Functional assessment of the fetal heart: a review

The purpose of this review is to evaluate the current modalities available for the assessment of fetal cardiac function. The unique anatomy and physiology of the fetal circulation are described, with reference to the difference between in-utero and ex-utero life. M-mode, early/atrial ratio, myocardial performance index, three-dimensional and four-dimensional ultrasound, tissue Doppler including strain and strain rate, speckle tracking, magnetic resonance imaging and venous flow assessment are described. The modalities are analyzed from the perspective of the clinician and certain questions are posed. Does the modality assess systolic function, diastolic function or both? Is it applicable to both ventricles? Does it require extensive post-processing or additional hardware, or does it make use of technology already available to the average practitioner? The reproducibility and reliability of the techniques are evaluated, with reference to their utility in clinical decision-making. Finally, directions for future research are proposed.