An experimental evaluation of staining techniques for the detection of early ischaemic injury to the myocardium.

A series of experimental infarcts of the posterior papillary muscle of the canine heart was used to assess the value of 6 special stains in the histological detection of early myocardial infarction. The infarcts were of 5-720 min duration and were compared not only with normal control myocardium but also with normal myocardium autolyzed for similar periods of time. All tissue was stained with H & E, PAS, PAS-diastase, PTAH, Masson's trichrome, Connor's modification of the acid fuchsin method, Puchtler's PAS-navy blue, and Lie's haematoxylin-basic fuchsin-picric acid. The zone of severely altered myofibres which separated normal from ischaemic tissue in infarcts aged 2 or more hours was demonstrated by all but PAS. Normal, border, and ischaemic zones of heart muscle were clearly differentiated only by PTAH and PAS-navy blue. PAS distinguished normal from glycogen-depleted ischaemic myocardium after only 40-60 min, but this change was also seen in autolyzed tissue.