Circulating N-terminal pro-B-type natriuretic peptide in fetal anemia before and after treatment

Fetal NT-proBNP levels and their course in severe anemia during intrauterine treatment

PURPOSE

In adults and fetuses, N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a marker of cardiac failure and myocardial remodelling. We examined the effect of anemia and intrauterine transfusion (IUT) on NT-proBNP concentrations in fetuses with anemia and established gestational age-dependent reference values of a control group.

METHODS

We analyzed NT-proBNP levels in anemic fetuses that underwent serial intrauterine transfusions (IUT), focusing on different causes and severity of anemia and comparing the results to a non-anemic control group.

RESULTS

In the control group, the average NT-proBNP concentration was 1339 ± 639 pg/ml, decreasing significantly with increasing gestational age (R = - 74.04, T = - 3.65, p = 0.001). Subjects had significantly higher NT-proBNP concentrations before initiation of IUT therapy (p < 0.001), showing fetuses with parvovirus B19 (PVB19) infection having the highest concentrations. Hydropic fetuses also showed an increased NT-proBNP concentration compared to non-hydropic fetuses (p < 0.001). During the course of therapy, NT-proBNP concentration before subsequent IUT decreased significantly from pathologically high levels, while MoM-Hb and MoM-MCA-PSV remained pathological.

CONCLUSION

NT-pro BNP levels in non-anemic fetuses are higher than in postnatal life, decreasing with ongoing pregnancy. Anemia is a hyperdynamic state and its severity correlates with circulating NT-proBNP levels. Highest concentrations occur in fetuses with hydrops and with PVB19 infection, respectively. Treatment by IUT leads to a normalisation of NT-proBNP concentrations, so the measurement of its levels may be useful in therapy monitoring.

NT-proBNP: A Useful Biochemical Marker for Prognosis in Rh-Isoimmunized Pregnancies

BACKGROUND

Rh incompatibility sometimes results in life-threatening conditions in fetus like severe anemia and jaundice, leading to kernicterus and even death. Even after an uneventful intrauterine transfusion (IUT), fetus may not survive despite correction of the fetal anemia. Finding appropriate markers may help in determining the prognosis of such cases. The N-terminal prohormone of brain natriuretic peptide (NT-proBNP) suggests some degree of heart failure.

OBJECTIVE

Present study was planned to evaluate its role in predicting the outcome of fetus in Rh-isoimmunized pregnant woman.

METHODS

This prospective study consisted of total 40 pregnant patients: 10 pregnant Rh-isoimmunized women with hydropic fetuses, 10 with non-hydropic fetuses and 20 control group. If the MCA-PSV was > 1.5 MOM, cord blood sampling and IUT was done and sent for fetal hematocrit and NT-proBNP.

RESULTS

The levels of NT-proBNP at various periods of gestation in hydropic, non-hydropic and control group fetuses showed positive correlation with the degree of fetal anemia.

CONCLUSION

Correlation of high levels of NT-proBNP to fetal anemia proves that hydrops fetalis is probably due to progressive high cardiac output myocardial failure, increased capillary permeability and perhaps reduced coronary flow.

Antenatal Prediction of Neonatal Survival in Sacrococcygeal Teratoma

OBJECTIVES

In sacrococcygeal teratoma, the presence of high-output cardiac failure resulting from arteriovenous shunting through the large tumor has been associated with an adverse outcome. The objective of this study was to determine whether the tumor size and cardiac biomarkers in cord blood can predict neonatal survival in sacrococcygeal teratoma.

METHODS

The study population consisted of 25 neonates with sacrococcygeal teratoma. Tumor size was calculated by the ellipsoid formula using dimensions measured by antenatal ultrasound ([length × width × depth in cm] × 0.52= volume in cm³ ). To adjust the gestational age, the tumor volume index (tumor volume/biparietal diameter) was adopted in the analysis. Cardiac biomarkers for heart failure (N-terminal pro-B-type natriuretic peptide [NT-pro-BNP] and cardiac troponin T [cTnT]) were measured in cord blood taken at the time of delivery.

RESULTS

The rate of neonatal death was 24% (6 of 25). The cases that resulted in neonatal death had a higher tumor volume index and higher concentrations of NT-pro-BNP and cTnT than those with survival. A tumor volume index of greater than 60 cm³ /cm, elevated NT-pro-BNP (>2000 pg/mL), and elevated cTnT (>0.08 ng/mL) had sensitivity of 100% for prediction of neonatal death.

CONCLUSIONS

The tumor volume index and cord blood biomarkers for heart failure can be promising prognostic markers for neonatal survival in sacrococcygeal teratoma.

N-terminal pro-B-type natriuretic peptide in amniotic fluid of fetuses with known or suspected cardiac load

Background

Myocardial dysfunction occurs in a variety of fetal disorders. Findings from adult cardiology, where n-terminal pro-B-type natriuretic peptide (nt-proBNP) is an established biomarker of left ventricular dysfunction have been extended to fetal life. Since fetal blood sampling is technically challenging we investigated amniotic fluid nt-proBNP for its suitability to diagnose fetal myocardial dysfunction.

Methods

Ultrasound, Doppler examination and echocardiography was applied to classify cases and controls. Amniotic fluid nt-proBNP to amniotic fluid total protein ratio was calculated and compared to the gestational age-dependent reference intervals. In a subset of cases, fetal and maternal plasma nt-proBNP levels were determined.

