Introduction

• Malformation of mitral and tricuspid valves. Most common congenital cardiac abnormality in the cat (17% of congenital heart lesions).
• Cause: developmental abnormalities resulting in a spectrum of lesions; excessively long or short chordae tendineae, abnormal number, position and distribution of papillary muscles, thickened, distorted valve leaflets.
• Signs: may be asymptomatic with systolic murmur, or exhibit signs of right- or left-sided congestive heart failure Heart: congestive heart failure.
• Diagnosis: clinical signs, radiography, Doppler and 2-D echocardiography, angiocardiography.
• Treatment: as for congestive heart failure.
• Prognosis: poor once clinical signs present.

Pathogenesis

Etiology

• Probably hereditary.

Pathophysiology

• Valvular malformation   →   valvular incompetence   →   congestive heart failure.

Mitral dysplasia

• Mitral regurgitation   →   left atrial and left ventricular volume overload   →   left atrial and ventricular dilation   →   increased left atrial pressure   →   pulmonary venous congestion   →   pulmonary edema (left-sided CHF).

Tricuspid dysplasia

• Triscupid regurgitation   →   right atrial and right ventricular overload   →   right atrial and ventricular dilation   →   increased right atrial pressure   →   increased central venous pressure   Central venous pressure jugular distension and chronic venous congestion of liver (right-sided CHF).

Timecourse

• Murmur from birth.
• Depends upon severity of the lesion.
• Survival time rarely >12 months after onset of CHF.

Diagnosis

Treatment

Outcomes