<prompt> The basic reason for reperfusion injury to the myocardium is:Generation of free radicalsExtension of the ischemic zoneIncreased ICFIncreased ECF  <response>: After MI, there is failure of Na-K pump resulting in NCX failure Thus intracellular Ca2 increases Now when perfusion is established nutrients are available, because of increased ICF Ca2, cardiac fibers contract very strongly Already muscle fibers are fragile due to M.I, now this contraction results in fuher damage. This is basic reason for reperfusion injury. 