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Can Cardiopulmonary Bypass Be Less Aggressive?

Division of Cardiothoracic Surgery Prince of Wales Hospital The Chinese University of Hong Kong Shatin, Hong Kong People's Republic of China Department of Cardiac Surgery 1 Department of Intensive Care University Hospital Erasme Free University of Brussels Route de Lennik 808 Brussels B-1070, Belgium

Less invasive cardiac surgery has recently become a focus of intense discussion especially with renewed interest in so-called off-pump operations. Avoiding the use of cardiopulmonary bypass (CPB) during open-heart surgery, in particular for coronary artery bypass grafting, sounds less invasive since it has been clearly demonstrated that CPB is associated with a systemic inflammatory response that may contribute to the postoperative morbidity.^1,2 In a recent survey, 81% of 137 practising cardiothoracic surgeons shared the opinion that avoiding CPB is less invasive, although 56% of them did not believe that a short period of CPB was really detrimental.³ However, scientific evidence especially long-term follow-up data has yet to prove the real benefits of off-pump practice. Thus, before trying to avoid the routine use of CPB, it is probably more important to ask the question if CPB could be less aggressive.

CPB carries less untoward effects today when compared with its infancy stage half a century ago, due to continued efforts to improve the managing protocol through a better understanding of the pathophysiologic concepts involved.² From somehow physiological cross-circulation⁴ to the use of bubble and membrane oxygenators, CPB has been established as a safe procedure and has gained worldwide acceptance among cardiac surgeons. Recently developed therapies aimed at interfering with the inflammatory response have included the administration of pharmacological agents such as corticosteroids, aprotinin, and antioxidants, as well as modification of techniques and equipment by the use of heparin-coated CPB circuits, intraoperative leukocyte depletion, and ultrafiltration.² These improved management modalities with complete revascularization have resulted in shorter recovery times^5,6 as well as improved event-free long-term survival in patients undergoing coronary artery bypass grafting.⁷ In fact, it has been observed recently that there is no difference in the incidence of cerebral injury in patients undergoing coronary artery bypass grafting with and without CPB.⁸

The inflammatory reactions occurring during and after CPB are extremely complex. With a much improved knowledge of the pathophysiologic changes during CPB it is still possible to make CPB even less aggressive. For instance, the release of proinflammatory cytokines has been suggested to play a key role in the development of postoperative complications.⁹ However, an endogenous anti-inflammatory, potentially protective response is also associated with CPB, as reflected in the production of an anti-inflammatory cytokine interleukin-10 (IL-10) as well as a preconditioning effect involving the stimulation of myocardial alpha adrenergic receptors and adenosine receptors.^9,10 It has been found that IL-10 may reduce pulmonary ischemia-reperfusion injury.¹¹ Interestingly, neither the heart nor the lung¹² but the liver¹³ is the major source of IL-10 during CPB, and the release of IL-10 is markedly increased in steroid-pretreated patients.⁹ To enhance IL-10 release in patients undergoing a longer duration of both CPB and cardiopulmonary ischemia, the timing of steroid administration can be crucial.¹⁴ Nevertheless, the balance between these proinflammatory and anti-inflammatory responses may be even more important. For example, in combination with the reduction of some other proinflammatory mediators, reduced IL-10 production has also been associated with the use of heparin-coated CPB circuits and, interestingly, this may lead to reduced myocardial injury in patients undergoing heart and heart-lung transplantation. (Authors' unpublished data).

Back to our question if CPB could be less aggressive. The answer is obvious. Therefore, the definition of less invasive cardiac surgery in the future may not be just off-pump but on-a-better-pump with not only enhanced biocompatibility of materials but also improved perioperative management.

REFERENCES

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8. Browne S, Westaby S, Taggart DP. Neuropsychological and respiratory injury following CABG surgery with and without cardiopulmonary bypass [Abstract]. Proceedings of the 11th annual meeting of the European Association for Cardiothoracic Surgery; 1997 Sept 28–Oct 1; Copenhagen; p. l22.

9. Wan S, LeClerc JL, Vincent JL. Cytokine responses to cardiopulmonary bypass: lessons learned from cardiac transplantation. Ann Thorac Surg 1997;63:269–76.[Abstract/Free Full Text]

10. Burns PG, Krukenkamp IB, Caldarone CA, et al. Does cardiopulmonary bypass alone elicit myoprotective preconditioning? Circulation 1995;92(Suppl II):II-447–51.

11. Eppinger MJ, Ward PA, Bolling SF, Deeb GM. Regulatory effects of interleukin-10 on lung ischemia-reperfusion injury. J Thorac Cardiovasc Surg 1996;112:1301–6.[Abstract/Free Full Text]

12. Wan S, DeSmet JM, Barvais L, et al. Myocardium is a major source of proinflammatory cytokines in patients undergoing cardiopulmonary bypass. J Thorac Cardiovasc Surg 1996; 112:806–11.[Abstract/Free Full Text]

13. Wan S, LeClerc JL, Schmartz D, et al. Hepatic release of interleukin-10 during cardiopulmonary bypass in steroid-pretreated patients. Am Heart J 1997;133:335–9.[Medline]

14. Wan S, DeSmet JM, Antoine M, et al. Steroid administration in heart and heart-lung transplantation: is the timing adequate? Ann Thorac Surg 1996;61:674–8.[Abstract/Free Full Text]

This Article Extract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Song Wan Jean-Louis Vincent Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Wan, S. Articles by Vincent, J.-L. Search for Related Content PubMed Articles by Wan, S. Articles by Vincent, J.-L.