Ventricular septal defects in a family of Yucatan miniature pigs

We have studied the hearts from a colony of Yucatan miniature pigs with spontaneously occurring congenital defects. Ventricular septal defect was encountered in 57 of 81 neonates from 15 consecutive litters. Of 73 hearts preserved for morphological assessment, 52 were found to have defects within the ventricular septum remarkably similar to those observed in humans with deficient ventricular septum. The defects, including 3 which had closed spontaneously, were perimembranous in 34, muscular in 12 and doubly committed and juxtaarterial in 6 hearts. Atrial septal defects were found in 12 of the 52 hearts with deficient ventricular septation; only 1 atrial septal defect was seen among 21 hearts with an intact ventricular septum. Anomalies of the aortic arch were associated with ventricular septal defect in 2 cases; 1 with a solitary arterial trunk and one with hypoplasia of the aorta and patent arterial duct. All these findings are replicated in human hearts. This strain of pig provides an ideal large animal model for morphologic and genetic investigations concerning the details of ventricular septation, including potential mechanisms of late spontaneous closure.