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High level of cholesterol increases coronary vasomotor tone during exercise
P Kaufmann1, C Matter, L Mandinov
1Cardiovascular Center, Division of Cardiology, University Hospital Zurich, Switzerland. Philipp.Kaufmann@dmr.usz.ch
Insights
High cholesterol increases coronary vasomotor tone in normal arteries during exercise, independent of stenosis. This suggests hypercholesterolemia-induced endothelial dysfunction impacts coronary artery disease patients.
Area of Science:
- Cardiovascular Physiology
- Atherosclerosis Research
- Endothelial Function Studies
Background:
- Coronary vasomotor tone regulates myocardial perfusion and ischemic threshold.
- Endothelial dysfunction, linked to risk factors, contributes to atherosclerosis.
- Atherosclerosis impacts myocardial perfusion and lowers the ischemic threshold.
Purpose of the Study:
- To investigate the impact of hypercholesterolemia on coronary vasomotor tone.
- To assess tone in normal and stenotic coronary arteries.
- To evaluate tone at rest and during exercise.
Main Methods:
- 48 patients categorized by serum cholesterol levels (normal vs. elevated).
- Coronary vasomotor tone measured via quantitative coronary angiography during rest and exercise.
- Analysis included both normal and stenotic coronary vessel segments.
Main Results:
- Normal segments showed no exercise-induced tone change in normal cholesterol group.
- Elevated cholesterol group exhibited significant exercise-induced tone increase in normal segments.
- Stenotic segments showed increased tone regardless of cholesterol levels.
Conclusions:
- Hypercholesterolemia induces abnormal coronary vasomotor tone in normal arteries during exercise.
- Stenotic arteries show increased tone independent of cholesterol levels.
- Findings suggest hypercholesterolemia affects non-stenosed arteries via endothelial dysfunction.
Background:
Coronary vasomotor tone plays an important role in the regulation of myocardial perfusion and influences ischemic threshold significantly. Endothelial dysfunction occurs in the presence of coronary risk factors and is closely linked to the development of atherosclerosis affecting myocardial perfusion and decreasing ischemic threshold.
Objective:
To study the effect of hypercholesterolemia on coronary vasomotor tone in normal and stenotic coronary arteries at rest and during exercise.
Patients And Methods:
In total 48 patients were included in the present analysis. Patients were divided into two groups according to the actual levels of serum cholesterol: 18 patients had normal (mean 181 +/- 28 mg%; group 1) and 30 had elevated (mean 263 +/- 46 mg%; group 2) levels of serum cholesterol according to the 4S criteria with a cutoff level of 213 mg% (5.5 mmol/l). Coronary vasomotor tone at rest and during supine bicycle exercise was calculated by dividing mean aortic pressure by radius of coronary vessel obtained using biplanar quantitative coronary angiography. A normal as well as a stenotic vessel segment in each patient were studied.
Results:
Normal vessel segments in patients with normal levels of cholesterol (group 1) exhibited no exercise-induced change in coronary vascular tone (+3%, NS), whereas a significant increase in tone (+24%, P < 0.01 versus rest) occurred in those with high levels of cholesterol (group 2). In contrast, stenotic segments in members of both groups exhibited an increase in vascular tone irrespective of the actual level of serum cholesterol.
Conclusions:
Hypercholesterolemia causes a pathologic increase in coronary vasomotor tone of angiographically normal vessel segments during exercise. A similar pathologic response occurs in stenotic arteries, but this is independent of the actual level of serum cholesterol. These findings suggest that hypercholesterolemia influences vasomotor tone of the nonstenosed coronary arteries in patients with coronary artery disease probably through the occurrence of endothelial dysfunction.