Diastolic mechanical properties of the left ventricle after global ischemia.

The purpose of this study was to evaluate left ventricular (LV) diastolic mechanical properties after induced global ischemia using reliable new methods. The diastolic function of nonoxygenated crystalloid solution (CC sO2) was compared with those of oxygenated crystalloid (CC cO2) and oxygenated fluorocarbon cardioplegic (FC cO2) solutions. Postischemic ventricular performance was studied in 3 equal (no. 7) groups of dogs subjected to 120 minutes of global ischemia induced at an average myocardial temperature of 18.5 +/- 1.4 degrees C. LV diastolic function (chamber and myocardial stiffness) and relaxation (the exponential fall in LV pressure) were evaluated by sonomicrometry and Millar micrometers before ischemia and at 45 and 60 minutes after ischemia. LV chamber and myocardial stiffness in the CC sO2 group was significantly (p less than 0.05) elevated after ischemia, while the CC cO2 and FC cO2 groups did not show increases in LV chamber and myocardial stiffness after ischemia. LV relaxation before and after ischemia was not changed in any group. The myocardial water content of the CC sO2 group was significantly higher than that of the CC cO2 and FC cO2 groups (p less than 0.05). We conclude that (1) the postischemic increase in LV chamber stiffness in the CC sO2 group was dependent not only on the increase in intrinsic myocardial stiffness but also due to an increase in myocardial edema, and (2) there was no correlation between the LV relaxation rate and the leftward shift of diastolic compliance curves in the CC sO2 group.