Chronic effects of arterial balloon dilatation on internal mammary artery endothelial function

Background: Manipulation for harvesting of the internal mammary artery (IMA ) for coronary artery bypass grafting has been shown to acutely impair endo thelium-dependent, but not endothelium-independent contractions and relaxat ions. Recently the use of a novel arterial balloon catheter to dilate the I MA has shown an increased IMA flow while preserving endothelial cell integr ity and function acutely. This study examines the chronic effects on endoth elial function of IMA segments subjected to arterial balloon catheter dilat ation in comparison to either no manipulation (control), luminal dilatation with papaverine, or temporary occlusion with soft or hard jaw in a porcine model. Methods: Porcine IMA-s were harvested one month after instrumentation. Ten IMA segments in each group were obtained and placed in organ chambers under isometric tension. Maximal endothelium-dependent contractions with arachid onic acid and relaxations with acetylcholine, and endothelium-independent c ontractions with norepinephrine and relaxations with sodium nitroprusside w ere measured. Results: Endothelium-dependent contractions and relaxations were significan tly impaired after hard jaw occlusion one month after IMA manipulation comp ared to control, long balloon, fibrous jaw, and papaverine groups. Endothel ium-independent contractions and relaxations of LN-LA, smooth muscle were u naffected at one month after manipulation. Conclusion: We conclude that arterial long balloon dilatation is not detrim ental to endothelial cell function chronically and is therefore an effectiv e and atraumatic method to relieve IMA spasm before coronary bypass graftin g.