AJP - Heart and Circulatory Physiology, Vol 254, Issue 6 1065-H1073, Copyright © 1988 by American Physiological Society
Functional consequences of acute anterior vs. posterior wall ischemia in canine left ventricles
B. D. Hoit and W. Y. Lew
Department of Medicine, Veterans Administration Medical Center, San Diego, California.
We compared the consequences of acute anterior and posterior wall ischemia
on regional left ventricular function in seven open-chest dogs.
Circumferentially oriented sonomicrometers were implanted in the midwall of
the anterior and posterior left ventricle. The left anterior descending
(LAD) and left circumflex (LCX) coronary arteries were each occluded for 3
min, with 45 min of reperfusion between the two occlusions. The ischemic
areas at risk, as assessed by postmortem perfusion techniques, were similar
for anterior (34.5 +/- 12.5 g) and posterior (32.3 +/- 9.4 g) wall
ischemia. Both occlusions produced a similar increase in end-diastolic
pressure. After LAD occlusion, total segment shortening (end diastole to
aortic valve closure) in the nonischemic posterior wall increased from 8.0
+/- 3.9 to 10.8 +/- 4.4%, solely caused by increased isovolumic shortening.
In contrast, with LCX occlusion, total segment shortening in the
nonischemic anterior wall increased significantly more, from 10.5 +/- 3.8
to 14.6 +/- 4.2% caused by nearly equal increases in isovolumic and
ejection phase shortening. Thus, with both LAD and LCX occlusions, there
was increased shortening in nonischemic areas during isovolumic systole,
which was "wasted" in paradoxically stretching the ischemic zone. However,
a compensatory increase in nonischemic area ejection phase shortening
occurred only with LCX occlusions. These findings may explain the greater
functional impairment that occurs with LAD than LCX occlusions.
