Ann Thorac Surg 2008;86:694. doi:10.1016/j.athoracsur.2008.02.062
© 2008 The Society of Thoracic Surgeons
Correspondence
Why Does the Preoperative BNP Level Predict the Degree of Postoperative BNP Elevation?
Naoki Yoshimura, MDa,
Roland Henaine, MDb,
Yoshio Ootaki, MDc,
Hironori Matsuhisa, MDd,
Takuro Misaki, MDd
a First Department of Surgery, University of Toyama, Graduate School of Medicine, 2630 Sugitani, Toyama 930-0194, Japan
b Department of Cardiovascular Surgery and Cardiac Transplantation, Hôpital Cardiovasculaire et pneumologique Louis Pradel, 28 Ave du Doyen Lepine, Bron, 69500 France
c Department of Cardiothoracic Surgery, Cleveland Clinic, 9500 Euclid Ave, Cleveland, OH 44195
d First Department of Surgery, University of Toyama, Graduate School of Medicine, 2630 Sugitani, Toyama, 930-0194, Japan
(Email: ynaoki{at}med.u-toyama.ac.jp; roland.henaine{at}chu-lyon.fr; otakiy{at}ccf.org).
To the Editor:
We read with great interest the article by Mainwaring and associates [1] concerning the changes in perioperative brain natriuretic peptide (BNP) levels in infants and children with ventricular septal defect (VSD). They demonstrated three important findings in their study. First, there was a close correlation between the preoperative levels of BNP and the amount of left-to-right shunt (Qp/Qs) through the VSD. Second, all of the patients demonstrated significant elevations in the postoperative BNP. Third, the degree of postoperative elevation in the BNP was correlated with the relative increase in the preoperative BNP and Qp/Qs. They concluded that the severity of heart failure preoperatively predicted the degree of postoperative BNP elevation. We have a few comments on this important investigation.
We previously reported that plasma BNP levels closely correlated with the biventricular volume in infants and children with congenital heart disease, and that the patients with Qp/Qs greater than 2.0 had higher correlation between the BNP levels and the left ventricular volume [2]. Our results were consistent with those of Mainwaring and associates [1]. We also evaluated the changes in the perioperative BNP levels in 30 patients who underwent a total cavopulmonary connection (TCPC) and 30 patients who underwent a definitive repair for Fallot's tetralogy [3]. In our study, the plasma BNP levels increased abruptly after the termination of the cardiopulmonary bypass (CPB) in patients with Fallot's tetralogy, as well as in those undergoing a TCPC. This result was also consistent with that of Mainwaring and associates [1]. However, the plasma BNP levels were significantly lower in the TCPC group than in the group with Fallot's tetralogy, even though the preoperative BNP levels were significantly higher in the TCPC group than in the group with Fallot's tetralogy [3]. The probable explanation is that the TCPC procedure offers the considerable advantage of lowering the ventricular volume load during the immediate postoperative period [4], whereas the volume overload in both ventricles increases immediately after repair for Fallot's tetralogy [5]. We observed that the mean left atrial pressure was lower for the TCPC group than for the Fallot's tetralogy group during the postoperative period [3].
It is unclear why the level of the postoperative elevation in BNP correlated with the relative increase in the preoperative BNP and Qp/Qs in the study by Mainwaring and associates [1]. It is well known that the secretion of BNP is stimulated by an increase of the ventricular end-systolic wall stress. The removal of a volume load after the closure of VSD should be associated with a decrease in the secretion of BNP. The degree of postoperative elevation in the BNP might be affected by perioperative variables, which included the ventricular volume load, the effects of CPB, and the surgical manipulation on myocardial function and wall stress. Further evaluation of preoperative and postoperative ventricular volume load by echocardiographic findings or changes in the central venous pressure may thus elucidate these questions. Finally, age of the patient at the time of surgery might also affect the degree of postoperative BNP elevation.
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References
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- Mainwaring RD, Parise C, Wright SB, Juris AL, Achtel RA, Fallah H. Brain natriuretic peptide levels before and after ventricular septal defect repair Ann Thorac Surg 2007;84:2066-2069.[Abstract/Free Full Text]
- Ootaki Y, Yamaguchi M, Yoshimura N, Oka S, Yoshida M, Hasegawa T. Secretion of A-type and B-type natriuretic peptides into the bloodstream and pericardial space in children with congenital heart disease J Thorac Cardiovasc Surg 2003;126:1411-1416.[Abstract/Free Full Text]
- Yoshimura N, Yamaguchi M, Oshima Y, et al. Suppression of the secretion of atrial and brain natriuretic peptide after total cavopulmonary connection J Thorac Cardiovasc Surg 2000;120:764-769.[Abstract/Free Full Text]
- Petrossian E, Reddy VM, McElhinney DB, et al. Early results of the extracardiac conduit Fontan operation J Thorac Cardiovasc Surg 1999;117:688-696.[Abstract/Free Full Text]
- Kurosawa H, Morita K, Yamagishi M, Shimizu S, Becker AE, Anderson RH. Conotruncal repair for tetralogy of Fallot: midterm results J Thorac Cardiovasc Surg 1998;115:351-360.[Abstract/Free Full Text]
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