title: Endothelium-dependent dilation of the coronary arteries in syndrome X: effects of the cold pressor test.
abstract: The coronary flow reserve is abnormal in syndrome X, but the response to the cold pressor test, which in normals produces flow-mediated endothelium-dependent epicardial coronary dilation, has not been studied. In this study, in 12 patients with typical syndrome X and angiographically normal coronary arteries, the response to the cold pressor test was abnormal with a mean fall in diameter (10 +/- 8%) in 6 patients, no change in 1, and a minimal increase (4 +/- 2%) in 5 patients (normal increase 12 +/- 1%). The coronary blood flow fell slightly during the cold pressor test, and the coronary vascular resistance increased significantly (from 2.4 +/- 1.1 to 3.2 +/- 1.7 mm Hg/cm.s-1.mm2; p = 0.05), both abnormal responses. This study confirms that in syndrome X patients there is coronary endothelial dysfunction which is apparent in response to physiological stimuli induced by the cold pressor test.
authors.affiliation: Department of Medicine, Chinese University of Hong Kong, Prince of Wales Hospital.
authors.forename: J E
authors.initials: JE
authors.lastname: Sanderson
authors.forename: K S
authors.initials: KS
authors.lastname: Woo
authors.forename: H K
authors.initials: HK
authors.lastname: Chung
authors.forename: W M
authors.initials: WM
authors.lastname: Chan
authors.forename: K K
authors.initials: KK
authors.lastname: Tse
authors.forename: H D
authors.initials: HD
authors.lastname: White
mesh_terms: D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D003080:Cold Temperature; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000503:physiopathology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D017566:Microvascular Angina / Q000503:physiopathology*; D008875:Middle Aged; D005996:Nitroglycerin / Q000494:pharmacology; D012212:Rheology / Q000187:drug effects; D014463:Ultrasonography; D014655:Vascular Resistance / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects; D014664:Vasodilation
chemical_list: D005996:Nitroglycerin