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 diet of echidnas is largely made up of ants and termites, although, they will eat other invertebrates especially grubs, larvae and worms. The strong forepaws are used to open up the ant or termite nest and the echidna then probes the nest with its sensitive snout.chidna (Photo by Steve Johnson). Echidnas, or spiny ant eaters as they are sometimes known, are familiar to most Australians. Echidnas are monotremes (mammals that lay eggs). There are only five species of monotreme in the world-the platypus and four species of echidna, three of which are restricted to New Guinea.