Effect of pressure phase plane derived τ and K on evaluation of left ventricular diastolic function in isolated rat heart during ischemia/reperfusion

AIM:To analyze and compare the changes of pressure phase plane(PPP) derived τ and K on isolated rat heart during ischemia/reperfusion,and to explore the value of PPP derived τ and K for evaluation of left ventricular diastolic dysfunction. METHODS:LVEDP,-d(p/dt)max,τ and K were measured and calculated during ischemia/reperfusion in Sprague-Dawley rat hearts. Meanwhile,the level of lactate dehydrogenase (LDH) in the coronary effluent was measured,and the ultrastructure changes in myocardium were observed under electron microscope. RESULTS:Compared with control group,τ increased and K reduced significantly in each ischemic group in a time dependent manner (P0.05). With prolonged ischemia,τ was even higher and K was even lower (P0.05). Compared with control group,except ischemia 15 min,LDH in other groups increased significantly at 10 min and 20 min after reperfusion (P0.05). Compared with ischemia 30 min,LDH of ischemia 45 min and ischemia 60 min were even higher at 10 min and 20 min after reperfusion (P0.05). With prolonged ischemia,the abnormal changes of the myocardial ultrastructure were observed. CONCLUSION:PPP derived τ and K may be promising indexes for quantitative assessment of left ventricular diastolic function on isolated rat heart during ischemia/reperfusion,and indication of the severity of ischemia/reperfusion injury.