J Thorac Cardiovasc Surg 2003;126:2111-2112
© 2003 The American Association for Thoracic Surgery
Reply to the Editor
Hari R. Mallidi, MD,
Stephen E. Fremes, MD
University of Toronto, Sunnybrook and Women's College HSC, Toronto, Ontario, Canada
Dr Savage correctly points out that the article published in the March issue of the Journal by our group was not simply a comparison of cold versus warm or tepid cardioplegia, but rather a comparison of the strategy of warm or tepid cardioplegia versus cold cardioplegia. The three cardioplegic and systemic perfusion strategies used in patients undergoing isolated coronary artery grafting surgery at our institution were described in detail in the article. Other possible cardioplegic and systemic perfusion strategies (such as warm systemic perfusion with cold cardioplegia, tepid systemic perfusion with cold cardioplegia, systemic hypothermia with warm or tepid cardioplegia, and so on) were not used in our institution.
One potential reason for avoiding strategies that have mixed cardioplegia and systemic perfusion temperatures (cold for one with warm or tepid for the other) is the concern that the myocardial temperature in the mixed temperatures situation would likely result in highly variable and inconsistent myocardial temperatures.1 It has been demonstrated that the delivery of cold cardioplegia results in decreased subepicardial and midwall ventricular perfusion. This datum, coupled with information that myocardial temperature is variable with cold cardioplegia, suggests that myocardial protection may be compromised by such a mixed temperature environment.2
However, others have shown no increase in the release of myocardial injury markers (troponin I and T) after normothermic systemic perfusion relative to hypothermic systemic perfusion when a regimen of cold cardioplegia with topical cooling was used for myocardial protection, and acceptable clinical results are possible.3 Furthermore, acceptable clinical results have been reported with the technique of cold cardioplegia with warm systemic perfusion.4 Thus considerable controversy continues to exist regarding whether cold cardioplegia with warm systemic perfusion is harmful; however, there are no studies demonstrating its superiority to the strategy of warm cardioplegia with tepid systemic perfusion.
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References
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- Bert A, Singh A. Right ventricular function after normothermic versus hypothermic cardiopulmonary bypass. J Thorac Cardiovasc Surg. 1993;106:988–996
- Torchiana DF, Vine AJ, Titus JS, Hahn C, Shebani KO, Geffin GA, et al. The temperature dependence of cardioplegic distribution in the canine heart. Ann Thorac Surg. 2000;70:614–620
- Birdi I, Caputo M, Underwood M, Angelini GD, Bryan AJ. Influence of normothermic systemic perfusion temperature on cold myocardial protection during coronary artery bypass surgery. Cardiovasc Surg. 1999;7:369–374
- Singh AK, Feng WC, Bert AA, Rotenberg FA. Warm body, cold heart: myocardial revascularization in 2383 consecutive patients. J Cardiovasc Surg (Torino). 1993;34:415–421
Related Article
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Study of warm perfusion rather than cardioplegia
- Edward B. Savage
J. Thorac. Cardiovasc. Surg. 2003 126: 2111.
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