Intro to EM - Syncope

Podcast – Intro to EM: The Patient with Syncope

Welcome to the St Emlyn’s podcast blog. Today, we delve into the crucial topic of syncope, exploring its diagnosis and management in the emergency department. Our aim is to provide comprehensive insights, helping healthcare professionals optimise patient care. This post covers definitions, causes, diagnostic approaches, and management strategies for syncope, ensuring you have the knowledge needed to handle these cases effectively.

Listening Time – 22:27

What is Syncope?

Syncope, commonly known as fainting, is a transient loss of consciousness due to a temporary reduction in blood flow to the brain. This condition can result from various underlying issues, including cardiac, neurological, and physiological causes. Recognizing and accurately diagnosing syncope is essential for emergency physicians, as it can sometimes indicate serious health problems.

Key Definitions

  • Syncope: A transient loss of consciousness caused by global cerebral hypoperfusion.
  • Transient Global Hypoperfusion: Temporary reduction in blood flow to the brain, leading to loss of consciousness.
  • Cardiac Output: The amount of blood the heart pumps through the circulatory system in a minute.
  • Mean Arterial Pressure (MAP): An average blood pressure in an individual during a single cardiac cycle.
  • Peripheral Resistance: The resistance of the arteries to blood flow.

Understanding the Physiology of Syncope

Syncope occurs when there is a sudden drop in cerebral perfusion pressure, leading to a temporary loss of consciousness. Several factors contribute to maintaining adequate cerebral perfusion, including cardiac output, mean arterial pressure, and peripheral resistance. Disruptions in any of these factors can result in syncope.

Cardiac Output

Cardiac output is determined by stroke volume and heart rate. Any condition that affects these parameters can lead to syncope. For instance, bradycardia (slow heart rate) or tachycardia (fast heart rate) can reduce cardiac output, causing transient loss of consciousness.

Mean Arterial Pressure

Mean arterial pressure is influenced by cardiac output and total peripheral resistance. A drop in mean arterial pressure can occur due to various reasons, including cardiac arrhythmias, structural heart problems, or vascular abnormalities, leading to syncope.

Peripheral Resistance

Peripheral resistance is the resistance of the arteries to blood flow. Conditions that alter peripheral resistance, such as vasodilation or vasoconstriction, can affect cerebral perfusion and potentially cause syncope.

Common Causes of Syncope

Understanding the different causes of syncope is essential for accurate diagnosis and effective management. The primary categories include cardiac causes, neurological causes, and physiological causes.

Cardiac Causes

Cardiac-related syncope is often due to issues with the heart’s structure or rhythm. Key cardiac causes include:

  1. Bradycardia: Abnormally slow heart rate, which can reduce cardiac output.
  2. Tachycardia: Abnormally fast heart rate, leading to decreased stroke volume and cardiac output.
  3. Structural Heart Disease: Conditions like aortic stenosis or hypertrophic cardiomyopathy can restrict blood flow and reduce cardiac output.
  4. Arrhythmias: Irregular heart rhythms, such as atrial fibrillation or ventricular tachycardia, can cause syncope by disrupting normal blood flow.

Neurological Causes

Neurological conditions can also lead to syncope. Common neurological causes include:

  1. Seizures: Epileptic seizures can cause a transient loss of consciousness, often confused with syncope.
  2. Stroke: Ischemic or hemorrhagic strokes can reduce blood flow to the brain, causing syncope.
  3. Transient Ischemic Attacks (TIAs): Temporary disruptions in blood flow to the brain can result in syncope-like episodes.

Physiological Causes

Physiological factors that can lead to syncope include:

  1. Vasovagal Syncope: A common form of fainting triggered by stress, pain, or prolonged standing. It involves a sudden drop in heart rate and blood pressure.
  2. Orthostatic Hypotension: A drop in blood pressure upon standing, often due to dehydration, medications, or autonomic dysfunction.
  3. Dehydration: Lack of sufficient fluids in the body can reduce blood volume and lead to syncope.
  4. Medications: Certain medications, especially those affecting blood pressure or heart rate, can cause syncope.

Diagnostic Approach to Syncope

Accurate diagnosis of syncope requires a systematic approach, including a thorough patient history, physical examination, and appropriate diagnostic tests.

Patient History

Taking a detailed patient history is crucial for identifying the cause of syncope. Key elements to explore include:

  1. Circumstances of the Episode: Understanding the context in which syncope occurred helps in identifying potential triggers.
  2. Prodromal Symptoms: Symptoms experienced before the episode, such as palpitations, dizziness, or nausea, can provide valuable clues.
  3. Witness Accounts: Eyewitness descriptions of the event can help distinguish between syncope and other conditions like seizures.
  4. Medical History: Previous medical conditions, medications, and family history can indicate underlying causes.

