Iatrogenic myocardial edema: increased diastolic compliance and time course of resolution in vivo

BACKGROUND: Perfusion-induced edema reduces diastolic compliance in isolated hearts, but this effect and the time for edema to resolve after blood reperfusion have not been defined in large animals. METHODS: Edema was induced by coronary perfusion with Plegisol (750 mL, 289 mOsm/L) during a 1-minute aortic occlusion in 6 pigs. This was followed by whole blood reperfusion, inotropic support, and circulatory assistance until sinus rhythm and contractile function were restored. A control group (n = 6) was treated similarly, with 1 minute of electrically induced ventricular fibrillation and no coronary perfusion. Recorded data included electrocardiogram, left ventricular pressure and conductance, aortic flow, and two-dimensional echocardiography. Preload reduction by vena caval occlusion was used to define systolic and diastolic properties. Data were recorded at baseline and at 15-minute intervals for 90 minutes after reperfusion. RESULTS: In the edema group, average left ventricular mass (132 +/- 7 [standard error of the mean] versus 106 +/- 4 g) and ventricular stiffness constant (0.15 +/- 0.02 versus 0.05 +/- 0.01) increased after Plegisol versus baseline (p < 0.05), returning to normal after 45 minutes of reperfusion. In controls, mass (118 +/- 6 versus 116 +/- 4 g) and ventricular stiffness (0.06 +/- 0.01 versus 0.05 +/- 0.01) did not change significantly. There was no significant change in systolic function. Myocardial water content at the end of the study was not different for the two groups. CONCLUSIONS: Crystalloid-induced edema and diastolic stiffness resolve after 45 minutes in pigs. This suggests that edema caused solely by cardioplegia during cardiac operations should not cause significant perioperative ventricular dysfunction.