The word "atrium" refers to a large open space, usually found in the center of a building, that allows light to come in and gives access to different rooms. Full definition
The Cardioband serves as an innovative and low - impact method of repairing leaky mitral valves in the left atrium of the heart. (sciencedaily.com)
Visitors were greeted with a view into a glassed in atrium that made for a rather unusual first impression. (hgtv.com)
This inability to close the mitral valve completely causes regurgitation (backward flow) of blood into the left atrium of the heart. (ivghospitals.com)