Disorders in glucidic metabolism and congenital heart diseases: detection and prevention

Associations of elevated glucose levels at each time point during OGTT with fetal congenital heart diseases: a cohort study of 72,236 births

BACKGROUND

It remains unclear how the condition of glucose metabolism during pregnancy affects fetal outcomes. This study aimed to investigate the associations of gestational diabetes mellitus (GDM) and elevated glucose levels at each time point during oral glucose tolerance test (OGTT) with congenital heart disease (CHD) risk in offspring.

METHODS

We conducted a retrospective cohort study of mothers with singleton pregnancies of 20 weeks or more registered at Maternal and Child Health Centers in Fujian Province, China. The OGTT results and offspring CHD occurrence were collected. We used logistic regression to analyse the association between elevated blood glucose at each time point during OGTT and CHD.

RESULTS

A total of 71,703 normal and 533 CHD fetuses were included. Compared to the corresponding normal group, women with GDM, elevated blood glucose at different time points in OGTT (0 h ≥ 5.1 mmol/L, 1 h ≥ 10 mmol/L, and 2 h ≥ 8.5 mmol/L) showed an increased risk of CHD in offspring (adjusted OR = 1.41, 1.36, 1.37, and 1.41, all P < 0.05, respectively). Compared to group 1 (normal OGTT 0 h, 1 h and 2 h), the risk of CHD was higher in group 3 (normal OGTT 0 h and abnormal OGTT 1 h or 2 h) and group 4 (abnormal OGTT 0 h, 1 h and 2 h), OR = 1.53 and 2.21, all P < 0.05, respectively. Moreover, we divided participants by advanced maternal age, multipara, assisted reproduction, fetal sex, and others, similar associations were observed in the subgroup analyses.

CONCLUSION

Elevated blood glucose at different time points during OGTT was associated with CHD in offspring. Fetuses of pregnant women with GDM should be screened for a high risk of CHD.

Evaluation of fetal cardiac functions in the setting of maternal diabetes: Application of the global spherical index, global strain and fractional area change by the speckle tracking technique

OBJECTIVE

To evaluate ventricular contractility and profile heart deformations in fetuses of hyperglycemic mothers using the Speckle tracking imaging (STI). The fractional area change (FAC), global longitudinal strain (GLS) and global sphericity index (GSI) of the 4-chamber view (4-CV) were computed.

STUDY DESIGN

Dynamic 4-CV images of 60 fetuses exposed to maternal diabetes (MD) and 60 controls were retrospectively collected between 19 and 37 weeks of gestation. Speckle-tracking analysis was used to compute and compare GSI, GLS and FAC of the right ventricle (RV) and the left ventricle (LV) between the groups. By definition, GSI was the ratio of the epicardial basal-apical length in end-diastole (BAL) to the overall transverse length of RV and LV in end-diastole (TL). The FAC was calculated by dividing the difference between end-diastolic area and end-systolic area by the end-diastolic area. Similarly, the GLS of the RV and LV was obtained by dividing the difference between the endocardial length in end-systole and endocardial length in end-diastole to the endocardial length in end-diastole. Data for conventional echocardiographic parameters, standard biological measurements of fetus and maternal baseline characteristics were also recorded and compared between the groups. Linear regression analysis was performed to assess the association between age, BMI and the inter-ventricular septum thickness (IVST).

RESULTS

Gestational age at the time of examination did not differ significantly between the control and gestational diabetes group (p = 0.74). In fetuses exposed to MD, the thickness of the IVS was higher while the FAC of RV, GLS of RV and the GSI were all significantly lower. The FAC and global strain of LV generally decreased with progress in gestation but the difference between the two groups was not statistically significant. Conventional echocardiography in fetuses exposed to MD revealed a lower mitral E/A ratio and a larger myocardial performance index (MPI) of the RV and LV. Although the annular plane systolic excursion (MAPSE), tricuspid annular plane systolic excursion (TAPSE) and septal annular plane systolic excursion (SAPSE) were also lower in this group, the difference was not statistically significant compared to fetuses of the control group. No regression relationship between age, BMI and IVST were noticed in any group.

