What is monomorphic ventricular tachycardia (VT)?

Updated: Dec 05, 2017
  • Author: Steven J Compton, MD, FACC, FACP, FHRS; Chief Editor: Jeffrey N Rottman, MD  more...
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When the ventricular activation sequence is constant, the electrocardiographic (ECG) pattern remains the same, and the rhythm is called monomorphic VT (see the image below). Monomorphic VT is most commonly seen in patients with underlying structural heart disease. There is typically a zone of slow conduction, most commonly the result of scarring or fibrillar disarray. Causes include prior infarct, any primary cardiomyopathy, surgical scar, hypertrophy, and muscle degeneration.

This tracing depicts monomorphic ventricular tachy This tracing depicts monomorphic ventricular tachycardia.

Reentrant tachycardias occur when an electrical wavefront travels slowly through the zone of slow conduction (usually damaged muscle protected by scar tissue), allowing the rest of the circuit time to repolarize. The wavefront breaks out of the scar, activates the ventricle, and reenters the slow conduction zone.

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