Mitral valvular endocardiosis in cats

© Rand, J (2006) Problem-based feline medicine. Saunders Elsevier, Sydney

This is a rare disorder in cats. Degeneration of the collagen matrix of the valve occurs resulting in laxity of the chord apparatus and prolapse of the valve. There is also thickening of the valve leaflets.

Clinical signs

Systolic murmur located over the apex of the heart. Gallop rhythm may be present. Tachypnoea or dyspnoea may be present in cases with concurrent congestive heart failure.

Diagnosis

Radiographs show marked left atrial enlargement, left ventricular enlargement, dorsal displacement of the trachea, pulmonary oedema, dilatation of the pulmonary veins relative to the pulmonary arteries. In rare cases, pleural effusion may be present.

ECG may reveal sinus tachycardia if heart failure is present. There is often left ventricular enlargement (R wave > 0.9 mV on lead II), left anterior fascicular block (LAFB) which may signify left ventricular enlargement as well. In LAFB, the QRS duration is normal, there is marked left axis deviation (between -60 and -90 degrees), small Q wave and tall R wave in leads I and aVL, deep S waves in lead II, III and aVF. Arrhythmias are uncommon.

On echocardiography, there is thickened and prolapsing mitral valve, with marked mitral regurgitation, and a hyperkinetic left ventricle with a fractional shortening often greater than 55%.

Treatment

Treatment is not usually required and doesn't seem to influence outcome. If severe atrial enlargement is present, consider beta-blocker therapy (Atenolol).

If congestive heart failure is present life expectancy is around 1-2 years.