METABOLIC DAMAGE TO HUMAN SAPHENOUS-VEIN DURING PREPARATION FOR CORONARY-ARTERY BYPASS-GRAFTING

Segments of saphenous vein from patients undergoing coronary artery by-pass graft surgery were frozen in liquid nitrogen immediately on dissection (control), after stripping of the adventitia and side branch ligation (manipulation), after distention with blood (distention), or at completion of the last proximal anastomosis (prepared vein). Vein was stored during the operation in patient''s heparinized arterial blood at room temperature. Frozen vein was extracted with perchloric acid. ATP, ADP, AMP, adenosine, inosine and hypoxanthine concentrations were measured by high pressure liquid chromatography. Prepared vein had .apprx. 50% lower ATP concentration and ATP/ADP ratio than control vein, higher concentrations of inosine and hypoxanthine and lower concentrations of AMP and adenosine. ATP concentration and ATP/ADP ratio did not correlate with the time elapsed between dissection and freezing of the prepared vein. The characteristic changes seen in prepared vein were not seen when control vein was simply stored in arterial blood at 23.degree. C, in normal saline at 23.degree. C or 4.degree. C, in Krebs-Ringer bicarbonate buffer at 37.degree. C or in St Thomas''s Hospital [UK] cardioplegic solution at 4.degree. C. Distension with unlimited pressure but not distension at < 300 mmHg gave rise to the same changes in aTP concentration and ATP/ADPratio as in the prepared vein. Vein suffered metabolic changes during preparation for bypass grafting and suggest that uncontrolled distention may contribute to these changes. Such biochemical measurement provide a quantitative estimate of tissue damage and allow objective comparison of different preparative techniques.