High level of cholesterol increases coronary vasomotor tone during exercise.
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.


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.
Kaufmann
P
P
Cardiovascular Center, Division of Cardiology, University Hospital Zurich, Switzerland. Philipp.Kaufmann@dmr.usz.ch
Matter
C
C
Mandinov
L
L
Frielingsdorf
J
J
Seiler
C
C
Hess
O M
OM
D002784:Cholesterol / Q000097:blood / Q000502:physiology; D017023:Coronary Angiography; D003326:Coronary Circulation / Q000502:physiology*; D003327:Coronary Disease / Q000503:physiopathology*; D003331:Coronary Vessels / Q000502:physiology*; D004730:Endothelium, Vascular / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D006937:Hypercholesterolemia / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012307:Risk Factors
D002784:Cholesterol