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.
The echidna has spines like a porcupine, a beak like a bird, a pouch like a kangaroo, and lays eggs like a reptile. Also known as spiny anteaters, theyâre small, solitary mammals native to Australia, Tasmania, and New Guinea. Theyâre usually between 12 and 17 inches long and weigh between 4 and 10 pounds.