Analysis of factors influencing ventricular filling patterns in fetuses of type I diabetic mothers

A proposed fetal risk scoring system for gestational diabetes to assist in optimising timing of delivery

Background. The pathophysiology of gestational diabetes, which is related to abnormal gluocose tolerance and hyperinsulinaemia, renders standard fetal monitoring models ineffective, insufficient and inappropriate, as these models revolve around detecting and prognosticating on placenta-mediated disease rather than increased metabolic rates due to hyperinsulinaemia, functional hypoxia and ischaemic trophoblastic thresholds. To improve perinatal morbidity and mortality in gestational diabetes, there is therefore a need to introduce new prognostic parameters and scoring systems. Objectives. A proposed risk scoring system has been developed, based on our previous studies, to risk-categorise patients with gestational diabetes in terms of fetal outcome in view of the fact that the pathophysiology of gestational diabetes is not recognised by standard monitoring models, which revolve around placental insufficiency rather than metabolic anomalies.Methods. Patients with diabetes from four case-control studies were combined to form a total sample of 159 cases for validation of the risk scoring system. Univariate logistic regression analysis was used to assess the effect of individual risk factors with proposed cut-offs on adverse pregnancy outcome. The diagnostic accuracy of the total summative score was assessed by computing the area under the receiver operating characteristic (ROC) curve. Results. Four potential parameters were identified to risk-categorise fetuses in a pregnancy complicated by gestational diabetes, i.e. the myocardial performance index (MPI), the E/A ratio (early diastolic filling/late diastolic filling, a marker of diastolic dysfunction), increasing fetal weight (macrosomia), and an increased amniotic fluid index. The total score, obtained by summation of the composite scores for these parameters, ranged from 0 to 11. The total score performed as an excellent predictor of adverse outcome, evidenced by an ROC area under the curve of 0.94. A cut-point of 6 on the score confers a sensitivity of 84.2% and specificity of 90.2% for predicting adverse outcome. Conclusion. To our knowledge, this is the first gestational diabetes scoring system proposed to predict an adverse outcome.

Evaluation of fetal cardiac function in pregnancies with well-controlled gestational diabetes

OBJECTIVE

To evaluate fetal ventricular diastolic function in pregnancies of women with gestational diabetes (GD), to determine whether minimal anomalies of glucose metabolism may influence fetal cardiac function.

STUDY DESIGN

Fetal ventricular filling time was measured by transabdominal ultrasound in singleton pregnancies between 34 and 37 weeks of gestation. We used a measurement which consists in the ratio between the diastolic time and the whole cardiac cycle time.

RESULTS

The study included 35 women with a GD and 217 non-diabetic. Right ventricular filling time (RVFT) was significantly lower in the GD group (mean of RVFT = 39.2 ± 4.4 vs 43.6 ± 4.6; p  <  0.01). Likewise, left ventricular filling time (LVFT) was shorter in the GD group compared to the non-GD group, though the difference was not significant (mean of LVFT = 43.6 ± 4.6 vs 44.6 ± 5.5; p  = 0.33).

CONCLUSIONS

Fetal right cardiac function is altered also in pregnancies where gestational diabetes is well controlled.

Cardiac Doppler in poorly controlled gestational diabetics and its link to markers of intra-uterine hypoxia and adverse outcome

The aim of the study was to investigate foetal cardiac function using the modified myocardial performance index (Mod-MPI) in poorly controlled gestational diabetics and its link with intrauterine markers for hypoxia and to an adverse outcome. In a prospective, cross sectional study, 44 consecutive women with severe or poorly controlled gestational diabetic pregnancies in their third trimester on insulin therapy were recruited and matched with 44 women with normal pregnancies which served as the control group. Using Doppler echocardiography the foetal Mod-MPI was calculated. The foetal Mod-MPI was significantly higher in the diabetic group compared to the controls indicating significant myocardial dysfunction. The Mod-MPI served as an excellent marker of adverse outcomes. Foetal myocardial function was significantly impaired in poorly controlled gestational diabetics and there was a significant link of Mod-MPI to intrauterine markers of hypoxia, as well as to an adverse outcome. Mod-MPI has the potential to improve foetal surveillance in gestational diabetes.IMPACT STATEMENTWhat is already known on this subject? Abnormal foetal cardiac function, as reflected in the modified myocardial performance index, has been reported to be significantly increased in foetuses of poorly controlled diabetics managed on insulin.What do the results of this study add? There is a significant link between abnormal foetal cardiac function to intrauterine markers of hypoxia, as well as to an adverse outcome; and that development of myocardial dysfunction could be one of the main mechanisms, inducing foetal compromise in poorly controlled gestational diabetes.What are the implications of these findings for clinical practice and/or further research? This study explores an interesting concept of foetal pathophysiology in gestational diabetes, namely the concept of "pseudo-hypoxia" in a foetus of a gestational diabetic mother, and this intrauterine "hypoxic stress" in turn leading to myocardial dysfunction. The Mod-MPI, a clinical marker for cardiac dysfunction, can therefore be used in the clinical setting to track a deteriorating metabolic state.

