Incomplete Atrioventricular Canal Malformation with Subaortic Stenosis in a Pig

Abstract

Incomplete atrioventricular canal malformation with subaortic stenosis was observed in a 9-month-old Large Yorkshire female pig. The pig showed poor growth, severe weakness, hyperpnea, and tachycardia. A week after the first examination, it was destroyed with the owner's agreement for dissection.
An autopsy revealed an atrial septal defect of the ostium primum about 8 mm in diameter. A mitral cleft was present in the central portion of the anterior leaflet. A tricuspid sac was formed at the site of the membranous septum. The inflow tract of the left ventricle was clearly shorter than the outflow tract. The basal portion of the ventricular septum had a scooped-out and concave appearance. The outflow tract of the left ventricle was narrowed and elongated by “gooseneck” formation.
Subaortic stenosis due to fibrous tissue proliferation was present immediately below the aortic valve with the lumen reduced to about 7mm in diameter.
The edge of the mitral cleft was thickened, indicating that mitral insufficiency of a mild to moderate degree might have been present. A part of the chordae tendineae of the tricuspid anterior leaflet was inserted into the septomarginal band which was of high take-off.