EMed

Ventricular Tachycardia

Monomorphic ventricular Tachycardia

  • Usually 120-300 beats/min Monoporphic VT
  • Rhythm regular or almost regular
  • ↑ QRS duration > 0.12 sec
  • V1: often RBBB morphology
  • Fusion or capture beats
  • Bizarre QRS complex and axis (axis negative in 1 and aVF), but may have a BBB morphology
  • Evidence of AV dissociation ( Cannon "a" waves in the JVP, P waves, capture beats, fusion beats, concordance in the chest leads )
  • VA block with Wenckebach
  • Concordance V1 to V6 (also seen with WPW)
  • If LBBB pattern likely to be coming from right ventricle (RBBB pattern likely from left ventricle)

RVOT

  • Monomorphic VT
  • Exercise induced
  • LBBB morphology with inferior axis (DDx ARVD)
  • Adenosine sensitive (cAMP mediated)
  • Good prognosis
  • Treat with β-blockers before radio ablation

Differential diagnosis

  • Could this be SVT with aberrant conduction or a pre-existing bundle branch block? link
  • In unstable patients: See Resusc Council UK algorithm(Hover for Algorithm)
  • In stable patients:
    • Treat ischaemia, correct electrolytes. Consider immediate cardioversion
    • Choice of drugs in stable patients: Amiodarone, Lidocaine, procainamide, sotalol
    • Avoid procainamide and sotalol if clinical signs of impaired LV fxn
    • Choose one agent only, and seek expert advice if you are at all unsure

Polymorphic ventricular tachycardia

Polymorphic VT
  • Irregular broad complex tachycardia
  • Variable QRS morphology
  • Often has an underlying cause such as electrolyte disturbance, toxins, or ischaemia
  • Leads to haemodynamic collapse

Arrhythmogenic Rt Vent Dysplasia (ARVD)

  • Fibrous tissue in Rt Vent particularly young patients
  • LBBB morphology during VT
  • ECG features:
    • Epsilon waves
    • T wave inversion V2-V3
    • Incomplete RBBB (particularly V1-V3)
    • Paroxysmal VT with LBBB pattern
  • DDx RVOT (above)
  • Involve cardiology:
    • 1% die per year
    • Hereditary (screen 1° relatives)
arvd - epsilon wave
Image from ECGpedia.org

Think

Management

  • In unstable patients: Go to the broad complex tachycardia treatment Resusc Council UK algorithm
  • In stable patients:
    • Treat ischaemia, correct electrolytes. Consider immediate cardioversion
    • Choice of drugs in stable patients: Amiodarone, Lidocaine, procainamide, sotalol, β-blockers
    • Avoid procainamide & sotalol if clinical signs are suggestive of impaired LV fxn
    • Lidocaine or β-blockers may be indicated if you suspect acute ischaemia
    • Choose one agent only, and seek expert advice if you are at all unsure

Last review Dr Íomhar O' Sullivan 17/01/23.