Objective:
Mitral valve (MV) leaflet thickening is a well-recognised feature of rheumatic heart disease (RHD). Few publications describe methods for measuring MV thickness except in established mitral stenosis. We aimed to establish methodology for, and define ranges of, MV thickness in children with and without RHD. This has implications for RHD screening.

Methods:
Prospective screening study conducted in a high risk population for RHD. Standard 2-dimensional and colour-Doppler echocardiography on students aged 10 – 13 years using portable Vivid E machines (GE Healthcare)was performed. Anterior mitral valve leaflet (AMVL) thickness was measured in mid-diastole at the tip and the mid-point (parasternal) and the mid-point in systole (apical). Posterior mitral valve leaflet (PMVL) mid-point thickness was measured in mid-diastole (parasternal). Measurements from 280 students with normal screening echocardiograms were compared to 55 students with RHD according to modified WHO criteria. 28 with RHD had definite morphological changes of the mitral valve and 26 had mitral regurgitation without definite morphological changes.

Results:
There were statistically significant differences between the RHD group and normal children for AMVL and PMVL thickness.(see graph) Measurements were reproducible with intra-class correlation co-efficients ranging between 0.76 - 0.90.

Conclusions:
1. We have developed an objective standardised method for measuring MV leaflet thickness.
2. Children with RHD had significantly thicker mitral valve leaflets than normal students.
3. Inter-observer comparison of the Vivid E measurements with other echocardiographic technology is needed.