Left Ventricular Performance and Coronary Flow

small microspheres, coronary flow initially increased, which suggests the effective release of a vasodilator substance. Return of coronary flow to control levels occurred only after the end-diastolic pressure rose, on the average, to above 30 mm Hg. After embolization with both sizes of microspheres, ventricular diastolic pressure-v6lume relationships showed decreased ventricular compliance. This was attributed, in part, to edema of the ventricular wall and, in part, to focal shortening of the sarcomeres where the circulation was compromised. Embolization with both sizes of microspheres ultimately caused a decrease in ventricular performance, although when the systolic pressure was increased the usual relationship between peak developed wall stress, and end-diastolic pressure showed less of a descending limb than that found in the nonembolized, isolated heart. It is felt that the data summarized above have bearing on ventricular performance and coronary flow in clinical situations where hearts are perfused through pump oxygenator systems and are thereby subject to emThis work was performed during Dr. Monroe's Tenureship of a Career Development Award from the National Institutes of Health. Dr. Manasek was supported by the Medical Foundation, Inc., Boston, Mass. Received for publication 3 December 1970 and in revised form 9 March 1971. bolization from aggregated clumps fibrin. of platelets and