Case Study

Severe hypertrophic cardiomyopathy in a 2 year old MN DSH cat

A 2-year-old MN DSH cat with history of a heart murmur was presented for acute onset dragging of the right hind leg. Abnormalities on physical examination were knuckling of the right rear paw, dragging of the leg, a cool foot pad, tachypnea, and a grade II/VI murmur. Bloodwork was within normal limits. On thoracic radiographs, cardiomegaly and a possible pulmonary mass or collapsed lung was present. The patient was treated with intravenous fluids, heparin, buprenorphine, and enalapril.

DX

Severe HCM, left atrium enlargement, systolic anterior motion.

Sonographic Differential Diagnosis

Severe HCM with left atrial enlargement and systolic anterior motion. Systemic disease such as hyperthyroidism or hypertension should be ruled out.

Image Interpretation

The echocardiogram for this patient presented a left atrium of excessive size with anechoic content and evidence of “smoke”. The atrial septum was deviated toward the right atrium. The LA/AO ratio was excessive for cats. The cranial and caudal mitral valve leaflets demonstrated mildly vegetative contour. The left ventricle demonstrated normal volume, excessive septal and free wall diastolic thicknesses, and prominent papillary muscles consistent with hypertrophic cardiomyopathy or secondary hypertrophy owing to systemic disease such as hyperthyroidism or hypertension. Ventricular function was exaggerated consistent with its hyperdynamic state. The aortic outflow tract revealed turbulent flow. Systolic anterior motion was noted on examination.

Outcome

Treatment with Lasix at 0.5mg/kg every 6-8 hours, nitroglycerin ointment every 6 hours, enalapril at 0.5 mg/kg SID to BID, pimobendan (off-label usage in cats) at 0.25-0.3 mg/kg BID, aspirin therapy, and heparin as needed was recommended for this cat. Blood pressure measurements and ECG were also advised. Although the risk of acute death existed, the owner opted to take the patient home and was discharged with buprenorphine, clopidogrel (Plavix), and enalapril.