Fetal atrial strain: a scoping review of physiology, methods, and clinical applications

Abstract

Abstract Background The evaluation of fetal cardiac function is moving towards the angle-independent myocardial deformation techniques, including the atrial strain obtained with speckle-tracking echocardiography. Angle-independent myocardial deformation techniques are gaining increasing traction and interest, where speckle-tracking-derived atrial strain (AS) has emerged as a potentially sensitive marker of subclinical myocardial dysfunction. Methods This scoping review aims to give an overview of the existing evidence regarding fetal atrial mechanics, which covers physiology, methodological aspects, reported reference values, and potential clinical use. Fetal atrial strain assessment is technically challenging. The traditional triphasic atrial cycle tends to be shortened with high fetal heart rate, creating a pattern of predominant reservoir domination. Furthermore, there are no standard acquisition protocols, gating strategies, and software implementations which may restrict the ability to replicate and compare studies conducted by different researchers. Results The inclusion criteria were met by only six heterogeneous studies because there is still a limited number of studies in this field. Therefore, the current results should be considered as tentative and exploratory. There is emerging evidence indicating fetal atrial strain varies with clinical circumstances. Lower atrial strain values have been reported in maternal diabetes, which may reflect a change in myocardial function. Placental insufficiency in contrast, however, seems to be accompanied by a relatively preserved atrial strain which may be due to adaptive cardiovascular responses to hypoxic stress. But the observations are based on small sample sizes and need to be validated further. Conclusions Fetal atrial strain is a promising quantitative measure of fetal cardiac function overall. Methodological heterogeneity, however, as well as limited reproducibility data and the relative scarcity of studies available suggest the need for standardized acquisition protocols and larger, well-designed studies to determine its clinical usefulness.