Core
Results:
ECG Foundations: Vectors, Leads, & Activation
Key Points: An ECG records voltage differences over time. The ECG tracing is a plot where the horizontal axis is time and the vertical axis is voltage. Leads are viewpoints….
Bidirectional Ventricular Tachycardia (BiVT)
Key Points: BiVT is a regular wide-complex tachycardia with strict beat-to-beat alternation of QRS axis and/or bundle-branch pattern (often an approximately 180° frontal-plane axis flip). In adults, assume digoxin toxicity…
Occlusion MI: STEMI Criteria & Beyond
Key Points: The ECG’s primary role in ACS is detecting acute coronary occlusion. Acute coronary occlusion myocardial infarction (OMI) is a time-critical diagnosis that requires immediate reperfusion. Time is myocardium….
STEMI (-) Occlusion MI: OMI Patterns
Key Points: Traditional STEMI criteria miss many acute coronary occlusions. A substantial proportion of true OMIs do not meet classic millimetric STEMI thresholds. OMI is a pathophysiologic diagnosis, not an…
QT Interval: Basics
Key Points: Definition: QT is measured from QRS onset to T-wave end. It reflects total ventricular depolarization plus repolarization. Use QTc: QT varies with heart rate. Interpret QTc, not the…
JT Interval: Basics
Key Points: The JT interval isolates ventricular repolarization by removing QRS duration from the QT. JT = QT − QRS. It is most useful when the QRS is wide, where…
PR Interval: Basics
Key Points: Definition: PR interval runs from P-wave onset to the first ventricular deflection (start of QRS). It reflects atrial depolarization plus conduction through the AV node and His-Purkinje system….
RR Interval: Basics
Key Points: The RR interval is the time between consecutive R waves. It is the most practical way to assess rate and regularity. RR is the backbone of rhythm interpretation:…
Waveforms, Segments, & Intervals: Basics
Key Points: Every ECG tracing is built from waveforms (deflections), segments (baseline portions between waveforms), and intervals (time that include waveforms plus segments). Waveforms describe electrical events (depolarization or repolarization)….
STAT ECG 101: The Acute Care ECG Workflow
Key Points: The ECG is the fastest bedside test for rhythm, conduction, ischemia, and tox-metabolic disease. It only saves lives when interpreted systematically and acted on. In acute care, the…
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…
STEMI in the Presence of Baseline ECG Abnormalities
Key Points: Baseline ECG abnormalities do not protect patients from occlusion MI. They increase miss rates because they distort the ST segment and T waves. The core question is not…
Lateral and High-Lateral STEMI: Criteria, Localization, and Pitfalls
Key Points: Lateral and high-lateral STEMI often present with subtle ST elevation and are commonly missed or labeled as nonspecific ST-T changes. Small-appearing ECG changes may represent true coronary occlusion…
Inferior STEMI: Criteria, RV Involvement, and Pitfalls
Key Points: Inferior STEMI is the most common STEMI subtype and is frequently complicated by right ventricular and posterior involvement. Inferior occlusion may present with classic ST elevation, subtle ischemic…
Anterior STEMI: Criteria, Localization, and Pitfalls
Key Points: Anterior STEMI represents large myocardial territory at risk and carries the highest mortality among STEMI subtypes. Early recognition and reperfusion are critical. LAD occlusion may present with classic…
Posterior STEMI: Criteria & Pitfalls
Key Points: High risk of missed diagnosis. Isolated posterior occlusion MI is frequently missed because ST elevation is absent on the standard 12-lead ECG. Instead, posterior infarction most often presents…
STEMI vs Early Repolarization: DDx
Key Points: Early repolarization (ER) is a common, benign ECG pattern that most often appears in young, healthy patients. It can closely resemble acute anterior STEMI, creating a high-risk diagnostic…
STEMI vs LV Aneurysm: DDx
Key Points: LV aneurysm pattern is a post MI scar pattern with persistent ST elevation in the prior infarct territory, usually with pathologic Q waves and a stable, non evolving…
STEMI Mimics: DDx
Key Points: ST elevation is a pattern, not a diagnosis. STEMI represents one cause of ST elevation and requires correlation with ECG morphology, distribution, evolution, and clinical context. Most ED…
ECG Tags
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