Surgical preparation of human saphenous vein for coronary artery bypass grafting involving distension and storage in iso-osmotic sodium chloride solution reduced tissue adenosine triphosphate (ATP) (mean(SEM] concentration from 280(20) nmol.g-1 wet wt (n = 25) to 140(30) nmol.g-1 wet wt (n = 12) and the adenosine triphosphate to adenosine diphosphate (ATP:ADP) concentration ratio from 2.4(0.1) to 1.2(0.2). Since removal of endothelium from freshly isolated vein did not affect ATP concentration or ATP:ADP ratio, these changes quantified medial damage. Distension of the vein at a pressure of 150 mmHg caused no change in ATP concentration or ATP:ADP ratio, but these values were reduced progressively by distension at 300 mmHg and 600 mmHg. Damage was not reversed but was exacerbated by subsequent incubation of the distended vein in blood. Distension of the vein at 600 mmHg caused release of tissue lactate dehydrogenase. The data show that acute medial damage can result from distension of the vein but that this does not occur at pressure equivalent to normal arterial pressure. Distension induced medial damage is unlikely to be rapidly reversible.

A prospective randomised study of four different methods of leg wound skin closure after removal of the long saphenous vein was carried out in 113 patients undergoing coronary artery bypass grafting. These methods were: (1) continuous nylon vertical mattress suture (27 patients); (2) continuous subcuticular absorbable (Dexon) suture (29 patients); (3) metal skin staples (Autosuture) (27 patients); and (4) adhesive sutureless skin closure ("Op-site") (30 patients).All wounds were examined by two independent observers at five, 10, and 45 days after operation. At five days, inflammation, extent of oedema, discharge, and infection were assessed. At 10 days attention was paid to the state of wound healing and at 45 days to the final cosmetic appearance. The use of continuous subcuticular suture resulted in significantly less discharge than did the use of metal staples, nylon vertical mattress suture, or Op-site. The incidence of established wound infection was 4*5% overall, with no infection in the wounds closed with Dexon. Assessment of the healing process showed subcuticular Dexon to be more effective than metal staples or vertical mattress nylon suture. The final cosmetic result showed continuous subcuticular suture to be superior to nylon vertical mattress suture and skin staples but as effective as Op-site sutureless skin closure.Coronary artery bypass grafting is now one of the most commonly performed operations in the world. The most widely used conduit for bypassing the obstructed coronary artery is still a reversed segment of the patient' s own long saphenous vein, and no synthetic substitute has yet been found that gives results as good as, let alone better than, autologous vein.' Nevertheless, removal of the entire long saphenous vein is necessary for multiple grafts and requires a long incision in the leg from ankle to groin.2 Despite complications from this wound possibly being troublesome and protracted, this part of the operation is often delegated to a junior member of the surgical team. Surprisingly little attention has been paid to the leg wound in coronary artery bypass grafting operations and in particular to the best method of skin closure. We report here the results of a prospective, randomised study of four different methods of leg wound skin closure.

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 heparinised arterial blood at room temperature. Frozen vein was extracted with perchloric acid. ATP, ADP, and AMP, adenosine, inosine and hypoxanthine concentrations were measured by high pressure liquid chromatography. Prepared vein had ca 50% lower ATP concentrations 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 degrees C, in normal saline at 23 degrees C or 4 degrees C, in Krebs-Ringer bicarbonate buffer at 37 degrees C or at St Thomas's Hospital cardioplegic solution at 4 degrees C. Distention with unlimited pressure did not distension at less than 300 mmHg gave rise to the same changes in ATP concentration and ATP/ADP ratio as in the prepared vein. These results show that vein suffered metabolic changes during preparation for bypass grafting and suggest that uncontrolled distention may contribute to these changes. Such biochemical measurements provide a quantitative estimate of tissue damage and allow objective comparison of different preparative techniques.

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