[Change in the width of the preischemic and late myocardial zones].

A new approach to the determination of the boundaries of the preischemic zone and zones compensating for the focal disorders of the contractile activity of the hepart is described. During 30 minutes of inschemia, the width, localization, and intensity of functioning of the borderline and compensation zones changed. On the 15th minute of disturbed coronary blood flow the compensation zone was widest. It consists of 4-5 adjacent myocardial areas with increased active shortening of the heart muscle. The width of the borderline zone is greatest on the 10th and 25th minutes. Myocardial areas located on the boundary of the zones may alter their condition and be now functionally borderline, now functionally remote.