Atrial natriuretic factor in patients with congenital heart disease: correlation with hemodynamic variables

Potential and Limitations of Atrial Natriuretic Peptide as Biomarker in Pediatric Heart Failure-A Comparative Review

Although B-type Natriuretic Peptide (BNP), N-terminal-proBNP (NT-proBNP), and mid-regional-proANP (MR-proANP) are included in current guidelines on heart failure in adults, no guideline considering these biomarkers in pediatric heart failure is available. A new drug class of neprilysin inhibitors as fixed-dose combination (Sacubitril/valsartan) has been introduced and is currently being investigated in children suffering from heart failure. Atrial Natriuretic Peptide (ANP) is discussed as a more useful alternative to BNP because it may grants better insights into the effects of this treatment. Thus, this review aimed to provide an overview of the current knowledge concerning ANP in pediatric heart failure and compares its suitability regarding diagnosis and prognosis of heart failure. A literature search using PubMed resulted in 147 publications of which 22 studies were classified as relevant. The review presents available ANP, NT-proANP, and MR-proANP level data in children (0-18 years). Summarizing, ANP shows only minor differences as marker for diagnosing and monitoring pediatric heart failure if compared to BNP. Due to its fast release, ANP offers the advantage of displaying rapid changes during therapy or operation. ANP is -like the other natriuretic peptides- influenced by age, presenting with the highest levels in very young infants. ANP also correlates with atrial pressure and volume overload in children. In addition, ANP determination in saliva appears to be a promising alternative to blood sampling. Similarly to NT-proBNP, NT-proANP, and MR-proANP offer better stability but only few data has been published in children and thus their potential is only presumable so far.

In vivo dilatation of the postnatal ductus arteriosus by atrial natriuretic peptide in the rat

BACKGROUND

Alpha-human atrial natriuretic peptide (hANP) reportedly increases in premature infants with patent ductus arteriosus (PDA).

OBJECTIVES

To clarify a possible hANP effect to reopen the postnatal ductus, we studied in vivo reopening of the postnatal DA by a recombinant hANP, carperitide, in rats.

METHODS

Near-term rat pups were incubated at 33 degrees C following caesarean section. The inner diameter of the ductus was measured with a microscope and a micrometer following rapid whole-body freezing. The DA constricted quickly after birth, and the inner diameter was 0.80 and 0.08 mm at 0 min (fetal state) and 60 min after birth. hANP concentration in the pup blood and the ductus-dilating effect of hANP were studied by subcutaneous injection of hANP at 60 min after birth, and by measurement 7, 15, 30 and 60 min later.

RESULTS

The peak hANP concentration was 790 pg/ml at 7 min with 1 mg/kg, which is similar to the level seen in preterm infants with symptomatic PDA. hANP dilated the postnatal ductus dose dependently and maximally at 7 min after injection. hANP dilated the postnatal constricted ductus completely to 0.79 mm in diameter with a large dose (10 mg/kg) and to 0.55 mm with 1 mg/kg.

CONCLUSIONS

hANP reopens the constricted postnatal DA dose dependently in rats. The increased hANP, accompanying premature PDA, may delay closure of the DA.

Clinical value of NT-ProBNP and BNP in pediatric cardiology

BACKGROUND

Although less common than in adults, heart disease is a significant cause for morbidity and death in infants and children. Congenital structural cardiac anomalies and acquired heart diseases may result in heart failure.

METHODS AND RESULTS

Available data suggest that the natriuretic peptide system has a similar role in health and disease in the pediatric age group as in adults. In healthy infants and children, levels of B-type natriuretic peptide (BNP) and the N-terminal segment of its pro-hormone (NT-proBNP) are elevated in the first few days after birth. Thereafter, their levels decrease and remain relatively constant throughout childhood. Infants and children with heart disease that causes significant pressure or volume overload of the right or the left ventricle have elevated BNP and NT-proBNP levels. In children with congestive heart failure, BNP and NT-proBNP levels correlate with functional capacity. Both peptides can differentiate cardiac from pulmonary causes in infants with respiratory distress. Limited data suggest that these peptides may also serve as markers in cyanotic, obstructive, and inflammatory heart diseases.

CONCLUSION

The present data suggest that both NT-proBNP and BNP are markers for heart disease in infants and children. Their use may improve clinical practice in pediatric cardiology.

