Ann Thorac Surg 2006;81:2272
© 2006 The Society of Thoracic Surgeons
Original article: Cardiovascular
Invited commentary
Brian W. Duncan, MD
Pediatric and Congenital Heart Surgery, The Children's Hospital, The Cleveland Clinic, 9500 Euclid Ave, Cleveland, OH 44195
(Email: duncanb{at}ccf.org).
Despite decades of utility in the management of children with medically refractory heart failure, few definitive guidelines exist regarding indications for the institution of extracorporeal membrane oxygenation (ECMO) in the management of these patients. Similarly, precise measurements are lacking that identify children with sufficient ventricular recovery to allow weaning from ECMO support. Assessment of serum brain natriuretic peptide (BNP) as a biomarker of the neurohumoral response to cardiac disease has been shown to have prognostic value for acute and chronic congestive heart failure. When analyzed in adults who require mechanical circulatory support, lower initial BNP levels that exhibit a rapid decline after institution of support have been reported to identify patients who are candidates for weaning.
The present study by Huang and coworkers [1] prospectively analyzed BNP levels in a small number of children with cardiac disease who required ECMO for cardiopulmonary support. The authors found that BNP levels were elevated prior to ECMO support and decreased after ECMO was instituted in all patients whether or not they survived to hospital discharge. The BNP levels were higher in nonsurvivors after ECMO was instituted and after weaning from support for the entire cohort. In the subgroup of patients who had undergone cardiac surgery, BNP decreased after support was instituted but it was higher at post-support time points in nonsurvivors.
There are too few patients in the present study to evaluate the two most important potential uses for BNP level determination in this setting: (1) Do BNP levels help to identify children with medically refractory heart failure who would not survive without ECMO? (2) Once on support, do these levels identify patients with sustainable ventricular recovery who can be weaned safely? No single laboratory test can definitively answer these questions, and interpretation of BNP levels in this setting has to be performed with particular care. A wide range of reported normal values for BNP levels exists in most studies. Of particular relevance for the present study, BNP levels have been reported to be substantially higher in children compared with adults, and the highest levels have been observed in newborns and infants. In addition, other cardiac conditions and the degree of volume loading of the heart may influence BNP levels independent of the severity of heart failure. With these considerations in mind, the present study provides a basis for future inquiry regarding the role of BNP measurements in children who require ECMO for cardiac failure.
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References
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- Huang S-C, Wu E-T, Ko W-J, et al. Clinical implication of blood levels of B-type natriuretic peptide in pediatric patients on mechanical circulatory support Ann Thorac Surg 2006;81:2267-2272.[Abstract/Free Full Text]
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