Final answer:
Systolic reflux of saline contrast in the inferior vena cava denotes the presence of tricuspid regurgitation.
Step-by-step explanation:
Systolic reflux of saline contrast in the inferior vena cava, as noted by two-dimensional echocardiography, indicates the presence of D. Tricuspid regurgitation. Tricuspid regurgitation occurs when the tricuspid valve, which is located between the right atrium and ventricle, fails to close properly, causing blood to flow back into the right atrium during systole. This disruption of the normal one-way flow of blood produces a heart murmur that can be detected using a stethoscope.