Core
Results:
Prolonged QT Interval: DDx
Key Points: The QT interval reflects the time it takes for total ventricular depolarization and repolarization (Q wave onset to T wave end). QT prolongation increases the risk of torsades…
Hypocalcemia
Key Points: Prolonged QTc is the hallmark ECG change in hypocalcemia, driven mainly by ST-segment prolongation with relatively normal T-wave shape. Hypocalcemia can increase arrhythmia risk, including TdP, but TdP…
Earliest Evidence of Occlusion MI
Key Points ACS is dynamic. Coronary arteries can occlude, partially reperfuse, and re-occlude over minutes to hours, and the ECG can show these shifts before biomarkers do. The earliest actionable…
ECG Evidence of Reperfusion After Occlusion
Key Points Reperfusion and re-occlusion can occur spontaneously or after therapy. The ECG often reflects these changes earlier than symptoms. Most useful bedside ECG marker of reperfusion is ST-segment resolution…
Early Reciprocal Changes: OMI Pattern
Key Points STEMI criteria alone miss some acute coronary occlusions, so look for subtle “occlusion clues,” not just traditional STEMI criteria cutoffs. Minor ST elevation under 1 mm paired with…
STEMI & Equivalent Patterns: Criteria & Pitfalls
Key Points STAT ECG: The most important initial test in evaluating acute coronary syndromes (ACS). The primary goal is to quickly identify patients with STEMI or STEMI-equivalent patterns that trigger…
Acute Coronary Syndromes (ACS)
Key Points ACS is a clinical syndrome: classified by ischemic symptoms + ECG + troponin. ACS exists on a continuum of unstable angina, NSTEMI, STEMI, and patients can evolve between…
de Winter T Waves: STEMI Equivalent Pattern
Key Points STEMI Equivalent: The de Winter ECG pattern is an uncommon STEMI equivalent indicative of an unstable proximal occlusion of the LAD (left anterior descending coronary artery). Treat the…
Pacemaker Syndrome
Key Points Pacemaker syndrome is a hemodynamic problem caused by loss of proper atrioventricular (AV) synchrony. Most commonly occurs with ventricular pacing that produces retrograde atrial activation, but can also…
Pacemakers: Basics
Key Points Pacemakers treat bradyarrhythmias by delivering timed atrial, ventricular, or dual-chamber pacing when intrinsic activity is slow or absent. Know the major device types encountered in the ED: single-chamber,…
High-Risk Pulmonary Embolism
Key Points: The ECG can provide early clues to high-risk PE and may identify patients at risk for rapid hemodynamic collapse. Right ventricular strain patterns are the core high-risk markers….
Pacemaker & ICD Emergencies
Key Points: Three primary pacemaker malfunctions: Failure to pace – no pacing spike when one is needed. Failure to capture – pacing spike appears but no depolarization follows. Failure to…
Himalayan T Waves
Key Points Tall, broad-based T–U fusion that looks like a mountain peak, usually from severe hypokalemia; think high torsades risk until proven otherwise. Hallmark is prolonged repolarization: QT appears long…
Pediatric ECG Red Flags
Key Points Any wide QRS (>90 ms) in an infant or small child is abnormal and should trigger evaluation for VT, sodium-channel blockade, or conduction disease. QTc >450 ms in…
Pediatric ECG in Cardiac Arrest
Key Points ECG rhythms in pediatric arrest differ from adults. Pulseless arrest in children is most often asphyxial, but ECG clues can reveal reversible metabolic, toxicologic, or structural causes. Wide…
Pediatric ECG: Basics
Key Points Pediatric ECGs are not scaled-down adult ECGs. Right axis deviation, large R waves in V1, and T wave inversions in V1 to V3 are expected in healthy children….
Pseudo-Wellens Waves
Key Points Pseudo-Wellens waves are anterior T-wave patterns that mimic the biphasic or deeply inverted T waves of true Wellens syndrome but are caused by non-LAD, non-ischemic physiology. These normal-variant…
Wellens Waves
Key Points Wellens waves are anterior precordial T wave abnormalities (biphasic or deeply inverted) most often in V2–V3, occasionally extending to V1 and V4–V6. They signal a high likelihood of…
Wellens Syndrome
Key Points Clinical diagnosis, not an ECG pattern alone. Wellens syndrome requires the characteristic ECG findings plus the appropriate clinical scenario. Morphology alone is insufficient and high-risk if misapplied. Critical…
Torsade de Pointes (TdP)
Key Points Definition: TdP is a specific subtype of polymorphic ventricular tachycardia associated with a prolonged QTc interval. It often presents with a “twisting” pattern on ECG but can be…
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