ESTIMATES OF REGIONAL WORK IN THE CANINE LEFT-VENTRICLE

Assessment of the magnitude of regional myocardial work requires knowl edge of regional fiber stress and fiber shortening. The theoretical de velopment and experimental validation of a method is presented which u sed values of estimated active and passive fiber stress according to a fluid-fiber model, and measured fiber strain values. This enables the construction of regional stress-strain diagrams, a regional analog of the pressure-volume area model by Suga and co-investigators, which ca n be linked to regional oxygen consumption. In the left ventricle, eit her normally or asynchronously activated, the method yields reliable d ata on strain and active and passive fiber stress. The relation betwee n estimated regional work and myocardial oxygen demand is in quantitat ive agreement with previously reported relations between global oxygen demand and measured pressure-volume area. During coronary artery occl usion, however, these values were less reliable, which might be due to inaqdequate knowledge of the (passive) material properties of the myo cardium. (C) 1998 Elsevier Science Ltd. All rights reserved.