REVERSAL OF IATROGENIC MYOCARDIAL EDEMA AND RELATED ABNORMALITIES OF DIASTOLIC PROPERTIES IN THE PIG LEFT VENTRICLE

Abstract

Objective: This study examines the resolution of iatrogenic edema and related changes in systolic and diastolic properties in the intact pig left ventricle. Methods: The coronary arteries were perfused for 50 to 60 seconds with diluted blood (hematocrit value 10% ± 1%, edema group, n = 5) or whole blood (hematocrit value 28% ± 1%, control group, n = 6) infused into the aortic root during aortic crossclamping in conditioned, anesthetized pigs. After whole blood reperfusion, preload reduction by vena caval occlusion was used to define systolic and diastolic properties at 15-minute intervals. Left ventricular pressure and conductance, aortic flow, and two-dimensional echocardiography were recorded. Results: Left ventricular mass (wall volume) in the edema group increased significantly compared with that in control pigs after crossclamp removal. Mass returned to preperfusion levels after 45 minutes. The ventricular stiffness constant (β) increased significantly in the edema group versus the control group, returning to baseline by 30 minutes. The diastolic relaxation constant (τ) and base constant (α) did not differ between groups. There was no significant change in contractility. Conclusion: Increases in left ventricular mass and diastolic stiffness induced by coronary perfusion with hemodiluted blood resolve after 45 minutes of whole blood perfusion in pigs. This study defines physiologic effects of edema in the normal heart while eliminating most common confounding experimental errors. (J Thorac Cardiovasc Surg 1998;115:1209-14)