Felis ISSN 2398-2950

Ventricular tachycardia

Contributor(s): Mark Oyama, Mark Rishniw

Introduction

  • Can be serious life-threatening dysrhythmia, often incidental non-life-threatening arrhythmia.
  • Cause: usually myocardial irritation due to primary cardiac or systemic disease.
  • Signs: weakness, collapse and death.
  • Diagnosis: electrocardiography.
  • Treatment: treat underlying disease, antidysrhythmic agents.
  • Prognosis: guarded for some, good for others.

Pathogenesis

Etiology

Primary cardiac disease

Extra-cardiac pathology

Predisposing factors

General

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

Specific

Pathophysiology

  • Spontaneous depolarization of ventricular myocardial cells.
  • More than 3 ventricular premature complexes (VPCs Ventricular premature contraction) in a row.
  • May progress to ventricular fibrillation Ventricular fibrillation in some cases.
  • 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 Hypoxemia.
  • Ectopic depolarization occurs in ventricular myocardial cells outside the normal impulse generating nodes and below the atrioventricular junction.
  • Ventricles are incompletely filled by the time of the ectopic discharge and contraction of myocardium follows abnormal sequence    →     reduced cardiac output on ectopic beat.
  • Hypotension and myocardial ischemia may     →   syncope, seizures Seizures, or progression of arrhythmia to ventricular fibrillation     →   death.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Harvey A M, Battersby I A, Faena M et al (2005) Arrhythmogenic right ventricular cardiomyopathy in two cats. J Small Anim Pract 46 (3), 151-156 PubMed.
  • Petrie J P (2005) Practical application of holter monitoring in dogs and cats. Clin Tech Small Anim Pract 20 (3), 173-181 PubMed.
  • Fox P R, Peterson M E, Broussard J D (1999) Electrocardiographic and radiographic changes in cats with hyperthyroidism: comparison of populations evaluated during 1992-1993 vs. 1979-1982. J Am Anim Hosp Assoc 35 (1), 27-31 PubMed.


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