The Diagnostic Value Of Brain Natriuretic Peptide In Children With Congestive Heart Failure

Congestive heart failure (CHF) is a pathologic state that heart function (systolic or diastolic function) descend and make opposite or absolute shortage of corporeal circulation so that whole body's metabolism can't be satisfied. Many studies discover a family of structurally related hormones in human body, Natriuretic peptides, in general, have a natriuretic,diuresis,vasodilatory effect and suppress the rennin-angiotensin-aldosterone system. This family includes atrial natriuretic peptide (ANP) ,brain natriuretic peptide (BNP),C-type natriuretic peptide (CNP). BNP, a 32-amino acid protein, was first isolated from porcine brain by Japonic Sudoh in 1988. As opposed to ANP and CNP, BNP amino acid sequence varies greatly among species, it exist in cardiac muscle mostly, especially in left ventricular. The nucleic acid sequence of the BNP gene contains the destabilizing sequence TATTTAT, which suggests that turnover of BNP messenger RNA is high and that BNP is synthesized in bursts. The half-life of BNP is longer and roughly for 20 minutes. Clinical doctor diagnose heart failure based on echocardiography,x-ray,cardiogram,clinical history,symptoms and signs Currently. Echocardiography is considered to be the"gold standard"for the diagnosis of left ventricular dysfunction, it is not readily available in all institutions, it is of limited availability in an urgent care setting, and it represents a costly intervention. New York Heart Association classification is a common means for describing clinical presentation and severity of CHF, yet it is a subjective measure confounded by personal judgement. Therefore, need a rapid and accurate blood examination method with high sensitivity and specificity. BNP is a cardiac neurohormone secreted from the ventricles in response to ventricular expansion and pressure overload. It can alleviate the body fluid overweight and vein blood gore in addition to natriuretic and diuresis. In the early-stage of CHF, the secretion of BNP increase. It resist or stay vasoconstrictor of corporeal circulation and nephritic circulation so that alleviate volume overload and sodium deposit. Because BNP is quickly secreted from the ventricles muscle cell directly in response to ventricles wall pressure increased, the concentration has a direct proportion with volume expansion and pressure overload, and has a positive correlation with ventricular functional class, so the levels can reflect damnification or failure of heart function. Many studies proved that BNP is the best single marker for left ventricular systolic dysfunction, diastolic dysfunction, hypertrophy, and increased end diastolic pressure in adults opposed to ANP and CNP. BNP levels in adults with CHF correlate strongly with the NYHA classification and have been shown to be an independent predictor of adverse outcome. This experiment selected 40 childrenwith CHF as studied group, in the same time, 40 children with surgical disease were selected as control group. Two groups have no difference in age and gender. Some diseases are excluded,such as infections,anaemia,water and electrolyte disturbances,hyperthyroidism,hypertension,nephritis,renal failure,liver failure,chromosome abnormal,phthisic,acute pulnlonary embolism,I measured the plasma BNP concentration and compared BNP levels among groups using t test and ANOVA. Correlation of BNP levels with left ventricular ejection fraction and heart function was carried out using linear regression analysis. The result is that children with CHF had significantly higher mean BNP levels compared to children with surgical disease(512.2±325.2pg/ml vs 46.9±20.9pg/ml)。With increasing heart classification, BNP levels increased : from 103.1 ±57.1 pg/ ml in children with classification-I ( n=9) to 380.0 ±36.6pg/ ml in children with classification-II (n=11), 643.7±73.9pg/ ml in children with classification-III (n=12), and 991.8 ±200.5 pg/ ml in children with classification-IV (n=8) . Significant positive correlations were found between BNP and heart classification (r=0.950 P<0.01). CHF group were divided into two groups according to the cause of disease: Group 1 (n=27) children with left ventricular systolic dysfunction caused by dilated cardiomyopathy and sever outflow block, Group 2(n=13) children with volume overload caused by left-to right shunt. The levels of BNP is 571.2±300.2pg/ml in Group 1,411.1 ±360.2 pg/ml in Group 2,there have no statistics meaning(P>0.1).A negative correlation between BNP and ejection fraction of Group 1 was fond through linear regression analysis (r=-0.793 P<0.01), The ejection fraction of Group 2 is 0.46-0.70. BNP and ejection fraction have no correlation (r = -0.057 P>0.1).The area under the curve is 0.952, a BNP level cutoff value at 65 pg/ml was 92.5% sensitive for the detection of CHF and 82.5% specific, negative predictive value is 91.7%; a BNP level cutoff value at 80 pg/ml was 92.5 sensitive for the detection of CHF and 87.5% specific, negative predictive value is 92.1%; a BNP level cutoff value at 90 pg/ml was 90.0% sensitive for the detection of CHF and 95.0% specific, negative predictive value is 90.5%; a BNP level cutoff value at 100 pg/ml was 87.5% sensitive for the detection of CHF and 97.5% specific, negative predictive value is 92.9%.A BNP cut point of 90 pg/ml exhibited the best specific ,sensitive and negative predictive value. The etiology and pathophysiology of CHF in children is quite different from adults. CHF in children with congenital heart disease is most commonly secondary to volume overload from left-to-right shunts, when ventricular function is usually well preserved, left ventricular pump dysfunction represents a minority of the pediatric patients with heart failure. This kind of heart failure also exist obvious nerve endocrine mess. The levels of BNP of CHF was found obviously highter than control group. And a significant positive correlations were...