Clinical Significance of B-type Natriuretic Peptide Levels and Impedance Cardiography in Maintenance Hemodialysis Patients

Han, Byoung Geun; Kim, Min Soo; Yu, Jong Myeong; Han, Seung Tae; Choi, Seung Ok

Abstract

BACKGROUND
The risk for cardiovascular morbidity and mortality is higher in hemodialysis (HD) patients than in general population. Early diagnosis, treatment and prevention of cardiovascular disease (CVD) are the best way to reduce the most important cause of death. However, cardiac geometric and/or functional alterations including left ventricular hypertrophy, atherosclerosis and/or systolic and diastolic dysfunction are not easily known to nephrologist in the sense that diagnostic procedure is limited because cardiac angiography and echocardiography are frequently needed. METHODS: To evaluate the cardiac alteration by non-invasive tools, we measured pre- and post-HD B-type natriuretic peptide levels and performed impedance cardiography (ICG) in 40 HD patients and 10 healthy adults as control. RESULTS: Pre- and post-HD BNP level, cardiac index (CI), cardiac output (CO), stroke volume (SV), systemic vascular resistance index (SVRI), systemic vascular resistance (SVR), acceleration index (ACI), velocity index (VI) and thoracic fluid content (TFC) in patients were significantly higher than those in normal control group (p<0.05). Pre-HD BNP level, stroke index (SI), SV and TFC were significantly different after HD (p<0.05). There were significant differences in pre-HD BNP level, SI, SV and VI between diabetes and non-diabetes groups (p<0.05). Pre-HD BNP level correlated significantly with post- HD BNP level, systolic blood pressure, diastolic blood pressure, CO, SVRI, SVR and TFC (p<0.05). In multiple linear regression analysis, SVR and TFC were positively associated with pre-HD BNP level (R2=0.289). The area under the ROC curve for cardiac alterations was 0.749 for pre-HD BNP level. A cut-point of 560 pg/mL for pre-HD BNP level was 80% sensitive and 72% specific in determining cardiac alterations. CONCLUSION: Even though cardiac alterations of patients were heterogeneous in our study, plasma BNP level and some parameters (SVR, TFC) of ICG seem to be available to nephrologist for detecting and monitoring cardiac conditions in HD patients.