Novel Technique for the Measurement of Fetal Right Modified Myocardial Performance Index Using Synchronized Images of Right Ventricular Inflow and Outflow and Clinical Application to Twin‐to‐Twin Transfusion Syndrome

Abstract

Objective To evaluate the reproducibility of the fetal right modified myocardial performance index (Mod‐MPI) obtained by synchronizing the inflow and outflow images of the right ventricle (RV) and to evaluate its feasibility through clinical application to twin‐to‐twin transfusion syndrome (TTTS). Methods We prospectively evaluated 77 normal fetuses. Two experienced operators individually measured the right Mod‐MPI using two different methods: (1) separate recording of the RV inflow and outflow using pulsed‐wave Doppler (conventional method) and (2) synchronization of RV inflow and outflow images using the MPI + ™ function based on the closure click of the pulmonary valve (new method). To evaluate the clinical utility of the new method, we measured the right Mod‐MPI in 33 TTTS fetuses using the new method before and after the fetoscopic laser coagulation (FLC). Results There was no statistical difference in Mod‐MPI values between the two methods (p = .242). For both operators, the intra‐ and interoperator reproducibility of Mod‐MPI was high with both methods (ICCs >0.950). Among the components of Mod‐MPI measured using the new method, ejection time showed the highest reproducibility, whereas isovolumetric relaxation time demonstrated the lowest reproducibility. In TTTS fetuses, the Mod‐MPI significantly decreased after FLC in recipients, and there was no difference in MPI values before and after FLC in donors. Conclusion Right Mod‐MPI measurement after the synchronization of RV inflow and outflow images is a reliable technique for evaluating fetal right cardiac function. This novel method can also independently evaluate the systolic and diastolic functions of the right heart.

How Automated Techniques Ease Functional Assessment of the Fetal Heart: Applicability of MPI+™ for Direct Quantification of the Modified Myocardial Performance Index

“…As a result of the highly heterogeneous measurement techniques used so far, with priority given to the lack of standard criteria regarding caliper placement, clinicians are currently confronted with a wide variation in the quoted reference values for the MPI to date-which still lack consistency-ranging from 0.35 to 0.60 as the mean values. The values of the RV-Mod-MPI for both operators corresponded with this expected distribution pattern and increased with GA (Figure 3), even though a significant correlation between the MPI and GA has been controversially discussed in the current literature [1,8,15,18,20,23,[26][27][28][29][30][31][32][33]. The present values of the RV-Mod-MPI were very similar to those of Kang et al, who investigated the clinical value of the MPI+™ tool for the assessment of cardiac function in TTTS.…”

“…The calculation of the RV-Mod-MPI in advanced gestational ages (GAs) requires the acquisition of two different anatomical planes in two different cardiac cycles with different fetal heart rates, because the tricuspid and pulmonary valves diverge at distinct anatomical levels. Due to this anterior displacement of the pulmonary valve (synonym: pulmonary-tricuspid discontinuity), which develops between the 20th and 26th weeks of gestation, the isovolumetric times (isovolumetric contraction time (ICT) and IRT) on the right side of the heart cannot be obtained from the same cardiac cycle individually [1,11,14,17,20,[23][24][25]. Consequently, it is suggested that the accuracy of the RV-Mod-MPI could be more influenced and possibly compromised by variations in the fetal heart rate.…”

“…There is a wide variation in the quoted reference values of the MPI to date-which are still inconsistent-ranging from 0.35 to 0.60 as the mean values. Therefore, a significant correlation between the MPI and the gestational age (GA) is controversially debated in the current literature [1,8,15,18,20,23,[26][27][28][29][30][31][32][33]. The Mod-MPI is less dependent on factors that impair image acquisition and quality than the other methods used for assessing fetal cardiac function (e.g., maternal BMI, anterior placenta, oligohydramnios), is less dependent on fetal anatomy and position or precise imaging and, by incorporating only time intervals, is less prone to artifacts such as fetal movements.…”

“…Future experts will progressively be guided by applications of artificial intelligence (AI), on whose algorithms prenatal diagnostics will rely on increasingly [36][37][38][39][40][41]. By now, the acquisition of the MPI can also be achieved automatically using AI [23,30,[42][43][44]. The aim of this study was to demonstrate the feasibility of whether less experienced operators might benefit from an automated tool of MPI quantification in the clinical routine.…”

Effect of oval foramen restriction and premature contraction of the arterial catheter on right heart function of fetuses and infants

“…The longitudinal displacement of the sampling line and the tricuspid valve ring at the sampling point was less than 15°, which ensured the reliability of the measurement data. The Tei index can reflect the overall right heart function, with high sensitivity changes in the right heart function due to its good reproducibility, and it is unaffected by the angle of the sampling line and the flow direction ( Herling et al, 2019 ; Kang et al, 2021 ; Soveral et al, 2021 ). The Tei index has been widely used in the evaluation of adult right heart function.…”