Supravalvular mitral stenosis in a cat: clinical, diagnostic and pathologic findings

Abstract

The present case report describes a rare case of a cardiac abnormality diagnosed as Supravalvular Mitral Stenosis in an asymptomatic cat. An 11-years old cat was presented for orthopedic evaluation, and during general clinical examination a heart rate of 180 bpm and left diastolic cardiac murmur grade III-IV/VI, between the mitral and aortic foci, were found. Radiographic, echocardiographic, angiocardiographic and post-mortem (the patient died during anesthesia performed to diagnose the orthopedic condition) magnetic resonance and pathologic findings are reported herein.

Keywords: Cat; Cor triatriatum sinister; Magnetic resonance; Supravalvular mitral stenosis; Ultrasonography.

Fig. 1

a Right latero-lateral radiography of the chest. No evident abnormalities of lungs and/or of the heart are visible. b Angiography: a double compartmented left atrium divided by a membrane (smaller white arrow) in a proximal chamber of the left atrium (PLA), and a distal chamber of the left atrium (DLA) and enlarged and tortuous pulmonary veins (PV) are evident

Fig. 2

a Left apical four-chamber view. PLA proximal chamber left atrium; DLA distal chamber left atrium; RA right atrium; LV left ventricle; RV right ventricle. b Right parasternal long-axis four-chamber view, color-Doppler exam. A high-velocity turbulent diastolic flow crossing PLA, DLA, mitral anulus, and the left ventricle chamber is visible

Fig. 3

a Left apical long-axis view, color- and CW Doppler exam. A high-velocity turbulent diastolic flow crossing PLA, DLA, mitral anulus, and the left ventricle chamber is visible. Spectral Doppler shows a flow with maximum diastolic velocity of 3.08 m/s and pressure gradient, calculated between the PLA and DLA, of 38 mmHg. b Modified left apical four-chamber view optimized for the right heart, CW Doppler exam. Tricuspid insufficiency, with a systolic regurgitant jet in the right atrium (3.06 m/s—37.6 mmHg)

Fig. 4

Post-mortem sagittal (a) and dorsal (b) cardiac MR scan. An incomplete hypointense membrane dividing the left atrium into two chambers is visible (red arrows). LA left atrium, LV left ventricle; RA right atrium; RV right ventricle

Fig. 5

Cardiac gross pathology. a Coronal section of the heart’s base; it is possible to clearly appreciate the communication between the left auricle (LAU) and the proximal atrial chamber (PLA). AO Aorta. b Double coronal section of the heart’s base, proximally and distally the partially obstructing septum. It is possible to see that the atrial distal chamber (DLA) is separated from left auricle’s lumen (LAU). AO Aorta; rDLA roof of the atrial distal chamber; O orifice of the obstructing septum

Fig. 6

Accessory membrane within left atrium composed by mature fibrous tissue with focal mild inflammatory infiltrate and fatty degeneration (arrow). The atrial myocardium is focally infiltrated by adipose tissue (asterisk) (HE, bar: 200 micron)