Aortic insufficiency (AI), also known as aortic regurgitation (AR), is the leaking of the aortic valve of the heart that causes blood to flow in the reverse direction during ventricular diastole, from the aorta into the left ventricle.
Definition of echidna. : a spiny-coated toothless burrowing nocturnal monotreme mammal (Tachyglossus aculeatus) of Australia, Tasmania, and New Guinea that has a long extensible tongue and long heavy claws and that feeds chiefly on ants; also : a related mammal (Zaglossus bruijni) of New Guinea having a longer snout and shorter spines.
See More Echidna Pictures >. Echidna was a half-woman, half-snake creature in Greek mythology, also known as the mother of all monsters, as she gave birth to most of the Greek mythical creatures. She was the wife of Typhon, who was the father of all monsters and the most fearsome and dangerous monster in said mythology. Both she and her husband were the children of Gaia and Tartarus. The couple attacked the Olympians, but Zeus managed to repel them, burying Typhon under Mount Etna; Echidna and her children were spared to continue challenging future heroes.