When does planimetery errs in estimating mitral valve orifice ?
Posted Oct 06 2010 10:26am
Planimetery is the age old method to measure the mitral valve area( MVA) by echocardiography.
2D echo is enough
Doppler errors avoided
In the presence of MR, planimetery orifice has an edge over other methods
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
Advantages and disadvantages of Pressure half time derived MVO will be posted soon.