Table 1.

Echocardiographic parameters for evaluation of degenerative mitral stenosis^14,17, 18, 19, 20

Imaging modality	Traditional strengths	Pitfalls in MAC
2D planimetry	Ability to directly measure MVA Historically accurate correlations with Gorlin's  hydraulic formula and with directly measured  anatomic orifices in explanted valves	Acoustic shadowing from calcifications may hinder measurement Optimal timing and optimal positioning of the MV  orifice requires operator experience.
3D planimetry from multiplanar reconstruction	Good correlation with continuity-derived valve area Can be used in mixed regurgitant and stenotic  disease Avoids assumptions of continuity equation	Acoustic shadowing from calcifications may hinder measurement Generally, requires TEE, which is semi-invasive Technical expertise and operator dependent
Pressure half time	Easy to perform	May overestimate valve area secondary to diastolic dysfunction
Continuity equation	Fundamentally accurate and favored method in absence of aortic or mitral regurgitation Transmitral flow-independent modality	Inaccuracy in setting of arrhythmias (especially atrial fibrillation) Limitations with concomitant aortic or mitral  regurgitation Accuracy and reproducibility are hampered by  number of measurements and increasing impact  of measurement error Calcification of the aortomitral curtain hinders  accurate assessment of the LVOT diameter
Transmitral gradient	Easy to perform	Flow dependent and varies with HR Tends to overestimate severity of stenosis
Dimensionless index	Less prone to measurement error than the continuity equation	Further studies and validation of cutoffs are needed