Improved endothelial function after a modified harvesting technique of the internal thoracic artery

One of the most important factors in bypass surgery is the preservation of endothelial function in the arterial graft. It was of interest, therefore, whether a slightly modified preparation procedure during surgery could contribute to improved endothelial function of the graft. We compared the functional activity of internal thoracic arteries (ITA) prepared according to the traditional harvesting method with occlusion by a clip, dissection at the distal end and storage of the artery in papaverine until its implantation (CA) with the functional activity of arteries which were also prepared and wrapped in papaverine, but were left perfused and dissected immediately before their anastomoses (PA).

Samples of ITA were obtained from a total number of 28 patients, undergoing bypass surgery, and randomly distributed into two groups. The arteries were cut into rings and suspended in organ baths, containing Krebs-Henseleit solution, for isometric tension recording. Cumulative concentration response curves were determined for the contractile agents endothelin-1 (ET-1), 5-hydroxytryptamine (5-HT), noradrenaline (NA) and potassium chloride (KCl) and the relaxant compounds acetylcholine (ACH) and sodium nitroprusside (SNP) during active tone induced by 30 mM KCl.

ET-1 and 5-HT stimulated rings from both groups within the same concentration ranges but elicited significantly (P<0.05) higher contractile responses in CA compared to PA. By contrast, concentration response curves for KCl and NA where nearly superimposable. On the other hand, maximal endothelium-dependent relaxant responses to ACH proved to be significantly stronger in PA (0.84+/-0.20 g) as compared to CA (0.31+/-0.05 g, P<0.05) while endothelium independent relaxant responses to SNP where similar in both groups.

These data suggest that leaving the ITA perfused during harvesting might improve considerably the endothelial function of the graft.