[Experimental demonstration of hemogenous growth of various collateral nets in chronic iliac av-fistulas]

A 2 cm long iliac av-fistula is established in 13 dogs. Flow and pressure measurements are performed in the distal fistula artery and the adjacent arteries before and immediately (stage I) as well as 3 months (stage II) and 6 to 12 months (stage III) post shunt. The development of extensive collaterals adjacent to the chronic iliac av-fistula is demonstrated angiographically and by post-mortem vascular casts. After occlusion of the proximal fistula artery a retrograde flow is directed towards the fistula even in the acute stage. This "free" retrograde flow increases from 70 ml/min to 1230 ml/min in stage II and 1755 ml/min in stage III. Collaterals of the tail artery contribute approximately 44%, of the contralateral iliac artery 20% and side branches of the abdominal aorta most of the remaining 36% of the retrograde arterial fistula flow. Successive occlusion of the tail artery and the contralateral iliac artery in stages II and III results in a nearly identical per cent decrease in "free" retrograde flow and in pressure. Even in the pre-fistula stage clamping of the iliac artery induces the same relative pressure-drop in the distal iliac artery. These findings indicate, that the three main collateral networks adjacent to the iliac artery all expand proportionally to their prefistula status in the 6 - 12 months following construction of the iliac av-fistula.