Vasoconstriction of stenotic coronary arteries during dynamic exercise in patients with classic angina pectoris: reversibility by nitroglycerin.

Abstract

To study the vasomotility of normal and diseased coronary arteries during dynamic exercise, symptom-limited supine bicycle exercise during cardiac catheterization was performed by 18 patients with classic angina pectoris. The cardiovascular response was assessed by hemodynamic measurements and computer-assisted determination of normal and stenotic coronary artery luminal areas from biplane coronary angiograms made before, during, and after exercise. After baseline measurements were recorded, 12 patients (group 1) performed bicycle exercise for 3.4 min (mean), reaching a maximum workload of 81 W (mean); at the end of exercise they received 1.6 mg sublingual nitroglycerin. After measurements at rest in six other patients (group 2), 0.1 mg intracoronary nitroglycerin was given, followed by exercise (3.8 min, 96 W; NS) and sublingual nitroglycerin as in group 1. During exercise in group 1, luminal area of the coronary stenosis decreased to 71% of resting levels (p less than .001), while area of the normal coronary artery increased to 123% of control (p less than .001). After sublingual nitroglycerin at the end of exercise, area of the normal vessel further increased to 140% of control (p less than .001), while luminal area of the stenosis dilated to 112% of resting levels (p less than .001 vs exercise, NS vs rest). Pretreatment with intracoronary nitroglycerin increased both normal (121%; p less than .05) and stenotic (122%; p less than .05) luminal areas, while preventing the previously observed narrowing of stenosis during exercise (114%; NS). Exercise resulted in a similar heart rate-systolic pressure product and caused angina pectoris in two-thirds of the patients in each group. However, patients pretreated with intracoronary nitroglycerin (group 2) had a lower mean pulmonary arterial pressure during maximum exercise (35 mm Hg) than those patients (group 1) not receiving pretreatment (47 mm Hg; p less than .001). Group 2 patients reached a percentage of their predicted work capacity (65%) that was about the same as that during previous upright bicycle exercise (71%; NS), while group 1 patients had a significantly lower work capacity (51% of predicted) than that before catheterization (82%; p less than .001). Hence, narrowing of coronary artery stenosis during dynamic exercise is attributable to active vasoconstriction due to its reversibility by preexercise intracoronary nitroglycerin. Patients who did not experience narrowing of stenosis during exercise (group 2) had less evidence of myocardial ischemia (lower mean pulmonary arterial pressure) and maintained their work capacity.(ABSTRACT TRUNCATED AT 400 WORDS)

Coronary artery constriction caused by the cold pressor test in human hypertension.

“…15 ' 62 ' 63 This abnormal vasoconstriction of coronary arteries may facilitate myocardial ischemia. 6465 In the present study, the decrease in coronary diameter observed during sympathetic stimulation (-8.2%) is quite substantial.…”

Effect of intracoronary and intravenous propranolol on human coronary arteries

“…In a previous report' 4 ', we have shown that normal coronary arteries dilate during dynamic exercise, but eccentric coronary stenoses show exercise-induced coronary vasoconstriction. The exact mechanism of this exercise-induced stenosis narrowing is not clear but might be due to endothelial dysfunction (atherosclerotic alterations) with an insufficient production of the endothelium-derived relaxing factor' 45 ' or due to a passive collapse of the free vessel wall within the stenosis during high flow states (Venturi mechanism) such as bicycle exercise' 71 .…”

Deleterious Effect of Coronary Brachytherapy on Vasomotor Response to Exercise

“…Therefore, almost no comparative data exist in the literature and sample sizes are small, as is the case with our study population. Gage et al 21 and Gordon et al 25 have shown vasoconstriction of stenotic but vasodilation of normal coronary vessel segments in response to exercise. Recently, we reported that stent implantation does not impair exercise-induced coronary artery vasodilation proximal and distal to the stented vessel, 17 as it was reported by Caramori et al 26 Sabate et al 19 have reported preserved endothelium-dependent vasodilation 6 months after brachytherapy, assessed by the vasomotor response to acetylcholine infusion.…”

“…Normal coronary arteries dilate during dynamic exercise. 21 Percutaneous transluminal coronary angioplasty of stenotic lesions normalizes or improves coronary vasomotion. 22 Stent implantation abolishes paradoxical vasoconstriction of coronary stenosis and renders a previous vasoresponsive vessel into a rigid tube.…”