Ann Thorac Surg 2002;73:608-609
© 2002 The Society of Thoracic Surgeons
Invited commentary
John A. Hawkins, MDa
a Division of Cardiothoracic Surgery, Primary Children’s Medical Center, 100 North Medical Dr, Salt Lake City, UT 84113, USA
e-mail: jhawkins{at}med.utah.edu
This study by Dr Hovels-Gurich and associates from Aachen, Germany, demonstrates a correlation between elevated levels of IL-6 and the severity of cyanosis that occurs prior to operation in a group of 10 infants with tetralogy of Fallot. They correspondingly found lower levels of preoperative IL-6 in a group of 10 infants who had predominantly left-to-right shunts, including atrioventricular canal or ventricular septal defect. They also measured levels of IL-10, an antiinflammatory cytokine, and compared the ratio of IL-6 to IL-10 in these two clinical groups. During cardiopulmonary bypass IL-6 levels were higher and IL-10 and ratio of IL-10 to IL-6 levels were lower in patients with preoperative cyanosis than those with a preoperative left-to-right shunt. The measurement of these cytokines in cyanotic and acyanotic infants are new and interesting and move a very active and interesting area of cytokine research into the realm of pediatric cardiovascular surgery and congenital heart disease.
The correlation of these cytokine differences with clinical outcome is difficult to interpret. The authors found that children with preoperative cyanosis or tetralogy of Fallot required a longer duration of inotropic support and a greater degree of inotropic support which primarily consisted of increased epinephrine. The patients in the cyanotic Group 1 also had an increased level of serum creatinine postoperatively and a decreased oxygenation index. While differences in cytokine between groups are new and interesting, correlation with clinical outcomes is more difficult. It is nearly impossible to separate out confounding variables between the two groups; for example, the near universal need for a ventriculotomy in the Group 1 patients and the fact that nearly all patients received a beta-blocker. Is it possible that the differences between groups were not limited to patients who were cyanotic or those who had a left-to-right shunt? Was it possible that preoperative beta-blockade may have contributed to the increased need for epinephrine? Was it possible that the use of epinephrine or preoperative beta-blockade may have changed the modulation and expression of cytokines postoperatively, rather than the preoperative degree of cyanosis? While the data are very interesting, it is impossible to separate out these confounding variables because of the small numbers of patients in each group. In addition, some of the perfusion techniques used by these authors are different than those used by many congenital heart surgeons around the world. Differences in practice also include the authors’ routine use of circulatory arrest for infants this size and what seems to be the routine use of epinephrine in patients following repair of tetralogy of Fallot. In my own experience, it is rarely, if ever, necessary to utilize circulatory arrest to repair tetralogy of Fallot and epinephrine is also uncommonly needed. Therefore, it is possible that the institutional bias for using epinephrine in children following repair of tetralogy of Fallot may explain the frequent usage of this drug.
The authors should be commended for elucidating a likely important area of cytokine research and the role of cytokines in the clinical outcome in infants undergoing open-heart surgery. We look forward to further studies from these authors as this knowledge is advanced.
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Cytokine balance in infants undergoing cardiac operation
- Hedwig H. Hövels-Gürich, Kathrin Schumacher, Jaime F. Vazquez-Jimenez, Ma Qing, Ulrike Hüffmeier, Brigitte Buding, Bruno J. Messmer, Götz von Bernuth, and Marie-Christine Seghaye
Ann. Thorac. Surg. 2002 73: 601-608.
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