Plasma atrial natriuretic peptide in fetuses with cardiac disease

OBJECTIVE

To investigate atrial natriuretic peptide (ANP) levels in fetuses with cardiac defects and to evaluate the relationships between plasma ANP levels and the presence of polyhydramnios.

METHODS

Plasma ANP levels were measured by radioimmunoassay in 27 fetuses with cardiac abnormalities and in 14 normal healthy fetuses.

RESULTS

Fetal plasma ANP levels were similar in the two studied groups (p = 0.18) but they were significantly higher in a subset of cases with cardiac disease and polyhydramnios (n = 7) than in those with cardiac disease and normal amniotic fluid (n = 20; p = 0.036) and controls (p = 0.01).

CONCLUSION

Polyhydramnios in fetuses with heart conditions might be explained by increased fetal diuresis secondary to increased ANP production.

Dysfunction of atrial and B-type natriuretic peptides in congenital univentricular defects

OBJECTIVE

To examine whether children with univentricular defects have intrinsic dysfunction in the natriuretic peptide system.

METHODS

We compared plasma levels of the fluid-regulating hormone vasopressin (antidiuretic hormone), aldosterone, atrial natriuretic peptide, and brain natriuretic peptide in children with congenital univentricular and biventricular defects. We enrolled 27 patients with univentricular defects and 27 patients with biventricular cardiac defects. Children who underwent Fontan and Glenn procedures were considered as patients with univentricular cardiac defects; children who underwent repair of tetralogy of Fallot or subaortic stenosis were considered as controls with biventricular defects.

RESULTS

Preoperative plasma atrial natriuretic peptide, brain natriuretic peptide, antidiuretic hormone, and aldosterone were comparable in both groups. Although plasma cyclic guanosine monophosphate levels were comparable between groups, there was a significant correlation between molar concentrations of plasma cyclic guanosine monophosphate and plasma atrial natriuretic peptide ( r = 0.42) and brain natriuretic peptide ( r = 0.44) in the biventricular group, but not in the univentricular group ( r = 0.19 for atrial natriuretic peptide; r = 0.13 for brain natriuretic peptide). All patients had a significant postoperative increase in plasma antidiuretic hormone. A significant postoperative increase in plasma brain natriuretic peptide was found in the patients with biventricular, but not univentricular, defects. In contrast, a significant increase in plasma aldosterone was observed only in the patients with univentricular defects.

CONCLUSIONS

There were distinct differences between univentricular and biventricular groups in their perioperative plasma fluid-regulating hormone responses. Specifically, patients with univentricular defects may have abnormal natriuretic peptide secretion and function. The natriuretic dysfunction may be on the basis of hypoplastic ventricular development.

Clinical implication of plasma natriuretic peptides in children with ventricular septal defect

BACKGROUND

There is little information available concerning plasma concentrations of B-type natriuretic peptide (BNP) in children with a ventricular septal defect. The aim of the present study was to determine hemodynamic factors that control plasma concentrations of BNP and the clinical implications of BNP compared with atrial natriuretic peptide (ANP) in children with ventricular septal defect.

METHODS

Fifty-nine patients with ventricular septal defect (28 boys and 31 girls) without pulmonary vascular disease were enrolled. The patients' ages ranged from 3 months to 13 years (mean 3.1 years). Plasma BNP and ANP were determined by immunoradiometric assay. Hemodynamic variables derived from cardiac catheterization were analyzed in terms of correlation with BNP and ANP.

RESULTS

It was found that plasma BNP significantly positively correlated with ANP (ANP = 2.1 x BNP + 25 pg/mL; r = 0.81, P < 0.0001) and BNP never exceeded ANP in the present patient series. Plasma BNP as well as ANP significantly positively correlated with pulmonary to systemic flow ratio (r = 0.65 and r = 0.59, respectively) and mean pulmonary artery pressure (r = 0.72 and r = 0.68, respectively). In addition, plasma BNP of > or =20 pg/mL and ANP of > or =50 pg/mL identified children with mean pulmonary artery pressure of > or =20 mmHg with a sensitivity of 82% and 97%, respectively, and a specificity of 89% and 84%, respectively.

CONCLUSION

Plasma BNP and ANP reflect pressure and volume loads to the pulmonary artery and right ventricle and may help to identify children with ventricular septal defect complicated by pulmonary hypertension that demands early intervention.

