Cw. Buffington et S. Watanabe, REGIONAL CONTRACTION IMPROVES, THEN DECLINES AFTER REPERFUSION OF ISCHEMIC MYOCARDIUM IN THE DOG, Journal of cardiac surgery, 9(3), 1994, pp. 417-421
Myocardial ischemia occurs during cardiac surgery and coronary artery
angioplasty. If ischemia is short-term or the heart is protected, cell
ular necrosis can be avoided. Nevertheless, myocardial stunning occurs
and can reduce cardiac performance in the hours after ischemia. Such
stunning is preceded by a short period of normal or above normal contr
action immediately after reperfusion. The time course of this phenomen
on was investigated in six anesthetized dogs subjected to a 10-minute
total coronary occlusion. Regional contraction was measured in the isc
hemic zone and in a remote zone of the heart with a sonomicrometer. Re
mote zone contraction increased during ischemia, returned toward basel
ine values after reperfusion, and was stable for the next hour, indica
ting little effect of time on the experimental preparation. In contras
t, ischemic zone contraction was abolished by 10 minutes of coronary o
cclusion, returned to baseline or greater levels within 1 to 3 minutes
following release of the occlusion, then gradually declined over 10 t
o 20 minutes to a level about 40% below baseline values, indicating my
ocardial stunning. These findings support the notion that a honeymoon
period of normal or above normal function exists during early reperfus
ion, and that stunning manifests later. This reperfusion ''honeymoon''
may create a false sense of security.