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Ann Thorac Surg 1997;63:152
© 1997 The Society of Thoracic Surgeons

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Invited Commentary

Invited Commentary

Division of Cardiac Surgery, Baystate Medical Center, 759 Chestnut Street, Springfield, MA 01199.

See also page 147.

Ischemic preconditioning can clearly be a factor in myocardial preservation, whether in the operating room or in the catheterization laboratory. This article by Cleveland and associates documents a 100% increase in contractile function in human trabeculae subjected to warm ischemia preceded by a single 5-minute ischemic preconditioning stimulus followed by 10 minutes of normothermic perfusion, a 45-minute normothermic simulated ischemia, and 120-minute normothermic reperfusion compared with tissue subjected to the same 45-minute warm ischemic stimulus without ischemic preconditioning. It is important to note that no apparent protection from ischemic preconditioning was seen when the tissue was subjected to 4-hour hypothermic ischemia instead of 45-minute normothermic ischemia. This clearly implies a difference in the response to ischemic preconditioning in the normothermic versus the hypothermic human heart, with the latter perhaps being unresponsive to preconditioning.

As noted by Cleveland and associates, there may be a role for preconditioning in the setting of normothermic myocardial preservation for cardiac operations, and the approach of intermittent normothermic cardioplegia used by some may be initiating ischemic preconditioning. This conclusion, however, can be answered only with better markers of preconditioning.

Finally, the data clearly do not support any advantage to myocardial preservation in the human transplant model with ischemic preconditioning. This finding differs from our data, which, in the cardioplegic setting with 4- or 6-hour hypothermic preservation, documented significant preservation with hypoxic rather than ischemic preconditioning in the rat heart model. Similarly, as noted by Cleveland and colleagues, Cave and Hearse [1] in the rat heart model documented myocardial preservation with ischemic preconditioning after up to 160 minutes of hypothermic ischemia. The different species studied and the different models used provide results that are not always consistent. In fact, the influence of ischemic preconditioning in the clinical setting remains to be further defined.

Reference

1. Cave AC, Hearse DJ. Ischaemic preconditioning and contractile function: studies with normothermic and hypothermic global ischemia. J Mol Cell Cardiol 1992;24:1113–23.[Medline]

This Article Alert me when this article is cited Alert me if a correction is posted 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): Richard M. Engelman Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Engelman, R. M. Search for Related Content PubMed Articles by Engelman, R. M. Related Collections Related Article