Cardinal Features

Monomorphic refers to a VT where each and every QRS complex is the same shape and size as the next. This form of tachycardia frequently occurs after myocardial infarction when it is a sign of extensive damage.

Cardinal features

The cardinal features of monomorphic VT are:

  • QRS rate 120-250 bpm
  • QRS rate is regular
  • QRS configuration is constant
  • QRS configuration is different from that in sinus rhythm
  • The QRS complexes are abnormally wide (0.12 seconds or longer)

Clinical presentation

As with all tachyarrhythmias, symptoms depend upon the ventricular rate and pre-existing cardiovascular state. As the majority of patients with VT have either congenital or acquired heart disease, sustained tachycardia often gives rise to symptoms and signs.

These symptoms and signs may be mild (consisting of dizziness or light-headedness), moderate (e.g. chest pain or shortness of breath), or severe (with cardiovascular collapse or profound shock). Surprisingly, some patients with severe heart disease may tolerate sustained VT remarkably well and remain asymptomatic.