Equis ISSN 2398-2977

Heart: supraventricular premature complex

Synonym(s): SVPC, atrial premature complex, APC

Contributor(s): Christopher Brown, Wendy Furness, Lesley Young, Nicola Menzies-Gow

Introduction

  • Cause: caused by abnormal impulses formed within cells of the atrial myocardium.
  • Signs: variable depending on frequency and etiology and presence of co-existent heart disease, but usually are an incidental finding.
  • Diagnosis: auscultation, ECG.
  • Treatment: variable, ranging from none, to appropriate treatment of underlying cardiac or systemic disease, to steroids and stall rest.
  • Prognosis: depends entirely on inciting cause.

Pathogenesis

Etiology

  • Hypoxia.
  • Atrial dilation secondary to mitral regurgitation or a large ventricular septal defect.
  • Inflammation of the atrial myocardium.
  • Electrolyte and metabolic disturbances.
  • Elevated sympathetic tone.
  • Fever.

Predisposing factors

Specific

  • Underlying cardiac disease.

Pathophysiology

  • If a premature supraventricular depolarization wave occurs after the refractory period of the ventricles it will be conducted and ventricular contraction will occur.
  • If premature atrial contractions occur at a very high rate (supraventricular tachycardia), they are usually blocked at the atrioventricular node in horses to maintain a relatively normal heart rate Heart: atrial tachycardia 02 - ECG.
  • Supraventricular tachycardia resulting in an overall reduction in cardiac output and performance limitation, or other clinical signs at rest is very rare in horses, as second degree atrioventricular block usually prevents an excessively high heart rate, unless the condition is secondary to severe cardiac disease.

Timecourse

  • Usually incidental finding.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

Other sources of information

  • Marr C M & Bowen I M (2010) Eds Cardiology of the Horse. 2nd edn. Elsevier Ltd. ISBN: 9780702028175.


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