Vein to artery grafts: a study of re-innervation in relation to neo-intimal hyperplasia

This study was undertaken to determine whether there is an association between the sympathetic re-innervation and development of neo-intimal smooth muscle hyperplasia in vein to artery grafts. Iliolumbar vein to iliac artery grafts were placed in 21 rats by microsurgical techniques. Graft innervation and neo-intimal thickness were examined at five time intervals between 1 and 32 weeks after grafting. Nerve fibres were demonstrated microscopically by formaldehyde-induced fluorescence of catecholamines. The degree of innervation was quantitated by counting the nerve profiles and this was compared with the amount of neo-intimal hyperplasia. The distance between adventitial nerve profiles and neo-intima ('diffusion' distance) was measured to determine whether there was a trophic interaction between the two. These data were compared with similar measurements in control iliac arteries in the same animals. Although the development of both graft innervation and neo-intimal hyperplasia occurred coincidentally, no definite quantitative association between the two was established.