The Perioperative Changes in and Clinical Value of B-type Natriuretic Peptide Levels in the Blood of Cardiosurgical Patients

Abstract

Objective: to study the time course of changes in brain natriuretic peptide (BNP) levels in patients with coronary heart disease, who undergo myocardial revascularization under extracorporeal circulation and to assess a relationship of the level of the biomarker to the clinical data in the early postoperative period. Subjects and methods. Fifty-two patients aged 62.2±1.1 years with a left ventricular ejection fraction (LVEF) of 51.1±1.4% were examined. The concentration of BNP was determined by immunofluorescence assay (Triage Meter Plus, Biosite Diagnostics, USA) before (BNP1) and at the end (BNP2) of surgery, in the morning of the first (BNP3) and second (BNP4) postoperative days. Central hemodynamics was invasively monitored using Swan-Ganz-type catheters. Results. The values of the biomarker were normal (51.6±3.5 pg/ml) in most cases. In the other patients, the level of the peptide was increased up to 165.8±16.1 pg/ml. The relationship between preoperative LVEF and BNP1 was moderate (r=-0.54; p<0.0001). BNP2 correlated closely with BNP1 (r=0.88; p<0.0001). Analysis of the clinical characteristics of the early postoperative period showed that BNP1 had a marked impact on cardiac index (CI) (r=-0.55; p=0.002) and dopamine dosage at the end of surgery (r=0.4; p=0.002), as well as on CI on postoperative day 1 (r=-0.5; p=0.008). In addition, BNP1 significantly affected the length of stay in an intensive care unit (ICU) (r=0.3; p=0.03). BNP2 was related to CI values (r=-0.4; p=0.03) and dopamine dosage (r=0.47; p=0.0004) at the end of surgery. Thus, BNP1 and BNP2, which were closely related, influenced the majority of the clinical characteristics under study. However, only did BNP1 affect the integral indicator «length of ICU stay». BNP3 and BNP4 were closely related and had no significant relationship to BNP1 and BNP2 or impact on the clinical parameters characterizing the postoperative period. Conclusion. The preoperative level of the peptide is related to the characteristics of cardiac performance and the postoperative length of ICU stay. The early postoperative values of BNP are correlated with CI and dopamine dosage both at the end of surgery and on postoperative day 1. The maximum BNP1 values exceeding the baseline ones by more than 4 times are recorded 18—22 hours postsurgery. Then the level of the peptide begins to drop. The clinical and pathophysiological significance of postoperative BNP changes calls for further investigations.

Keywords

• b-type natriuretic peptide, bnp, coronary heart disease, operations under extracorporeal circulation.