Unexplained fainting

Frequently asked questions

The following FAQs may help you understand fainting and the cause of fainting which you can talk to your doctor about.

What is fainting?

Fainting is a sudden loss of consciousness that occurs when blood pressure drops and not enough oxygen reaches the brain.¹ The loss of consciousness is sometimes called ‘passing out’ or ‘blacking out'.

Your healthcare provider may use the medical term Syncope when referring to your fainting.

What are the causes of fainting?

Fainting can be caused by many things. The most common reason for fainting is a sudden drop in blood pressure, which reduces blood flow and oxygen to the brain.¹ Many patients have a medical condition they may or may not know about that affects the nervous system or heart.

You may also have a condition that affects blood flow through you body and causes your blood pressure to drop when you change positions (for example going from lying to standing).

What is cardiac monitoring?

If your doctor suspects that your fainting is heart-related, cardiac monitoring may be necessary. Cardiac monitoring is used to either identify or rule out a heart rhythm disorder and to determine an appropriate course of treatment. The type of cardiac monitor used is often determined by the frequency of your faints. If your faints occur often and a few days apart a holter may be useful. If your faints are separated by weeks or months a longer monitor such as an event recorder or insertable cardiac monitor may be more appropriate.³ Common types of cardiac monitoring systems include:

Common types of cardiac monitoring systems include:

Holter Monitors: A portable external monitor that includes wires with patches that attach to the skin. It continuously measures and records the heart’s activity for 1-2 days. It is best suited for very frequent faints that occur often and typically a few days apart.^3-6
Event Recorders: A recorder worn on the body for up to 30 days^.3-6 It typically requires activation by pushing a button to record the heart’s activity. Best suited for fainting that occurs every few weeks.
Insertable Cardiac Monitoring Systems: Placed just under the skin during a minimally invasive procedure, it automatically detects and records abnormal heart rhythms for up to 4.5 years. It is best suited for fainting that occurs less frequently. For example, once a month.^3-6

Please always speak to a healthcare professional for more information.

1 Michele Brignole, Angel Moya, Frederik J de Lange, Jean-Claude Deharo, Perry M Elliott, Alessandra Fanciulli, Artur Fedorowski, Raffaello Furlan, Rose Anne Kenny, Alfonso Martín, Vincent Probst, Matthew J Reed, Ciara P Rice, Richard Sutton, Andrea Ungar, J Gert van Dijk, 2018 ESC Guidelines for the diagnosis and management of syncope, European Heart Journal, Volume 39, Issue 21, 01 June 2018, Pages 1883–1948, https://doi.org/10.1093/eurheartj/ehy037

2 Ganzeboom KS, et al. Lifetime cumulative incidence of syncope in the general population: a study of 549 Dutch subjects aged 35-60 years. J Cardiovasc Electrophysiol. 2006;17:1172-1176.

3 Brignole M, etal. 2018 ESC Guidelines for the diagnosis and management of syncope, European Heart Journal, Volume 39, Issue 21, 01 June 2018, Pages 1883–1948, https://doi.org/10.1093/eurheartj/ehy037.

4 Shen WK. et al. 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope: A report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. Heart Rhythm. 2017 Aug;14(8):e155-e217. doi: 10.1016/j.hrthm.2017.03.004. Epub 2017 Mar 9. PMID: 28286247

5 Brignole M, et al. 2013 ESC Guidelines on cardiac pacing and cardiac resynchronization therapy: the Task Force on cardiac pacing and resynchronization therapy of the European Society of Cardiology (ESC). Developed in collaboration with the European Heart Rhythm Association (EHRA). Eur Heart J. 2013 Aug;34(29):2281-329. doi: 10.1093/eurheartj/eht150. Epub 2013 Jun 24. PMID: 23801822.

6 National Institute for Health and Clinical Excellence, Transient loss of consciousness ('blackouts') in over 16s, Clinical Guideline [CG109], Published date: 25 August 2010 Last updated: 01 September 2014, www.nice.org.uk.

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Frequently asked questions

The following FAQs may help you understand fainting and the cause of fainting which you can talk to your doctor about.

What is fainting?

How common is fainting?

What are the causes of fainting?

What are the risks of fainting?

What if my doctor suspects fainting is heart related?

What is cardiac monitoring?

Speak to your GP

Discover insertable cardiac monitors

Why am I fainting?