ISSN 2398-2977      

Heart: myocarditis

pequis
Contributor(s):

Introduction

  • Inflammatory changes/necrosis of myocytes.
  • Cause: various:
    • Idiopathic
    • Viral.
    • Bacterial.
    • Toxic.
  • Signs: vary depending upon underlying etiology: dysrhythmias frequently seen, poor performance, malaise, congestive heart failure, sudden death.
  • Diagnosis: very difficult - no pathognomic signs; echocardiography.
  • Treatment: in most cases of extensive myocardial damage or necrosis, treatment is ineffectual once clinical signs are apparent.
  • Prognosis: guarded.

Pathogenesis

Etiology

Pathophysiology

  • Damage, inflammation +/- necrosis of myocardium and conduction tissues   →   systolic and diastolic dysfunction and dysrhythmias.
Acute
  • Direct damage to monocytes or ischemia due to coronary artery occlusion   →   myocardial inflammation and reduced myocardial contractile efficiency.
  • Death/inflammation of monocytes   →    increased automaticity and provokes arrhythmia.

Chronic

  • Replacement fibrosis and loss of contractile tissue cause progressive systolic and diastolic dysfunction of the myocardium resulting in global compromise of cardiac function and signs of low output heart failure.
  • Ultimately the cardiac remodelling results in a hypocontractile dilated ventricle that mimics dilated cardiomyopathy in other species.

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.
  • Kiryu K, Machida N, Kashida Y et al (1999) Pathologic and electrocardiographic findings in sudden cardiac death in racehorses. J Vet Med Sci 61 (8), 921-928 PubMed.
  • Traub-Dargatz J L, Schlipf J W Jr, Boon J et al (1994) Ventricular tachycardia and myocardial dysfunction in a horse. JAVMA 205 (11), 1569-1573 PubMed.
  • Machida N, Nakamura T, Kiryu K, Haramaki S & Too K (1992) Cardiopathological observation on a case of persistent ventricular tachycardia in a pony mare.  J Vet Med Sci 54 (6), 1213-1216 PubMed.
  • Button C, Scrutchfield W L, Clark R G et al (1980) Multiple atrial dysrhythmias in a horse. JAVMA 177 (8), 714-719 PubMed.

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