Arrhythmia
Results:
Ventricular Escape Rhythms
Key Points Wide QRS Complex Rhythm: Ventricular escape rhythms (aka idioventricular rhythms) are characterized by a wide QRS duration (>120 ms), absent or dissociated P-waves, and a regular, slow ventricular…
Junctional Escape Rhythms
Key Points Narrow QRS Complexes typically indicate junctional escape rhythms, originating near the AV node or proximal His-Purkinje system. These generally have a more favorable prognosis. Wide QRS Complexes suggest…
The Bix Rule (Unmasking Atrial Flutter)
Key Points The Bix Rule refers to a simple but powerful ECG clue: if you observe a consistent P wave located exactly halfway between two QRS complexes, suspect concealed atrial…
Ashman Phenomenon
Key Points Definition: Ashman phenomenon is an aberrant intraventricular conduction pattern triggered by cycle-length variation. It is most often seen in atrial fibrillation but can appear in any supraventricular rhythm….
Junctional Tachycardia
Key Points Origin: Junctional tachycardia is a rare type of paroxysmal supraventricular tachycardia (SVT) that originates from the AV node or the bundle of His. Mechanism: The arrhythmia is caused…
Atrial Tachycardia
Key Points: Definition: Atrial tachycardia is a supraventricular arrhythmia characterized by rapid atrial depolarizations from one or more ectopic foci outside the SA node. Atrial Rate: > 100 bpm, typically…
Sinus Node Dysfunction (Sick Sinus / Brady-Tachy Syndrome)
Key Points Spectrum, not one rhythm: Look for sinus brady, pauses, arrest, alternating atrial tachyarrhythmias (AF, flutter, ATach). Symptoms matter: Syncope, presyncope, fatigue usually come from cerebral/systemic hypoperfusion, especially after…
Slow Atrial Fibrillation
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,…
Atrial Flutter with Variable Conduction
Key Points Mechanism: Typical atrial flutter arises from a large re-entry circuit in the right atrium. The atrial rate is usually near 300 beats per minute. ECG hallmark: Continuous “saw-tooth”…
Bradycardia: DDx
Key Points Common Offenders: Beta-blockers, calcium channel blockers, and digoxin often top the list of medication-induced bradycardia. High Vagal Tone or AV Block can arise from structural heart disease, ischemia,…
Flutter Waves (F waves)
Key Points Mechanism: Produced by a macro-reentrant circuit within the right atrium. Atrial Rate: Typically ~300 bpm (range 240–360 bpm). ECG Appearance: Characteristic saw-tooth baseline undulations without an isoelectric interval….
Polymorphic Ventricular Tachycardia (PMVT)
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…
Nonsustained Ventricular Tachycardia
Key Points Definition: NSVT is defined as ≥3 consecutive ventricular beats, QRS duration >120 ms, rate typically 100-250 bpm (usually > 120 bpm), lasting less than 30 seconds without causing…
Atrial Fibrillation with WPW
Key Points: WPW Syndrome: A condition characterized by ventricular pre-excitation due to a congenital accessory pathway, often associated with symptomatic arrhythmias. ECG Recognition: The WPW pattern is best identified when…
Ectopic Atrial Rhythm
Key Points Definition: Ectopic atrial rhythms occur when atrial depolarization originates from a site other than the sinoatrial (SA) node, producing P waves with abnormal morphology and axis on ECG….
Brugada Syndrome (BrS)
Key Points Life-Threatening Sodium Channelopathy: Predisposes to ventricular arrhythmias (VF/VT) and sudden cardiac death (SCD), often in otherwise “healthy” hearts. When to Suspect BrS: Patients with syncope, unexplained “seizures,” ventricular…
WPW Syndrome and Pseudo-MI Patterns
Key Points WPW Pattern Mimics: Wolff-Parkinson-White (WPW) syndrome can produce an ECG pattern that mimics conditions such as myocardial infarction, ventricular bigeminy, accelerated idioventricular rhythm, and electrical alternans. ST Segment…
Atrial Parasystole
Key Points Definition: A rare arrhythmia in which a secondary atrial focus fires at its own inherent rate, largely “shielded” from sinus node impulses. Characteristic ECG Finding: Two distinct P-wave…
WPW with Antidromic SVT
Key Points WPW Syndrome: Wolff-Parkinson-White (WPW) syndrome is a condition characterized by ventricular pre-excitation due to a congenital accessory pathway in patients with symptomatic arrhythmias. ECG Recognition: The classic WPW…
WPW with Orthodromic SVT
Key Points WPW syndrome is caused by congenital ventricular pre-excitation via an accessory pathway. The classic sinus rhythm pattern includes a short PR interval, delta wave, and a widened QRS,…
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