07/15/2024
🔴 ECG Pointers: 7 Can’t-Miss ECG Patterns of High-Risk Syncope – the “ABCDE Left Right” Mnemonic
💦Syncope is a relatively common chief complaint in the emergency department, with a broad differential that ranges from reassuringly benign to acutely life-threatening. While there is no substitute for a thorough history and physical exam, obtaining an electrocardiogram (ECG) is a key aspect of nearly every syncope workup. Prompt recognition of high-risk ECG patterns is a critical skill for emergency medicine attendings,.
💦Main ECG Pointers:
The “ABCDE Left Right” mnemonic can be used to highlight seven can’t-miss patterns of high-risk syncope that emergency medicine providers of any training level must be able to promptly recognize and manage.
AV block
Brugada pattern
QTc prolongation
Delta waves (Wolff-Parkinson-White)
Epsilon waves (arrhythmogenic right ventricular cardiomyopathy)
Left ventricular hypertrophy
Right ventricular strain
🫀A – Atrioventricular (AV) Block
second degree Mobitz type II is diagnosed when the dropped QRS is preceded by beats with a fixed PR interval.The hallmark of third degree AV block is complete atrial-ventricular
🫀B – Brugada Pattern
causes a characteristic “coved” (type I) or “saddleback” (type II) appearance of the ST segment, typically in leads V1 and/or V2.2 Family history of sudden cardiac death should raise suspicion for this diagnosis.
🫀C – QTc prolongation
The QT interval is measured from the beginning of the QRS complex to the end of the T wave, and is classically measured in lead II or V5/V6. The corrected QT (QTc) interval represents the QT interval as adjusted for a heart rate of 60 beats per minute. QTc prolongation can be caused by a number of pathologies, including electrolyte derangements (i.e., hypokalemia, hypomagnesemia, hypocalcemia), increased intracranial pressure, medication-induced (antipsychotics, antidepressants, and antiarrhythmics), or congenital, as in the case of Long QT syndrome. The QT interval is considered prolonged if it measures greater than 440 milliseconds in males or greater than 460 milliseconds in females. The QT interval can be grossly estimated as normal if it measures less than half the length of the preceding RR interval.
🫀D – Delta Waves
Delta waves are the pathognomonic shortened PR interval with slurred QRS upstroke characteristic of Wolff-Parkinson-White (WPW). These ECG changes are caused by electrical conduction along an accessory pathway between atrial and ventricular myocytes that bypasses the atrioventricular node. When present, delta waves can be seen in limb leads and/or precordial leads.
🫀E – Epsilon Waves
Epsilon waves are the characteristic inflection point seen between the QRS and the ST segment that classically represents arrhythmogenic right ventricular cardiomyopathy (ARVC), When present, the epsilon wave is typically most prominent in precordial leads V1 and/or V2. In patients with ARVC, cardiac myocytes become replaced with fat and fibrous tissue, causing conduction impairment that manifests as the epsilon wave.
🫀Left – Left Ventricular Hypertrophy
ECG evidence of left ventricular hypertrophy (LVH) after a syncopal episode raises concern for impaired cardiac outflow, which may represent underlying hypertrophic cardiomyopathy (HCM), aortic stenosis, Many different voltage criteria can be used to diagnose LVH, however the Sokolov-Lyon criteria (the sum of the deepest S wave depth in lead V1 or V2 plus the tallest R wave in either V5 or V6 is greater than 35 mm) is one of the most widely accepted..
🫀Right Ventricular Strain
Key ECG findings of right heart strain are ST segment depressions and T wave inversions in the right-sided precordial leads V1-V4 and/or inferior limb leads II, III, aVF, typically accompanied by right axis deviation and/or a dominant R wave in V1. ECG evidence of right ventricular strain after a syncopal episode raises concern for pulmonary embolism. The classic SIQIIITIII pattern often tested on license exams is unfortunately neither sensitive nor specific for pulmonary embolism
http://www.emdocs.net/ecg-pointers-7-cant-miss-ecg-patterns-of-high-risk-syncope-the-abcde-left-right-mnemonic/
