Tachyarrhythmia
Results:
VT vs SVT with Aberrancy: DDx
Key Points ECG alone cannot reliably distinguish VT from SVT-aberrancy in many cases. Use ECG features to rule in VT, not to exclude it. Default: treat regular WCT as VT…
RV Outflow Tract Tachycardia (RVOT VT)
Key Points Idiopathic monomorphic VT arising from the right ventricular outflow tract. Most patients have no structural heart disease; catecholamine and cAMP-mediated triggers are common. Classic ECG pattern: LBBB morphology…
Fascicular Ventricular Tachycardia (Idiopathic Left Fascicular VT)
Key Points Idiopathic reentrant VT arising within the left Purkinje system, most often the left posterior fascicle. Patients are usually young and lack structural heart disease. Signature ECG: RBBB-like morphology…
Slow Ventricular Tachycardia (VT)
Key Points Definition: Slow ventricular tachycardia is defined as a wide complex tachycardia with a ventricular rate between 100–120 bpm. Distinction: Typical sustained VT usually exceeds 120 bpm. When encountering…
R-on-T Phenomenon
Key Points Definition: The R on T phenomenon occurs when an ectopic impulse (often a PVC or cardioversion shock) falls on the T wave of the preceding beat. Mechanism: Interrupting…
Multifocal Atrial Tachycardia (MAT)
Key Points Definition: Multifocal Atrial Tachycardia (MAT) is a rare type of irregularly irregular supraventricular tachycardia (SVT) characterized by the presence of at least three or more different P wave…
Wide & Irregular Tachycardia: DDx
Key Points Definition: QRS >120 ms with an irregular ventricular rate. Clinical Priority: Always first consider AF with accessory pathway (AF + WPW) and polymorphic VT (PMVT, including torsades) —…
Supraventricular Tachycardias (SVTs)
Key Points Definition: SVT refers to any tachyarrhythmia that originates above the ventricles (atria, AV node, or bundle of His). Most present as regular narrow-complex tachycardias, although aberrant conduction can…
Atrial Flutter 2:1 Conduction
Key Points Mechanism: Atrial flutter results from a macro re-entry circuit typically located within the right atrium, causing rapid and regular atrial activation (~300 bpm commonly). ECG Appearance: Classic “saw-tooth”…
Narrow & Irregular Tachycardia: DDx
Key Points Narrow irregular tachycardia = QRS <120 ms with variable R–R interval. The big three DDx: Atrial fibrillation (AF) with RVR, atrial flutter with variable block, multifocal atrial tachycardia…
Narrow & Regular Tachycardia: DDx
Key Points Narrow regular tachycardia = QRS <120 ms with a steady R–R interval. The big three DDx: sinus tachycardia, SVT (AVNRT/AVRT/junctional), and atrial flutter with fixed AV conduction (commonly…
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….
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…
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”…
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…
Wide Complex Tachycardias: does response to Valsalva maneuvers or adenosine rule out ventricular tachycardia?
A 54-year-old man with no significant PMHx presents to the ED with palpitations. He is hemodynamically stable with a normal blood pressure. The following ECG is obtained prior to the…
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