[Evaluation of arteriovenous shunts following venous by-pass with the saphenous vein in situ. A suggested approach (author's transl)].

An isotopic method employing microspheres of serum-albumin of a mean diameter of 15 microns was used to study the problem raised by the development of arteriovenous fistulae following saphenous by-pass in situ, enabling measurement of shunt flow and qualitative evaluation of the distal bed. Shunt blood flow varies greatly from practically negligible quantities to a maximum of 90%. Comparing data from angiography during operation with these data showed a parallel between the worst angiographic appearances, the poorest scintigraphy images, and the most marked shunts. Sustained clinical manifestations of the fistulae were apparent in shunts of over 60% only. Signs of ischaemia were absent, even in shunts taking 90% of by-pass blood flow. Arteriovenous fistulae induced by by-pass operations employing the saphenous vein in situ appear, therefore, to be relatively well-tolerated. Ligature of the most important, preferably proximal, collaterals is nevertheless recommended, to reduce disturbing side-effects as far as possible, and loss of flow to the distal arterial bed in cases with very large fistulae.