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Mitral Valve Dysplasia

Mitral Valve Dysplasia. Accession 108713 Erica Fields, DVM. Marley Sheenan. 5.5 month old female Great Dane Hit by a car 2 days prior, diagnosed with hemoabdomen, pulmonary contusions Now appears more stable, transient mild anemia resolved

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Mitral Valve Dysplasia

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  1. Mitral Valve Dysplasia Accession 108713 Erica Fields, DVM

  2. Marley Sheenan • 5.5 month old female Great Dane • Hit by a car 2 days prior, diagnosed with hemoabdomen, pulmonary contusions • Now appears more stable, transient mild anemia resolved • Follow-up radiographs performed to assess pulmonary contusions

  3. Referral radiographs 12/27/08 Alveolar pattern, Mild shift

  4. Referral radiographs 12/27/08

  5. Referral radiographs 12/27/08

  6. NCSU radiographs 12/29/08

  7. NCSU radiographs 12/29/08 Left atriomegaly Left ventriculomegaly

  8. Left atrial enlargement Left ventriculomegaly Pulmonary venous hypertension Unstructured interstitial pattern (pulmonary edema) Marked left atrial dilation Ruptured chordae tendinae The mural leaflet is tethered to the left ventricular wall Mitral valve regurgitation Imaging Studies

  9. Mitral Valve Dysplasia • Both dogs and cats • One of the most important cardiac malformations in cats • Cause unknown; breed-related • 5th most common cardiac defect in one study • ALWAYS—valves incompetent (regurgitant); SOMETIMES—valves stenotic as well Ettinger, 1995 and Tidholm, 1997

  10. Bull Terrier Golden Retriever Great Dane Newfoundland German Shepherd Mastiff

  11. Nature of Abnormalities • Shortened, rolled, notched, or thickened valve leaflets • Fusion and thickening, short or long chordae • Direct insertion of cusps into papillary muscles • Upward malpositioning of papillary muscles Ettinger, 1995

  12. Pathophysiology • Regurgitation—volume overload • Dilation and hypertrophy of atrium and ventricle • Predisposition to cardiac arrhythmias, esp. atrial fibrillation • Potential for valve stenosis and obstruction to ventricular filling Ettinger, 1995

  13. Short, thick chordae tendinae, direct insertion of leaflet on papillary muscle

  14. Clinical Signs • Soft to loud holosystolic murmur over valve/apex • Sometimes, soft diastolic rumble over valve inflow tract (stenosis) • Gallop • Atrial fibrillation • Exercise intolerance/signs of CHF (can develop within first year of life) • Of congenital cardiac defects, one of the most common to present with clinical signs Ettinger, 1995 and Tidholm, 1997

  15. Treatment and Prognosis • Medical support/palliation of CHF • Surgical therapy available • Valvuloplasty • Mechanical prostheses • Bioprostheses • Behr bioprosthesis article Prognosis variable: if significant cardiomegaly is present at diagnosis, prognosis is poor. Behr, 2007; Griffiths, 2004; Orton, 2005

  16. References • Behr, et al. The Cardiovascular system: Dysplasia of the atrioventricular valves. In Textbook of Veterinary Internal Medicine, 4th ed. Ettinger and Feldman. WB Saunders Company, Philadelphia. 1995. • Behr L, Chetboul V, Sampedrano CC, Pouchelon JL, Laborde F, and Borenstein N. 2007. Beating heart mitral valve replacement with a bovine pericardial bioprosthesis for treatment of mitral valve dysplasia in a bull terrier. Veterinary Surgery 36: 190-198. • Griffiths LG, Orton EC, and Boon JA. 2004. Evaluation of techniques and outcomes of mitral valve repair in dogs. JAVMA 224 (12): 1941-1945. • Orton EC, Hackett TB, Mama K, Boon JA. 2005. Technique and outcome of mitral valve replacement in dogs. JAVMA 226 (9): 1508-1511. • Tidholm A. 1997. Retrospective study of congenital heart defects in 151 dogs. Journal of Small Animal Practice 38: 94-98.

  17. Questions?

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