The investigation and management of factors affecting early femorodistal vein graft patency.

This thesis investigates the principal factors responsible for early failure of femorodistal vein grafts. Chapter 1 provides an overview of severe lower limb ischaemia which is their principal indication. Chapter 2 outlines the role of surgery in the management of the severely ischaemic limb, concentrating on the development of distal bypass using autogenous vein. Chapter 3 considers the multiple causes of vein graft failure, concentrating on the early period and includes an account of currently employed methods designed to reduce the problem. Chapter 4 is a retrospective review of the results of 130 in situ vein grafts performed at Leicester Royal Infirmary in the 8 year period prior to the commencement of this study. The primary early failure rate was 30%, with two thirds of patients undergoing amputation. Chapter 5 outlines the methods used in a series of 42 patients undergoing distal vein bypass. Preoperative assessment included arteriography and 3 methods using Doppler ultrasound. Doppler signal augmentation by dependancy and by Pressure Generated Runoff (PGR) were compared. Intraoperative methods included on-table arteriography, prebypass resistance measurement, completion flow and resistance measurement, and completion arteriography. A new system of continuous monitoring using Doppler ultrasound was employed to study the early postoperative period. There were 10 early failures, 9 of which resulted in amputation. None of the preoperative investigations was able to discriminate between successful and failed cases, although dependant Doppler and PGR provided additional qualitative information regarding distal runoff. Prebypass resistance was the best single investigation for predicting outcome prior to reconstruction. Measurement of graft resistance provided the best means of bypass assessment, although maximum benefit was achieved when combined with arteriography. The continuous monitoring system proved to be a reliable means of following early graft haemodynamics and was able to predict outcome in 93% of cases.