Postmortem magnetic resonance imaging findings of tricuspid atresia with ventricular and atrial septal defects and subvalvular pulmonic stenosis in a Japanese native Noma horse

Figures

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  Fig. 1.. Three different views of the heart. (A) Left appearance of the heart. The heart appeared to have a large cardiac base and narrow cardiac apex. The anterior interventricular groove was shifted to the right. (B) MRI in the sagittal plane at the level of the aortic valve. No wall separating the right and left ventricles was observed ventral to the aortic valve. (C) Appearance of the left side of the heart in a 3D image reconstructed from MRI. The myocardial portion was made more permeable so that the luminal structure could be observed. The lumen of the ductus arteriosus was narrow. AO, aorta; DA, ductus arteriosus; LA, left atrium; LV, left ventricle; MRI, magnetic resonance imaging; PA, pulmonary artery; RV, right ventricle.

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  Fig. 2.. Multiplanar reconstructed MRI. (A) T2-weighted image in the axial plane at the level of the right ventricle. The right atrium and right ventricle were separated by a wall, and the tricuspid valve was not seen. (B) T1-weighted image in the axial plane at the level of the pulmonary artery. The lumen was narrow near the pulmonary artery valve (red arrowhead). No separating wall was observed between the right and left ventricles. (C) T2-weighted image in the four-chamber plane created by multiplanar reconstruction. A traffic channel was present between the right and left atria (blue arrowhead). A very thin membranous structure (green arrowhead), potentially indicative of an atrial septum, was seen ventrally. LA, left atrium; LV, left ventricle; MRI, magnetic resonance imaging; PA, pulmonary artery; RA, right atrium; RV, right ventricle.

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  Fig. 3.. 3D images of the heart lumen reconstructed from magnetic resonance imaging. (A) Cranial appearance. (B) Right appearance. (C) Caudal appearance. The right atrium and ventricle were not continuous. The right atrium communicated with the left atrium, and the left ventricle communicated with the right ventricle. This allowed venous blood returning to the right atrium to shunt to the left atrium, left ventricle, and aorta. Red region, aorta; green region, pulmonary artery; dark blue region, left atrium; light blue region, left ventricle; yellow region, right atrium; pale orange region, right ventricle.

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  Fig. 4.. Postmortem images of the heart lumens. (A) Image of the lumen of the right atrium. There was no evidence of a tricuspid valve or valve mouth formation between the right ventricle and right atrium. (B) Image of the lumens of the left atrium and left ventricle. The foramen ovale was partially covered by a fenestrated membrane with an uncovered dorsal rim (yellow arrowhead). The left and right atria were therefore continuous. (C) Image of the pulmonary artery valve. The pulmonary artery valve comprised two semilunar valves. (D) Image of the lumen of the right ventricle. The lumen was narrow near the pulmonary artery valve (red arrowheads). A communication opening was observed in the left ventricle. LA, left atrium; LV, left ventricle; PV, pulmonary artery; RA, right atrium; RV, right ventricle.