experience 'pre-syncope'. Pre-syncope refers to the period just before a person is about to faint, characterised by specific symptoms.^2,4 Some typical pre-syncopal symptoms are listed below. 

• Fast heart rate
• Sweating
• Feeling hot or cold
• Dizziness
• Loss of vision
• Heightened awareness of senses, particularly related to hearing
• Nausea 
• Around meal times
• Whilst using the toilet

Some patients do not experience symptoms of pre-syncope or experience them for a very short amount of time before they fall. It is especially important for older adults who have no pre-syncopal symptoms to get checked by their doctor, as it may indicate a problem with their heart.² 

These symptoms are then followed by the faint, or the syncope, itself. This involves a brief loss of consciousness, normally lasting under 20 seconds.³ Recovery occurs shortly after the patient has fallen to the ground. Around 20% of young people and up to 50% of older adults experience memory loss in relation to their loss of consciousness.² This is sometimes normal, though patients who experience memory loss associated with syncope should see their GP or doctor to ensure there are no underlying problems.

Symptoms that are referred to as 'red flags' for causes of syncope are listed below, and if you or someone you know has experienced one or more of these, it is important to see a doctor as soon as possible.² 

• Loss of consciousness while sitting or lying down
• Loss of consciousness while driving
• Heart palpitations prior to fainting
• Fainting during exercise
• Chest pain and/or shortness of breath
• Syncope in a patient already diagnosed with heart disease
• Family history of sudden unexplained death

Diagnosis of vasovagal syncope

Doctors diagnose vasovagal syncope by ruling out other causes of loss of consciousness and by taking a thorough history from their patient. Patients may also be asked about any family history of vasovagal syncope and fainting, as studies have found that children of a mother who faints are more likely to experience fainting themselves.⁵ 

There are a few tests that may also be done on any patients who present with recurrent faints. The first of these is called a tilt-table test, in which a patient is secured to a flatbed which slowly inclines at different intervals over 45 minutes.⁶ A tilt table test is positive when the patient's blood pressure drops during the test, indicating that they may be prone to experiencing vasovagal syncope.⁷ 

Other tests that are typically run by doctors include an electrocardiogram (ECG), which involves sticking probes to the chest to monitor heart activity, and a blood pressure reading.⁶ Sometimes, doctors will run a blood test to check for low red blood cells or signs of heart problems, depending on what symptoms the patient presents with. These results can help identify causes of vasovagal syncope as well as rule out other causes of loss of consciousness.

Management and treatment of vasovagal syncope

Initially, vasovagal syncopes can be managed with advice and lifestyle changes. Patients are advised to avoid triggers if possible, for example, hot or humid environments, prolonged standing and dehydration.⁷ Additionally, once patients are able to notice their pre-syncopal symptoms, they are advised to lie down if possible, with their legs raised or sit with their head between their legs. This can help prevent syncope from occurring and prevent harm from falls.⁷

Another method of avoiding a vasovagal syncope is through the use of counterpressure manoeuvres.⁷ These are actions that involve muscle tensing and can delay or stop syncope from occurring. Examples of specific actions that use counterpressure manoeuvres are listed below.⁴ 

• Leg crossing while tensing the buttock and thigh muscles
• Gripping of the hands together while the forearms are held out in front of oneself
• Squatting

Sometimes, doctors will prescribe medications to prevent vasovagal syncope if they find that it is due to a specific cause, such as low blood pressure. A drug called fludrocortisone is sometimes prescribed for this matter, though there is only weak clinical evidence to prove that it is effective.⁶ In the past, a class of drugs called beta blockers were used to manage repeated vasovagal syncope, however, it has now been found that they are ineffective and are not routinely used anymore in the UK.¹    

Living with Vasovagal Syncope

Some individuals will experience vasovagal syncope only once throughout their lifetime,  though many more will be prone to faints and experience them many times. Finding coping strategies is really important for these individuals so they can avoid injury from falling and become less anxious about the prospect of it happening.

Below are listed some of the strategies that some patients may like to use in coping with vasovagal syncope.⁴ 

1. Take note of the symptoms you feel before you fall.
2. If you begin to experience these symptoms, lie with your legs raised or sit with your head between your legs.
3. Stay hydrated.
4. Increase your salt intake, as long as your doctor agrees this will be beneficial.
5. Tell family and friends that you are prone to fainting, and let them know how they can help if you start feeling unwell in front of them.

If you faint and injure yourself, for example, by hitting your head or bruising or cutting part of your body, it is important to consider seeking medical help. By calling 111 or using the NHS 111 website, you can assess whether you need to go to A&E, book an appointment with a GP, or use self-care measures at home.

Syncope is common in 10 to 30-year-olds; however, after this age bracket, incidence decreases until the age of 60. This means that young people who present with recurrent syncope may find that they experience it less often as they reach middle age.8 Regardless, vasovagal syncope has been shown to be harmless, and people who experience vasovagal syncope lead normal lives.

Summary

Vasovagal syncope, or the ‘simple faint’, although not directly problematic, can be anxiety-provoking and lead to injuries. By following the advice in this article, as well as consulting a doctor, you will be able to find a way to manage episodes of vasovagal syncope and reduce the frequency of syncopes you experience.