Left posterior fascicular block

The printable version is no longer supported and may have rendering errors. Please update your browser bookmarks and please use the default browser print function instead.
His-Purkinje system and hemiblocks

Criteria

Diagnostic criteria include[1]:

  1. Right axis deviation (>110)
  2. QRS < 120ms
  3. qR in III and aVF
  4. rS in I and aVL

LAFB vs LPFB[2]

LAFB LPFB
Axis Left axis deviation Right axis deviation
I and aVL Upright QRS Downgoing QRS
III Downgoing QRS Upright QRS

Significance

  • Usually associated with disease
  • Isolated LPFB associated with MI[3]
  • Exclude other causes of RAD (PE, COPD, RVH, Lateral MI)

See Also

References

  1. Surawicz B, et al. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part III: intraventricular conduction disturbances. Journal of the American College of Cardiology. 2009; 53(11): 976–981.
  2. Mattu A and Brady WJ. ECG's for the Emergency Physician. BMJ Books. Sep 19, 2003.
  3. Godat FJ and Gertsch M. Isolated left posterior fascicular block: a reliable marker for inferior myocardial infarction and associated severe coronary artery disease. Clin Cardiol. 1993; 16(3):220-226.