Myocardial stunning--we do not know the mechanism nor is there "overwhelming evidence" for a major role of free radicals.

Shattock (17) has very much overstated the case for free radical formation as the initiating cause of stunning. To say that either free radicals or calcium ions initiate stunning is to prejudge the issue, because no one has yet compared in the same model the effects of modulation of calcium and of free radicals. Therefore, the true initiator of stunning is still not known and will remain so until further experiments are undertaken in the same closed chest model, comparing (1) generators of free radicals with induced calcium overload and (2) free radical scavengers with calcium antagonists or modulators.