Assessment of long-axis ventricular function in the fetal heart with a tissue-tracking algorithm

Objective: Tissue-tracking echocardiography (TTE) is a method for quantitative assessment of myocardial contraction and relaxation. The purpose of this study was to assess the feasibility of TTE in fetuses and investigate fetal myocardial properties in normal pregnancies. Methods: Two hundred thirty pregnant women participated in the study. Fetal four-chamber-view cineloops were saved for off-line analysis. Reference values for the global longitudinal peak velocity (V), strain (S), strain rate (SR), and displacement (D) in the fetal heart were established using data from 62 right ventricles (RV) and 68 left ventricles (LV). Furthermore, the change of the motion (V and D) and deformation (S and SR) in the course of the pregnancy was analyzed. Intraobserver variability was assessed in a total of 137 cases. The remaining 93 cases were excluded, as there was no tracking possible. Results: Normal fetuses exhibit a statistically significant increase in all motion parameters in both ventricles with increasing gestational age (GA). In contrast, the deformation parameters with advancing GA decrease. RV has a higher diastolic V and SR than LV. Conclusions: The increase in motion is attributable to fetal cardiac growth, whereas the decrease in deformation parameters indicates an intrauterine adaptation mechanism. RV appears to have a different relaxation pattern than LV. This study establishes a base for further utilization of TTE in fetal medicine and emphasizes a distinct diastolic difference between RV and LV function.