Physical Examination

A comprehensive physical examination is essential to identify any abnormalities that might contribute to syncope. Key components include:

  1. Vital Signs: Blood pressure, heart rate, and respiratory rate should be measured and monitored.
  2. Cardiovascular Examination: Checking for heart murmurs, irregular rhythms, or signs of heart failure.
  3. Neurological Examination: Assessing for neurological deficits or signs of seizure activity.

Diagnostic Tests

Several diagnostic tests can help identify the cause of syncope:

  1. Electrocardiogram (ECG): An ECG is crucial for identifying arrhythmias, conduction abnormalities, or signs of ischemia.
  2. Holter Monitoring: Continuous ECG monitoring over 24-48 hours can capture transient arrhythmias not seen on a standard ECG.
  3. Echocardiogram: An ultrasound of the heart to assess structural abnormalities.
  4. Tilt-Table Test: Used to diagnose vasovagal syncope or orthostatic hypotension by monitoring blood pressure and heart rate responses to changes in position.
  5. Blood Tests: Assessing electrolyte levels, blood glucose, and cardiac biomarkers can provide additional clues.

Management Strategies for Syncope

The management of syncope depends on identifying the underlying cause and addressing it appropriately. Here are key management strategies based on the cause of syncope:

Cardiac Syncope

For cardiac-related syncope, management focuses on stabilizing the heart’s rhythm and function:

  1. Bradycardia: Pacemaker implantation may be necessary for patients with significant bradycardia.
  2. Tachycardia: Medications like beta-blockers or anti-arrhythmics can help control heart rate. In some cases, catheter ablation may be required.
  3. Structural Heart Disease: Surgical interventions or medications to improve blood flow and reduce symptoms.
  4. Arrhythmias: Implantable cardioverter-defibrillators (ICDs) for patients at risk of life-threatening arrhythmias.

Neurological Syncope

Managing neurological causes of syncope involves addressing the underlying neurological condition:

  1. Seizures: Antiepileptic medications to control seizures and prevent future episodes.
  2. Stroke: Immediate intervention to restore blood flow in ischemic strokes or control bleeding in hemorrhagic strokes.
  3. TIAs: Medications and lifestyle changes to reduce the risk of future TIAs or strokes.

Physiological Syncope

For physiological causes of syncope, lifestyle modifications and specific treatments can be effective:

  1. Vasovagal Syncope: Avoiding triggers, increasing fluid and salt intake, and using compression stockings. In severe cases, medications like fludrocortisone or midodrine may be prescribed.
  2. Orthostatic Hypotension: Gradual position changes, increased hydration, and reviewing medications. Fludrocortisone or midodrine can also be helpful.
  3. Dehydration: Rehydration with oral or intravenous fluids.
  4. Medication Review: Adjusting or discontinuing medications that contribute to syncope.

Safety Netting and Follow-Up

Safety netting is a critical aspect of syncope management, ensuring that patients receive appropriate follow-up care and instructions. Key elements include:

  1. Discharge Instructions: Providing clear guidance on what to do if symptoms recur, including when to seek immediate medical attention.
  2. Follow-Up Appointments: Scheduling follow-up visits to monitor the patient’s condition and adjust treatment as needed.
  3. Education: Educating patients and caregivers about the potential causes of syncope and the importance of adherence to prescribed treatments and lifestyle changes.


Syncope is a common but complex condition that requires careful evaluation and management in the emergency department. By understanding the underlying causes, utilizing appropriate diagnostic tools, and implementing effective management strategies, healthcare professionals can optimize patient outcomes and reduce the risk of recurrent episodes.

This comprehensive guide aims to provide valuable insights into the diagnosis and management of syncope, helping healthcare providers deliver high-quality care. For further information, examples, and case studies, visit the St Emlyn’s blog, where we continue to share knowledge and expertise in emergency medicine.

Remember, accurate diagnosis and timely intervention are key to managing syncope effectively. Stay vigilant, consult with senior colleagues when needed, and always prioritize patient safety.

Thank you for reading. If you have any questions, cases to share, or need further information, please get in touch. We look forward to continuing the conversation and improving patient care together.

Podcast Transcription

Where to listen

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Cite this article as: Iain Beardsell, "Podcast – Intro to EM: The Patient with Syncope," in St.Emlyn's, August 22, 2015,

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