Abstract
Four cases of the double left atrioventricular orifice and three cases of the right atrioventricular orifice were observed in 696 cattle hearts with congenital anomalies. Among the four cases of the double left atrioventricular orifice, the septal and parietal leaflets of the left atrioventricular valve were joined by a broad valvular tissue and created two orifices were of similar size in cases 1, 2 and 3. In case 4 a small hole that provided subvalvular apparatus was present within the posterior part of the parietal leaflet. In these four cases the leaflets of the left atrioventricular valve were thin and delicate. Among three cases of the double right atrioventricular orifice, the central parts of the septal and parietal leaflets of the right atrioventricular valve were joined by a broad valvular tissue and created two orifices were of similar size in cases 5 and 7. In case 6 the central parts of the septal and angular leaflets were joined by a broad valvular tissue. The free margins of the right atrioventricular valve were thickened in cases 5 and 7. In case 6 widened anterior valve commissure and a patch of jet lesion on the atrial surface of the septal leaflet near the commissure were detected.
