Vasovagal Syncope

Vasovagal syncope

Established for over a decade, Melbourne Heart Group provides the highest level of cardiology.

Vasovagal Syncope

What is Syncope?

Syncope is a medical term used to describe the occurrence of losing consciousness, commonly known as fainting or passing out. There are various medical conditions that can lead to syncope, including seizure disorders, abnormalities in heart rhythm (such as both slow and fast rhythms), and issues related to heart valves. You have been referred to a cardiologist as your doctors suspect that your syncope may be related to heart abnormalities.

In the majority of cases, syncope is attributed to a condition called Vasovagal syncope (VVS), which is also referred to as neurocardiogenic syncope (NCS). Other terms used to describe VVS include vasodepressor syncope or common faint. This type of syncope frequently occurs in young, healthy individuals and is more prevalent among women.

What is vasovagal syncope (VVS)?

Vasovagal syncope occurs when the autonomic (involuntary) nervous system sends exaggerated signals that lead to low blood pressure and / or low heart rate, resulting in decreased blood flow to the brain and causing syncope (fainting). It is believed to be associated with the body’s “fight-or-flight” response to perceived stressors. In certain stressful situations, your body can respond by increasing blood pressure and heart rate as part of the “fight” response. However, in VVS, the autonomic nervous system triggers a “vagal” response, causing low blood pressure and a slower heart rate, which can lead to syncope. This can be compared to the “playing dead” response observed in some animals as a defence mechanism.

The symptoms of VVS include dizziness, light-headedness, and syncope, along with other associated symptoms such as nausea, clamminess, sweating, abdominal discomfort, blurry vision, muffled hearing, and a feeling of darkening vision or a curtain coming down. These symptoms serve as warning signs before syncope occurs, providing an opportunity to take preventive measures. Lying down when experiencing these warning symptoms can help prevent syncope from escalating.

The underlying mechanism of VVS is believed to involve inappropriate or exaggerated relaxation of blood vessels and / or a decrease in heart rate, leading to low blood pressure at a time when the body requires increased blood flow. This response is mediated by the vagus nerve, hence the term “vasovagal.” When blood vessels relax and blood pools, this information is transmitted to the brain through the autonomic nervous system. Normally, the brain responds by activating the sympathetic nervous system, which increases heart rate, vascular tone, and blood pressure. However, in VVS, it is unclear why this response is insufficient, leading to a downward spiral of lower blood pressure and heart rate, ultimately resulting in syncope.

Syncope is a normal physiological response that prompts you to lower your head closer to the ground to facilitate blood flow to the brain. Attempting to stand up or walk during an episode can exacerbate symptoms and worsen the situation. It is common for individuals to feel drained and fatigued after an episode, and this feeling may persist for minutes, hours, or even the entire day.

How do I find out if I have VVS?

While VVS can be identified based on your symptoms, description, and specific situations, it is crucial to rule out other potentially serious causes of syncope. This typically involves undergoing a series of basic tests, including a 12-lead ECG, 24-hour Holter monitor, 24-hour blood pressure monitor, and often an echocardiogram. In certain cases where seizures are suspected, an electroencephalogram (EEG) might be recommended. While tilt table tests were previously utilized to diagnose VVS, their use has become less frequent in recent times.

What can I do to prevent VVS?

In most cases, non-pharmacologic (not using medications) treatment is the mainstay of treatment for people with VVS. Three most important aspects of managing VVS include hydration, preventing exacerbation, symptom recognition, and special manoeuvres.


Ensuring proper hydration is crucial in preventing VVS episodes. It is important to take steps to prevent dehydration, and this includes limiting or avoiding alcohol and caffeinated beverages. Monitoring the colour of your urine is a helpful indicator of hydration status, aiming for clear urine rather than yellow. As a general guideline, consuming approximately 2 litters of water per day is recommended. In cases where blood pressure remains low despite adequate hydration, increasing salt intake may be necessary. Salt helps retain water within the blood vessels. However, it is important to note that excessive salt intake can be harmful for individuals with normal or high blood pressure. Increased salt intake may be beneficial only for those with low blood pressure. Additionally, consuming an additional 300-500ml of fluids 30 minutes before engaging in sustained exercise can be advantageous.

