739-4 Left Ventricular Systolic Dysfunction may Precede Diastolic Dysfunction by Intervention of Extracorporeal Circulation

The aim of this study was to investigate the influence of extracorporeal circulation during cardiac surgery on left ventricular contractile and diastolic function by means of pressure volume relationship. Study population was 12 patients received cardiac surgery (LVEF exceeded 50% without localized asynergy left ventricle). We measured the end-systolic and end-diastolic pressure-volume relationship by using conductance catheter with micromanometer tip which was inserted through left atrium into left ventricle. End-systolic elastance (Ees), peak positive dp/dt (+dp/dt max) time constant of isovolumic pressure decay (TL:Weiss and TD:Raff and Glantz). and stiffness constant k of end-diastolic pressure-volume relationship were obtained before and after extracorporeal circulation. The end-diastolic pressure-volume relationship was well fit by exponential curve (r=0.95±0.28, p<0.001).Ees decreased from 2.10±0.85 to 1.34±0.75mmHg/ml (p<0.05). +dp/dt max showed no significant tendency in change, because of the considerable change in loading condition. TL and TD did not change significantly. End-diastolic pressure-volume relationships moved on the same exponential fitting curve, and k remained unchanged (0.019±0.005 to 0.021±0.006, n.s.) before and after extracorporeal circulation.In conclusion, extracorporeal circulation decreased left ventricular contractility, but had no significant influence either active or passive phases of left ventricular diastolic function. This fact suggested that left ventricular systolic dysfunction may precede diastolic dysfunction by intervention of extracorporeal circulation