Dl. Kraitchman et al., Noninvasive assessment of myocardial stunning from short-term coronary occlusion using tagged magnetic resonance imaging, J CARD M RE, 2(2), 2000, pp. 123-136
Brief myocardial ischemia of less than 20 min duration, followed by reperfu
sion is known to cause transient contractile dysfunction, often termed myoc
ardial stunning. Tagged magnetic resonance imaging offers a noninvasive met
hod that can be used to quantify this regional mechanical dysfunction in st
unned myocardium. To this end, a closed-chest canine model of myocardial st
unning was created by short-term (similar to 20-min) coronary: occlusion, v
ia inflation of an angioplasty balloon placed fluoroscopically in the left
anterior descending (LAD) coronary followed by reperfusion. Changes in myoc
ardial strain before occlusion during occlusion, and at 15 and 30 min after
reperfusion were determined rising repeated-measures analysis of variance.
After instrumentation but before coronary occlusion, global reductions in
myocardial strain were observed relative to animals that did not undergo co
ronary catheterization procedures. Declines of 46% and 49% in regional myoc
ardial blood flow in the LAD and left circumflex bed, respectively: from pr
einstrumentation levels occurred die to coronary angiography and placement
of a deflated angioplasty balloon in the LAD for I hr. During LAD occlusion
, maximum myocardial shortening was significantly reduced in the anterior a
nd anteroseptal regions of the left ventricular apex (i.e., ischemic region
) but returned to baseline values by 30 min after reperfusion. No augmentat
ion of myocardial function was observed in the nonischemic regions during o
cclusion or reperfusion. Thus, this noninvasive technique to evaluate myoca
rdial ischemia demonstrated a graded response in myocardial function to isc
hemia and persistent regional dysfunction or "myocardial stunning" after sh
ort-term coronary occlusion.