Left ventricular torsional mechanics in term fetuses and neonates

Abstract

Objective Left ventricular (LV) torsion is an important aspect of cardiac mechanics and is fundamental to normal ventricular function. The myocardial mechanics of the fetal heart and the changes that occur during the transition to the neonatal period have not been explored previously. The aim of this study was to evaluate perinatal changes in LV torsion and its relationship with myocardial function. Methods This was a prospective study of 36 women with an uncomplicated term pregnancy. Fetal and neonatal conventional, spectral tissue Doppler and two‐dimensional (2D) speckle tracking echocardiography were performed a few days before and within hours after delivery to measure cardiac indices including LV rotational parameters derived from short‐axis views at the base and apex of the heart. Linear regression analysis was used to examine the relationship between LV rotational parameters and cardiac geometric and functional indices in term fetuses and neonates. Perinatal changes in LV rotational parameters were assessed. Results There were three patterns of LV twist in term fetuses: those with reversed‐apex‐type LV twist had the lowest median values of LV torsion (0.1°/cm), with higher values (1.6°/cm) in those with infant‐type LV twist and the highest values (4.4°/cm) in those with adult‐type LV twist. LV torsion was associated significantly with cardiac geometric and functional indices. Perinatal evaluation revealed a significant increase in LV torsion following delivery in fetuses exhibiting reversed‐apex‐type LV twist (increase of 2.8°/cm, P = 0.009) and a significant decrease in those with adult‐type LV twist (decrease of 3.2°/cm, P = 0.008). Conclusions This study demonstrates the feasibility of 2D speckle tracking imaging for accurate assessment of rotational cardiac parameters in term fetuses. There are unique perinatal patterns of LV twist that demonstrate different values of LV torsion, which was found to correlate with indices of ventricular geometry and myocardial function. Differences in patterns of LV twist may therefore reflect differences in compensatory myocardial adaptation to the physiological environment/loading conditions in late gestation in fetuses and postnatal cardiac adjustment to the acute loading changes that occur at delivery. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Main Patterns of Fetal Cardiac Remodeling

“…Fetal cardiac dysfunction may affect the systolicthe ability to pump enough blood into circulation -and/ or diastolic -the ability to relax the myocardium to fill the ventricles -function. Changes in cardiac architecture may also lead to alterations in ventricular rotation and torsion [6][7][8]. In most clinical situations, fetal cardiac dysfunction is subclinical.…”

“…2c). In addition, 35% of the cases present mild pericardial effusion and most of them show signs of systolic and diastolic dysfunction (reduced longitudinal motion and impaired relaxation) [8,26]. It has been postulated to be a compensatory fetal cardiac hypertrophic response to myocardial damage associated with toxicity.…”

Urgent neonatal balloon atrial septostomy in simple transposition of the great arteries: predictive value of fetal cardiac parameters

“…Fetuses in the BAS subgroup also had increased RV/LV‐CO ratio at the expense of a significant fall in LV‐CO and reduced LV basal circumferential strain, thus revealing LV dysfunction from pulmonary hypoxemia and increased LV afterload due to ductus arteriosus constriction 29 . Significantly increased LV apical systolic rotation in these fetuses might reflect a compensatory mechanism for improving LV diastolic dysfunction as a result of the ventricular interaction in which expansion of the RV chamber causes an apparent decrease in LV compliance 30,63 . Elevated LV apical rotation can also be a result of an increased afterload faced by the left ventricle, resulting in subendocardial microvascular insufficiency, increased oxygen demand and LV myocardial helical imbalance 29,30 .…”

“…Significantly increased LV apical systolic rotation in these fetuses might reflect a compensatory mechanism for improving LV diastolic dysfunction as a result of the ventricular interaction in which expansion of the RV chamber causes an apparent decrease in LV compliance 30,63 . Elevated LV apical rotation can also be a result of an increased afterload faced by the left ventricle, resulting in subendocardial microvascular insufficiency, increased oxygen demand and LV myocardial helical imbalance 29,30 .…”

“…The time-interval values were adjusted by cardiac cycle length, normalizing for the difference in heart rate. Other fetal and neonatal indices were normalized by dividing corresponding measurements by the ventricular length or EDD, according to the study methodology and previous publications [30][31][32][33][34] . Detailed analysis of the intraand interobserver reproducibility of echocardiographic measurements obtained using the ultrasound machine utilized for this study has been reported previously 32,33,35 and is summarized in Appendix S2.…”