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…
Key Points Rapid Ventricular Rates: Atrial flutter with 1:1 conduction is associated with very rapid ventricular rates (250-320 bpm), leading to significant symptoms and rapid hemodynamic compromise. This rhythm is…
Key Points Classically associated with pericardial tamponade but seen in fewer than 30% of confirmed cases. Combination of low-voltage QRS + sinus tachycardia strongly suggests pericardial effusion/tamponade. Always perform rapid…
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…
Key Points Definition: PMVT is a ventricular tachycardia characterized by beat-to-beat variations in QRS morphology, axis, and duration, reflecting multiple ventricular foci or reentrant circuits. Clinical Importance: PMVT is often…
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 hyperacute…
Key Points High Risk of Missed Diagnosis: Isolated posterior occlusion MI is frequently missed due to the absence of ST elevation on standard 12-lead ECG. Instead, ST depression in V1–V3…
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