Neurally mediated reflex syncope

Last reviewed: 30 Aug 2023
Last updated: 30 Jun 2022



History and exam

Other diagnostic factors

  • history of recurrent faints
  • absence of structural heart disease
  • provocative factor
  • nausea
  • lightheadedness
  • pallor
  • diaphoresis
  • diminished vision or hearing
  • physical injury
  • fatigue after episode
  • palpitations
  • bradycardia
  • absence of family history of sudden death
  • neuralgia
Other diagnostic factors

Risk factors

  • prior syncope
  • prior history of arrhythmias, myocardial infarction, heart failure, or cardiomyopathy
  • severe aortic stenosis
  • prolonged standing
  • emotional stress (especially in a warm, crowded environment)
  • dehydration/hypovolemia
  • preceding episode of nausea and/or vomiting
  • preceding episode of severe pain
More risk factors

Diagnostic investigations

1st investigations to order

  • 12-lead ECG
  • serum hemoglobin
  • plasma blood glucose
  • serum beta-hCG (human chorionic gonadotropin)
  • cardiac enzymes
  • D-dimer level
  • serum cortisol
  • BUN and serum creatinine
More 1st investigations to order

Investigations to consider

  • echocardiogram
  • tilt-table test
  • carotid sinus massage (CSM)
  • insertable loop recorder
  • electrophysiologic study
  • Valsalva maneuver
  • active standing test
  • cold pressor test
  • cough test
More investigations to consider

Emerging tests

  • adenosine triphosphate (ATP) test

Treatment algorithm


vasovagal faint

situational faint

carotid sinus syndrome



Bryant Lin, MD
Bryant Lin

Clinical Assistant Professor of Medicine

Division of Primary Care and Population Health

Stanford University School of Medicine




BL declares that he has no competing interests.

Paul J. Wang, MD, FACC, FHRS
Paul J. Wang

Professor of Medicine

Stanford Arrhythmia Service

Stanford University School of Medicine




PJW receives fellowship support, honoraria, and clinical trial support from Medtronic, which manufactures LINQ, an implantable loop recorder.


Dr Bryant Lin and Dr Paul J. Wang would like to gratefully acknowledge Dr David G. Benditt and Dr John T. Nguyen, previous contributors to this topic.


DGB has consultant and equity positions: Medtronic Inc., St Jude Medical Inc., Transoma Inc., Cardionet Inc. DGB is also an author of several references cited in this topic. JTN declares that he has no competing interests.

Peer reviewers

Sanjiv Petkar, MBBS, MD, DM (Cardiology), MRCP

Consultant Cardiologist

Hull and East Riding of Yorkshire NHS Trust

Castle Hill Hospital

East Yorkshire



SP has received sponsorship in the past from Medtronic, Inc. and St Jude Medical, Inc. for attending conferences. He has received speaker's fees from Medtronic, Inc. In addition, he was in receipt of a research grant from Medtronic, Inc. to the University of Manchester.

Kenneth A. Ellenbogen, MD

Kontos Professor of Cardiology

Medical College of Virginia




KAE declares that he has no competing interests.

Andrew Parfitt, MBBS, FFAEM

Clinical Director

Acute Medicine

Associate Medical Director

Consultant Emergency Medicine

Guy's and St Thomas' NHS Foundation Trust

Clinical Lead and Consultant

Accident Emergency Medicine

St Thomas' Hospital




AP declares that he has no competing interests.

  • Differentials

    • Orthostatic syncope (postural or orthostatic intolerance syncope syndromes)
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  • Guidelines

    • Recommendations for tilt table testing and other provocative cardiovascular autonomic tests in conditions that may cause transient loss of consciousness
    • 2018 ESC guidelines for the diagnosis and management of syncope
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