Results

Specimen from 391 fetuses could be analyzed (171 cases, 220 controls). There was a high correlation between amniotic fluid and fetal blood nt-proBNP levels (r = 0.441 for cases; r = 0.515 for controls), whereas no correlation could be detected between maternal and fetal (blood and amniotic fluid) nt-proBNP concentrations. Specificity and positive likelihood ratio of amniotic fluid nt-proBNP to amniotic fluid total protein ratio were high (0.97 and 4.3, respectively).

Conclusion

Amniotic fluid nt-proBNP measurement allows diagnostic confirmation of fetal myocardial dysfunction. It may serve as a useful adjunct in addition and correlation to existing tests of myocardial function, particularly in the context of invasive fetal therapy, where access to the amniotic cavity is part of the procedure.

Reference intervals for N-terminal pro-B-type natriuretic peptide in amniotic fluid between 10 and 34 weeks of gestation

BACKGROUND

In adult and pediatric cardiology, n-terminal pro-B-type natriuretic peptide (nt-proBNP) serves as biomarker in the diagnosis and management of cardiovascular dysfunction. Elevated levels of circulating nt-proBNP are present in fetal conditions associated with myocardial pressure or volume load. Compared to fetal blood sampling, amniocentesis is technically easier and can be performed from early pregnancy onwards. We aimed to investigate amniotic fluid (AF) nt-proBNP concentrations in normal pregnancies between 10 and 34 weeks of gestation.

METHODS

Nt-proBNP and total protein (TP) was measured in AF by chemiluminescence assay (photometry, respectively). To adjust for a potential dilutional effect, the AF-nt-proBNP/AF-TP ratio was analyzed. Reference intervals were constructed by regression modeling across gestational age.

RESULTS

132 samples were analyzed. A negative correlation between AF-nt-proBNP/AF-TP ratio and gestational age was observed. Curves for the mean and the 5% and 95% reference interval between 10 and 34 weeks of gestation were established.

CONCLUSION

In normal pregnancy, nt-proBNP is present in AF and decreases during gestation. Our data provide the basis for research on AF-nt-proBNP as biomarker in fetal medicine.

Comparison of cardiac troponin T and N-terminal pro-B-type natriuretic peptide between fetuses with hemoglobin Bart's disease and nonanemic fetuses

OBJECTIVE

The objective of this study was to compare the levels of fetal serum cardiac troponin T (cTnT), representing cardiac injury, and N-terminal pro-B-type natriuretic peptide (nt-proBNP), representing cardiac volume overload, between fetuses affected and not affected by hemoglobin (Hb) Bart's disease, as well as between anemic and nonanemic fetuses.

METHODS

One hundred fourteen pregnancies at risk for fetal Hb Bart's disease scheduled for cordocentesis at 18 to 22 weeks were recruited into the study. Fetal blood was collected to test for cTnT, nt-proBNP and Hb levels as well as Hb typing.

RESULTS

Serum nt-proBNP was significantly higher in Hb Bart's fetuses (24 cases) than in unaffected fetuses (63 cases), whereas cTnT was significantly lower in the affected group than in the unaffected group. The serum nt-proBNP levels significantly increased with the degree of fetal anemia; cTnT levels decreased in fetuses with high degree of anemia.

CONCLUSIONS

At mid-pregnancy, nt-proBNP was significantly higher in fetuses with Hb Bart's disease than in nonanemic fetuses; cTnT was significantly lower in anemic than in normal fetuses. This study suggests that cardiomegaly from fetal anemia in early gestation is not associated with fetal cardiac injury or myocardial dysfunction but presents as cardiac volume overload from a compensatory process to maintain adequate tissue oxygenation.

Cardiorenal syndrome is present in human fetuses with severe, isolated urinary tract malformations

OBJECTIVE

We analyzed the association between renal and cardiovascular parameters in fetuses with isolated severe urinary tract malformations.

METHODS

39 fetuses at a mean gestational age of 23.6 weeks with nephropathies or urinary tract malformations and markedly impaired or absent renal function were prospectively examined. Fetal echocardiography was performed, and thicknesses of the interventricular septum, and left and right ventricular wall were measured. Blood flow velocity waveforms of the umbilical artery, middle cerebral artery, and ductus venosus were obtained by color Doppler ultrasound. Concentrations of circulating n-terminal pro-B-type natriuretic peptide (nt-proBNP), cystatin C, ß2-microglobulin, and hemoglobin were determined from fetal blood samples.

RESULTS

Malformations included 21 cases of obstructive uropathy, 10 fetuses with bilateral nephropathy, and 8 cases of bilateral renal agenesis. Marked biventricular myocardial hypertrophy was present in all cases. The ratio between measured and gestational age-adjusted normal values was 2.01 (interventricular septum), 1.85, and 1.78 (right and left ventricular wall, respectively). Compared to controls, levels of circulating nt-proBNP were significantly increased (median (IQR) 5035 ng/L (5936 ng/L) vs. 1874 ng/L (1092 ng/L); p<0.001). Cystatin C and ß2-microglobulin concentrations were elevated as follows (mean ± SD) 1.85±0.391 mg/L and 8.44±2.423 mg/L, respectively (normal range 1.66±0.202 mg/L and 4.25±0.734 mg/L, respectively). No correlation was detected between cardiovascular parameters and urinary tract morphology and function. Despite increased levels of nt-proBNP cardiovascular function was preserved, with normal fetal Doppler indices in 90.2% of cases.

CONCLUSION

Urinary tract malformations resulting in severe renal impairment are associated with biventricular myocardial hypertrophy and elevated concentrations of circulating nt-proBNP during fetal life. Cardiovascular findings do not correlate with kidney function or morphology.