Felis ISSN 2398-2950

Heart: ventricular premature contraction

Synonym(s): VPC, PVC

Contributor(s): Phil Fox, Philip K Nicholls, Pedro Oliveira

Introduction

  • Cause: usually myocardial irritation or damage due to primary cardiac or systemic disease.
  • Signs: depends on frequency - may be asymptomatic or weakness and lethargy.
  • Diagnosis: electrocardiography.
  • Treatment: treat underlying disease, antidysrhythmic agents if required.
  • Prognosis: variable - occasional VPCs do not effect mortality. Guarded related to significant underlying pathology.

Pathogenesis

Etiology

Primary cardiac disease

Extra-cardiac pathology

  • Electrolyte abnormalities.
  • Trauma.
  • Systemic disease:
  • Hypothermia Hypothermia.
  • Drug therapy.
  • Autonomic stimulation.

Predisposing factors

General

  • Underlying heart failure with poor cardiac output resulting in myocardial hypoxia.

Pathophysiology

  • Spontaneous depolarization of ventricular myocardial cells.
  • If all arise from a single focus (unifocal)   →   they appear similar in configuration.
  • If all have different configuration (multifocal)   →   multiple sites of ectopic depolarization.
  • Ectopic depolarization occurs in ventricular myocardial cells outside the normal impulse generating nodes and below the atrioventricular junction.
  • Impulse is not usually conducted in a retrograde fashion to the atria.
  • Ventricles are incompletely filled by the time of the ectopic discharge therefore cardiac output on ectopic beat is reduced.
  • Ventricular contraction due to VPC is usually followed by a compensatory pause until the next sinus impulse is generated.
  • If VPCs occur frequently cardiac output may be significantly affected due to poor ventricular filling.

Timecourse

  • May be present for prolonged periods before diagnosis.
  • If become frequent or progress to ventricular tachycardia Ventricular tachycardia then severity of signs ensures early diagnosis.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

Other sources of information

  • Ettinger S J, Feldman E C, Cote E (2017) Cardiac Arrhythmias. In: Textbook of Veterinary Internal Medicine. 8th edn, Elsevier. Chapter 248.
  • Smith F K W Jr, Tilley L P, Oyama M, Sleeper M (2016) Electrocardiography. and Treatment of cardiac arrhythmias. In: Manual of canine and feline cardiology. 5th edn, Saunders Elsevier. Chapters 3 and 17. 
  • Bonagura J D, Twedt D C (2014) Feline cardiac arrhythmias. In: Kirks Current Veterinary Therapy XV. Elsevier Saunders. Chapter 173. 


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