Table 2

Morphology and characteristics of premature ventricular beats that may be encountered in clinical practice

PatternQRS morphologyOrigin of ectopic beatCommentFigure
Common patterns in athletes
InfundibularLBBB with late precordial transition (R/S=1 after V3) and inferior axis.Right ventricular outflow tract.Usually benign. Figure 1A
LBBB and inferior axis but with small R-waves in V1 and early precordial transition (R/S=1 by V2 or V3).Left ventricular outflow tract.Usually benign. Figure 1B
FascicularTypical RBBB with superior axis and QRS <130 ms.Left posterior fascicle of the left bundle branch.Usually benign. Figure 1C
Typical RBBB with inferior axis and QRS <130 ms.Left anterior fascicle of the left bundle branch.Usually benign. Figure 1D
Uncommon patterns in athletes
Atypical RBBB and QRS ≥130 ms.Mitral valve annulus, papillary muscles or left ventricle.May be associated with myocardial disease. Figures 3 and 5
LBBB with superior or intermediate axis.Right ventricular free wall or interventricular septum.May be associated with myocardial disease. Figure 4
  • LBBB: negative QRS complex in lead V1.

  • Atypical RBBB: positive QRS complex in lead V1 not resembling a typical RBBB.

  • Typical RBBB: rSR’ pattern in lead V1 and an S-wave wider than R-wave in lead V6.

  • Inferior QRS axis: positive QRS in the inferior leads (II, II, aVF).

  • Superior QRS axis: negative QRS in the inferior leads aVF.

  • Intermediate QRS axis: positive QRS complexes in both aVF and aVL.

  • Precordial transition: precordial lead in which the QRS complex becomes predominantly positive.

  • LBBB, left bundle branch block; RBBB, right bundle branch block.