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Adventitial Dissection of the Radial Artery Graft: A New Surgical Approach to Reduce Graft Spasm
Stefan C. Sandker1, Gianclaudio Mecozzi1, Sara C. Arrigoni2, Azuwerus van Buiten3, Massimo A. Mariani2, Hendrik Buikema2, Jan G. Grandjean1.
1Thoraxcenter Twente, Enschede, Netherlands, 2Department of Cardiothoracic Surgery, University Medical Center Groningen, Groningen, Netherlands, 3Department Clinical Pharmacology, University Medical Center Groningen, Groningen, Netherlands.
OBJECTIVE: 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. This tendency to spasm, occurring in 5 to 10% of the patients, has been correlated to a significant proportion of early RA graft failures. 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. 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 left internal mammary artery segments (LIMA; n=11) of patients undergoing CABG were collected and pairwise assessment of vasoreactivity to potassium chloride, U-46619 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 U-46619 (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 LIMA 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). 
CONCLUSIONS: 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.
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