Layer-specific deformation analysis in severe aortic valve stenosis, primary mitral valve regurgitation, and healthy individuals validated against invasive hemodynamic measurements of heart function

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.

Surface Registration with Eigenvalues and Eigenvectors

This paper presents a novel surface registration technique using the spectrum of the shapes, which can facilitate accurate localization and visualization of non-isometric deformations of the surfaces. In order to register two surfaces, we map both eigenvalues and eigenvectors of the Laplace-Beltrami of the shapes through optimizing an energy function. The function is defined by the integration of a smoothness term to align the eigenvalues and a distance term between the eigenvectors at feature points to align the eigenvectors. The feature points are generated using the static points of certain eigenvectors of the surfaces. By using both the eigenvalues and the eigenvectors on these feature points, the computational efficiency is improved considerably without losing the accuracy in comparison to the approaches that use the eigenvectors for all vertices. In our technique, the variation of the shape is expressed using a scale function defined at each vertex. Consequently, the total energy function to align the two given surfaces can be defined using the linear interpolation of the scale function derivatives. Through the optimization of the energy function, the scale function can be solved and the alignment is achieved. After the alignment, the eigenvectors can be employed to calculate the point-to-point correspondence of the surfaces. Therefore, the proposed method can accurately define the displacement of the vertices. We evaluate our method by conducting experiments on synthetic and real data using hippocampus, heart, and hand models. We also compare our method with non-rigid Iterative Closest Point (ICP) and a similar spectrum-based methods. These experiments demonstrate the advantages and accuracy of our method.

The impact of arterial hypertension on left ventricular strain in patients with aortic stenosis and preserved ejection fraction

OBJECTIVE

The influence of arterial hypertension on aortic stenosis severity is still controversial. The aim of this study was to evaluate the influence of hypertension on LV strain in patients with moderate and severe aortic stenosis.

METHODS

This cross-sectional study included 115 patients with moderate and severe aortic stenosis and preserved LV ejection fraction (>50%) and 89 age-matched normotensive and hypertensive controls who underwent comprehensive echocardiographic examination. Aortic stenosis patients were divided into normotensive and hypertensive groups.

RESULTS

There was no significant difference in LV ejection fraction between hypertensive and normotensive aortic stenosis patients. LV mass index gradually increased with the grade of aortic stenosis. LV global longitudinal strain, as well as endocardial and epicardial longitudinal strains, was significantly lower in hypertensive patients with severe aortic stenosis than in their normotensive counterparts. There was no significant difference in LV global circumferential strain between normotensive and hypertensive patients with severe aortic stenosis. Among patients with moderate aortic stenosis, there was no difference in global longitudinal strain between normotensives and hypertensive patients, whereas circumferential was significantly lower in hypertensive patients. LV radial strain was reduced in patients with severe aortic stenosis than in control subjects. SBP and mean aortic valve gradient were associated with LV global longitudinal and circumferential strains in aortic stenosis patients independently of LV mass index, LVEF, age and BMI.

CONCLUSION

Hypertension had additional significant negative influence on LV mechanics in patients with significant aortic stenosis. Blood pressure was associated with LV global longitudinal and circumferential strains in aortic stenosis patients independently of main clinical and demographic characteristics.