Neurohormonal activation and the chronic heart failure syndrome in adults with congenital heart disease

BACKGROUND

Neurohormonal activation characterizes chronic heart failure, relates to outcome, and is a therapeutic target. It is not known whether a similar pattern of neurohormonal activation exists in adults with congenital heart disease and, if so, whether it relates to common measures of disease severity or whether cardiac anatomy is a better discriminant.

METHODS AND RESULTS

Concentrations of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), endothelin-1 (ET-1), renin, aldosterone, norepinephrine, and epinephrine were determined in 53 adults with congenital heart disease, comprising 4 distinct anatomic subgroups (29 female; 33.5+/-1.5 years of age; New York Heart Association class 2.0+/-0.1, mean+/-SEM) and 15 healthy control subjects (8 female; 32.3+/-1.3 years of age). Systemic ventricular function was graded by a blinded echocardiographer as normal or mildly, moderately, or severely impaired. Adults with congenital heart disease had elevated levels of ANP (56.6 versus 3.1 pmol/L), BNP (35.8 versus 5.7 pmol/L), ET-1 (2.5 versus 0.7 pmol/L, all P<0.0001), renin (147 versus 16.3 pmol/L), norepinephrine (2.2 versus 1.6 pmol/L, both P<0.01) and aldosterone (546 versus 337 pmol/L, P<0.05). There was a highly significant stepwise increase in ANP, BNP, ET-1, and norepinephrine according to New York Heart Association class and systemic ventricular function, with even asymptomatic patients having evidence of significant neurohormonal activation. In contrast, there was no direct relationship between the 4 anatomic subgroups and any of the neurohormones studied.

CONCLUSIONS

Neurohormonal activation in adult congenital heart disease bears the hallmarks of chronic heart failure, relating to symptom severity and ventricular dysfunction and not necessarily to anatomic substrate. Neurohormonal antagonism across this large and anatomically diverse population should be considered.

Elevation of atrial natriuretic peptide prohormone. Hemodynamic background of the elevation of N-terminal natriuretic peptide prohormone in children with congenital heart disease

We postulated previously that variables related to pulmonary flow are independent predictors of levels of atrial natriuretic peptide in children with congenital heart disease. The aim of this study was to test this hypothesis in relation to other hemodynamic and clinical variables. During catheterization we measured the levels of plasma N-terminal atrial natriuretic peptide prohormone in the plasma of 68 children with congenital heart disease. All had undergone complete clinical, echocardiographic and invasive hemodynamic investigations. The influence on the prohormone was analyzed for 10 different variables in a multiple linear regression model. The variability could be explained in large parts (adjusted R2 =77.2%) by variations in atrial pressures or sizes, together with the degree of excessive pulmonary blood flow and signs of heart failure. A value for atrial natriuretic peptide prohormone above 800 pmol/l predicted hemodynamic imbalance (defined as elevated pressures in left or right atrium or the pulmonary arteries, and/or Qp/Qs > 1.5) with a specificity of 94%, a sensitivity of 73%, a positive likelihood ratio of 12.2, and a negative likelihood ratio of 0.29. In conclusion, variables related to pulmonary blood flow are influential determinants of the levels of atrial natriureic peptide in children with congenital heart disease. Atrial pressures, and symptoms of heart failure are also of major importance.

Interventional catheterization decreases plasma levels of atrial natriuretic peptide (ANP) in children with congenital heart defects

