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
- Pressure half time
- Continuity equation
- PISA method
Advantages and disadvantages of Pressure half time derived MVO will be posted soon.
Dr.S.Venkatesan MD 