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Prospective, Randomized, Blinded Trial to Investigate Endothelial Dysfunction in Saphenous Vein Grafts subjected to a MAQUET® Vasoshield Pressure Limiting Syringe versus Non-Regulated Vessel Dilation in Patients Undergoing Coronary Artery Bypass Grafting
Vinod H. Thourani1, Benjamin Predmore1, Christopher Nickum1, Keith Causey1, Michael Halkos1, John D. Puskas1, Robert A. Guyton1, Omar Lattouf1, Samantha Levine1, Kim Baio1, Pierluca Lombardi2, David Lefer1.
1Emory University School of Medicine, Atlanta, GA, USA, 2Maquet Medical, Newark, NJ, USA.
OBJECTIVE: Endothelial damage during EVH of the saphenous vein (SV) may occur during the preparation of the graft secondary to the unregulated dilation of the vessel in order to isolate and clip branch vessels. The objective of this study was to evaluate a novel, pressure-regulated syringe compared to the currently utilized non-regulated syringe.
METHODS: Twenty pts undergoing CABG requiring at least 2 SV were prospectively enrolled at an US academic institution from 10/2011 to 6/2012. EVH was performed by 2 experienced PAs. The harvested SV was transected into 3 pieces, one was used for a Control group and the remaining were randomized to: Vasoshield limiting syringe (Group 1, max pressure 150mmHg) or non-regulated vessel dilation (Group 2). SV sections were collected in ice-cold K-H buffer and rings of 2-3 mm width were mounted on wires connected to a force transducer in a tissue bath at 37°C. The person performing these tests was blinded to the dilation method. Rings were stretched to a resting tension of 1.5g over 1hr. U-46619 (10-6M) was used to constrict the rings, and acetylcholine (Ach, 10-4M) and sodium nitroprusside (SNP, 10-4M) were used to relax the vessel segment. Percent relaxation was calculated based on the U-46619 constriction. A one-way ANOVA or nonparametric Kruskal-Wallis test were performed for statistical significance.
RESULTS: There was a significant difference in the amount of tension generated following addition of U-46619 between Groups. While Control and Group 1 rings did not significantly differ, Group 2 rings generated significantly less tension than other rings indicating impaired function of vascular smooth muscle in those with the un-regulated syringe (Figure 1). There were no significant differences between Groups in percent relaxation to the endothelium-dependent vasodilator, Ach, or the endothelium-independent vasodilator, SNP (Figure 1).
CONCLUSIONS: In small cohort randomized trial, the Vasoshield pressure limiting syringe retains vascular contraction in those SV segments harvested endoscopically when compared to non-regulated vessel dilation. Further structural and morphologic characteristics will be important to ascertain vessel integrity. 
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