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Coronary collateral vessels: their significance for left ventricular histologic structure
Insights
Coronary collateral vessels significantly protect the left ventricular myocardium from fibrosis in patients with severe coronary artery disease. This finding highlights the protective role of collateral circulation in maintaining heart muscle health.
Area of Science:
- Cardiovascular Medicine
- Cardiac Pathology
- Interventional Cardiology
Background:
- The protective role of coronary collateral vessels in left ventricular myocardium under conditions of coronary artery disease remains incompletely understood.
- Coronary artery disease (CAD) can lead to myocardial damage, and the presence of collateral circulation may influence the extent of this damage.
Purpose of the Study:
- To investigate whether coronary collateral vessels offer protection to the left ventricular myocardium in patients with coronary artery disease.
- To quantify the extent of myocardial fibrosis in relation to the presence or absence of collateral supply in severe coronary stenosis.
Main Methods:
- Light microscopic morphometry was performed on myocardial tissue samples obtained via transmural biopsy during open-heart surgery from 56 patients with CAD.
- Patients were categorized based on the degree of stenosis in the left anterior descending coronary artery and the presence or absence of collateral supply determined by preoperative angiography.
- Myocardial fibrosis was quantified, with biologically significant differences defined as transmural fibrosis exceeding +/- 6.2 percent.
Main Results:
- Patients with severe left anterior descending artery stenosis (>95%) but without collateral supply (Group B) exhibited significantly higher myocardial fibrosis (68%) compared to a control group with less stenosis (Group A, 17%).
- Patients with severe stenosis (>95%) and collateral supply (Group C) showed significantly less myocardial fibrosis (29%) compared to those without collateral supply (Group B, p < 0.001).
- The fibrosis levels in Group C were not significantly different from the control Group A (p > 0.05), indicating a protective effect of collateral vessels.
Conclusions:
- Myocardium supplied by collateral vessels in cases of severe coronary stenosis demonstrates substantially less fibrosis compared to myocardium without collateral supply.
- Coronary collateral vessels play a significant protective role in mitigating myocardial damage and fibrosis in the setting of severe coronary artery disease.
- These findings underscore the importance of collateral circulation in preserving myocardial viability and function.
Abstract:
Whether coronary collateral vessels protect the left ventricular myocardium is unknown. Light microscopic morphometry was carried out on myocardial tissue samples from 56 surgically treated patients with coronary artery disease. Transmural biopsy of the myocardium perfused by the left anterior descending coronary artery was obtained during open heart surgery. In initial reproducibility studies of biopsy samples of 17 patients a sampling error for evaluation of myocardium was defined and differences in transmural fibrosis exceeding +/- 6.2 percent were considered biologically significant. Stenosis of the left anterior descending artery was determined from preoperative angiography. Group A (control group) comprised patients with less than 75 percent area reduction of the left anterior descending coronary artery (mean +/- standard deviation 65 +/- 10 percent). Patients in group B (more than 95 percent area reduction [mean 99 +/- 2 percent] without collateral supply on arteriography) were compared with patients in group C (identical stenosis [mean 99 +/- 2 percent] but with collateral supply). Fibrosis averaged 17 percent in group A, 68 percent in group B (p less than 0.001 versus group A) and 29 percent in group C (p greater than 0.05 versus group A, p less than 0.001 versus group B). Thus, in severe coronary stenosis myocardium supplied by collateral vessels shows less fibrosis on biopsy sample than does myocardium without collateral supply.