Quantitative assessment of fetal ventricular function: Establishing normal values of the myocardial performance index in the fetus

Objective: Assessment of ventricular function in the fetus has been limited for many reasons, including relative cardiac size and atypical orientation of fetal cardiac structures. A myocardial performance index (MPI) has been described in adult and pediatric populations as an echocardiographic measure of global (systolic and diastolic) ventricular performance. Because the MPI is a Doppler index, it is independent of ventricular geometry and can be applied to both left and right ventricular function. This study attempts to define the MPI in a group of normal fetuses and compare these data to other published studies of this index. Study Design: The right ventricular (RV) and left ventricular (LV) MPI were measured in 125 normal fetuses (20-40 weeks gestation, mean age 28 weeks). These fetuses were divided into five gestational age groups for comparison. These data were compared to 152 normal children (age 3-18 years, mean age 9.3 years). Results: In normal fetuses, the LV MPI was 0.36 ± 0.06 and the RV MPI was 0.35 ± 0.05. This was not statistically different from the group of normal children in whom the LV MPI was 0.35 ± 0.03 and the RV MPI was 0.32 ± 0.03. In addition, no significant change in the fetal MPI was seen with advancing gestational age. Conclusion: This study demonstrates that fetal ventricular function can be quantitatively measured with the MPI. The MPI provides an easily obtainable and reproducible measure of fetal ventricular performance that can be readily incorporated into all fetal echocardiographic examinations.