Figure 2.

Four-chamber views of a representative echocardiogram in a normal subject. In end-systole (A), the right atrium (RA) is at its largest volume, and the right ventricle (RV) is at its smallest volume. During early diastole (B), the tricuspid valve opens, and the right atrium has emptied a significant amount of its volume. At end-diastole (C), the atria are contracting, and the tricuspid annulus is being pulled further toward the right atrium, resulting in additional volume displacement from the right atrium. LA: left atrium; LV: left ventricle.