Aims: Previous reports have demonstrated that myocardial velocities are not sufficiently sensitive in foetal heart studies. Strain (S) imaging is a new non-invasive ultrasonic technique able to quantify regional myocardial deformation properties. Strain imaging has a superior sensitivity than myocardial velocity for non-invasive assessment of ventricular function. However, Doppler-derived strain imaging has been used to quantify myocardial deformation properties in the foetal heart with rather limited results, because of angle dependency, sensitivity to extracardiac movement, the need for good-quality images, long and time-consuming post-processing and the low reproducibility of Doppler-derived strain. Recently, a novel method for motion estimation based on two-dimensional (2D) tissue tracking strain (2D-S) echocardiography using time-domain processing has been developed, providing rapid assessment of regional myocardial strain that is independent of both cardiac translation and angle dependency, with a very good reproducibility. However, no information on 2D-S in human foetuses has so far been provided.
Methods: We studied 100 consecutive normal foetuses (gestation range: 20-32 weeks; no evidence of structural cardiovascular disease by 2D echo and Doppler study) using 2D-S imaging. Left ventricle (LV) and right ventricle (RV) peak myocardial negative strain values were obtained.
Results: Strain data were obtained from all the studied subjects, the duration of post processing was 3 +/- 2 min for each patient dataset. Peak longitudinal deformation parameters were homogeneous in all the three studied walls (strain: septum = -25 +/- 5%; lateral wall = -25 +/- 4%; RV free wall = -24 +/- 4%; P = NS). There were significant correlations between gestational age and peak longitudinal strain (P < 0.001; R: -0.73). Inter and intra-observer variability for strain was good, <3 and <6%, respectively.
Conclusion: This study demonstrated that 2D-S is a feasible and reproducible approach to assess regional ventricular function in the foetal heart, ready for the clinical application.