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Session: Poster session II
Session starts: Thursday 24 January, 16:00

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Stefan Sandker (Thoraxcenter Twente, Medisch Spectrum Twente, Enschede)
Hendrik Buikema (Department of Clinical Pharmacology, University Medical Center Groningen, Groningen)
Jan Grandjean (Thoraxcenter Twente, Medisch Spectrum Twente, Enschede)

Abstract:
Introduction Over the last two decades, the radial artery (RA) has become a routinely used graft for coronary artery bypass graft surgery (CABG). A potential disadvantage of the RA is its higher susceptibility to vasospasm compared to other arterial grafts [1]. This tendency to spasm, occurring in 5 to 10% of the patients, has been correlated to a significant proportion of early RA graft failures [1, 2]. It is generally accepted that the adventitia provides structural support to the vessel. Although, in the last decade, several studies have indicated that the adventitia also has an active role in vasomotor tone [3]. In this study we investigated the effects of adventitial dissection of the RA for reducing vasospasm. Methods Following harvesting, adventitial dissection was carried out as longitudinal dissection of total adventitia and all bundles of circumferential collagen fibers on the ventral side of the RA using coronary scissors. Surplus radial artery segments (n=35) with and without adventitial dissection and internal mammary artery segments (IMA; n=11) of patients undergoing CABG were collected and pairwise assessment of vasoreactivity to potassium chloride (KCl), U46619 and acetylcholine was performed in organ bath experiments. Results Full curve and maximal vasoconstriction to potassium chloride (p=0.015 and p=0.001) and U46619 (p=0.048 and p=0.001) was significantly reduced for adventitial dissected RA compared to non-adventitial dissected RA. Furthermore, vasoconstriction responses of the IMA were significantly less compared to (non) adventitial dissected RA (p<0.05). Endothelium-dependent relaxation to acetylcholine of adventitial dissected RA was significantly increased (p=0.006) compared to non-adventitial dissected RA. Maximal vasorelaxation to acetylcholine was 33.1±4.6% for adventitial dissected RA compared to 20.9±3.5% for non-adventitial dissected RA (p=0.018). Conclusion The adventitial dissected RA is less susceptible to vasoconstriction and more prone to vasorelaxation ex vivo. Therefore, we recommend to perform adventitial dissection of the RA graft to reduce vasospasm for arterial revascularization in CABG. Previously, our research group has demonstrated that the use of adventitial dissected RA as Y-graft is an effective treatment for patients undergoing off-pump CABG [4]. REFERENCES [1] Kobayashi J. Radial artery as a graft for coronary artery bypass grafting. Circ J 2009; 73: 1178-1183. [2] Attaran S, John L, El-Gamel A. Clinical and potential use of pharmacological agents to reduce radial artery spasm in coronary artery surgery. Ann Thorac Surg 2008; 85: 1483-1489. [3] Auger FA, D'Orleans-Juste P, Germain L. Adventitia contribution to vascular contraction: hints provided by tissue-engineered substitutes. Cardiovasc Res 2007; 75: 669-678. [4] Halbersma WB, Arrigoni SC, Mecozzi G, Grandjean JG et al. Four-year outcome of OPCAB no-touch with total arterial Y-graft: making the best treatment a daily practice. Ann Thorac Surg 2009; 88: 796-801.