OBJECTIVES The aim of this study was to analyze whether L-arginine (L-arg.) has comparable or additive effects to physical exercise regarding endothelium dependent vasodilation in patients with chronic heart failure (...
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OBJECTIVES The aim of this study was to analyze whether L-arginine (L-arg.) has comparable or additive effects to physical exercise regarding endothelium dependent vasodilation in patients with chronic heart failure (CHF). BACKGROUND Endothelial dysfunction in patients with CHF can be corrected by both dietary supplementation with L-arg. and regular physical exercise. METHODS Forty patients with severe CHF (left ventricular ejection fraction 19 +/- 9%) were randomized to an L-arg. group (8 g/day), a training group (T) with daily handgrip training, L-arg, and T (L-arg. + T) or an inactive control group (C). The mean internal radial artery diameter was determined at the beginning and after four weeks in response to brachial arterial administration of acetylcholine (ACh) (7.5, 15, 30 mu g/min) and nitroglycerin (0.2 mg/min) with a transcutaneous high-resolution 10 MHz A-mode echo tracking system coupled with a Doppler device. The power of the study to detect clinically significant differences in endothelium-dependent vasodilation was 96.6%. RESULTS At the beginning, the mean endothelium-dependent vasodilation in response to ACh, 30 mu g/min was 2.54 +/- 0.09% (p = NS between groups). After four weeks, internal radial artery diameter increased by 8.8 +/- 0.9% after ACh 30 mu g/min in L-arg. (p < 0.001 vs. C), by 8.6 +/- 0.9% in T (p < 0.001 vs. C) and by 12.0 +/- 0.3% in L-arg, + T (p < 0.005 vs. C, L-arg. and T). Endothelium independent vasodilation as assessed by infusion of nitroglycerin was similar in all groups at the beginning and at the end of the study. CONCLUSIONS Dietary supplementation of L-arg. as well as regular physical exercise improved agonist-mediated, endothelium-dependent vasodilation to a similar extent. Both interventions together seem to produce additive effects with respect to endothelium-dependent vasodilation. (C) 2000 by the American College of Cardiology.
One of the concerns in using radial artery as coronary artery bypass grafts centers around its unusual propensity for vasospasm when experimentally exposed to norepinephrine. This case report demonstrates an absence o...
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One of the concerns in using radial artery as coronary artery bypass grafts centers around its unusual propensity for vasospasm when experimentally exposed to norepinephrine. This case report demonstrates an absence of vasospasm in a radial artery graft on high dose norepinephrine and may provide reassurance when cu-agonists are required in this setting. (C) 1999 by The Society of Thoracic Surgeons.
Background. Although prone to spasm, the radial artery (RA) is commonly used as a graft in coronary artery bypass surgery (CABG). Successful use of the RA as a graft is dependent on techniques to manage vasospasm duri...
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Background. Although prone to spasm, the radial artery (RA) is commonly used as a graft in coronary artery bypass surgery (CABG). Successful use of the RA as a graft is dependent on techniques to manage vasospasm during operation. We routinely store the RA in a papaverine blood solution after harvesting, a procedure which might damage the endothelium and predispose the RA to postoperative spasm. The aim of the present study was to evaluate the vasodilator and vasoconstrictor responsiveness in freshly obtained and stored segments of RA. Methods. Discarded segments of RA were obtained at operation from patients undergoing CABG and mounted as 3-mm rings in organ baths for isometric recording of changes in smooth muscle force production. Responses to cumulative additions of acetylcholine, noradrenaline, serotonin, angiotensin II, and the thromboxane A2 mimetic U46619 were normalized to contractions induced by a high potassium solution. Results. Endothelium-dependent relaxation to acetylcholine was not different between preparations from freshly-obtained and blood-stored RA segments. However, maximum contractions to all vasoconstrictors studied were markedly increased in preparations from stored arteries. The sensitivity (pEC(50)) of stored arteries to U46619, noradrenaline, and angiotensin were also enhanced when compared to preparations from freshly-obtained segments. Conclusions. Papaverine blood solutions do not damage the endothelium of the RA. The observed heightened vasoconstrictor reactivity of stored arteries, most likely mediated by elements of the blood, indicates that asangineous storage solutions should be explored. (C) 1999 by The Society of Thoracic Surgeons.
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