What is the term for the average gradient derived from all velocities within the flow between two chambers?

• A. Max PG
• B. Mean PG
• C. Peak PG
• D. End-Diastolic PG

Answer: (B)

The term describes the mean pressure gradient. It represents the average pressure difference across the flow between two chambers over the entire flow period, not just at a single moment. In practice, Doppler velocity data across the valve are converted to instantaneous gradients (via 4V^2), and those values are averaged over the duration of flow to obtain the mean gradient. This provides a single value that reflects both how high the gradient gets and how long the flow lasts, giving a more overall measure of the obstruction’s impact. A maximum or peak gradient captures only the highest instantaneous value and can be affected by brief velocity spikes, while an end-diastolic gradient is tied to a specific early or late phase and may not represent the systolic flow when the gradient is typically highest. Hence the mean gradient best fits the description.