Influence of site of regional ischemia on nonischemic thickening in anesthetized dogs

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Abstract

The effect of varying the site of acute regional ischemia on nonischemic myocardial function was examined by comparing regional thickening during 2-3 min circumflex (Circ) vs. left anterior descending (LAD) coronary artery occlusions in eight open-chest dogs. Cross-sectional midwall two-dimensional echocardiograms were obtained, and systolic thickening was measured at 16 equal-spaced points around the circumference. The distribution and extent of hypoperfusion was assessed by radiolabeled microspheres. The echo slice was subdivided into a hypoperfused region (Hypo), four adjacent nonischemic regions (ADJ1-4), and the remaining remote segments (Remote). The extent of hypoperfusion (%LV mass) was similar with both sets of occlusions (LAD, 29.4 ± 2.8%; Circ, 26.0 ± 4.4%; P = NS), as was endo- and epicardial flow in the nonischemic regions. Yet, even with like-sized Hypo regions, thickening of nonischemic myocardium was significantly greater during Circ than during LAD occlusions (P < 0.001). These results are consistent with recently reported disparities of global functional impairment during LAD vs. Circ ischemia. The responses likely reflect differences in regional wall geometry, loading, and the three-dimensional distribution of coronary hypoperfusion between the two vascular territories.

Original languageEnglish (US)
Pages (from-to)25/5
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume256
Issue number5
StatePublished - Jan 1 1989

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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