MATERIALS AND METHODS: The chick embryos, 242, 242 and 215 eggs, were irradiated with X-ray at the dose of 500, 750 and 1000 cGy, respectively, during the incubation period between 0 and 9 days. A control group of 90 eggs received no irradiation. After 2 weeks of incubation, the embryos were sacrificed and examined.

RESULTS: The survival rate of irradiated group was significantly lower than that of control group (62.5 vs. 87.8%, p<0.0001). The incidence rate of cardiovascular malformation was significantly higher in the irradiated than the control group (16.2 vs. 2.5%, p<0.005). The rate of cardiovascular malformation in the irradiated group increased from 9.4% with 500 cGy to 24.5% with 1000 cGy (p<0.05). There were a total of 33 cases of cardiac malformation, of which 24 were ventricular septal defects and 9 were complex congenital heart diseases. The higher the administered dose of radiation, the higher the observed incidence rate of cardiac malformation and the more complex the cardiac anomaly. Also, the rates of exocardia, exencephaly, beak anomalies and anopia were all increased in the irradiated group.

CONCLUSION: X-ray irradiation of chick embryos increased the rates of death and cardiovascular malformation. The highest dose resulted in greater complexity of the cardiovascular malformation.