Atresia of the Left Atrioventricular Orifice in Two Calves

Abstract

Two cases of atresia of the left atrioventricular orifice with situs solitus of atria were observed in Japanese Black calves. The atresia of the orifice was derived from atresia of the left atrioventricular valve in one case and absence of the left atrioventricular connection in another, respectively. Both cases revealed the right atrium connected to the morphological left ventricle and concordant ventriculoarterial connection.