Abnormal structure of the bulbus cordis, which is the single outflow tract of the heart during early embryogenesis.
Comment:
The portion of the embryonic heart that receives blood is called the sinus venosus. There are two horns, the left and the right, that pump blood into the primordial atrium, which is then pumped into the ventricle and the bulbus cordis. From the bulbus cordis, it goes into the aortic sac which is connected to the first aortic arch.