Planimetery is the age old method to measure the mitral valve  area( MVA) by echocardiography.

Advantage

• Simple modality
• 2D echo  is enough
• Doppler errors avoided
• In the presence of MR, planimetery orifice has an edge over other methods

Disadvantage

• Optimal gain setting becomes  important .There is  significant inter and intra observer variability.
• Shape of the orifice is not constant  ( MVO is funnel like) . Narrowest diameter is usually measured.
• Planimetery is  a purely an anatomical orifice,while blood flows through both primary and secondary mitral orifices .Sub valvular fusion makes secondary MVO the  narrowest point  . Measuring it becomes difficult as it has no defintion of border.
• Gross errors possible in calcified valve.
• In post commissurtomy  the  lateral extent of split is often  not tractable

How to improve the accuracy of planimetery ?

Color Doppler aided  2D  planimetery . This can improve some of the limitations , as  it provides a hemodynamic MVO(Some what physiological ) Of course  , pressure halftime derived MVO is purely a physiological orifice .

Other options to measure MVO

1. Pressure half time
2. Continuity equation
3. PISA method

Advantages and disadvantages  of Pressure half time derived MVO will be posted soon.