Doppler-derived right ventricular myocardial performance index in neonates: Normal values

Doppler-derived myocardial performance index [MPI], defined as the sum of isovolumetric contraction and relaxation durations divided by ejection time, is an easily measured and reproducible index that shows both systolic and diastolic myocardial function. The goal of this study was to define normal values of right ventricular MPI in neonates in the first 48 to 72 hours of life. Fifty-one quiet or sleeping healthy and term neonates underwent complete M-mode, two-dimensional color-Doppler echocardiographic examination and RV MPI was calculated in them. Statistical analysis was performed using SPSS software. A P value less than 0.05 was considered as significant. RV MPI was shown to be 0.23 +/- 0.14 in healthy neonates. There was no correlation between RV MPI and either age or weight of the newborn infants. While this value closely resembles the results of some researchers, it is lower than that previously reported by other investigators in healthy children. The lower value of RV MPI in neonates may be possibly related to the higher pulmonary arterial pressure or right ventricular mass in the first few days of life in neonates. Further study to evaluate the effect of pulmonary arterial pressure and right ventricular mass on RV MPI is recommended