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…
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…
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…
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…
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…
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…
Key Points Spectrum of Arrhythmias: Sinus node dysfunction produces alternating periods of inappropriate bradycardia (sinus bradycardia, pauses, arrest) and paroxysmal atrial tachyarrhythmias (AF, atrial flutter, atrial tachycardia). Symptom Driver: Transient…
Key Points Diagnosis: Wellens syndrome is a clinical diagnosis that requires more than just the presence of Wellens waves; it necessitates a thorough history and consideration of other potential causes…
Key Points Definition: Atrial fibrillation with a slow ventricular response, usually < 60 bpm. ECG: Irregularly irregular rhythm, no discrete P waves, slow R-R intervals. Common causes: AV-nodal blockers (digoxin,…
Key Points A STAT ECG is the most important initial test in patients with suspected acute coronary syndrome (ACS), enabling rapid identification of acute coronary occlusion myocardial infarction (OMI), a…
Key Points STEMI Diagnosis and Contiguous Leads: While current guidelines typically require ST elevation (STE) in at least two contiguous leads for the diagnosis of STEMI, this practice is not…
Key Points Definition: The precordial swirl sign refers to a rotational pattern of ST-segment abnormalities across the precordial leads, suggesting a dynamic and evolving occlusion myocardial infarction (OMI). It is…
Key Points Narrow therapeutic window: Small dosing errors or renal decline can push serum digoxin above the safe range. Excess automaticity + AV block: Toxicity increases atrial and ventricular irritability…
Key Points High-Risk PE: High-risk pulmonary embolism (PE) is a life-threatening condition requiring immediate recognition and treatment. The ECG can provide early, life-saving clues in the diagnosis of high-risk PE. Critical…
Key Points Beyond Electrical Alternans: Although classically linked to tamponade, electrical alternans is present in fewer than 30% of confirmed cases. It’s abscence should never rule out tamponade. Low Voltage…
Key Points Coronary Occlusion After Shockable Arrest: ~30% of patients resuscitated from ventricular fibrillation (VF) arrest have an acute coronary occlusion and present with STEMI on ECG. Among patients without…
Key Points Definition: Progressive lengthening of the PR interval until one atrial impulse fails to conduct to the ventricles (a dropped QRS complex). Site of Block: Typically within the AV…
Key Points Definition: A form of second-degree AV block in which every other atrial impulse is blocked, producing a 2:1 atrioventricular conduction ratio. Diagnostic Challenge: Differentiating between Mobitz I and…
Key Points Definition: A severe form of second-degree AV block—most often Mobitz II—characterized by multiple consecutive non-conducted P waves (e.g., 3:1 or 4:1 conduction). PR Intervals: Constant before conducted beats,…
Key Points Definition: Mobitz II is a type of second-degree AV block defined by sudden, intermittent failure of atrial impulses to conduct to the ventricles, without progressive PR interval lengthening…
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