CONCLUSION

This study found that diastolic dysfunction among fetuses of gestational diabetic mothers is accompanied by global cardiac deformation and functional decrease of the RV in systole in the second and third trimester. The GSI, global strain and FAC acquired by SRI can be used as convenient and reliable quantitative parameters in the assessment of cardiac function in fetuses exposed to gestational diabetes.

Fetal cardiac function by mitral and tricuspid annular plane systolic excursion using spatio-temporal image correlation M-mode and left cardiac output in fetuses of pregestational diabetic mothers

Objective

To assess the mitral and tricuspid annular plane systolic excursions (MAPSE and TAPSE, respectively) and cardiac output (CO) in fetuses of pregnant women with pregestational diabetes mellitus (DM) using spatio-temporal image correlation M-mode (STIC-M) and virtual organ computer-aided analysis (VOCAL).

Methods

This study was prospective and cross-sectional. It included 45 fetuses each from mothers with pregestational DM and healthy mothers, with gestation ages ranging from 20 to 36.6 weeks. The fetal cardiac volumes were obtained and analyzed by STIC and VOCAL methods. MAPSE and TAPSE were measured by STIC-M in the apical or basal four-chamber view. The values of the right (RV) and left ventricular (LV) CO were calculated by STIC and VOCAL.

Results

The median values of TAPSE were 6.1 and 6.2 mm in the diabetic and control groups (P<0.001), respectively. The median values of MAPSE were 4.6 mm in the fetuses of mothers with diabetes and 4.8 mm in fetuses of healthy mothers. The fetal LV CO (60.4 L/min vs. 71.1 L/min; P=0.033, respectively) and RV CO (65.2 vs. 70.1 L/min; P=0.026, respectively) were lower in the pregestational DM group than in the control group. A significant effect of pregestational DM was observed in all functional parameters after adjusting, with fetal heart rate as covariant. There was moderate significant positive correlation between MAPSE and LV CO (r=0.53; P=0.0001) and between TAPSE and RV CO (r=0.46; P=0.0001).

Conclusion

Significant difference in functional parameters (TAPSE, MAPSE and LV CO) obtained by STIC and VOCAL were observed in the fetuses of the pregestational DM group compared to those of the control group.

Fetal Cardiac Function and Ventricular Volumes Determined by Three-Dimensional Ultrasound Using STIC and VOCAL Methods in Fetuses from Pre-gestational Diabetic Women

To assess the fetal cardiac function and ventricular volumes by three-dimensional (3D) ultrasound using spatio-temporal image correlation (STIC) and virtual organ computer-aided analysis (VOCAL) methods in fetuses from pre-gestational diabetic women. This was a prospective and cross-sectional study that evaluated 53 fetuses from pre-gestational diabetic women and 53 fetuses from healthy mothers between 20 and 34 weeks of gestation. Only fetuses with no structural or genetic abnormalities and singleton pregnant women were included in this study. The fetal cardiac volumes were assessed by STIC and VOCAL methods. The ejection fraction, stroke volume, and cardiac output were calculated from these measurements to evaluate fetal cardiac function. The Mann-Whitney U test was performed to compare the two groups. For calculation of intra- and interobserver reproducibility's, we used concordance correlation coefficients. The mean differences in the right atrial volumes between the diabetic and normal groups ranged from 0.05 mL to 0.1 mL (p = 0.917 and 0.355, respectively). The median of left atrium (LA) volume measurement in pre-gestational diabetic group was significantly lower than healthy mothers (LA: 0.62 vs. 0.68 mL; p < 0.001). The fetal right and left ventricular volumes were similar in both groups. No significant differences in ejection fraction, stroke volume and cardiac output were observed (p value range 0.086-0.815). The majority of fetal atrial/ventricular volumes showed good intra- and interobserver reliabilities. Conversely, the majority cardiac function parameters showed poor intra- and interobserver agreements. STIC and VOCAL methods gave reproducible quantitative results for fetal atrial and ventricular volumes. Significant differences in fetal left atrial volumes were observed between the two groups, which be related to LA atrial dysfunction and /or left ventricle (LV) compliance, reflecting earlier stages of cardiac dysfunction.

