Fig. 4

Scatter plots with the 5th, 50th, and 95th percentiles of the left myocardial performance index as a function of GA. The superimposed dots on the plot represent the raw values. (oICT, isovolumetric contraction time measured by placing the caliper at the beginning of valve clicks (sec); pICT, isovolumetric contraction time measured by placing the caliper at the peak of valve clicks (sec); oIRT, isovolumetric relaxation time measured by placing the caliper at the beginning of valve clicks (sec); pIRT, isovolumetric relaxation time measured by placing the caliper at the peak of valve clicks (sec); oLV-MPI, myocardial performance index of left ventricle measured by placing the caliper at the beginning of valve clicks; pLV-MPI, myocardial performance index of left ventricle measured by placing the caliper at the peak of valve clicks)