Canis ISSN: 2398-2942

Heart: ventricular premature contraction

Synonym(s): VPC, PVC, VEB

Contributor(s): Mark Rishniw, Pedro Oliveira

Introduction

  • Common in dog.
  • 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 or Holter monitoring.
  • Treatment: treat underlying disease, antidysrhythmic agents if required (treatment of dysrhythmia may not improve prognosis).
  • Prognosis: variable.

Pathogenesis

Etiology

Primary cardiac disease

Extra-cardiac pathology

Predisposing factors

General

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

Specific

Pathophysiology

  • Spontaneous depolarization of ventricular myocardial cells.
  • If all appear similar in configuration - uniform, monomorphic.
  • If all have different configuration - multiform, polymorphic.
  • Severe shock or autonomic stimulation → myocardial ischemia and myocyte damage.
  • Myocardial disease or damage → changes in resting potential, sodium and calcium currents across cell membranes → arrhythmogenesis.
  • This effect may be enhanced by other factors, eg hypoxemia.
  • 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 and contraction of myocardium is chaotic → reduced cardiac output on ectopic beat.
  • 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.
  • More than three VPCs in a row → ventricular tachycardia Ventricular tachycardia.

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

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Treatment

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Outcomes

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

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) Ventricular arrhythmias in dogs. In: Kirks Current Veterinary Therapy XV. Chapter 172, Elsevier Saunders.


ADDED