Stability of hibernating myocardium in pigs with a chronic left anterior descending coronary artery stenosis: absence of progressive fibrosis in the setting of stable reductions in flow, function and coronary flow reserve
James A. Fallavollita, MD, FACCa,
Michael Logue, MDa and
John M. Canty, Jr., MD, FACCa
a Veterans Affairs Western New York Health Care System and the Departments of Medicine and Physiology/Biophysics at the University at Buffalo, Buffalo, New York, USA
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Figure 1 Representative trichrome images from pigs with hibernating myocardium. Images from representative animals studied three, four or five months after instrumentation were stained with Masson’s trichrome to facilitate quantification of connective tissue (blue). The left anterior descending coronary artery regions (upper row) illustrate the generalized and diffuse connective tissue staining pattern that was present in hibernating myocardium. Total connective tissue staining was slightly higher in hibernating myocardium as compared with the normally perfused region of the same animal (lower row). Magnification 600x.
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Figure 2 Transmural distribution of regional perfusion in pigs with hibernating myocardium. Microsphere measurements of perfusion at rest (black circles), during submaximal epinephrine infusion (white diamonds) and during adenosine vasodilation (black squares) are presented for the normal remote region (upper graph) and the hibernating LAD region (lower graph). Flow values for each condition were nearly identical in the LAD and normal regions at each time point. A critical impairment of subendocardial flow reserve was present in each group with vasodilated flow unable to increase over resting values. The degree of vasodilation and the transmural pattern of distribution was the same in each group demonstrating stable coronary physiology over the course of the study. LAD = left anterior descending coronary artery.
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Figure 3 Transmural distribution of regional FDG deposition in pigs with hibernating myocardium. There was a marked transmural gradient in FDG deposition (extraction x flow) in the hibernating LAD regions (black squares) with regionally increased deposition in the inner two-thirds of the myocardial wall in each group. There were no significant differences in FDG deposition between groups of animals (3 months, n = 12; 4 months, n = 18; 5 months, n = 6) in any region or mural layer. FDG = 18F-2-deoxyglucose; LAD = left anterior descending coronary artery.
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Figure 4 Survival in pigs chronically instrumented with a fixed left anterior descending coronary artery stenosis. The Kaplan-Meier Curve and the 95% confidence intervals for the line illustrate the temporal progression of survival for this model. The total number of animals at each time is shown in parentheses. See text for discussion.
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