日本小児循環器学会雑誌 Pediatric Cardiology and Cardiac Surgery

Truncus arteriosus is a congenital heart disease that is caused by insufficient septation of the cardiac outflow tract and arterial truncus. Fetal echocardiographic diagnosis of this disease is important because of its high neonatal mortality. About 30％ of chromosome 22q11.2 deletion syndrome is associated with truncus arteriosus. Bis-diamine, administered to pregnant rats, induces these congenital anomalies similar to those seen in chromosome 22q11.2 deletion syndrome. This is a study of cross-section of the truncus arteriosus which is induced by bis-diamine in fetal rats. Bis-diamine was administered to pregnant rats on 9th and 10th day, and full-term fetuses were fixed with a whole-body freezing method. The frozen fetal thorax was cut with a freezing microtome transversely, and the cut surface was photographed serially for subsequent stereo-microscopic study.

Congenital heart disease was present in 90％ of the studied hearts, including truncus arteriosus in 17％. Study of four typical cases of truncus arteriosus in cross-section revealed ventricular septal defect, absence of the right ventricular outflow tract, and proximal main pulmonary artery. In addition, there were dysplasia of the truncal valve including prolapse, thickening, quadricuspid-leaflets, large and small leaflets, and origin of the distal main pulmonary artery or right and left pulmonary artery from the truncus arteriosus. Moreover, right-sided truncus arteriosus arch and anomalous origin of the right subclavian artery, were clearly shown. These model pictures of truncus arteriosus will be helpful in clinical fetal echocardiographic diagnosis of truncus arteriosus.