Felis ISSN 2398-2950

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 posterior fascicle. Selective block of the anterior fascicle results in deviation of the ECG mean electrical axis to the left. 
  • The anatomy of the feline left bundle branch is not easily categorized in this way and the terminology left anterior fascicular block is likely a misnomer in this species. The author and many others prefer to describe this phenomenon in cats simply as a left axis shift (or deviation), rather than use it as evidence of a "left anterior fasicicular block".

ECG characteristics

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Clinical importance

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Treatment

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Further Reading

Publications

Referred papers

Other sources of information

  • Goodwin J K (2001) Electrocardiography. In: Tilley J K& Goodwin J K (eds) Manual of Canine and Feline Cardiology. 3rd edn. W B Saunders, pp 43-70.
  • Tilley L P (1985) Essentials of canine and feline electrocardiography: interpretation and treatment. Lea & Febiger.


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