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[Coronary collateral function evaluated by coronary hemodynamics and myocardial lactate metabolism during rapid
A Mikuniya1, H Totsuka, Y Fujino
1Second Department of Internal Medicine, Hirosaki University School of Medicine.
Insights
Coronary collateral function in ischemic myocardium was assessed using coronary hemodynamics and lactate metabolism. Findings reveal that collaterals improve coronary flow reserve, though myocardial lactate extraction decreases with pacing.
Area of Science:
- Cardiology
- Physiology
- Medical Imaging
Context:
- Assessing coronary collateral function is crucial for understanding myocardial ischemia.
- Coronary artery stenosis can impair blood flow and myocardial metabolism.
- Coronary collateral circulation may compensate for reduced blood supply in ischemic regions.
Purpose:
- To elucidate coronary collateral function in the ischemic myocardium.
- To study coronary hemodynamics and myocardial lactate metabolism in collateral-dependent myocardium.
- To evaluate coronary stenosis using cross-sectional area, great cardiac vein flow, and myocardial lactate extraction ratio before and during rapid atrial pacing.
Summary:
- Thirty-eight patients were categorized into three groups based on coronary arteriograms: normal (Group A), stenosis without collaterals (Group B), and stenosis with collaterals (Group C).
- Cross-sectional areas were reduced in Groups B and C compared to Group A.
- A linear relationship between cross-sectional area and % delta GCVF was observed in Group B but modified in Group C.
- Myocardial lactate extraction ratio decreased significantly during rapid atrial pacing in Groups B and C, but not in Group A.
- In patients with total LAD occlusions, GCVF and coronary resistance were similar to Group A.
Impact:
- This study provides insights into the hemodynamic and metabolic function of coronary collaterals in ischemic myocardium.
- Findings suggest that while collaterals enhance flow reserve, they may not fully preserve myocardial lactate metabolism under stress.
- The study highlights the utility of GCVF and MLER in assessing coronary stenosis and collateral function.
Abstract:
To elucidate coronary collateral function in the ischemic myocardium, we studied coronary hemodynamics and myocardial lactate metabolism of the collateral-dependent myocardium before and during rapid atrial pacing. Subjects consisted of 38 patients who were categorized into 3 groups according to their coronary and coronary collateral arteriographic findings: 14 patients with normal coronary arteriograms (Group A), 15 with significant stenosis in the left anterior descending coronary artery (LAD) without collaterals (Group B), and 9 with LAD stenosis and collaterals (Group C). Estimates of cross-sectional area (CSA) obtained from the orthogonal coronary arteriograms, and the great cardiac vein flow (GCVF) and myocardial lactate extraction ratio (MLER) before and during rapid atrial pacing were used as parameters to evaluate coronary stenosis. The results were as follows: 1. The cross-sectional areas in Groups B and C were 86% and 91% of that in Group A, respectively. 2. In Group B, there was a good linear relationship between cross-sectional area and % delta GCVF, as shown in % delta GCVF = 2.90 + 36.22 x CSA (r = 0.61, p < 0.05). This relationship was modified in Group C, increasing % delta GCVF against CSA. 3. Myocardial lactate extraction ratio in Groups B and C decreased significantly after rapid atrial pacing, while, it remained unchanged in Group A. This ratio after rapid atrial pacing did not differ significantly between the 2 groups. 4. In 3 of 4 patients with total LAD occlusions, GCVF and anterior coronary resistance before and during rapid atrial pacing were similar to those of Group A.(ABSTRACT TRUNCATED AT 250 WORDS)