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 (RV) MPI in neonates in the first 48 to 72 hours of life. Fifty-one quiet or asleep 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 a SPSS software. P value less than 0.05 was considered as significant. RV MPI was 0.23±0.14 in healthy neonates. There was no correlation between RV MPI and either age or weight of the newborn infants. RV MPI in healthy neonates was 0.23+0.14 in our study. While this closely resembles the results of some researchers, is lower than those previously reported by the other investigators in healthy children. The lower value of RV MPI in neonates may be possibly explained by its relation to the higher pulmonary arterial pressure of the lower 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.