CARDIAC ADAPTATION TO ONE-HOUR OF MILD REGIONAL LOW-FLOW ISCHEMIA IN THE PIG

Objective: The aim was to determine the cardiac consequences of a 1 h period of mild regional low flow ischaemia in the pig heart. Methods: In eight pentobarbitone sodium anaesthetised pigs (weight range 23-38 kg), the mid left anterior descending coronary artery was constricted by a hydraulic occluder. Transmural coronary blood flow Doppler flowme try) was reduced to approximate to 70% of control for 1 h. After compl ete release of the occluder cardiac function was monitored for 2 h. Le ft ventricular segment lengths were continuously recorded in the regio n subjected to low flow ischaemia and in a control region supplied by the circumflex artery. Results: After 1 h with a 28(SEM 3)% reduction in coronary blood flow, the systolic shortening index decreased from 1 00 to 68(7) (p < 0.001). This index transiently normalised upon reperf usion. Thereafter it declined, reaching a nadir of 72(5) at 1.25 h of reperfusion, and subsequently improved to 82(6) at 2 h of reperfusion. Conclusions: Normalisation of local myocardial function appears durin g the first minutes of reperfusion after 1 h of mild low flow ischaemi a and is followed by a period of stunning.