Left ventricular sphericity index predicts systolic dysfunction in rats with experimental aortic regurgitation

Analysing functional implications of differences in left ventricular morphology using statistical shape modelling

Functional implications of left ventricular (LV) morphological characterization in congenital heart disease are not widely explored. This study qualitatively and quantitatively assessed LV shape associations with a) LV function and b) thoracic aortic morphology in patients with aortic coarctation (CoA) with/without bicuspid aortic valve (BAV), and healthy controls. A statistical shape modelling framework was employed to analyse three-dimensional (3D) LV shapes from cardiac magnetic resonance (CMR) data in isolated CoA (n = 25), CoA + BAV (n = 30), isolated BAV (n = 30), and healthy controls (n = 25). Average 3D templates and deformations were computed. Correlations between shape data and CMR-derived morphometric parameters (i.e., sphericity, conicity) or global and apical strain values were assessed to elucidate possible functional implications. The relationship between LV shape features and arch architecture was also explored. The LV template was shorter and more spherical in CoA patients. Sphericity was overall associated with global and apical radial (p = 0.001, R² = 0.09; p < 0.0001, R² = 0.17) and circumferential strain (p = 0.001, R² = 0.10; p = 0.04, R² = 0.04), irrespective of the presence of aortic stenosis and/or regurgitation and controlling for age and hypertension status. LV strain was not associated with arch architecture. Differences in LV morphology were observed between CoA and BAV patients. Increasing LV sphericity was associated with reduced strain, independent of aortic arch architecture and functional aortic valve disease.

The Role of Extracellular Matrix in the Experimental Acute Aortic Regurgitation Model in Rats

BACKGROUND

Mechanisms involved in cardiac remodelling by aortic regurgitation (AR) and the moment when cardiac dysfunction begins are largely unknown. This study aimed to investigate cardiac morphology and function after 1, 4, 8, and 12 weeks of experimental AR in Wistar rats. Extracellular matrix was also investigated as the potential mechanism that underlies the AR remodelling process.

METHODS

Male Wistar rats underwent surgical acute AR (AR group, n=51) or a sham surgery (sham group, n=32). After the procedure, serial transthoracic echocardiograms were performed at 1, 4, 8, and 12 weeks. Morphometry of cardiac tissue and the activities of metalloproteinase 2 (MMP-2) and tissue metalloproteinase inhibitor-1 (TIMP-1) were analysed. Statistical analysis was performed by two-way ANOVA. Significance level was 5%.

RESULTS

The AR group presented an increase in the sphericity index (week 1); an increase in the left atrium, left ventricular mass index, TIMP-1 and MMP-2 activities, and collagen fraction (week 4); an increase in myocyte area (week 8); and a reduction in fraction shortening (week 12). First, the chamber became more spherical; second, MMP-2 and TIMP-1 were activated and this may have contributed to hypertrophy and atrial enlargement, until systolic dysfunction occurred.

CONCLUSIONS

This study showed a sequence of abnormalities that preceded myocardial dysfunction in an experimental model of AR. First, haemodynamic volume overload led to a more spherical left ventricle chamber. Second, MMP-2 and TIMP-1 transitorily increased and may have contributed to atrial enlargement, eccentric hypertrophy, and systolic dysfunction.

Evaluation of the sphericity index of the fetal heart during middle and late pregnancy using fetalHQ

OBJECTIVE

To explore the feasibility of the fetal heart quantitative technique (fetalHQ) for evaluating the sphericity index (SI) of the fetal heart during middle and late pregnancy.

METHODS

Ninety-six normal fetuses in middle and late gestation who underwent systemic ultrasound examination in the Department of Ultrasound of the Maternal and Child Health Care Hospital of Hunan Province in November 2020 were enrolled, and dynamic images of the four-chamber view of the fetal heart were collected. The correlation between the global sphericity index (GSI), ventricular 24-segment SI, and gestational age (GA) was analyzed, and the differences between the left and right ventricular 24-segment SI were compared.

RESULTS

The success rate of fetalHQ analysis was 93.75%. There was no significant linear correlation between GSI and ventricular 24-segment SI and GA (all ps > .05). The differences in SI between segments 1 and 9 and 15 and 24 in the left and right ventricles were statistically significant (all ps < .05), while the differences in SI between segments 10 and 14 were not statistically significant (all ps > .05). In segments 1-9, the SI of the right ventricle was smaller than that of the left ventricle, indicating that the right ventricle was significantly more spherical than the left ventricle. In segments 15-24, the opposite was true.

CONCLUSION

FetalHQ is a simple and reliable method for evaluating the GSI and 24-segment SI of the left and right ventricles. It can provide some theoretical basis for the clinical quantitative evaluation of fetal heart geometry and lay a foundation for the quantitative evaluation of fetal heart function in cases of structural and functional abnormalities.

Association Between Left Ventricle Diastolic Dysfunction and Unfavorable Prognostic Markers in Patients with Aortic Insufficiency

INTRODUCTION

The presence of symptoms, systolic dysfunction and Left Ventricle (LV) dilation are considered unfavourable prognostic markers in Aortic Valve Insufficiency (AVI). The role of diastolic dysfunction, which is considered unfavourable outcome marker in cardiac pathologies, is not well established in AVI.

AIM

To evaluate if the presence of diastolic dysfunction may be associated with unfavourable prognostic markers in AVI patients.

MATERIALS AND METHODS

A cross-sectional prospective study was performed on 22 patients with moderate or severe AVI. They underwent clinical evaluation and transthoracic echocardiography. Associations between clinical, epidemiological and echocardiographic were evaluated by Student t-test for normally distributed variables or Mann-Whitney test for non-normal distribution. Comparison between proportions was performed by Chi-square test.

RESULTS

There was an association between increased LV filling pressure, assessed by E' and E/E' of Mitral Tissue Doppler, and impaired LV systolic function, respectively: R = 0.563, R2 = 0.281; p = 0.008 and R = 0.639, R2 = 0.378; p = 0.002. The LV indexed mass also was inversely associated with the LV ejection fraction (R = 0.62, R2 = 0.35 and p = 0.003).

CONCLUSION

There was an association of LV diastolic dysfunction and ventricular hypertrophy with impaired left ventricle systolic function. Increased LV filling pressure and LV indexed mass should be considered in the management of AVI patients.