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Purpose: N-terminal pro-brain natriuretic peptide (NT-proBNP) has been useful as a predictor of mortality in patients with end-stage renal disease (ESRD). However, its level in chronic hemodialyzed patients might be influenced by impairment of renal function and acute fluid removal during hemodialysis (HD). The aim of the present study is to investigate the effect of a HD session on NT-proBNP and cardiac function.Methods: Fourteen ESRD patients (11 females; median age 71 years, interquartile range 55-82) underwent blood sample to determine NT-proBNP and transthoracic echocardiography, immediately before and after HD (Polyflux 1.7 H, blood flow 300 ml/min). Exclusion criteria were left ventricular ejection fraction (EF)<50% and significant valvular disease. Echocardiographic parameters included left ventricular diameters and volumes, fractional shortening, EF, septal and posterior wall thickness, indexed left ventricular mass, left atrial (LA) volume, maximal diameter of the inferior vena cava (IVC) during expiration, and pulmonary artery systolic pressure (PASP). Diastolic function was assessed with pulsed-wave Doppler by the early and late peak velocity (E, A), and deceleration time; from tissue Doppler imaging, lateral mitral annular early peak (Em), late (Am), and systolic (Sm) velocities were measured. E/Em was considered as an estimate of left ventricular filling pressure. Changes in variables were calculated as follows: (predialytic value-postdialytic value)*100/ predialytic value. Wilcoxon's signed rank-test and Spearman's correlations were used as appropriate.Results: Baseline NT-proBNP significantly correlated with EF (p=0.02, r=-0.61), LA volume (p=0.008, r=0.68), and PASP (p=0.01, r=0.66). No patient experienced symptomatic hypotension during HD; heart rate showed no significant changes after session. NT-proBNP before HD was 8408 pg/ml (2136-27791) and after HD was 5565 pg/ml (1896-16551) with a median significant decrease of 28% (p=0.001). Left ventricular diameters and volumes, indexed left ventricular mass, LA volume, E, E/A, and IVC diameter significantly decreased after HD (p<0.05 all). Percentage changes in NT-proBNP level and E/Em showed a significant positive relationship (p=0.02, r=0.65), whilst Em showed a borderline significant negative relationship (p=0.049, r=-0.58). CONCLUSIONS:Fluid removal by HD affected both NT-proBNP and cardiac function. Furthermore, we observed as expected a significant correlation between predialytic NT-proBNP and EF and LA volume, whilst changes in NTproBNP after HD were significantly correlated with changes in left ventricular filling pressure.