Longitudinal Study by Two-Dimensional Speckle-Tracking Echocardiography of the Left Ventricle Rotational Mechanics during Postnatal Adaptation in Healthy Newborns

Early changes in left ventricular myocardial function by 2D speckle tracking layer-specific technique in neonates with hyperbilirubinemia

Background

Hyperbilirubinemia (HBN) can cause myocardial injury in neonates. Advancement in myocardial deformation imaging allows the detection of subclinical changes in myocardial contractility. The present study aimed to evaluate the changes in left ventricular contractility in newborns with hyperbilirubinemia by 2D speckle tracking imaging (STI).

Methods

A group of 134 neonates who reached the diagnostic level of HBN as the HBN group was selected. The control group included 56 healthy newborns. The interventricular septum, anterior partition, anterior wall, sidewall, posterior wall, and inferior wall were separated into the basal, middle, and apical segments. In each segment, speckle tracking analysis was performed in the subintimal, middle, and subadventitial myocardium. The overall longitudinal strain of the myocardium in different ventricular walls and segments and global longitudinal strain (GLS) were computed. At the same time, the laboratory results of blood gas analysis, blood routine tests, liver function, and myocardial enzyme spectrum in HBN neonates were collected and correlated with the left ventricular stratified strain parameters.

Results

The gradient of the left ventricular GLS had the same characteristics in both groups of newborns. There was a decreasing trend of longitudinal strain (LS) from the intima to the adventitia (i.e., GLSendo > GLSmid > GLSepi). This gradient was also present in stratified LS in each myocardial segment (P<0.001). The LS showed an increasing trend from the basal to the apical segment (P<0.001). The LS of the ventricular septum, anterior wall (or anterior septum), inferior wall, lateral wall, and posterior wall showed a decreasing trend (P<0.001). Stratified strain parameters of the ventricular wall (i.e., the 3-layer myocardium: LSendo-SEPT, LSmid-SEPT, and LSepi-SEPT) were all significantly lower in the HBN group than in the control group (P=0.019, P=0.019, and P=0.023, respectively). LSedo-ANT, LSmid-ANT, and LSepi-ANT were also reduced, and the difference between LSendo-ANT and LSepi-ANT was statistically significant. The segmental stratified strain parameters (i.e., the apical 3-layer myocardium: LSepi-a, LSmid-a, and LSepi-a) decreased, and the difference in LSepi-a was statistically significant (P=0.043). Overall strain parameters (i.e., the 3-layer myocardial overall strain: GLSendo, GLSmid, and GLSepi) were reduced, but the difference was not statistically significant (P=0.612, P=0.653, and P=0.585, respectively). The subclinical changes in systolic function in the HBN group, reflected by the parameters of longitudinal myocardial strain, correlate to some extent with multiple results of laboratory tests.

Conclusions

2DSTI stratified strain technology can quantitively evaluate changes in the LS of the left ventricle in different ventricular walls, wall segments, and layers of the myocardium.

Polarized Light Imaging of the Myoarchitecture in Tetralogy of Fallot in the Perinatal Period

Background: The pathognomonic feature of tetralogy of Fallot (ToF) is the antero-cephalad deviation of the outlet septum in combination with an abnormal arrangement of the septoparietal trabeculations. Aims: The aim of this article was to study perinatal hearts using Polarized Light Imaging (PLI) in order to investigate the deep alignment of cardiomyocytes that bond the different components of the ventricular outflow tracts both together and to the rest of the ventricular mass, thus furthering the classic description of ToF. Methods and Materials: 10 perinatal hearts with ToF and 10 perinatal hearts with no detectable cardiac anomalies (control) were studied using PLI. The orientation of the myocardial cells was extracted and studied at high resolution. Virtual dissections in multiple section planes were used to explore each ventricular structure. Results and Conclusions: Contrary to the specimens of the control group, for all ToF specimens studied, the deep latitudinal alignment of the cardiomyocytes bonds together the left part of the Outlet septum (OS) S to the anterior wall of the left ventricle. In addition, the right end of the muscular OS bonds directly on the right ventricular wall (RVW) superior to the attachment of the ventriculo infundibular fold (VIF). Thus, the OS is a bridge between the lateral RVW and the anterior left ventricular wall. The VIF, RVW, and OS define an "inverted U" that roofs the cone between the interventricular communication and the overriding aorta. The opening angle and the length of the branches of this "inverted U" depend however on three components: the size of the OS, the size of the VIF, and the distance between the points of insertion of the OS and VIF into the RVW. The variation of these three components accounts for a significant part of the diversity observed in the anatomical presentations of ToF in the perinatal period.