The effects of crystalloid potassium cardioplegic solution on arterialized canine vein grafts. Assessment of chronic prostacyclin production and histopathologic alterations.

Efforts to improve myocardial preservation during aortocoronary bypass procedures have led to the perfusion of saphenous vein segments with potassium cardioplegic (KCP) solutions after completion of the distal anastomosis. Recent reports show that the procurement of veins leads to varying degrees of damage, particularly to the endothelial surface, as a result of the dissection itself, the hydrostatic pressure required to distend the veins in obtaining hemostasis and the composition of the solutions used to irrigate the harvested segments. The biologic activity of arterialized vein segments is largely unknown. We tested the hypothesis that the degree of venous injury inherent in vein harvesting may be compounded by perfusion with a potassium-rich solution, a known vascular irritant. The external jugular vein was removed from 18 dogs. Half of the vein was perfused with 300 ml of a KCP solution at 4 degrees C (40 mEq/l KCl, 10 ml sodium bicarbonate, pH 7.6, osmolarity 340 mosmol) and the other half with lactated Ringer's solution (LR). The treated vein was reversed and interposed into the excluded internal carotid circulation. A sham dissection was done on the opposite jugular vein. The veins were harvested after 6 weeks and assayed for spontaneous and arachidonate-stimulated (AS) prostacyclin activity as well as light microscopic analysis of morphologic changes. Spontaneous and AS production of prostacyclin did not differ significantly in the sham, LR and KCP groups: 1539 +/- 709 and 4166 +/- 1802, 1569 +/- 763 and 3767 +/- 2706, 1860 +/- 1233 and 3947 +/- 3347 pg/ml). Light microscopic analysis revealed an intense adventitial fibrotic reaction in the KCP group and the appearance of fibroblast-like cells in the outer layer of the vein wall. The intima was intact in all three groups. We conclude that intimal damage sustained during harvesting is repaired within 6 weeks, and there is no impairment to surface production of prostacyclin. The intense adventitial fibrotic reaction observed in the KCP-treated group has not been previously reported, and its significance remains unexplained.