bidirectional VT
Ventricular tachycardia characterized by alternating QRS axis, creating a distinctive ECG pattern of beat-to-beat morphology changes.
Full Definition
Bidirectional ventricular tachycardia is a specialized form of polymorphic ventricular tachycardia characterized by alternating QRS complexes with different morphologies and axes, typically shifting between right and left axis deviation in a beat-to-beat alternating pattern. This creates a distinctive 'bidirectional' appearance on the ECG. Bidirectional VT is classically associated with digitalis toxicity, but can also occur in catecholaminergic polymorphic ventricular tachycardia (CPVT), a genetic condition affecting calcium handling in cardiac myocytes. The mechanism typically involves triggered activity due to delayed afterdepolarizations originating from alternating ventricular foci. Recognition is crucial as it often indicates serious underlying pathology requiring immediate intervention.
Usage
Usage note: May be abbreviated as bidirectional VT or BiVT in clinical shorthand.
In Context
- "The patient's ECG showed classic bidirectional VT with alternating QRS morphologies, raising suspicion for CPVT." — Emergency department note
- "Bidirectional VT resolved after digoxin levels normalized following toxicity management." — Cardiology consultation note