| Title | Pretreatment with phenoxybenzamine attenuates the radial artery's vasoconstrictor response to alpha-adrenergic stimuli. | | Author(s) | Corvera JS, Morris CD, Budde JM, Velez DA, Puskas JD, Lattouf OM, Cooper WA, Guyton RA, Vinten-Johansen J | | Institution | Cardiothoracic Research Laboratroy, Division of Cardiothoracic Surgery, Carlyle Fraser Heart Center at Crawford Long Hospital, Emory University School of Medicine, Atlanta, GA 30308, USA. | | Source | J Thorac Cardiovasc Surg 2003 Nov; 126(5):1549-54. | | MeSH | Adrenergic alpha-Antagonists
Case-Control Studies
Comparative Study
Coronary Artery Bypass
Coronary Disease
Female
Humans
Intraoperative Period
Male
Muscle, Smooth, Vascular
Norepinephrine
Phenoxybenzamine
Phenylephrine
Probability
Radial Artery
Reference Values
Sensitivity and Specificity
Tissue and Organ Harvesting
Vasoconstriction
Vasoconstrictor Agents
| | Abstract | BACKGROUND: Although the radial artery bypass conduit has excellent intermediate-term patency, it has a proclivity to vasospasm. We tested the hypothesis that brief pretreatment of a radial artery graft with the irreversible adrenergic antagonist phenoxybenzamine attenuates the vasoconstrictor response to the vasopressors phenylephrine and norepinephrine compared with the currently used papaverine/lidocaine.
METHODS: Segments of human radial artery grafts were obtained after a 30-minute intraoperative pretreatment with a solution containing 20 mL of heparinized blood, 0.4 mL of papaverine (30 mg/mL), and 1.6 mL of lidocaine (1%). The segments were transported to the laboratory and placed into a bath containing Krebs-Henseleit solution and 10, 100, or 1000 micromol/L phenoxybenzamine or vehicle. The segments were tested in organ chambers for contractile responses to increasing concentrations of phenylephrine and norepinephrine (0.5-15 micromol/L).
RESULTS: Contractile responses to 15 micromol/L phenylephrine in control radial artery segments averaged 44.2% +/- 9.1% of the maximal contractile response to 30 mmol/L KCl. Papaverine/lidocaine modestly attenuated contraction to 15 micromol/L phenylephrine (32.1% +/- 5.9%; P =.22), but 1000 micromol/L phenoxybenzamine completely abolished radial artery contraction (-7.2% +/- 4.4%; P <.001). The effect of 10 and 100 micromol/L phenoxybenzamine on attenuating vasocontraction was intermediate between 1000 micromol/L phenoxybenzamine and papaverine/lidocaine. Responses to 15 micromol/L norepinephrine in control radial artery segments averaged 54.7% +/- 7.5% of maximal contraction to 30 mmol/L KCl. Papaverine/lidocaine modestly attenuated the contraction response of radial artery segments (35.6% +/- 5.1%; P =.04). In contrast, 1000 micromol/L phenoxybenzamine showed the greatest attenuation of norepinephrine-induced contraction (-10.5% +/- 2.0%; P <.001).
CONCLUSIONS: A brief pretreatment of the human radial artery bypass conduit with 1000 micromol/L phenoxybenzamine completely attenuates the vasoconstrictor responses to the widely used vasopressors norepinephrine and phenylephrine. Papaverine/lidocaine alone did not block vasoconstriction to these alpha-adrenergic agonists. | | Language | eng | | Pub Type(s) | Journal Article
| | PubMed ID | 14666031 |
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