Anomalous origin of the left coronary artery from the pulmonary trunk and its relationship with the morphology of the cardiac semilunar valves in Syrian hamsters.

The conditions of the aortic and pulmonary valves and the arrangement in the origin of the coronary arteries were studied in 247 Syrian hamsters belonging to a single family subjected to high endogamous pressure. Most specimens (n = 216) were examined using a stereomicroscope. The remaining 31 were studied histologically. In 110 specimens both cardiac semilunar valves were normal. The aortic valve was bicuspid and the pulmonary valve was normal in 79 animals, while a normal aortic valve and a bicuspid pulmonary valve occurred in 37. In the remaining 21 specimens both semilunar valves were bicuspid. In 34 cases, the left coronary artery originated from the pulmonary trunk. Statistical analyses indicate that there is no significant relationship between the bicuspid condition of the pulmonary valve and the fact that a coronary artery arises from the pulmonary trunk. On the other hand, they substantiate that the frequency of this coronary artery anomaly significantly increases when the aortic valve is bicuspid. The present findings agree with the hypothesis that abnormal migration of the neural crest cells may be responsible for the combined occurrence of bicuspid aortic valve and anomalous origin of the left coronary artery from the pulmonary trunk. In addition, they suggest that the neural crest cells involved in the formation of the pulmonary valve diverge from those migrating into the aortic valve and those imposing spatial order upon the development of the proximal coronary arteries.