Introduction: The internal mammary artery's endothelium continuously produces nitric oxide in a large quantity resulting in local and downstream vasodilatation, inhibition of platelet aggregation and in the tunica media prevents smooth muscle cell proliferation.
Objective: The aim of this study was to measure the concentration of the internal mammary artery bypass graft's endothelium derived nitric oxide's stable metabolite, (nitrite) at the venous drainage site (great cardiac vein) of the recipient coronary artery (left anterior descending), and to prove that the change of the biochemical milieu provides morphological stability (vasodilation and lack of atherosclerosis) in the recipient coronary artery based on recoronarographies.
Method: Authors investigated the levels of endothelium derived nitric oxide in intraoperative settings of 50 off pump, partly heparinized coronary bypass surgery cases sampling from the internal mammary free cut end flow (81.2 +/- 12.1 mumol/l), the great cardiac vein (anterior interventricular vein) prior and after arterial bypass graft completion and in the systemic circulation (42.9 +/- 7.1 mumol/l), The stable metabolite concentration measurement was carried out with the modified Takafumi Ohta method utilizing fluoroscopy. Out of the 200 samples 164 were feasible to analyze.
Results: A significant increase was found in the great cardiac vein, comparing concentrations measured prior and after IMA anastomosis completion: 46.7 +/- 11.4 mumol/l, and 71.12 +/- 13.1 mumol/l, respectively (p < 0.05).
Conclusion: Based on these findings, due to the continuous protective (vasodilatative and antiatherogen) effect of the IMA provided EDNO, the recipient artery shows no pathological changes in time. This was proved by studying recoronarographies of 103 patients--with prior coronary bypass surgery in 5-12 years using the IMA, and with new symptomatology. Out of 87 functioning IMA to LAD grafts, 85 LAD showed no atherosclerotic changes, while in the same patients' other coronary systems significant, de novo stenotic lesions had developed.