Effect of delay in retroperfusion therapy on infarct size reduction.

Retroperfusion of arterial blood through the coronary sinus reduces infarct size if therapy starts immediately after coronary artery occlusion. To determine if a new system of non-electrocardiogram-synchronized retroperfusion is able to reduce infarct size after delays consistent with clinical use, anesthetized pigs were subjected to 4 hours of left anterior descending coronary artery occlusion followed by 1 hour of reperfusion. Retroperfusion of arterial blood commenced immediately after occlusion of the left anterior descending coronary artery in the no-delay group (n = 10) and after a 1-hour (n = 10) and a 2-hour (n = 8) delay in two other groups. In the control group (n = 10), no therapy was used. In all groups, retroperfusion of arterial blood was terminated after 4 hours of occlusion of the left anterior descending coronary artery. Infarct size, expressed as a percentage of the in vivo area at risk (+/- the standard deviation), was smaller in the no-delay group (44.1 +/- 12.9) and marginally smaller in the 1-hour delay group (71.0 +/- 9.8) compared with controls (86.3 +/- 7.5) (p < 0.05). Infarct size in the 2-hour delay group (75.0 +/- 10.7) was not significantly different from controls. Mean coronary sinus pressure (+/- the standard deviation) was 56 +/- 25 mm Hg, 39 +/- 9 mm Hg, and 47 +/- 9 mm Hg in the no-delay, 1-hour delay and 2-hour delay groups, respectively. Thus, this new retroperfusion system limits infarct size by 50% if it is started immediately after coronary occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)