Canis ISSN: 2398-2942

Heart: left anterior fascicular block

Synonym(s): Left axis shift

Contributor(s): Dan Ohad, Mark Oyama

Pathophysiology

  • The bundle branches of the cardiac conduction system arise from the bundle of His as it exits the atrioventricular node.
  • In human beings, the left bundle branch can often be divided into an anterior and a posterior fascicle. Selective block of the anterior fascicle results in deviation of the ECG mean electrical axis to the left.
  • The anatomy of the canine left bundle branch is not easily categorized in this way and the terminology left anterior fascicular block is likely a misnomer in this species. Experimental damage to the left anterior portion of the canine bundle branch does not cause the typical ECG pattern ECG: overview seen in humans with this condition, and the author and many others prefer to describe such axis shift when it does occcur in dogs simply as a "left axis shift (or deviation)", rather than use it as evidence of a "left anterior fascicular block".

ECG characteristics

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Clinical importance

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Treatment

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Further Reading

Publications

Refereed papers


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