Syncope

Definition

Syncope, commonly known as fainting, is a transient loss of consciousness and postural tone, typically resulting from a temporary reduction in blood flow to the brain. It is usually followed by a spontaneous and complete recovery.

Aetiology

Syncope can be categorised into several types based on its underlying cause:

Vasovagal syncope: Often triggered by stress, pain, or prolonged standing.
Cardiac syncope: Due to heart-related issues such as arrhythmias, structural heart disease, or myocardial infarction.
Orthostatic hypotension: A sudden drop in blood pressure upon standing.
Situational syncope: Triggered by specific situations such as coughing, swallowing, or micturition.
Neurologic syncope: Related to neurological conditions such as seizures or transient ischemic attacks.

Pathophysiology

Syncope occurs when there is a transient decrease in cerebral perfusion. This can result from a variety of mechanisms, including reflex-mediated vasodilation and bradycardia (vasovagal syncope), inadequate cardiac output (cardiac syncope), or failure of the autonomic nervous system to maintain blood pressure (orthostatic hypotension).

Risk factors

Age (older adults are more prone to orthostatic hypotension and cardiac syncope)
Cardiovascular disease
Dehydration
Medications that lower blood pressure
Diabetes
Neurological conditions

Signs and Symptoms

Sudden loss of consciousness
Brief duration (usually less than a few minutes)
Spontaneous recovery
Preceding symptoms (e.g., light-headedness, dizziness, palpitations, nausea)
Absence of prolonged confusion or neurological deficit post-recovery

Red Flags

Syncope during exertion
Associated chest pain or palpitations
Family history of sudden cardiac death
Syncope with injury
Abnormal ECG findings
Neurological signs or prolonged confusion

Investigations

Clinical history and physical examination, focusing on identifying triggers and underlying conditions
Electrocardiogram (ECG) to detect cardiac arrhythmias or structural heart disease
Blood tests to check for metabolic abnormalities (e.g., glucose, electrolytes)
Orthostatic blood pressure measurements to assess for orthostatic hypotension
Holter monitor or event recorder for intermittent cardiac arrhythmias
Neuroimaging (MRI or CT scan) if there are focal neurological signs or red flags
Echocardiography to evaluate cardiac structure and function

Management

Primary Care Management:

Identify and avoid triggers (e.g., prolonged standing, dehydration)
Increase fluid and salt intake if appropriate
Teach physical counterpressure manoeuvres (e.g., leg crossing, handgrip) to prevent vasovagal syncope
Review and adjust medications that may contribute to hypotension
Referral to a cardiologist or neurologist for further evaluation if cardiac or neurological causes are suspected

Example Management for Syncope:

A patient presenting with vasovagal syncope may be advised to avoid known triggers such as prolonged standing and dehydration. Increasing fluid and salt intake can be beneficial. For recurrent episodes, teaching physical counterpressure manoeuvres such as leg crossing and handgrip may help prevent syncope. If syncope occurs during exertion or is associated with chest pain or palpitations, referral to a cardiologist for further evaluation is warranted.

References:

NICE. (2023). Syncope: Management. Retrieved from https://cks.nice.org.uk/topics/syncope/management/
NHS. (2023). Fainting (Syncope). Retrieved from https://www.nhs.uk/conditions/fainting/
European Society of Cardiology. (2018). Guidelines for the diagnosis and management of syncope. Retrieved from https://www.escardio.org/Guidelines/Clinical-Practice-Guidelines/Syncope-Guidelines
O'Sullivan, S. B., & Schmitz, T. J. (2016). Physical Rehabilitation. 6th ed. F.A. Davis Company.
Ropper, A. H., & Samuels, M. A. (2019). Adams and Victor's Principles of Neurology. 11th ed. McGraw-Hill Education.