Atrial natriuretic peptide (ANP) is one of the cardiac peptides implicated in volume and sodium homeostasis. We investigated the effect of interventional catheterization on plasma levels of ANP, aldosterone, and cortisol in 28 children with various congenital heart defects (CHD). Patients were divided by age into two groups: group A--infants and children over 3 months of age (n = 22), and group B--newborns (n = 6). These were compared to age-matched control groups. In group A, interventions included pulmonic valvotomy (n = 8), aortic valvotomy (n = 4), balloon angioplasty of native coarctation of the aorta (n = 3), balloon dilatation of the mitral valve (n = 1), and Rashkind double umbrella closure of patent ductus arteriosus (n = 6). Group B interventions included pulmonic valvotomy (n = 3), aortic valvotomy (n = 1), and balloon atrial septosomy (n = 2). In group A, mean ANP levels were markedly higher than in age-matched controls (125.2+/-15.8 vs. 24.6+/-4.6 pg/ml) (P <0.0001), and decreased immediately after intervention (75.6+/-11.4 pg/ml, P <0.02), and more markedly on follow-up (42.9+/-5.0 pg/ml, P < 0.0001). In group B (newborns), mean basal plasma levels were high before and after intervention and were not different from age-matched controls (243+/-42.1 vs. 220.8+/-16.2 pg/ml). There was a significant decrease on follow-up measurement (62.1+/-12.7 pg/ml, P < 0.005). In both groups, plasma cortisol levels increased significantly immediately following catheterization (P < 0.02), and normalized on follow-up. Basal aldosterone levels were normal in group A and high in Group B (9.9+/-3.8 vs. 167.6+/-16.9 ng/dl) (P < 0.001). It is suggested that plasma ANP levels are increased in children with CHD, without overt heart failure, and decrease significantly following successful intervention. In newborns with CHD, the physiological high ANP levels obscure the effect of the CHD.

Presence of immunoreactive endothelin-1 and atrial natriuretic peptide in human pericardial fluid

This study was undertaken to characterize endothelin-1 (ET-1) and atrial natriuretic peptide (ANP) concentrations in human pericardial fluid, blood plasma, right atrial appendage and papillary muscle by use of specific radioimmunoassays. In patients undergoing cardiac surgery (n=16) pericardial fluid mean immunoreactive (ir-) ET-1 and ir-ANP levels were 36-fold and 4-fold higher than corresponding plasma levels, respectively. In high performance liquid chromatography (HPLC) pericardial fluid ir-ET-1 was indistinguishable from human ET-1[1-21] and the majority of pericardial fluid ir-ANP coeluted with human ANP[99-126]. Atrial tissue ir-ET-1 and ir-ANP concentrations were 17-fold and 870-fold higher than in ventricular tissue. Our present study demonstrated for the first time the presence of ir-ET-1 in the pericardial fluid in humans. Human pericardial fluid contained far the highest concentrations of ET-1 among all biological fluids tested thus far. The functions of pericardial fluid ET-1 and ANP on cardiac performance and coronary vascular tone require further investigations.

Atrial natriuretic peptide and nitric oxide in children with pulmonary hypertension after surgical repair of congenital heart disease

ANP causes pulmonary vasodilation in some children with pulmonary hypertension secondary to congenital heart disease. In a small group of patients, ANP lowered mean pulmonary artery pressure and pulmonary vascular resistance index > 20% without changing systemic vascular resistance index. Inhaled NO is an effective pulmonary vasodilator and is a more selective pulmonary vasodilator than ANP. The utility of ANP may be limited by its nonselective effects as more selective vasodilator agents are available.

Decreased plasma atriopeptin response to volume-overloading maneuvers and exercise after atriopulmonary anastomosis of Fontan

Atriopulmonary anastomosis results in a chronic right atrial pressure-volume overload. Water and salt retention is a frequent clinical observation in patients after atriopulmonary anastomosis. The purpose of this study was to examine if this could be related to an inability to increase already elevated circulating atriopeptin (ANP) in response to central volume-overloading conditions. Eighteen patients (mean age 16 +/- 6 years) with an atriopulmonary anastomosis underwent routine cardiac catheterization during which a 5-minute head-down 10 degrees tilt was performed. Peripheral venous and right atrial blood samples were obtained under basal conditions, and after tilting and angiography for determination of ANP concentrations. At a different time, circulating ANP levels were measured during a maximal graded exercise protocol. Increased circulating ANP concentrations were found under basal conditions (114 +/- 10 pg/ml). Tilting and cardioangiography resulted in significant increases in mean atrial pressure (basal: 12 +/- 0.7 mm Hg; tilt: 13.4 +/- 0.63 mm Hg; after angiography: 15.8 +/- 0.8 mm Hg), but not in atrial or peripheral ANP. Compared with the expected threefold increase in plasma ANP induced by maximal exercise in healthy control subjects, only a slight (0.25-fold) increase was found in patients. These observations suggest a reduced stimulus-release response after atriopulmonary anastomosis, which could be related to a loss of atrial stretch receptor sensitivity, achievement of the limit for maximal right atrial secretion, or an alteration in right atrial compliance, or a combination.