All 4 Uses

atrium
in
Cutting for Stone
(Edited)

Deepak put a purse-string suture around the right atrium, the upper chamber of the heart that received blood from the vena cava.
Part 4 *

atrium = chamber at the top of the heart
Now he made a nick in the atrium of the heart, in the center of his purse-string suture.
Part 4
Then he slid his newly fashioned tube into the atrium, using the purse string to cinch the tissue around the tube which he pushed down through the orifice of the inferior vena cava, and down to where our problem was.
Part 4
The revolving doors led to a glass-walled atrium, the ceiling extending up at least three stories and accommodating a real tree.
Part 4 *

atrium = large public room containing plants

Definitions:

(1) (atrium as in: atrium of the building)
a central open space in a building -- often a large skylit hall near the entrance

In ancient Roman houses and early Christian churches, an atrium was an open courtyard. In many modern buildings, it is an indoor space that may include plants, water features, and balconies or walkways to other rooms.
(2) (atrium as in: right atrium of the heart)
chamber from which blood enters the heart
(3) (meaning too rare to warrant focus)
Much less commonly, atrium can refer to anatomical structures other than the heart.