Performance Characteristics and Oxygen Debt in a Nonfailing, Metabolically Supported, Isolated Heart Preparation

¹ From the Laboratory of Cardiovascular Physiology, National Heart Institute, Bethesda, Maryland

Performance characteristics, stability and ventricular function curves were studied in an isolated heart preparation in which the metabolic state of the perfusing blood was kept at or near normal by continued exchange with a supporting dog. In contrast to the progressive failure exhibited by the classical isolated heart or heart-lung preparations, the isolated supported heart's performance did not differ from the performance of the heart in an open-chest, anesthetized dog with a complete circulation. Myocardial O₂ consumption could be determined with a high degree of precision. O₂ debt comparable to that which occurs in skeletal muscle was not observed.