Felis ISSN 2398-2950

Heart: atrial premature complexes

Synonym(s): APC, dropped beat

Contributor(s): Phil Fox, Simon Swift

Introduction

  • Beats arising from ectopic foci originating in the atria. Generally a sign of atrial disease/enlargement or cardiomyopathy.
  • Cause: irritation to the atria - enlargement or disease.
  • Signs: arrhythmia detected on examination.
  • Diagnosis: electrocardiography.
  • Treatment: specific treatment not usually needed, treat underlying disease.
  • Prognosis: usually good depending on underlying disease.

Pathogenesis

Etiology

Pathophysiology

  • Irritation of the atrial myocardium causes premature depolarization of a region of the atria which spreads across the atria to the AV node. This produces a P wave which may be abnormal in shape (negative, positive or biphasic) and the P-R interval may be prolonged.
  • If the SA node is reset, a non-compensatory pause is present.
  • If the APC is very early, the AV node may be refractory resulting in no ventricular contraction (QRS). If the AV node or His-Purkinje system are partially refractory, an aberrant QRS may follow, often with a right bundle branch pattern.

Timecourse

  • Depends on underlying disease.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

Other sources of information

  • Ettinger S (1995) Cardiac Arrhythmias. In: Textbook of Veterinary Internal Medicine. pp 965-968.
  • Tilley L P (1992) Essentials of Canine and Feline Electrocardiology. pp 215-216.


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