Overview
The valve calculation panel is available for selected aortic or mitral stenosis. It samples simultaneous modeled pressures over ten nominal beats to estimate the active flow period and mean gradient. These estimates are not measured anatomic or Doppler valve areas.
A correct-looking formula can still be inappropriate when the flow supplied to it is not the actual flow across that valve. The model explicitly withholds conventional area estimates during MCS or a shunt rather than substituting total systemic flow.
Sampling and validity
The calculation uses 6,000 midpoint samples across ten nominal beats. Only the active phase contributes to the mean gradient and flow period. Forward flow must be positive, rhythm organized and the gradient meaningful. Zero flow, VF, MCS and shunts invalidate the conventional estimate.
Hakki has a rate-related limitation outside the usual 60–100 bpm teaching range. Regurgitation can make net forward CO lower than true valve flow and underestimate a CO-based area. That limitation is shown rather than silently declaring an anatomic valve severity.
Regurgitant volumes
Regurgitant volume is derived from the same fractions and forward stroke volumes as the PV model. Combined leaks account for recirculation through the connected valves. The resulting values are internal model estimates; they are not independently measured PISA, vena-contracta or volumetric echo results.
References & further reading
