Equis ISSN 2398-2977

Chordae tendineae: rupture

Contributor(s): Karen Blissit, Karen Blissitt, Christopher Brown, Lesley Young

Introduction

  • Chordae tendineae are fibrous strands attaching the cusps of the mitral and tricuspid valves to papillary muscles in the ventricular wall.
  • Rupture of these chordae   →   valvular incompetence and, if major chordae are ruptured, acute left or right-sided heart failure; if minor chordae are ruptured   →   heart failure after a more prolonged period (months).

Pathogenesis

Etiology

  • Inflammatory and degenerative changes in the chordae.
  • In other species, bacterial endocarditis   Heart: endocarditis  , chronic valvular endocardiosis, indirect trauma, severe physical exertion have been implicated as possible etiologies.

Pathophysiology

  • Chordae anchor valve cusps to papillary muscles.
  • Degenerative change   →   rupture   →   valvular incompetence   →   clinical signs of heart failure.
  • Spontaneous rupture often occurs in horses with no obvious predisposing cause.
Mitral chordal rupture
  • Mitral valve normally remains closed during systole to prevent retrograde flow into atrium.
  • Blood from left ventricle   →   aorta.
  • In mitral incompetence blood flow into aorta but also backward through mitral valve into left atrium   →   decreased cardiac output and ventricular volume overload (left ventricular failure)   →   elevated left atrial pressures   →   pulmonary edema   Thorax: cardiogenic pulmonary edema - radiograph  . Pulmonary edema   →   hypoxic vasoconstriction   →   pulmonary hypertension   →   2° right ventricular failure.

Tricuspid chordal rupture

  • Tricuspid valve closed in systole to prevent retrograde flow of blood from RV to RA.
  • Rupture of chordae results in vlave prolapse and tricuspid valve regurgitation.
  • Turbulent retrograde blood flow causes systolic cardiac murmur audible from the right hemithorax.
  • Tricuspid chordal rupture rarely results in onset of right heart failure, as resultant regurgitation is generally well tolerated.

Timecourse

  • Usually acute onset, occasionally degree of compensation seen.

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.
  • Holmes J R & Miller P J (1984) Three cases of ruptured mitral valve chordae in the horse. Equine Vet J 16 (2), 125-135. (Thorough account of clinical observations and diagnostic procedures) PubMed.


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