Mitral Valve Mitral Valve DysplasiaDysplasiaAccession 108713Accession 108713

Erica Fields, DVMErica Fields, DVM

Marley SheenanMarley Sheenan

5.5 month old female Great Dane5.5 month old female Great Dane Hit by a car 2 days prior, diagnosed with Hit by a car 2 days prior, diagnosed with

hemoabdomen, pulmonary contusionshemoabdomen, pulmonary contusions Now appears more stable, transient mild Now appears more stable, transient mild

anemia resolvedanemia resolved Follow-up radiographs performed to Follow-up radiographs performed to

assess pulmonary contusionsassess pulmonary contusions

Alveolar pattern,

Mild shift

Referral radiographs

12/27/08

Referral radiographs 12/27/08

Referral radiographs 12/27/08

NCSU radiographs 12/29/08

Left atriomegaly

Left ventriculomegaly

NCSU radiographs

12/29/08

Imaging StudiesImaging Studies

Left atrial Left atrial enlargementenlargement

Left ventriculomegalyLeft ventriculomegaly Pulmonary venous Pulmonary venous

hypertensionhypertension Unstructured Unstructured

interstitial pattern interstitial pattern (pulmonary edema)(pulmonary edema)

Marked left atrial Marked left atrial dilationdilation

Ruptured chordae Ruptured chordae tendinaetendinae

The mural leaflet is The mural leaflet is tethered to the left tethered to the left ventricular wallventricular wall

Mitral valve Mitral valve regurgitationregurgitation

Ettinger, 1995 and Tidholm, 1997Ettinger, 1995 and Tidholm, 1997

Mitral Valve DysplasiaMitral Valve Dysplasia

Both dogs and catsBoth dogs and cats One of the most important cardiac One of the most important cardiac

malformations in catsmalformations in cats Cause unknown; breed-relatedCause unknown; breed-related 55thth most common cardiac defect in one study most common cardiac defect in one study ALWAYS—valves incompetent (regurgitant); ALWAYS—valves incompetent (regurgitant);

SOMETIMES—valves stenotic as wellSOMETIMES—valves stenotic as well

Bull Terrier

Golden Retriever

NewfoundlandGreat Dane

German Shepherd Mastiff

Ettinger, 1995Ettinger, 1995

Nature of AbnormalitiesNature of Abnormalities

Shortened, rolled, notched, or thickened Shortened, rolled, notched, or thickened valve leafletsvalve leaflets

Fusion and thickening, short or long Fusion and thickening, short or long chordaechordae

Direct insertion of cusps into papillary Direct insertion of cusps into papillary musclesmuscles

Upward malpositioning of papillary Upward malpositioning of papillary musclesmuscles

Ettinger, 1995Ettinger, 1995

Pathophysiology Pathophysiology

Regurgitation—volume overloadRegurgitation—volume overload Dilation and hypertrophy of atrium and Dilation and hypertrophy of atrium and

ventricleventricle Predisposition to cardiac arrhythmias, Predisposition to cardiac arrhythmias,

esp. atrial fibrillationesp. atrial fibrillation Potential for valve stenosis and Potential for valve stenosis and

obstruction to ventricular fillingobstruction to ventricular filling

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

Ettinger, 1995 and Tidholm, 1997Ettinger, 1995 and Tidholm, 1997

Clinical SignsClinical Signs

Soft to loud holosystolic murmur over Soft to loud holosystolic murmur over valve/apexvalve/apex

Sometimes, soft diastolic rumble over valve Sometimes, soft diastolic rumble over valve inflow tract (stenosis)inflow tract (stenosis)

GallopGallop Atrial fibrillationAtrial fibrillation Exercise intolerance/signs of CHF (can Exercise intolerance/signs of CHF (can

develop within first year of life)develop within first year of life) Of congenital cardiac defects, one of the most Of congenital cardiac defects, one of the most

common to present with clinical signscommon to present with clinical signs

Behr, 2007; Griffiths, 2004; OrtonBehr, 2007; Griffiths, 2004; Orton, 2005, 2005

Treatment and PrognosisTreatment and Prognosis

Medical support/palliation of CHFMedical support/palliation of CHF Surgical therapy availableSurgical therapy available

ValvuloplastyValvuloplasty Mechanical prosthesesMechanical prostheses BioprosthesesBioprostheses Behr Behr bioprosthesisbioprosthesis article article

Prognosis variable: if significant cardiomegaly Prognosis variable: if significant cardiomegaly is present at diagnosis, prognosis is poor. is present at diagnosis, prognosis is poor.

ReferencesReferences

Behr, et al. The Cardiovascular system: Dysplasia of the atrioventricular Behr, et al. The Cardiovascular system: Dysplasia of the atrioventricular valves. In Textbook of Veterinary Internal Medicine, 4valves. In Textbook of Veterinary Internal Medicine, 4thth ed. Ettinger and ed. Ettinger and Feldman. WB Saunders Company, Philadelphia. 1995.Feldman. WB Saunders Company, Philadelphia. 1995.

Behr L, Chetboul V, Sampedrano CC, Pouchelon JL, Laborde F, and Behr L, Chetboul V, Sampedrano CC, Pouchelon JL, Laborde F, and Borenstein N. 2007. Beating heart mitral valve replacement with a Borenstein N. 2007. Beating heart mitral valve replacement with a bovine pericardial bioprosthesis for treatment of mitral valve dysplasia in a bovine pericardial bioprosthesis for treatment of mitral valve dysplasia in a bull terrier. Veterinary Surgery 36: 190-198.bull terrier. Veterinary Surgery 36: 190-198.

Griffiths LG, Orton EC, and Boon JA. 2004. Evaluation of techniques Griffiths LG, Orton EC, and Boon JA. 2004. Evaluation of techniques and outcomes of mitral valve repair in dogs. JAVMA 224 (12): 1941-and outcomes of mitral valve repair in dogs. JAVMA 224 (12): 1941-1945.1945.

Orton EC, Hackett TB, Mama K, Boon JA. 2005. Technique and Orton EC, Hackett TB, Mama K, Boon JA. 2005. Technique and outcome of mitral valve replacement in dogs. JAVMA 226 (9): 1508-1511.outcome of mitral valve replacement in dogs. JAVMA 226 (9): 1508-1511.

Tidholm A. 1997. Retrospective study of congenital heart defects in 151 Tidholm A. 1997. Retrospective study of congenital heart defects in 151 dogs. Journal of Small Animal Practice 38: 94-98. dogs. Journal of Small Animal Practice 38: 94-98.

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