The Journal of Thoracic and Cardiovascular Surgery, Vol 84, 353-358, Copyright © 1982 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Limitation of myocardial infarct size after surgical reperfusion for acute coronary occlusion
D Wood, C Roberts, SH Van Devanter, R Kloner and LH Cohn
We investigated the effect of different forms of myocardial protection on
infarct size and on the necrotic myocardial process after reperfusion for
acute occlusion of the left anterior descending coronary artery (LAD) in
dogs. Three control groups were formed: a 1 hour, 2 hour, and 6 hour
locally ischemic control. Three experimental groups were locally ischemic
for 1 hour and then reperfused after an additional hour of local ischemia
on cardiopulmonary bypass with the heart protected by intermittent
ischemia, cold potassium cardioplegia, or blood cardioplegia. To delineate
the area at risk, the LAD was temporarily occluded 30 seconds before the 6
hour sacrifice time, and monastral blue dye was injected through a
polyvinyl catheter placed in the left atrial appendage. The LAD area at
risk (AR) was not stained. After 6 hours the heart was excised and treated
with triphenyltetrazolium chloride (TTC) to define the area of myocardial
necrosis (AN). The AN/AR ratio was determined for each animal by
planimetry. Mean values were then computed in each of the six groups and
evaluated by the Student's t test for paired data. The 1 hour control group
had an AN/AR ratio of 64% +/- 5%; the 2 hour control group, 80% +/- 6%; and
the 6 hour control group, 92% +/- 1%. The intermittent ischemia group had
an AN/AR ratio of 83% +/- 2%; the crystalloid cardioplegic group (2 hours
of ischemia) had a ratio of 69% +/- 4%, similar to the 1 hour control but
significantly smaller than the 2 hour control (p less than 0.05); and the
blood cardioplegia group had an AN/AR ratio of 48% +/- 8%, significantly
better than any other group. These data demonstrate that myocardial
necrosis after coronary occlusion is a time-related phenomenon and will
increase to encompass a large fraction of the area at risk unless there is
physical or pharmacologic modification during reperfusion, such as
crystalloid or blood cardioplegia.
