PRESSURE-VOLUME ANALYSIS OF CHANGES IN CARDIAC-FUNCTION IN CHRONIC CARDIOMYOPLASTY

Reports of clinical improvement in human studies of dynamic cardiomyop lasty lack support by consistent objective hemodynamic evidence. Anima l studies have also yielded conflicting results, likely due to nonunif orm models, particularly the use of unconditioned wraps, and to limita tions in commonly used study modalities caused by exaggerated heart mo tion during wrap stimulation. Our purpose was to assess the primary fu nctional properties of the heart wrapped by conditioned muscle using p ressure-volume relation analysis based on conductance catheter volume data. Compared with the unstimulated state, 1:1 stimulation caused an increase in contractility and decreases in end-diastolic volume and st roke work. Assisted beats during 1:2 stimulation showed an increase in contractility and a decrease in end-diastolic volume. Unassisted beat s (1:2) showed decreases in end-diastolic volume and stroke work. Ther e was no augmentation of cardiac output or ejection fraction with stim ulation (1:1 or 1:2). We conclude that in the nonfailing heart, increa sed contractility does not augment cardiac output, ejection fraction, and stroke work because of a simultaneous decrease in end-diastolic vo lume. These changes in contractility and end-diastolic volume may prov e therapeutic for dilated cardiomyopathy.