The object of this study was to determine the difference between two methods for myocardial performance index(MPI) in children, using the conventional and pulsed Doppler echocardiography.

A total of 27 children with anatomically normal hearts were enrolled for the study. all were examined by conventional and pulsed Doppler echocardiography at Gangneung Asan Hospital between December, 2005 and February, 2006. First, we measured the time interval(a1) between the mitral inflows from apical 4-chamber view, and the ejection time(ET1) from apical 5-chamber view. And then, we calculated MPI1, isovolumic contraction time(ICT1) and isovolumic relaxation time (IRT1). Secondly, we measured ICT2, ET2 and IRT2 from apical 5-chamber view with a Dopper signal placed at just below junction between mitral and aortic valve at the same cardiac cycle. And then, we calculated MPI2. We compared MPI1 to MPI2. All MPIs were calculated by using the formula, MPI=(ICT+IRT)/ET.

The mean age was 5.7±2.2 years old(M:F=15:12). The MPI2 was higher than MPI1: 0.277±0.083 vs. 0.428±0.081(MPI1 vs MPI2, P =0.000). Also, the ICT2 was higher than ICT1: 56±15 msec vs 97±18 msec(ICT1 vs ICT2, P =0.000) and the IRT2 was higher than IRT1: 42±8 msec vs 53±9 msec(IRT1 vs IRT2, P =0.000). But, the ET2 was lower than ET1: 260±16 msec vs 254±14 msec (ET1 vs ET2, P =0.01). There was, as well, positive linear correlation between MPI1 and MPI2.

This study showed that there is a difference between MPI1 and MPI2 in connection with estimating methods. However, the two MPIs had a positive linear correlation. Judging from our results, the MPI of the new method might be a useful index of venticular global function in children.