Flecainide, Propafenone, Quinidine (rarer) Digoxin
Inappropriate use of IV verapamil
Frequent or difficult to terminate Conduction slowing in reentrant VT ("incessant" VT) circuits
Atrial tachycardia with AV block; ventricular bigeminy and others
DAD-related triggered activity (±T vagal tone)
Severe hypotension and/or myocardial ischemia
Na+ bolus reportedly effective in some cases
Cardiac resuscitation (DC cardioversion)
Most often in patients with advanced myocardial scarring Coexistence of abnormal impulses with abnormal sinus or AV nodal function Misdiagnosis of VT as PSVT ^ inappropriate use of verapamil
*In each of these cases, recognition and withdrawal of the offending drug(s) are mandatory.
ABBREVIATIONS: AV, atrioventricular; DAD, delayed afterdepolarization; DC, direct current; EAD, early afterdepolarization; WPW, Wolff-Parkinson-White supraventricular tachycardia; IV, intra-8 venous; T, increase; decrease; ?, unclear. o
AV node ^Conducting system Purkinje fiber
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