abnormal cardiovascular development abnormal aortic sac morphology 2014-01-01T13:21:06Z MP:0012510 MPheno.ontology any structural abnormality of the dilated structure that is lined by endothelial cells and located at the arterial pole of the heart just above (distal to) the truncus arteriosus in mammalian embryos; it is the primordial vascular channel from which the aortic arches (and eventually the dorsal aortae) arise; the aortic sac is homologous to the ventral aorta of gill-bearing vertebrates csmith