Sarcomere relaxation and ischaemic myocardial injury.

Material from hearts known to have had recent myocardial infarction and biopsies of dog hearts subjected to an experimental procedure producing ischaemic injury, were examined by polarising microscopy. A technique which depends on the relaxation of sarcomeres on ischaemic areas of myocardia was used and assessed for its value in the diagnosis of early myocardial infarction. We found no statistically significant difference in sarcomere lengths in ischaemic and control heart muscle in man. The dog study failed to show changes with a study period of up to 2 h after ligation. We do not support the suggestion that sarcomere length is a useful measurement in the demonstration of early myocardial ischaemic injury in man.