Syncope is described as a brief loss of consciousness and postural tone caused by transient global cerebral hypoperfusion. It is followed by a complete recovery. An estimated 80% of pediatric syncope is due to autonomic (vasovagal or neurocardiogenic) syncope. Our role as providers is to identify the patients who have a life-threatening etiology to their syncope. The majority of these are cardiac and so today we will review what to look for in your screening ECG. 

History and physical examination are critical components to any emergency department evaluation but are especially helpful in syncope patients.

A review of red-flag symptoms can be found in the linked PEMBlog post.

Cardiac Syncope

Most life-threatening etiologies are related to cardiac syncope and are estimated to be 1.5%-6% of pediatric syncope. This is why ECG is recommended for all initial episodes of syncope with a reported sensitivity as high as 96%. Therefore, what are we looking for with our ECG?

Concerning ECG findings

• Long QT syndrome: QTc longer than 480 msec. 
• Brugada syndrome: ST elevation in V1-V3 with a negative T wave (slide or saddleback morphology).
• Wolf-Parkinson-White syndrome: Short PR interval of <120 ms with associated slurred. upstroke and wide QRS complex (delta wave).
• Hypertrophic Obstructive Cardiomyopathy: Precordial high voltages with deep Q waves.

Long QT syndrome

Long QT (LQT) syndrome has three subtypes classified as LQT1, 2 and 3. The upper limit of a normal corrected QT (QTc) is widely agreed to be < 450 msec. In a syncope patient, a QTc >480 msec may be suggestive of LQT as the etiology of the syncopal episode. Your history and medication reconciliation will assist in determining acquired vs congenital variants. In LQT, syncope is related to torsades de pointes and death occurs due to ventricular fibrillation.

LQT1 is most common, triggered by emotional or physical stress (diving, swimming). One form of LQT1, AR Jervell and Lange-Nielsen syndrome is associated with congenital deafness. LQT2 is associated with stress or at rest and can be triggered by loud noises which are pathognomonic. LQT3 is associated with bradycardia. Most are AD Romano-Ward syndrome with variable penetrance. Acquired long QT can be caused by electrolyte disorders, eating disorders and/or medications.

Brugada Syndrome

Brugada syndrome is an inherited cardiac sodium channel disorder. There are three types of changes seen on ECG. Type 1 ECG changes of V1, V2 ST segment elevation with associated T wave inversion is diagnostic but not always present. Type 2 and 3 seen below are supportive but not always diagnostic of Brugada and should prompt Cardiology evaluation. Type 2 is described as a saddleback shape. Type 3 can appear like type 1 or type 2 but with <2 mm of ST elevation. The sodium channel abnormality predisposes to polymorphic ventricular tachycardia which can lead to sudden death.

Wolf-Parkinson-White Syndrome

Wolf-Parkinson-White syndrome has a classic triad of delta wave, shortened PR interval and widened QRS complex. It is also known as pre-excitation.

Structural Heart Disease

There are several structural heart disease etiologies of syncope. Hypertrophic obstructive cardiomyopathy (HOCM) is caused by abnormalities in the cardiac sarcomere proteins leading to blockage of the outflow tract from hypertrophied interventricular septum. The hallmarks of a syncope presentation from this include a history of dyspnea, exercise intolerance, syncope and angina. The risk of sudden death is high. Assess for large amplitude QRS complexes with ST-segment changes and deep narrow Q waves. Left atrial enlargement can also be seen. Other structural disorders who may present similarly are aortic valve stenosis and coronary abnormalities. 

Others

SVT and Bradycardia can be additional causes of syncope identified through telemetry and ECG. Addressing these may require medical intervention or pacing depending on the etiology (medication related vs structural). 

Discussing obtaining an ECG with patients and families

Presentations to the emergency department for syncope can be stressful for families. I recommend framing the ECG discussion as screening the electrical connections of the heart to ensure that the heart is not the reason for the scary syncopal episode that they experienced. This must be grounded in a discussion of the most common etiologies of syncope and what makes their particular presentation concerning vs reassuring (see above).

References

Burns, Ed, et al. “QT Interval.” Life in the Fast Lane • LITFL, 14 May 2022, litfl.com/qt-interval-ecg-library/. 

Buttner, Robert, et al. “Pre-Excitation Syndromes.” Life in the Fast Lane • LITFL, 2 Feb. 2022, litfl.com/pre-excitation-syndromes-ecg-library/. 

Buttner, Robert, et al. “Hypertrophic Cardiomyopathy (HCM).” Life in the Fast Lane • LITFL, 22 May 2022, litfl.com/hypertrophic-cardiomyopathy-hcm-ecg-library/.

Fleisher, Gary R., et al. Textbook of Pediatric Emergency Medicine. Wolters Kluwer/Lippincott Williams & Wilkins Health, 2015. 

Larkin, John, et al. “Brugada Syndrome.” Life in the Fast Lane • LITFL, 20 Sept. 2022, litfl.com/brugada-syndrome-ecg-library/. 

Ritter, Saskia, et al. “What is the yield of screening echocardiography in pediatric syncope?.” Pediatrics 105.5 (2000): e58-e58.

Sanatani, Shubhayan, et al. “Canadian Cardiovascular Society and Canadian Pediatric Cardiology Association position statement on the approach to syncope in the pediatric patient.” Canadian Journal of Cardiology 33.2 (2017): 189-198.

Sobolewski, Brad. “It’s Not the Heart? Red Flags in Children with Syncope.” PEMBlog, 8 Feb. 2020, pemcincinnati.com/blog/redflags-syncope/.

Pre-Publication Peer Review

This post underwent pre-publication peer review on Thursday May 11, 2023. A group of Pediatric Emergency Medicine fellows and attending reviewed this post, offered feedback, and appraised the content using the structure of the revised METRIQ score.