الفهرس 
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Abstract
The young heart differs from that of the adult heart both in health and in disease and thus cardiac markers differ in the pediatric population.Heart diseases in infants and children can be classified as either congenital or acquired. Congenital cardiac disease is more common. Lesions that cause left-to-right shunt are the most prevalent. Cyanotic lesions make up nearly one fifth of all lesions, and obstructive lesions are the third important group (Samanek and Voriskova 1999).Acquired lesions are either myocardial, valvular or inflammatory (Samanek&Voriskova, 1999).NPs are a group of structurally similar but genetically distinct peptides that have diverse actions in cardiovascular, renal, and endocrine homeostasis. BNP mediates natriuresis, vasodilatation, renin inhibition, antimitogenesis, and lusitropic properties (Chen & Burnett, 2000).Synthesis of BNP is mainly in cardiac myocytes and small proportion is synthesized in cardiac fibroblasts. The main stimulus for release is increased ventricular end diastolic pressure and ventricular wall tension (Hall 2004).BNP reduces extracellular fluid volume through natriuresis and diuresis by direct action on the kidney and through suppression of the renin–angiotensin–aldosterone axis. It also mediates arterial and venous vasodilatation, inhibits the production of renin and aldosterone and inhibits the growth of cardiac and vascular myocytes (Davis, Bamforth et al. 2006).Recent studies support the notion that HF patients actually manifest a state of BNP insufficiency, due to both a deficiency of biologically active BNP and resistance to its effects (Shimizu et al., 2002).In general, BNP and its prohormoneNTproBNP levels are reasonably correlated, and either can be used in patient care, although clinicians must understand their differences and that absolute levels are not interchangeable.Normal values of BNP plasma concentration are totally different in pediatric and adult patients. BNP level is high soon after birth due to the physiological water loss that occurs in the first week of life (Modi, Betremieux et al. 2000).