The Bicuspid Condition of the Aortic Valve Does Not Alter the Incidence of Accessory Coronary Artery Ostia in Syrian Hamsters (Mesocricetus auratus).

In man and Syrian hamsters (Mesocricetus auratus), the prevalence of anomalies in the origin of the coronary arteries is significantly higher in individuals with bicuspid than with normal aortic valves. In hamsters, the incidence of accessory ostia is similar in individuals with normal and anomalous coronary arteries, all of them possessing a normal (tricuspid) aortic valve. In order to evaluate whether or not the presence of bicuspid aortic valves alters the incidence of accessory ostia, 1,050 hearts from hamsters with bicuspid valves were examined. In 594 of them the coronary arteries were normal. The remaining 456 hearts showed coronary artery anomalies characterized by the absence of any artery arising from the left side of the valve. The incidence of accessory ostia was 3.9% in hamsters with normal coronary arteries and 2.2% in those with anomalous coronary patterns. Overall, 3.1% of the accessory ostia were associated with a septal artery and another 0.2% with a conal artery. These data referring to the bicuspid valves were compared with those already published on normal valves. The results of statistical analyses showed that having a bicuspid aortic valve does not alter the incidence of accessory coronary ostia. In the set of tricuspid and bicuspid valves, the incidence of accessory ostia was significantly lower on the left side than on the right side of the valve. This, together with the fact that in the present animal model the coronary anomalies were characterized by the absence of arteries on the left side of the valve, suggests that the embryonic region corresponding to the left side of the aortic valve primordium is particularly associated with preventing the normal development of coronary vessels.

The arrangement of the coronary artery trunks is subject to inheritance factors: A study in Syrian hamsters.

The concept that anatomical variations in the coronary artery tree might be influenced by genes is relatively old. However, empirical evidence on the effect of genotype on the coronary morphology is still scarce. In the Syrian hamster, there is a septal coronary artery which arises from the left or from the right coronary artery and supplies most of the interventricular septum. The aim was to decide whether the anatomical origin of the septal artery is subject to inheritance factors. Overall, 483 internal casts of the heart and coronary arteries were examined. All the hamsters included in this study had normal coronary arteries. The results of 74 crosses were compared statistically to seek for any significant difference between the phenotypes of the offspring and the phenotypes of the parents. The left septal artery was over-represented in the offspring of crosses between parents having both a left septal artery (p < .01), while the right septal artery was over-represented in the offspring of crosses between parents, one with a right and the other with a left septal artery (p < .001), and, more markedly, in the offspring of crosses between parents both with a right septal artery (p < .001). These results are the first to reveal that the coronary artery pattern is influenced by genetic factors, at least in its proximal portion with regard to the aorta.