Characterization of the lateral interface between normal and ischemic tissue in the canine heart during evolving myocardial infarction.

A new nonrotating multiple biopsy device has been developed to allow the rapid, simultaneous and contiguous sampling of cardiac muscle in the large mammalian heart. Each cutter obtains 40 adjacent transmural left ventricular biopsy samples, each of 4 mm section. The epicardial 1.8 mm of each biopsy section was analyzed for flow, adenosine triphosphate, adenosine diphosphate, adenosine monophosphate, creatine phosphate and lactate. Use of this procedure in the dog heart 30 minutes after coronary arterial ligation permitted characterization of the nature of flow and metabolic gradients as the sampling site moved from the core of an areas of regional ischemia to the surrounding normal tissue. These studies of metabolic and flow geometry in the lateral plane indicate the existence of a sharp interface of flow and metabolism between normal and ischemic tissue. The absence of intermediate levels of flow and metabolism indicate that, in the lateral plane at least, a quantitatively significant and spatially identifiable "border zone" region does not exist. However, these findings, do not preclude the existence of such a zone of jeopardized tissue in the transmural plane or the occurrence of a temporal border zone to which interfaces of flow and metabolism may migrate with time.