1989 Volume 1 Issue 1-2 Pages 23-33
A spectrum of cardiac anomalies was produced experimentally in chick embryos stages 17 to 20 by temporary mechanical displacement of the conotruncus. Forty-two embryos that survived more than 14 embryonic days were studied. According to the type and severity of the major cardiac anomalies, the embryos were divided into eight groups; 1) normal hearts (2 cases), 2) isolated ventricular septal defect (6 cases) ; 3) ventricular septal defect with overriding of the aorta (3 cases), 4) double outlet right ventricle with overriding of the aorta (4 cases), 5) double outlet right ventricle with normal atrioventricular connection (10 cases), 6) double outlet right ventricle with overriding of the tricuspid valve (7 cases), 7) double outlet right ventricle with double inlet left ventricle (8 cases), and 8) other cases.
In groups 6 and 7, complete and partial forms of left juxtaposition of the atrial appendages were associated with four and three cases, respectively.
In most cases, both the aorta and the pulmonary artery were dextroposed (called here “dextroposition of the great arteries”) . There were close relations among: 1) the degree of the dextroposition of the great arteries, 2) the severity of overriding of the tricupsid valve, and 3) the severity of positional abnormality of the atrial appendages. The effects of manipulation on cardiogenesis are considered to be disturbance of the leftward migration of the conotruncus, and the rightward expansion and migration of the atrioventricular canal.
