Modified myocardial 2D-strain parameters in stressed right ventricles of fetuses

Introduction: 2D-strain imaging based on speckle tracking is a new non-invasive, angle independent ultrasonic technique able to quantify regional myocardial deformation properties. Regional systolic strain is showing a strong relation to stroke volume and ejection fraction. Up to now there is no experience with this technique in fetal hearts.

Methods: We matched 17 fetuses with right ventricular stress due to specific congenital heart defects (7 TOF; 2 HLHS, 2 AVSD, 2 dyspl. PV) or stress (3 RV-hypertrophy, 1 thrombus in DA) with 17 normal controls. After segmentation of a transverse four-chamber-view-raw-data-loop into a singleheart cycle with TDIQ-software (Toshiba Medical Systems) we tracked the endo- and epicardium of the RV with Speckle Tracking Imaging (STI) software (Toshiba Medical Systems). 2D-strain was quantified automatically in 6 myocardial RV segments as longitudinal shortening and radial thickening.

Results: Semi-automatic 2D-strain quantification is feasible in the fetal heart. Whereas the global radial and longitudinal peak strain showed no differences between groups, radial thickening strain values of the basal lateral segment of the RV were significant lower (15.12 versus 10.69; p=0.041) and the time to peak in relation to the duration of the single heart cycle in this region was shorter (0.70 versus 0.58; p=0.036) in the impaired group.

Conclusion: This is the first report of the application of 2D-strain imaging by speckle tracking in a transverse FCV of a fetus. Changes of regional strain may can display RV remodelling in CHD and serve as future indicator of impaired myocardial function.