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OBJECTIVES: There is an increasing use of arterial conduits for coronary artery bypass grafting, and the radial artery is commonly used as the third graft. The major drawback of the radial artery is its proclivity to spasm. Both papaverine and phenoxybenzamine have been recommended as topical vasodilators in clinical practice. We compared the efficacy of both drugs to prevent radial artery spasm and their ability to preserve endothelial function. METHODS: The ability of both drugs to prevent alpha-adrenoreceptor mediated constriction was tested in vitro in an organ bath in radial artery segments obtained from 20 patients. Vessel viability was determined by potassium (K(+)) constriction, and endothelial function was assessed by observing endothelium-dependent relaxation by a synthetic analogue of acetylcholine, carbachol. RESULTS: Papaverine consistently abolished and prevented spasm for up to a maximum of 30 min in all segments. In contrast, phenoxybenzamine consistently abolished and prevented radial artery spasm in all segments for at least 6 h. Whereas papaverine damaged the endothelium of 70% of vessels, there was no evidence of endothelial damage in any arterial segments after exposure to phenoxybenzamine. CONCLUSIONS: Phenoxybenzamine more effectively prevents alpha-adrenoreceptor mediated spasm of the human radial artery than papaverine. It is also less harmful to the endothelium.

Type

Journal article

Journal

Eur J Cardiothorac Surg

Publication Date

04/2001

Volume

19

Pages

482 - 486

Keywords

Adrenergic alpha-Antagonists, Humans, In Vitro Techniques, Papaverine, Phenoxybenzamine, Phosphodiesterase Inhibitors, Radial Artery, Vasodilator Agents, Vasomotor System