Stroke volume calculated from LVOT Doppler depends on LVOT area; why is the diameter critical?

• A. Because the area is proportional to the square of the diameter, so errors in diameter are not important.
• B. Because the diameter is used to calculate velocity.
• C. Because the diameter does not affect the calculated area.
• D. Because the LVOT diameter is used to compute LVOT area and small diameter errors disproportionately alter SV.

Answer: (D)