Assessment of the Fetal Myocardial Performance Index in Well-Controlled Gestational Diabetics and to Determine Whether It Is Predictive of Adverse Perinatal Outcome

This study was aimed at determining if the myocardial performance index (MPI) is altered in well-controlled gestational diabetics and if so whether it is predictive of adverse perinatal outcome. In a prospective cross-sectional study, 54 consecutive women with well-controlled gestational diabetes controlled on insulin or metformin in the third trimester were recruited and matched with 54 women with normal pregnancies (control group). Using Doppler echocardiography, the MPI was calculated. Sonographic biophysical and placental resistance Doppler markers in both groups were also determined. An abnormal outcome was defined as any of the following: stillbirth; neonatal death; neonatal intensive care admissions; tachypnea with pulmonary edema; neonatal cord pH < 7.15; 5-min Apgar score < 7, polycythemia; and nucleated red blood cells > 10/100 white blood cell counts, hypoglycemia. The MPI was significantly higher in the diabetic group compared to controls (p < 0.0001). Rate of adverse outcome was 22% in the diabetic group. The diabetic group with adverse outcomes had significantly elevated MPI values compared to the diabetic group with normal outcomes. There were 26 diabetics controlled on metformin and 28 controlled on insulin. The adverse outcome rate was slightly higher in the IDDM group compared to the non-insulin-dependent group but was not statistically significant. The main adverse outcomes were low Apgars (18%), hypoglycemia (22%), polycythemia (13%) and low pH in 7%. All control births had normal outcomes. MPI served as an independent predictor of adverse outcome. The MPI z-score had a good diagnostic accuracy as evidenced by the area under the ROC curve of 0.83. An MPI z-score exceeding 4.55 conferred a 90% sensitivity and 74% specificity, with 77% of outcomes correctly classified with a likelihood ratio of 3.5. The MPI is impaired in fetuses in well-controlled gestational diabetes, with fetuses with an adverse outcome having significantly higher MPI values compared to the fetuses with normal outcome in the diabetic group. MPI has the potential to improve fetal surveillance in gestational diabetes.

Determination of the fetal myocardial performance index in women with gestational impaired glucose tolerance and to assess whether this parameter is a possible prognostic indicator of adverse fetal outcome

AIM

The aim of this study was to investigate if the myocardial performance index (MPI) is altered in fetuses in women with gestational impaired glucose tolerance (GIGT), controlled on diet and whether this parameter is also predictive of adverse outcome in this group, as in poorly controlled gestational diabetes.

METHODS

In a prospective cross-sectional study, 32 women with GIGT on diet in the 3rd trimester were recruited and matched with 32 women with normal pregnancies (control group). Using Doppler echocardiography, the MPI was calculated. Placental resistance Doppler markers in both groups were also determined. An abnormal outcome was defined as any of the following: stillbirth, neonatal death, neonatal intensive care unit (NICU) admissions, tachypnea with pulmonary oedema, neonatal cord pH <7.15, five minute Apgar score <7, and cardiomyopathy.

RESULTS

The cases had a significantly higher median MPI compared to controls, p value <.0001. There were eight abnormal outcomes recorded in the 32 fetuses in the study group, corresponding to an adverse outcome rate of 25%. Fetuses with an adverse outcome had significantly higher MPI measurements compared to the GIGT fetuses with normal outcome. The MPI served as an excellent predictor of adverse outcome in the GIGT fetuses, with a total area under the ROC curve of 0.96. An MPI z-score greater than 4.0 conferred a sensitivity of 100% and specificity of 80%. No abnormal outcomes were noted in the control group.

