ischaemic preconditioning of the human heart. - Leicester Research ...

7.4.2 In vitro studies
Figures 7.3A and 7.313 show the results of the CK leakage and MTT reduction of the
atnal slices obtained before CPB and 10min after initiation of
CPB They
demonstrate that the increase in CK leakage and the decrease in MTT reduction
caused by ischaemia/reoxygenation in the atfial muscles obtained prior to the
institution of bypass were significantly improved in the slices obtained 10 min afler
the initiation of bypass and that in fact this level of protection was identical to that of
preconditioning. Thus, muscles that were obtained 10 min after the initiation of
bypass were already preconditioned and the application of ischaemic preconditioning
did not result in additional benefit to that seen with ischaernic preconditioning alone
7.5 DISCUSSION
The present studies have shown that the human heart is preconditioned by the
institution of cardiopulmonary bypass and that the use of ischaernic preconditioning
in combination with other protective interventions such as cardioplegia do not result
in additional protection. They have also clearly demonstrated that the human heart can
be protected by ischaernic preconditioning when patients are operated on without the
use of cardiopulmonary bypass. These findings have obvious Important clinical
implications and they warrant further discussion
Preconditioning of the Human Heart
Expenmental findings on ischaernic preconditioning cannot
be directIN
extrapolated to humans because its mechanisms may be different from other animal
species. As a result, for both logistic and ethical reasons, no clinical study can meet
the strict conditions of experimental studies on preconditioning in which infarct size is
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