Preventing exacerbation:

Identifying and avoiding situations that can worsen VVS is a key strategy in managing the condition. Sleep deprivation has been found to be a significant risk factor, so ensuring an adequate amount of sleep is important. Other common triggers include prolonged standing, working in hot or stuffy environments, post-exercise pauses, and encountering painful stimuli such as needle procedures, seeing blood, or receiving distressing news. While it may not always be possible to completely avoid these situations, being aware of their potential to exacerbate VVS is crucial. Recognising and preparing for these circumstances can help individuals better manage and navigate through potential episodes.

Symptom recognition:

Being able to recognise early warning symptoms is crucial in controlling or preventing a full syncope episode. These symptoms may include dizziness, light-headedness, queasiness, nausea, clamminess, excessive sweating, abdominal discomfort, blurred vision, muffled hearing, and a sensation of curtains closing or darkening of vision. People around you may notice that you appear pale, gray, or that colour is draining from your face. Understanding and acknowledging these symptoms is essential for implementing appropriate special manoeuvres to help manage the situation effectively.

Special manoeuvres:

Once you recognize the symptoms of VVS, it is important to promptly initiate specific manoeuvres to address the condition. VVS is characterized by the pooling of blood in the peripheral areas of the body, triggering the symptoms. The primary objective of these manoeuvres is to restore blood flow to the brain. The most effective approach is to lie down on your back, as this allows for optimal blood return. Alternatively, raising your legs or keeping your knees bent can assist in improving blood circulation to the brain. Another option is to assume a low squatting position, which helps compress peripheral blood vessels and prevent further pooling. If lying down or squatting is not feasible, crossing your legs, tensing your leg muscles, and engaging your abdominal muscles can aid in restoring blood flow to the brain. It is worth mentioning that attempting to stand up or walk during a VVS episode will exacerbate symptoms and potentially worsen the situation. Therefore, it is crucial to lie down and avoid standing up when experiencing a vasovagal episode.

Are there any medical treatments for VVS?

In the majority of cases, medical interventions are not necessary and are not recommended as the initial approach for VVS. While there are various medications available that may provide some relief for VVS symptoms, it is important to note that these medications do not offer a cure for the condition. Medications are typically reserved for severe cases of VVS and are considered only when other preventive measures have proven ineffective. If you continue to experience significant difficulties with VVS despite implementing the aforementioned strategies, it may be beneficial to seek the expertise of specialists who specialise in managing autonomic dysfunction. These specialists can provide further guidance and support in managing your condition.

What are other associated conditions?

Additional cardiac conditions related to autonomic dysfunction include inappropriate sinus tachycardia (IST) and postural orthostatic tachycardia syndrome (POTS). For most individuals with these conditions, the main focus of treatment involves simple measures such as lifestyle modifications, ensuring adequate hydration, and optimising blood pressure control. Once these foundational aspects have been addressed effectively, medications like Ivabradine may be considered when the primary issue is an elevated normal heart rate. It is important to note that these conditions can have sporadic periods of exacerbation but generally tend to improve over time. Medications can be gradually tapered and reintroduced as needed based on individual circumstances.

Do I need a pacemaker for slow heart rate?

The recommendation of a pacemaker for VVS is relatively rare. In many cases, individuals either outgrow the condition or develop a better understanding and management of their symptoms over time. There are specific criteria that we use to assess whether a pacemaker might be beneficial. For older individuals, a pacemaker may be considered if the VVS episodes are frequent, unpredictable, accompanied by prolonged pauses in heart rhythm, or result in severe injuries.

What is the long-term outlook with VVS?

The long-term outlook is positive in people with VVS. Once adequate treatment is instituted, people can expect to lead a normal life. VVS can occur in clusters over time and can sometimes recur later in life.

Visit Our Clinic

Suite 17, Cabrini Hospital
183 Wattletree Rd, Malvern VIC 3144

Contact Our Clinic

Tel: 03 9500 0296
Fax: 03 9500 1464