polymorphic VT
Ventricular tachycardia with continuously changing QRS morphology, indicating multiple activation wavefronts or shifting electrical axis.
Full Definition
Polymorphic ventricular tachycardia is a form of ventricular tachycardia characterized by continuously changing QRS morphology, amplitude, and axis from beat to beat. Unlike monomorphic VT, which maintains a consistent QRS appearance, polymorphic VT demonstrates marked variability in the electrical activation pattern of the ventricles. This arrhythmia can occur in the setting of acute ischemia, electrolyte abnormalities, drug toxicity, or genetic conditions affecting cardiac ion channels. Torsades de pointes is a specific subtype of polymorphic VT associated with QT prolongation. Polymorphic VT carries a higher risk of degenerating into ventricular fibrillation and requires urgent recognition and treatment. The underlying mechanism typically involves multiple reentrant circuits or triggered activity from various ventricular locations.
Usage
Usage note: Often abbreviated as PMVT in clinical notes.
In Context
- "The patient developed polymorphic VT during the acute phase of myocardial infarction, requiring immediate cardioversion." — Emergency department report
- "Polymorphic VT episodes were successfully suppressed with beta-blocker therapy and electrolyte correction." — Cardiology discharge summary