Premature ventricular contractions are early beats arising from an ectopic focus located in the ventricles.

Electrocardiographic Criteria

  • Premature beat with a wide QRS (> 120 ms)
  • They may show more than one morphology (polymorphic)
  • The ST segment and T wave deviate opposite to the main QRS vector
  • Compensatory pauses are usually complete

Classification

By morphology, they can be classified as:

  • Monomorphic: when they share the same morphology;
  • Polymorphic: when they show more than one morphology.

According to their relationship with the underlying rhythm, they can be:

  • Bigeminal: one PVC alternating with one normal beat;
  • Trigeminal: after two normal beats, the third is a PVC;
  • Quadrigeminal: after three normal beats, the fourth is a PVC.

ECG in Premature Ventricular Contractions

Electrocardiogram showing premature ventricular contractions (ventricular bigeminy)

Ventricular bigeminy. PVCs (beats with a wide QRS complex) alternating with normal beats (narrow QRS complexes preceded by a P wave).

Electrocardiogram showing premature ventricular contractions (ventricular trigeminy)

Ventricular trigeminy. In ventricular trigeminy, after every two normal beats, the third is a PVC.

References

  1. Scheffer MK, De Marchi MFN, de Alencar Neto JN, Felicioni SP. Eletrocardiograma de A a Z. São Paulo: Manole, 2024.
  2. Samesima N, God EG, Kruse JCL, Leal MG, et al. Diretriz da Sociedade Brasileira de Cardiologia sobre a Análise e Emissão de Laudos Eletrocardiográficos – 2022. Arq Bras Cardiol. 2022;93(3 Suppl 2):2–19.