Core
Results:
Normal QRS Axis
Key Points Normal Axis Range: –30° to +90° Lead I: QRS complex is positive Lead aVF: QRS complex is positive → This combination confirms a normal QRS axis Frontal plane…
LV Aneurysm vs STEMI: DDx
Key Points Left Ventricular Aneurysm (LVA): Causes persistent ST elevation lasting more than 2 weeks post-MI, typically seen in the anterior leads but can also affect the inferior leads. Occurs…
Intervals
Key Points Definition: ECG intervals measure the duration of electrical activity across different parts of the cardiac cycle. They reflect conduction times through the atria, AV node, ventricles, and repolarization…
Fusion Beats
Key Points Definition: A fusion beat occurs when two impulses — one from the normal conduction system (typically supraventricular) and one from an ectopic ventricular focus (e.g., during VT) —…
History of the “STAT ECG”
Key Points The ECG is a cornerstone of acute care medicine, offering immediate, non-invasive insight into cardiac function in critically ill patients. Its evolution spans over a century, from rudimentary…
Atrial Flutter 1:1 Conduction
Key Points Rare, dangerous presentation. When atrial flutter conducts 1:1 through the AV node (or an accessory pathway), the ventricular rate can approach the atrial rate ~240–320 bpm, producing rapid…
Computer Interpreted “Normal” ECGs
Key Points Do not fully trust computer interpretations of “normal” ECGs, they may miss significant abnormalities. Computer algorithms can miss early ischemic signs such as reciprocal changes in aVL and…
STEMI (-) Occlusion MI: OMI Patterns
Key Points Traditional STEMI Criteria Alone Miss Acute Coronary Occlusion MI: Widely used but insufficiently sensitive or specific, many genuine occlusions (OMIs) do not meet strict STEMI criteria. Current Guidelines…
Occlusion MI: STEMI Criteria & Beyond
Key Points A STAT ECG is the most critical first test in suspected acute coronary syndrome (ACS). It allows for early recognition of acute coronary occlusion myocardial infarction (OMI), a…
Pseudonormalization of T Waves
Key Points Definition: Pseudonormalization is the apparent normalization of previously inverted T waves, often signaling reocclusion of a coronary artery that had recently reperfused. Mechanism: During reperfusion, ischemic T wave…
STEMI vs Severe Hyperkalemia: DDx
Key Points The ECG Chameleon: Severe hyperkalemia can produce ST segment elevations, wide QRS complexes, and conduction delays that closely resemble STEMI or ventricular tachycardia. Early misinterpretation can lead to…
Right Bundle Branch Block (RBBB)
Key Points RBBB delays right ventricular activation. The left ventricle depolarizes normally via the left bundle; the right ventricle is activated late through myocardial spread. ECG hallmark: wide QRS and…
STEMI vs Wide QRS (BBBs & Paced Rhythms): DDx
Key Points Wide QRS & Repolarization Abnormalities: Bundle branch blocks (BBBs) and ventricular-paced rhythms (RV, LV, BiV) cause abnormal ventricular depolarization, leading to secondary ST segment and T wave changes—even…
Occlusion MI in Ventricular Paced Rhythms: STEMI Equivalent Pattern
Key Points 1. Paced Rhythms and Acute MI Detection: Ventricular paced rhythms significantly alter ST segment and T wave morphology, complicating acute myocardial infarction (MI) recognition. Accurate ECG interpretation in…
Occlusion MI in Left Bundle Branch Block: STEMI Equivalent Pattern
Key Points LBBB Does Not Exclude Acute Coronary Occlusion: LBBB alters ventricular activation, leading to expected secondary ST/T abnormalities. However, acute occlusion myocardial infarction (OMI) can and must still be…
Modified Sgarbossa Criteria: STEMI Equivalent Pattern
Key Points Wide QRS Rhythms Can Mask OMI: Left bundle branch block (LBBB) and right ventricular (RV)-paced rhythms alter ventricular depolarization, producing expected secondary ST/T changes. However, acute occlusion MI…
Sinus Tachycardia
Key Points Definition: Sinus tachycardia is a regular rhythm originating from the sinoatrial (SA) node, defined by a heart rate >100 bpm in adults or above age-adjusted norms in children….
Hyperkalemic Periodic Paralysis (Impressive Syndrome)
Key Points What It Is: A rare autosomal dominant sodium channelopathy that leads to episodic muscle weakness or paralysis in the setting of elevated serum potassium. Named after “Impressive,” the…
Trifascicular Block
Key Points Definition: Trifascicular block describes ECG evidence of impaired conduction across all three fascicles: right bundle branch (RBB), left anterior fascicle (LAF), and left posterior fascicle (LPF). Common Usage:…
Sinus Bradycardia
Key Points Definition: Sinus bradycardia is a rhythm originating from the sinoatrial (SA) node with a rate < 60 bpm. Physiological Occurrence: Common in young, healthy adults, athletes, and during…
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