CONCLUSIONS

The MPI is impaired in fetuses in GIGT women, with fetuses with an adverse outcome having significantly higher MPI measurements compared to the fetuses with normal outcome in the GIGT group. MPI has the potential to improve fetal surveillance in gestational diabetes.

Significance of HbA1c Test in Diagnosis and Prognosis of Diabetic Patients

Diabetes is a global endemic with rapidly increasing prevalence in both developing and developed countries. The American Diabetes Association has recommended glycated hemoglobin (HbA1c) as a possible substitute to fasting blood glucose for diagnosis of diabetes. HbA1c is an important indicator of long-term glycemic control with the ability to reflect the cumulative glycemic history of the preceding two to three months. HbA1c not only provides a reliable measure of chronic hyperglycemia but also correlates well with the risk of long-term diabetes complications. Elevated HbA1c has also been regarded as an independent risk factor for coronary heart disease and stroke in subjects with or without diabetes. The valuable information provided by a single HbA1c test has rendered it as a reliable biomarker for the diagnosis and prognosis of diabetes. This review highlights the role of HbA1c in diagnosis and prognosis of diabetes patients.

Decreased fetal cardiac performance in the first trimester correlates with hyperglycemia in pregestational maternal diabetes

OBJECTIVE

In-vitro animal studies suggest that high glucose levels impair fetal cardiac function early in gestation. We aimed to study whether evidence of first-trimester myocardial dysfunction can be detected in fetuses of women with pregestational diabetes mellitus.

METHODS

Women with diabetes mellitus underwent fetal echocardiography at 11-14 weeks' gestational age. In fetuses with normal anatomy, the cardiac preload, diastolic function, global myocardial performance and placental afterload were studied by Doppler of the ductus venosus (DV), mitral and tricuspid early/atrial (E/A) ratios, left and right ventricular myocardial performance index (MPI) and umbilical artery (UA) Doppler, respectively. Cases were matched for gestational age and UA and DV Doppler with controls that had no diabetes mellitus.

RESULTS

Sixty-three singleton diabetic pregnancies were matched with 63 controls. Mean gestational age at enrollment was 12.6 (range, 11.1-13.6) weeks. Diabetic mothers had moderate to poor glycemic control (median (range) glycosylated hemoglobin A1 (HbA1c), 7.5 (5.1-12.7)%, and the HbA1c level was ≥ 7% in 37 (59%)). Fetuses of diabetic mothers exhibited worse measures of diastolic dysfunction: the isovolumetric relaxation time (IRT) was significantly prolonged (left ventricle: 36.9 ± 7.4 ms vs. 45.8 ± 6.8 ms; right ventricle: 35.6 ± 8 ms vs. 46.4 ± 7.3 ms, P < 0.0001 for both). The mitral E/A ratio was lower in diabetics (0.55 ± 0.06 vs. 0.51 ± 0.08, P = 0.03), and the global myocardial performance was lower in both ventricles (left ventricle MPI: 0.5 ± 0.08; right ventricle MPI: 0.52 ± 0.08, P = 0.03 and P < 0.0001, respectively). This lower global myocardial performance was caused by a prolonged myocardial relaxation time, which was most marked in diabetics with an HbA1c of ≥ 7% (P < 0.001 vs. controls for both ventricles). There were no significant correlations between cardiac Doppler parameters and DV, UA indices and fetal heart rate (P > 0.05 for all).

CONCLUSIONS

Fetuses of poorly controlled diabetic mothers demonstrate significant differences in first-trimester diastolic myocardial function compared with non-diabetic controls. The decrease in myocardial performance is more marked with increasing HbA1c and appears to be independent of preload and afterload. The ability to document these cardiac functional changes this early in pregnancy opens potential new avenues to understand the consequences of maternal glycemic status.

Maternal diabetes and the fetal heart

Maternal diabetes mellitus significantly affects the fetal heart and fetal-placental circulation in both structure and function. The influence of pre-conceptional diabetes begins during embryonic development in the first trimester, with altered cardiac morphogenesis and placental development. It continues to have an influence on the fetal circulation through the second and third trimesters and into the perinatal and neonatal period.

Increased periconceptual maternal glycated haemoglobin in diabetic mothers reduces fetal long axis cardiac function

OBJECTIVE

To compare ventricular long axis function in fetuses of diabetic mothers (FDM) with contemporaneously studied normal controls (N) and to assess the effect of pre-pregnancy diabetic control on these measurements.

DESIGN

Long axis function was compared in 41 FDM and 159 N fetuses in a cross sectional observational study.

