Quantification of regional left and right ventricular longitudinal function in 75 normal fetuses using ultrasound-based strain rate and strain imaging.

Previous reports have demonstrated that myocardial velocities are not sufficiently sensitive in fetal heart studies. Strain (S) and strain rate (SR) imaging is a new noninvasive ultrasonic technique able to quantify regional myocardial deformation properties. SR imaging has a superior sensitivity than myocardial velocity for noninvasive assessment of ventricular function, but this technique has not been used in the fetal heart. Our aim was to evaluate the feasibility of S/SR imaging in the fetal heart and to study characteristics of myocardial deformation properties and their changes with the gestational age in healthy fetuses. We studied 75 normal fetuses (weeks gestation 25 +/- 4, no evidence of structural cardiovascular disease by 2-D echo and Doppler study) using S/SR imaging. Left (LV) and right ventricle (RV) peak myocardial systolic, early diastolic and SR values during atrial contraction were obtained but, for S, we measured only peak systolic values. The sample volume was placed in the mid-segment of LV septal, lateral and RV free wall. S and SR curves were obtained in all the studied population. Peak longitudinal systolic deformation was homogeneous in all the walls studied. Moreover, fetal myocardial S and SR during diastole were characterized by a higher deformation during atrial contraction than during early filling. Peak systolic and peak diastolic ratios of regional myocardial deformation properties significantly correlated with the gestational age. Inter- and intraobserver variabilities for S and SR parameters were < 15%, < 18% and < 13%, < 15%, respectively. SR imaging is feasible in selected healthy fetuses, with a limited reproducibility; we presented normal values for the fetal heart; S/SR during fetal life are homogeneous in both LV and RV; and longitudinal myocardial deformation properties increase with the gestational age.