Caracterización de la exposición prenatal de un grupo de niños de 0 a 5 años con cardiopatía congénita atendidos en Cali, Colombia. La importancia del ácido fólico

Introducción. Con una prevalencia estimada de 4 a 9 casos por cada 1 000 nacimientos, las cardiopatías congénitas (CC) tienen gran impacto en la morbimortalidad pediátrica. La variabilidad de prevalencia se ha atribuido a diferencias regionales en cuanto a factores genéticos, ambientales, entre otros.Objetivo. Obtener datos sobre variables de exposición prenatales de pacientes con CC atendidos en Cali, Colombia.Materiales y métodos. Se aplicó una encuesta a las madres de 30 pacientes de 0 a 5 años con CC atendidos en 2 clínicas de alta complejidad (tercer y cuarto nivel) de Cali. La encuesta estaba orientada a múltiples variables de exposición y la información recolectada fue digitalizada en una base de datos en el programa Microsoft Excel para hacer un análisis estadístico descriptivo.Resultados. Se evidenciaron varias exposiciones potencialmente asociadas a CC, tales como índice de masa corporal alterado, administración inadecuada de suplementos de ácido fólico y exposición a vitamina A, rayos X, alcohol y cigarrillo.Conclusión. El consumo insuficiente o inoportuno de ácido fólico podría facilitar la generación de efectos teratogénicos de sustancias oxidantes. Por lo tanto, se debe educar a las mujeres de Cali sobre la importancia de una ingesta adecuada de ácido fólico y sobre los riesgos de la exposición a agentes teratogénicos durante el embarazo para reducir las tasas de incidencia de CC en esta ciudad.

A Novel TBX1 Loss-of-Function Mutation Associated with Congenital Heart Disease

Congenital heart disease (CHD) is the most prevalent type of birth defect in humans and is the leading non-infectious cause of infant death worldwide. There is a growing body of evidence demonstrating that genetic defects play an important role in the pathogenesis of CHD. However, CHD is a genetically heterogeneous disease and the genetic basis underpinning CHD in an overwhelming majority of patients remains unclear. In this study, the coding exons and splice junction sites of the TBX1 gene, which encodes a T-box homeodomain transcription factor essential for proper cardiovascular morphogenesis, were sequenced in 230 unrelated children with CHD. The available family members of the index patient carrying an identified mutation and 200 unrelated ethnically matched healthy individuals used as controls were subsequently genotyped for TBX1. The functional effect of the TBX1 mutation was predicted by online program MutationTaster and characterized by using a dual-luciferase reporter assay system. As a result, a novel heterozygous TBX1 mutation, p.Q277X, was identified in an index patient with double outlet right ventricle (DORV) and ventricular septal defect (VSD). Genetic analysis of the proband's available relatives showed that the mutation co-segregated with CHD transmitted in an autosomal dominant pattern with complete penetrance. The nonsense mutation, which was absent in 400 control chromosomes, altered the amino acid that was completely conserved evolutionarily across species and was predicted to be disease-causing by MutationTaster. Biochemical analysis revealed that Q277X-mutant TBX1 lost transcriptional activating function when compared with its wild-type counterpart. This study firstly associates TBX1 loss-of-function mutation with enhanced susceptibility to DORV and VSD in humans, which provides novel insight into the molecular mechanism underlying CHD and suggests potential implications for the development of new preventive and therapeutic strategies for CHD.

Evaluation of the regional ventricular systolic function by two-dimensional strain echocardiography in gestational diabetes mellitus (GDM) fetuses with good glycemic control

OBJECTIVE

The aim is to quantitatively assess regional ventricular systolic function by two-dimensional strain (2DS) echocardiography in gestational diabetes mellitus (GDM) fetuses with good glycemic control.

METHODS

We studied 60 consecutive normal fetuses and 35 fetuses of GDM mothers with good glycemic control by echocardiography. M-mode and two-dimensional echocardiography were used to measure ejection fraction and wall dimensions of left ventricle and right ventricle. Both left and right ventricle peak systolic myocardial strain values were obtained by 2DS echocardiography.

RESULTS

Compared with normal fetuses, the thickness of the interventricular septum (IVS) and the thickness of right ventricular wall were significantly increased in GDM fetuses (p < 0.05). Compared with those of normal fetuses, the peak systolic myocardial strain decreased significantly in the apical segments of the IVS and the apical segments of the left ventricular lateral wall in GDM fetuses (p < 0.05), as well as the apical and middle segments of right ventricular wall in GDM fetuses (p < 0.05). Peak negative 2DS values in 60 normal fetuses increased with the gestational age, showing a significant linear correlation(r = -0.625, p < 0.001). The average ventricular strain was not correlated to ventricular wall thickness (r = 0.127, p = 0.394).

