No-Touch Harvesting Of Saphenous Veins May Improve Early Graft Patency Rates

Nitric oxide synthase is preserved when the saphenous vein is harvested using a no- touch technique. Consequently, improved nitric oxide availability may prove to be an important mechanism in the success of this technique, say researchers.

There is an association between using the saphenous vein for coronary by pass surgery grafts and a one-year occlusion rate as high as 30 percent.

Researchers from the University College Hospital and the Royal Free Hospital, in London, England, and the Orebo Medical Centre in Orebo, Sweden, questioned whether harvesting veins with a non-distended pedicle of surrounding tissue, using a non-touch technique may improve early patency rates. Furthermore, they asked if the distribution of nitric-oxide synthase and the quantity of the veins would differ if this new technique for harvesting was used. In addition, they also studied the separate contribution of perivascular tissue removal and distension to alterations in the nitric oxide synthase.

Participants included 10 patients on whom coronary artery bypass grafting surgery was performed using the non-touch and the conventional technique. They contributed 10 segments of saphenous veins from which surrounding tissue was stripped but not distended following which samples were taken.

The distribution of nitric oxide synthase was studied using reduced nicotinamide adenine dinucleotide phosphate-diaphorase histochemistry, and staining was quantified by image analysis. Identifying specific nitric oxide synthase isoforms was undertaken by immunohistochemistry whilst the associated cell types were identified by immunomarkers.

It was established that there was a higher nitric oxide synthase content in no-touch vessels by comparison with those harvested more conventionally (35.5 percent; P<.05 with variance analysis). There was an association between this content and endothelial nitric oxide synthase on the lumen while all three isoforms were present in the media. There was also a presence of all three isoforms of nitric oxide synthase in the intact adventitia of no touch vessels, which were associated with microvessels and perivascular nerves. Harvesting veins using the conventional technique resulted in perivascular tissue stripping and venous distension contributing to reduced nitric oxide synthase. Journal of Vascular Surgery 2002 Vol 35 No 2 pp 356-362. “Localization of nitric oxide synthase in saphenous vein grafts harvested with a novel “no-touch” technique: Potential role of nitric oxide contribution to improved early graft patency rates”