Causes and Diagnosis of Wide QRS Complex Tachycardia

Main Causes of Wide QRS Complex

A wide QRS complex (>120 ms) is primarily caused by three major mechanisms: ventricular tachycardia, supraventricular tachycardia with bundle branch block or aberration, and supraventricular tachycardia with AV conduction over an accessory pathway, according to the American College of Cardiology 1, 2
Characterized by ventricular-atrial (VA) dissociation with ventricular rate faster than atrial rate, the American College of Cardiology recommends considering ventricular tachycardia as a primary cause 1, 3
QRS width >140 ms with right bundle branch block (RBBB) pattern or >160 ms with left bundle branch block (LBBB) pattern suggests ventricular tachycardia, as stated by the American College of Cardiology 1, 2
RS interval >100 ms in any precordial lead is highly suggestive of ventricular tachycardia, according to the American College of Cardiology 2
Negative concordance pattern in precordial leads is diagnostic for ventricular tachycardia, as recommended by the American College of Cardiology 2
Bundle branch block may be pre-existing or may occur during tachycardia when one bundle branch is refractory due to rapid rate, according to the American College of Cardiology 1, 3
Antidromic AVRT involves anterograde conduction over accessory pathway and retrograde conduction over AV node, as stated by the American College of Cardiology 1
Electrolyte abnormalities, particularly hyperkalemia, can cause QRS widening, according to the American College of Cardiology 5

AV dissociation with ventricular rate faster than atrial rate is a key diagnostic criterion for ventricular tachycardia, as recommended by the American College of Cardiology 1, 6
QRS width >140 ms with RBBB or >160 ms with LBBB pattern is suggestive of ventricular tachycardia, according to the American College of Cardiology 1, 6
RS interval >100 ms in any precordial lead is highly suggestive of ventricular tachycardia, as stated by the American College of Cardiology 2, 6
History of previous myocardial infarction strongly suggests ventricular tachycardia, according to the American College of Cardiology 6
First occurrence of wide QRS tachycardia after infarction suggests ventricular tachycardia, as recommended by the American College of Cardiology 6

If diagnosis of SVT cannot be proven or easily made, treat as if ventricular tachycardia is present, according to the American College of Cardiology 1, 6
Intravenous medications for SVT (particularly verapamil or diltiazem) may precipitate hemodynamic collapse if given to patients with ventricular tachycardia, as stated by the American College of Cardiology 1, 2
Immediate DC cardioversion is recommended for hemodynamically unstable patients, according to the American College of Cardiology 6
For stable patients with presumed ventricular tachycardia, IV procainamide, sotalol, or amiodarone may be used, as recommended by the American College of Cardiology 6
Adenosine can be used for stable, regular, monomorphic wide-QRS tachycardia for both diagnosis and treatment, according to the American College of Cardiology 6
Patients should be referred to an arrhythmia specialist after successful termination of wide QRS-complex tachycardia of unknown etiology, as stated by the American College of Cardiology 6