What is situational syncope? Causes, diagnosis and treatment explained

Written by: Dr Boon Lim
Published:
Edited by: Emily Lawrenson

Have you ever heard of syncope? Chances are that you aren’t aware of the terminology, but you almost certainly know of someone who this has happened to. Syncope (pronounced sin-cope-pee) is the medical term for fainting, or passing out, and it refers to a temporary loss of consciousness as the blood flow to the brain suddenly declines. There are several types of syncope, including vasovagal syncope, situational syncope, and cardiac syncope, and it is estimated that syncope in some form affects 1 in 3 individuals at some stage in their life. In this article, leading cardiologist and expert in syncope, Dr Boon Lim, talks us through situational syncope, what it means for the patient, and how it is diagnosed.

What is situational syncope?

Situational syncope is when a patient faints in response to a specific trigger, or a specific situation. Some triggers can include:

  • Swallowing
  • Coughing
  • Prolonged periods of straining (e.g on the toilet, or weightlifting, playing brass instruments)
  • Sneezing
  • Sudden abdominal pain
  • Having blood taken (phlebotomy)

One of the most common examples of situational syncope is syncope following micturition – which, simply put, means fainting after going for a pee. The most common scenario for this is a patient who gets up in the middle of the night, walks to the toilet, and goes for a pee. Then, as they are standing up, or stand up from the toilet, or even as they turn to walk back to the bed, they experience syncope, and have a fall.

What causes situational syncope?

The reasons for why an individual might faint in a particular situation are different for every specific case. For example, syncope may be in response to pain felt, or even pre-empting pain, such as when giving blood. For some people the sight of a needle is enough to trigger their nervous system, which controls blood pressure and heart rate, to shut down temporarily leading to loss of consciousness. In other situations, such as a coughing fit, syncope occurs as a result of an acute change in blood pressure.

One way to explain syncope as a reaction to a coughing fit is like this: in the chest wall, the lungs and the heart share the same fixed cavity. When coughing, you increase the pressure within the lungs to generate, as it were, more space, which means that the veins that return the blood supply to the heart have pressure placed upon them, therefore blood return into the heart is reduced. As a result, the heart is beating with an empty chamber, so the cardiac output on the blood pressure goes down, which may cause the patient to faint.

Situational syncope and the reason behind fainting in each particular case is different, and must be assessed individually.

How is situational syncope diagnosed?

Situational syncope is diagnosed principally on the patient’s history of fainting and assessing the episodes of syncope they have experienced. As a specialist, I take a thorough history and spend time with the patient, asking them about all the factors preceding each episode of syncope. This often allows the diagnosis of a situation which triggers syncope, and thus the cause.

If there is any doubt behind the diagnosis, we may use a tilt-table test to help us pinpoint the cause. During a tilt-table test, the patient lies on a table which is slowly tilted upward, while blood pressure and heart rate are monitored to detect any changes. Whilst patients are on the tilt table we then ask them to reproduce specific triggers – such as coughing, or an active coughing fit, to see whether we can track any reduction in the blood pressure or heart rate that may accompany the coughing. We can do the same for patients who are referred to us for swallow syncope, recreating the situation which is suspected to cause the fainting episode, such as through drinking a glass of water. The tilt-table test is a useful tool, as it can help make or confirm the diagnosis of situational syncope.

How is situational syncope treated?

An accurate diagnosis can help the patient to avoid certain triggers and allow the patient and specialist to create management strategies. Situational syncope is usually benign, and simple strategies such as increasing hydration, salt, improving awareness of warning symptoms, and taking early evasive action to abort syncope, and getting down to a seated or lying position rapidly, can usually be enough to significantly reduce your symptoms.

By Dr Boon Lim
Cardiology

Dr Boon Lim is one of London's leading cardiologists and electrophysiologists. He specialises in heart rhythm disturbances, pacing and syncope at Imperial College and at his Harley Street clinic. He leads the established Imperial Syncope Diagnostic Service at Hammersmith Hospital and is frequently invited to national and international meetings to share his experience. He has a special interest in the mapping and ablation of atrial fibrillation (AF) and is highly-skilled at using modern 3-D mapping technologies. Dr Lim was awarded several prestigious prizes during his medical training at Cambridge University where he obtained a double First Class Honours Degree. He has continued his passion for education and research serving as an Honorary Senior Lecturer at Imperial College where he supervises several PhD students.

Dr Lim is very actively engaged in all aspects of research with a particular interest in developing the best techniques for treating atrial fibrillation. He is invited to speak both nationally and internationally to discuss his findings and to teach other physicians about the best techniques for complex mapping and ablation of atrial fibrillation and other complex arrhythmias. He leads a very active syncope research team based at the Imperial Syncope Diagnostic Unit and is looking to improve healthcare delivery for patients through use of effective online education to help improve the quality of life for patients across the UK. 

 

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