Fetal myocardial index during labor

Background
The Myocardial Performance Index (MPI) is a Doppler derived myocardial function tool and can be used to evaluate systolic and diastolic function in fetuses. The objectives of this study were to investigate the MPI during labor and compare it to values in non-laboring women.

Methodology
40 women with uncomplicated, term, singleton pregnancies were recruited to this prospective observational study at Thomas Jefferson University Hospital. Controls were a retrospective cohort of women > 34 weeks who underwent third trimester fetal echocardiography. Fetal left and right sided isovolumic contraction time, isovolumic relaxation time and ejection time were recorded before, during and after contractions. Right and left sided MPI was then calculated.

Results
Laboring patients and non-laboring patients were comparable for age, race, gravidity and parity. During labor the average left MPI was 0.63 ± 0.17 and the average right MPI was 0.62 ± 0.20. The coefficient of correlation between MPI and cervical dilation was 0.15 for left MPI Index and 0.14 for right MPI. When comparing non-laboring to laboring women, the average left MPI for non-laboring women was 0.34 ± 0.04, p = <0.001.

Conclusions
Myocardial Performance Index is a non-invasive, easily attainable measure of cardiac function that can be obtained during labor and does not change with cervical dilation. MPI is significantly different between laboring and non-laboring women. The fetal MPI may help define fetal status in labor.