SETTING

Fetal medicine unit.

METHODS AND RESULTS

Echocardiography confirmed structural normality. Pulsed wave valvar Doppler velocimetry, lengthening and shortening myocardial velocities, and amplitude of ventricular long axis movement were recorded at the base of the left and right ventricular free walls and septum. Periconceptual diabetic control was assessed by haemoglobin A1c (HbA1c) in early pregnancy. Doppler and myocardial velocities were negatively related and myocardial thickness was positively related with HbA1c. In both cohorts all variables except mitral and tricuspid late filling (A wave) velocities were dependent on gestational age. FDM gestational age related values were higher for most variables and robust analysis of covariance showed significantly different maturation patterns in mitral valve E:A ratio (p = 0.036) and pulmonary velocity (p = 0.04), late lengthening myocardial velocities (left p = 0.016 and right p = 0.066), left myocardial shortening velocities (p = 0.008), and left free wall (p = 0.03) and septal (p = 0.04) amplitude of motion. FDM septal thickness was significantly increased throughout gestation (p < 0.0001).

CONCLUSION

Periconceptual diabetic control influences fetal cardiac performance and myocardial hypertrophy but, unlike the pathophysiology of adult ventricular hypertrophy, is accompanied by functional adaptation. It is unlikely to explain the increased rate of late stillbirth observed in diabetic pregnancies.

Behavior of septum primum mobility in third-trimester fetuses with myocardial hypertrophy

OBJECTIVES

The mobility of the septum primum (SP) in the fetus is a diastolic phenomenon and could be related to left atrial pressure. We studied the linear displacement of the SP in the left atrium in fetuses of diabetic mothers (FDM) with and without septal hypertrophy (SH) and in normal fetuses of normoglycemic mothers. In this study we set out to test the hypothesis that the linear displacement of the SP flap valve is less marked in fetuses with SH than in those without SH.

METHODS

The ratio between the linear displacement of the flap valve and the left atrial diameter (excursion index (EI)) was compared in ten FDM with SH, eight FDM with normal septal thickness and eight normal fetuses of non-diabetic mothers. Atrioventricular flow velocities were also compared in the three groups.

RESULTS

Comparison of the three groups showed that in FDM with SH, the mean EI was 0.36 +/- 0.09, in FDM without SH it was 0.51 +/- 0.09 (P = 0.001) and in the control fetuses it was 0.49 +/- 0.12 (P = 0.03). There was a significant negative correlation between septal thickness and EI in FDM with SH. There was no correlation between septal thickness and atrioventricular flow velocities.

CONCLUSION

Mobility of the SP in FDM with SH is reduced and there is an inverse correlation between the linear displacement of the SP and septal thickness. These findings may be related to changes in left ventricular diastolic function secondary to myocardial hypertrophy.

Altered fetal circulation in type-1 diabetic pregnancies

OBJECTIVE

Type-I diabetic pregnancies are associated with congenital cardiac malformations, fetal cardiomyopathy, venous thrombosis and altered placental vascularization, even with tight maternal glucose control. The aim of this study was to investigate if, with good glucose control achieved with continuous subcutaneous insulin infusion, normal blood flow within the fetal heart can be achieved.

METHODS

Seventeen fetuses of women with well-controlled type-I diabetes were studied longitudinally to evaluate effects on the fetal circulation. Doppler frequency shift tracings, valve diameters and intercept angles were measured at right and left atrioventricular valve orifices at 4-week intervals starting at 15 weeks' gestation. Atrioventricular valve flow was calculated and compared to normal fetal data obtained in previous studies.

RESULTS

Maximum and mean temporal velocities across the atrioventricular valves increased in both groups during gestation but significantly more in fetuses of type-I diabetic pregnancies. Combined ventricular output, both absolute and per kg estimated fetal weight, were also greater in these fetuses. In the normal group the ratio of the right/left ventricular output decreased significantly during gestation (from 1.34 +/- 0.28 to 1.08 +/- 0.28 standard deviations), but in type-I diabetic pregnancies this decrease did not occur (1.2 +/- 0.26 to 1.25 +/- 0.29 standard deviations)[corrected].

CONCLUSIONS

These data indicate that there are significant differences in the fetal circulation between normal pregnancy and well-controlled type-I diabetic pregnancy, suggesting the existence of a compensatory mechanism which increases fetal cardiac output and causes cardiac hypertrophy.