serial sections of the atrioventricular ( av ) conduction system were microscopically studied in 12 autopsied hearts : four with complete type common av orifice ( cavo ) , two with atrial septal defect of the ostium primum type ( asd-i ) , two with ventricular septal defect of the persistent common av canal type ( vsd-c ) and four without heart disease .
C0018787
hearts
C0018799
heart disease