Cardiac adaptation to one hour of mild regional low flow ischaemia 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 flowmetry) was reduced to approximately 70% of control for 1 h. After complete release of the occluder cardiac function was monitored for 2 h. Left ventricular segment lengths were continuously recorded in the region 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 100 to 68(7) (p < 0.001). This index transiently normalised upon reperfusion. 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 during the first minutes of reperfusion after 1 h of mild low flow ischaemia and is followed by a period of stunning.