Transposition of Great Arteries_A7861

**Transposition of Great Arteries** The exterior of the heart is remarkable for uniform biventricular and biatrial enlargement. The interatrial septum has been obliterated and a patch of pericardium has been applied between the right and left atrium to cause blood to drain from the superior and inferior vena cavae under the patch into the former left atrium. The pulmonary trunk exists from the left ventricle with the ascending pulmonary artery and its divisions being markedly dilated. Four large pulmonary veins drain into a left atrium. Once more, the inter-atrial wall has been surgically excised and blood flows over a flap into what was at one time the anatomic right atrium and drains into the right ventricle. The right ventricular outflow is narrow due to ventricular wall and septal hypertrophy. An aortic valve measuring 0.6 cm has tricuspid leaflets of normal thickness and non-fused. The ascending aorta gives rise to a normal aortic arch with three normal vessels arising from it.