Circulation, Vol 72, 413-430, Copyright © 1985 by American Heart Association
LR Bush, LM Buja, G Tilton, M Wathen, P Apprill, J Ashton and JT Willerson
We evaluated the ability of propranolol and diltiazem alone and in
combination to enhance the recovery of left ventricular (LV) segmental
function during 1 month of reperfusion after two temporary occlusions of
the left anterior descending coronary artery (LAD) in conscious dogs
instrumented with ultrasonic crystals for the measurement of regional net
systolic wall thickening (NET). LV segments were classified according to
their contractile function after 1 hr of LAD occlusion: class 1, greater
than 67% of preocclusion (control) NET; class 2, 0% to 66.9%; class 3, less
than 0% (paradoxical systolic wall thinning). Propranolol (1 mg/kg iv) or
diltiazem (20 micrograms/kg/min) was given 65 min after LAD occlusion in
dogs that had 2 (group I) or 4 hr (group II) of LAD occlusion. Diltiazem
plus propranolol (same doses) were given to another group of dogs that
underwent 4 hr (but not 2) of LAD occlusion. Untreated control dogs
received 25 ml of saline and underwent 2 or 4 hr of LAD occlusion. The NET
of class 2 and 3 segments in group I control dogs increased significantly
during 1 month of reperfusion, from 32 +/- 5% and -43 +/- 6% to 66 +/- 9%
and 26 +/- 9%, respectively (p less than .05). Neither diltiazem nor
propranolol enhanced the long-term recovery of these segments in group I
dogs. However, diltiazem prevented further deterioration of contractile
dysfunction observed in control dogs immediately after reperfusion in both
segment classes. The NET of class 2 segments in group II control dogs after
4 weeks of reperfusion remained at levels observed during LAD occlusion: 30
+/- 4% to 37 +/- 12%. Class 3 NET increased from -33 +/- 5% to 12 +/- 12%
with 1 month of reperfusion, but these segments were essentially akinetic.
Propranolol or diltiazem alone did not produce significant overall
increases in NET, but diltiazem again prevented further declines in NET of
class 2 and 3 segments during early reperfusion. However, the combination
of diltiazem and propranolol significantly enhanced overall recovery of
class 2 NET in group II dogs (44 +/- 3% to 88 +/- 7%) and prevented the
worsening of NET associated with early reperfusion. Compared with untreated
dogs, propranolol plus diltiazem also significantly decreased the extent of
histologic necrosis in class 2 and 3 segments as well as the
macrohistochemically determined infarct size in group II dogs.(ABSTRACT
TRUNCATED AT 400 WORDS)
ARTICLES
Effects of propranolol and diltiazem alone and in combination on the recovery of left ventricular segmental function after temporary coronary occlusion and long-term reperfusion in conscious dogs
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