Which method estimates mitral valve area using the continuity equation?

Which method estimates mitral valve area using the continuity equation?

• A. Planimetry
• B. Mean gradient
• C. Continuity equation
• D. Pressure half time

Answer: (C)

The method tested uses the continuity principle: the same volume of blood moves through the LVOT and the mitral valve during a heartbeat, so you can derive mitral valve area from how much flow goes through the LVOT compared to the flow across the mitral valve. In practice, you measure the LVOT cross-sectional area (CSA) from the LVOT diameter, and you obtain the velocity-time integrals (VTIs) for both the LVOT and the mitral valve. The mitral valve area is then calculated as MVA = (CSA_LVOT × VTI_LVOT) / VTI_MV. This approach is especially useful when direct visualization of the mitral orifice is difficult or when other methods are unreliable, because it relies on flow conservation rather than direct planimetry of the valve opening or on deceleration timing alone. However, accuracy depends on precise measurement of LVOT diameter and proper alignment to obtain the VTIs, and it can be affected by factors like MR or complex flow.

The method tested uses the continuity principle: the same volume of blood moves through the LVOT and the mitral valve during a heartbeat, so you can derive mitral valve area from how much flow goes through the LVOT compared to the flow across the mitral valve. In practice, you measure the LVOT cross-sectional area (CSA) from the LVOT diameter, and you obtain the velocity-time integrals (VTIs) for both the LVOT and the mitral valve. The mitral valve area is then calculated as MVA = (CSA_LVOT × VTI_LVOT) / VTI_MV. This approach is especially useful when direct visualization of the mitral orifice is difficult or when other methods are unreliable, because it relies on flow conservation rather than direct planimetry of the valve opening or on deceleration timing alone. However, accuracy depends on precise measurement of LVOT diameter and proper alignment to obtain the VTIs, and it can be affected by factors like MR or complex flow.