CONCLUSIONS

2DS is a feasible approach to assess regional ventricular systolic function in the fetal hearts and it can be used to examine cardiac systolic function in GDM fetuses with good glycemic control.

The effect of pregestational diabetes on fetal heart function

Pregestational diabetes affects nearly 2% of all pregnancies. Moreover, Type 2 diabetes in child-bearing women is on the rise because of the childhood obesity epidemic. Pregestational diabetes can affect the fetal heart in several ways. First, the risk of fetal congenital heart disease is markedly increased; second, fetal hypertrophic cardiomyopathy may occur even with good glycemic control; third, studies have shown impaired function of the hearts of some infants and fetuses of diabetic pregnancies, which can occur with and without septal hypertrophy. Small-for-gestational-age infants of diabetic mothers may have diminished cardiovascular health in the long term. This review mainly discusses methods to detect fetal diabetic cardiomyopathy prenatally. The focus is on the noninvasive diagnostic markers that can serve as an outcome measure for future therapeutic trials, which are still lacking. There is some experimental research on treatment strategies to prevent fetal heart disease in diabetic pregnancies but little clinical data.

Role of Nodal-PITX2C signaling pathway in glucose-induced cardiomyocyte hypertrophy

Pathological cardiac hypertrophy is a major cause of morbidity and mortality in cardiovascular disease. Recent studies have shown that cardiomyocytes, in response to high glucose (HG) stimuli, undergo hypertrophic growth. While much work still needs to be done to elucidate this important mechanism of hypertrophy, previous works have showed that some pathways or genes play important roles in hypertrophy. In this study, we showed that sublethal concentrations of glucose (25 mmol/L) could induce cardiomyocyte hypertrophy with an increase in the cellular surface area and the upregulation of the atrial natriuretic peptide (ANP) gene, a hypertrophic marker. High glucose (HG) treatments resulted in the upregulation of the Nodal gene, which is under-expressed in cardiomyocytes. We also determined that the knockdown of the Nodal gene resisted HG-induced cardiomyocyte hypertrophy. The overexpression of Nodal was able to induce hypertrophy in cardiomyocytes, which was associated with the upregulation of the PITX2C gene. We also showed that increases in the PITX2C expression, in response to Nodal, were mediated by the Smad4 signaling pathway. This study is highly relevant to the understanding of the effects of the Nodal-PITX2C pathway on HG-induced cardiomyocyte hypertrophy, as well as the related molecular mechanisms.

Novel PITX2c loss-of-function mutations associated with complex congenital heart disease

Congenital heart disease (CHD) is the most common form of birth defect in humans and is the leading non-infectious cause of infant mortality. Emerging evidence strongly suggests that genetic risk factors play an important role in the pathogenesis of CHD. However, CHD is of pronounced genetic heterogeneity, and the genetic defects responsible for CHD in an overwhelming majority of patients remain unclear. In this study, the entire coding region and splice junction sites of the PITX2c gene, which encodes a paired-like homeodomain transcription factor crucial for proper cardiovascular morphogenesis, was sequenced in 170 unrelated neonates with CHD. The available relatives of the mutation carriers and 200 unrelated ethnically matched healthy individuals were genotyped. The disease-causing potential of the PITX2c sequence variations was predicted by MutationTaster and PolyPhen-2. The functional effect of the mutations was characterized using a luciferase reporter assay system. As a result, 2 novel heterozygous PITX2c mutations, p.R91Q and p.T129S, were identified in 2 unrelated newborns with transposition of the great arteries and ventricular septal defect, respectively. A genetic scan of the pedigrees revealed that each mutation co-segregated with CHD transmitted in an autosomal dominant pattern with complete penetrance. The mutations, which altered the amino acids completely conserved evolutionarily, were absent in 400 normal chromosomes and were predicted to be causative. Functional analysis revealed that the PITX2c mutations were both associated with significantly diminished transcriptional activity compared with their wild-type counterpart. This study demonstrates the association between PITX2c loss-of-function mutations and the transposition of the great arteries and ventricular septal defect in humans, providing further insight into the molecular mechanisms responsible for CHD.