MPI

Assessing Fetal ‍Wellbeing: The Potential of Modified Myocardial Performance Index (Mod-MPI) alongside Doppler ⁤Indices

A recent study investigated fetal ‌hemodynamics in pregnancies complicated by absent or reversed end-diastolic flow (AEDF) in the umbilical artery, comparing outcomes in AEDF positive,⁣ AEDF negative, and control groups.The research highlighted ⁣significant differences in⁤ pulsatility index (PI) values across the three groups for the umbilical artery, middle cerebral artery, and‍ both uterine‌ arteries (p < 0.001). Specifically, the AEDF (+) group exhibited a markedly elevated umbilical artery PI (UA-PI) of 2.03 ± 0.23 compared to 1.01 ± 0.19 and 1.01 ± 0.14 in the AEDF (-) and control⁢ groups, respectively, indicating increased placental vascular resistance‌ and fetal ⁢circulatory‍ loading. A "brain-sparing response" ‌was observed in the AEDF (+) group, characterized by lower ‍middle cerebral artery PI (MCA-PI) values (1.54 ± 0.45), suggesting preferential blood flow directed towards the‍ fetal​ brain as a compensatory mechanism for hypoxia. Moreover, significantly higher PI values were found in the ⁣right‌ (1.74 ± 0.57)⁣ and left​ (1.95 ± 0.71) uterine arteries ‍within the AEDF (+)⁢ group, pointing ⁢to maternal-origin uterine perfusion insufficiency.

The study also explored the role of Modified Myocardial Performance Index (Mod-MPI) as an‌ indicator of fetal cardiac function. While​ the composite mod-MPI did ‌not show significant differences between groups, analysis of its individual components – isovolumetric relaxation ‌time (IRT), isovolumetric contraction time (ICT), and ejection time (ET) – alongside conventional⁣ Doppler indices (UA PI, MCA‌ PI, and the cardio-thoracic ratio or⁤ CPR) showed potential for ‌incremental value ​in identifying fetuses at risk. ​ The E/A ⁣ratio, a ‌measure‍ of‍ left ventricular diastolic function, remained similar across groups despite ⁤reductions in⁤ both E and A velocities ‌in the AEDF (+) subgroup, suggesting proportional declines in early and late diastolic filling ⁤accompanied by a shortened systolic ejection time.

Although receiver operating characteristic (ROC) analyses of‌ the individual MPI components​ yielded area under the curve (AUC) values below 0.50 in this dataset, the researchers propose that a combined predictive model incorporating UA Doppler abnormalities, CPR < 1.0, and alterations in MPI components (ET shortening, prolonged⁤ IRT, reduced E/A ratio) could‍ be clinically ⁤beneficial. ⁣ They suggest future, larger, prospective,⁢ multicenter studies are needed to establish ​clinically applicable cut-offs and refine antenatal surveillance strategies for fetal growth⁣ restriction (FGR).

The study acknowledges limitations, including its single-centre design which may limit generalizability. ‌ Measurements obtained via pulsed-wave Doppler are susceptible‍ to variations due ⁣to fetal position, breathing, heart rate variability, ⁣and operator technique. The absence of long-term neurodevelopmental and cardiac ‌follow-up data also restricts the ability to‌ correlate ‍prenatal Doppler findings with later ⁤functional outcomes. Despite these limitations, the ⁤study underscores the potential of integrating Mod-MPI components with established Doppler indices to enhance the assessment of fetal⁣ wellbeing in high-risk pregnancies.