Brugada Syndrome is an abnormal ECG (Right Bundle Branch Block Pattern with coved ST elevation over the right precordial leads of V1-V3), which leads to ventricular fibrillation (VF) and sudden cardiac death (SCD) in patients with structurally normal hearts. It has been recognized as a clinical entity since 1992. Why should all ED physicians know about this entity? Although a rare syndrome, it is often mistaken as a STEMI and more importantly the clinical spectrum can be asymptomatic to SCD.(more…)
Torsades de pointes is a polymorphic form of ventricular tachycardia. Why does this occur? What does it characteristically look like? Why is this an important form of ventricular tachycardia to differentiate from the more classic monomorphic ventricular tachycardia? View this short 9 minute video on QT intervals and Torsades de Pointes.
Augmented leads (aVR, aVF, and aVL) were developed to derive more localized information looking at the right, lower, and left part of the heart respectively. Specifically, lead aVR obtains information from the right upper side of the heart. It also gives reciprocal information on the left lateral side of the heart, which is already covered by leads aVL, I, II, V5, and V6. This is the main reason lead aVR has become forgotten.
Wellen’s Syndrome was first described in 1982 in which 75% of patients with t wave inversions in V2-V4 went on to have an acute myocardial infarction (MI). This was again repeated in 1989, and showed that all patients with this morphology had >50% LAD stenosis. The incidence in the United States is about 10-15%.
You are handed an ECG for a 50 year old man with moderate chest pain for 2 hours now and no associated symptoms typical for ACS, PE, aortic dissection, or any other red flags of chest pain. He has no prior ECG’s on file.
- Is this early repolarization or ST elevation MI?
- Should I activate the cardiac catheterization lab?
Image courtesy of Dr. Steve Smith at HQMedEd-ecg.blogspot.com
Here are some great literature-based pearls compiled by Dr. Jason West (@JWestEM), an EM resident from Jacobi/Montefiore.
PV Card: ECG – Early Repolarization vs ST Elevation MI
Adapted from [1–7]
Go to ALiEM (PV) Cards for more resources.
Furthermore, there is a formula to differentiate early repolarization vs STEMI, per Dr. Smith’s publication6:
(1.196 x STE60V3) + (0.059 x QTc) – (0.326 x RA V4)
- STE60V3 = STE elevation height at 60 msec (1.5 small boxes) after the J-point in lead V3 (mm)
- QTc = The computer-read QTc interval
- RA V4 = R wave amplitude in lead V4 (mm)
A result of > 23.4 is predictive of a LAD occlusion causing a STEMI, rather than early repolarization.
P.S. The above ECG image shows early repolarization.
- Brady W, Syverud S, Beagle C, et al. Electrocardiographic ST-segment elevation: the diagnosis of acute myocardial infarction by morphologic analysis of the ST segment. Acad Emerg Med. 2001;8(10):961-967. [PubMed]
- Brady W, Perron A, Syverud S, et al. Reciprocal ST segment depression: impact on the electrocardiographic diagnosis of ST segment elevation acute myocardial infarction. Am J Emerg Med. 2002;20(1):35-38. [PubMed]
- Smith S. Upwardly concave ST segment morphology is common in acute left anterior descending coronary occlusion. J Emerg Med. 2006;31(1):69-77. [PubMed]
- Larson D, Menssen K, Sharkey S, et al. “False-positive” cardiac catheterization laboratory activation among patients with suspected ST-segment elevation myocardial infarction. JAMA. 2007;298(23):2754-2760. [PubMed]
- Nfor T, Kostopoulos L, Hashim H, et al. Identifying false-positive ST-elevation myocardial infarction in emergency department patients. J Emerg Med. 2012;43(4):561-567. [PubMed]
- Smith S, Khalil A, Henry T, et al. Electrocardiographic differentiation of early repolarization from subtle anterior ST-segment elevation myocardial infarction. Ann Emerg Med. 2012;60(1):45-56.e2. [PubMed]
- Chung S, Lei M, Chen C, Hsu Y, Yang C. Characteristics and prognosis in patients with false-positive ST-elevation myocardial infarction in the ED. Am J Emerg Med. 2013;31(5):825-829. [PubMed]