PRESERVED ENDOTHELIAL FUNCTION AND MORPHOLOGY IN CANINE ARTERIAL GRAFTS UNDER CONDITIONS OF POOR DISTAL RUNOFF

Late graft failure is still a significant problem particularly in vess els with poor runoff, In the present study, we examined whether poor r unoff conditions contributed to either functional or morphological cha nges in experimental canine autogenous arterial grafts. Four weeks aft er grafting, isometric tension studies were performed on rings obtaine d from femoral arterial grafts with poor runoff and the findings were compared to rings from grafts with normal runoff. The flow rate and ta u variation (wall shear stress variation) ire the limbs with poor runo ff (18.5 +/- 4.2 ml/min, 52.9 +/- 7.0 dyne/cm(2)) were significantly l ower than those of the control limb (66.4 +/- 9.2 ml/min, 201.1 +/- 9. 6 dyne/cm(2)). Acetylcholine (ACh), adenosine 5'-diphosphate (ADP), an d A23187 (calcium ionophore) caused comparable endothelium-dependent r elaxations in the two groups. Smooth muscle relaxation in response to sodium nitroprusside was also comparable in the two groups. No apparen t intimal thickening of the arterial grafts was observed in the canine arterial grafts with normal or poor runoff. Scanning electron microsc opy demonstrated mild endothelial cell damage in implanted autogenous arterial grafts. At 7 to 14 days after grafting, the endothelial cell layer in both groups of grafts appeared to be normal. These results ar e markedly different from our previous findings with vein grafts in wh ich pronounced intimal thickening was associated with an impairment of the endothelium-dependent responses under conditions of poor runoff. Based on these findings, the intact endothelial function and the absen ce of intimal thickening under conditions of poor runoff may thus expl ain the improved patency of autogenous arterial grafts compared to the vein grafts in aortocoronary revascularization. (C) 1997 academic Pre ss.