Potential role of coronary vasoconstriction in ischaemic heart disease: effect of exercise.
Coronary vasomotion plays an important role in the regulation of coronary perfusion at rest and during exercise. Normal coronary arteries show coronary vasodilation of the proximal (+20%) and distal (+40%) vessel segments during supine bicycle exercise. However, patients with coronary artery disease show exercise-induced vasoconstriction of the stenotic vessel segments. The exact mechanism of exercise-induced stenosis narrowing is not clear but might be related to a passive collapse of the disease-free vessel wall (Venturi mechanism), elevated plasma levels of circulating catecholamines, an insufficient production of the endothelium-derived vasorelaxing factor or increased platelet aggregation due to turbulent blood flow with release of thromboxane A2 and serotonin. Various vasoactive drugs, such as nitroglycerin and calcium antagonists, prevent exercise-induced stenosis vasoconstriction. An additive effect on coronary vasodilation of the stenotic vessel segment was observed after combination of nitroglycerin with diltiazem. Thus, exercise-induced stenosis narrowing plays an important role in the pathophysiology of myocardial ischaemia during dynamic exercise. The antianginal effect of vasoactive substances can be explained--besides the effect on pre- and afterload--by a direct action on coronary stenosis vasomotion.
Hess
O M
OM
Department of Internal Medicine, University Hospital, Zürich, Switzerland.
Büchi
M
M
Kirkeeide
R
R
Niederer
P
P
Anliker
M
M
Gould
K L
KL
Krayenbühl
H P
HP
D000792:Angiography; D002216:Captopril / Q000009:adverse effects / Q000494:pharmacology; D003326:Coronary Circulation / Q000187:drug effects; D003327:Coronary Disease / Q000503:physiopathology*; D003331:Coronary Vessels / Q000187:drug effects; D015444:Exercise; D006801:Humans; D005996:Nitroglycerin / Q000494:pharmacology; D014661:Vasoconstriction
D002216:Captopril; D005996:Nitroglycerin