ECHOCARDIOGRAPIUC ASSESSMENT OF MITRAL VALVE AREA USING THE PROXIMAL ISOVELOCITY SURFACE AREA METHOD IN PATIENTS UNDERGOING BALLOON MITRAL VALVULOPLASTY. S.P. Wong*, H.A. Coverdale, M.E. Legget,
Department of Cardiology, Green Lane Hospital, Auckland, New Zealand.
Standard echocardiographic measurement of mitral valve area (MVA) following balloon mitral valvuloplasty (BMV) is problematic due to compliance changes in the left atrium and ventricle affecting the pressure- half time (PHT) method. This study aimed to compare the accuracy of MVA measured by the proximal isovelocity surface area (PISA) and standard echo methods (direct planimetry, PHT, and the continuity equation (CONT)) to corresponding pre- and post-procedural WA measurements derived by the Gorlin equation during BMV. Seven patients underwent transthoracic (TTE) and transoesophageal echo (TOE) before, and TTE after, BMV. The PISA MVA was calculated using:
MVA =2,pr2 x a /1 80 x Vr/Vpeak,
where r = radius of PISA, Vr = aliasing velocity, Vpeak = peak mitral inflow velocity, and a= the angle subtended by the mitral leaflets. For each study, the PISA method was used in two planes with three separate aliasing velocities. Bland-Altman analysis was used to compare each echo method with the corresponding Gorlin MVA. The mean and standard deviation (SD) of the differences are listed below. (Values are in cm2, with accuracy and precision inversely proportional to mean and SD respectively).
Pre-procedure Post-procedure
|
MVA |
Mean |
SD |
Mean |
SD |
|
Direct |
<0.01 |
0.23 |
<0.01 |
0.56 |
|
PHT |
<-0.01 |
0.45 |
0.54 |
0.93 |
|
CONT |
0.25 |
0.32 |
0.50 |
0.61 |
|
PISA 4 Chamber (Vr=28cm/s) |
0.21 |
0.19 |
-0.11 |
0.70 |
|
PISA 2 Chamber (Vr=28cm/s) |
0.19 |
0.25 |
0.06 |
0.77 |
|
PISA TOW Vplane (Vr=28cm/s) |
0.03 |
0.43 |
N/A |
N/A |
Conclusion: At an optimal aliasing velocity the PISA method of MVA measurement is usefifi in the echocardiographic assessment of mitral stenosis particularly following BMV.
