Maintaining Patency of Vascular Access for Haemodialysis

All types of vascular access, a necessity for haemodialysis, are prone to thrombosis and if untreated this results in failure. Thrombosis results from the combination of impaired blood flow, endothelial and vessel wall injury and a propensity towards pro-coagulative states, either intrinsic or aggravated by dialysis or dehydration. The treatment of access thrombosis relies on removal of the clot (thrombectomy) and treatment of the underlying problem. In most cases this is stenosis secondary to neointimal hyperplasia which can occur early (failure to mature) or later. Pharmacological approaches have largely been shown to be ineffective at prevention of thrombosis. The mainstay of preventing access failure may be in surveillance and detecting stenosis prior to occlusion although the optimal protocol to achieve this remains undefined. Management of thrombosed access is via either surgical and radiological approaches. Multiple techniques and devices are available for thrombectomy and the choice is usually based on local expertise and availability rather than evidence as few trials have been performed to allow robust comparisons. This paper outlines the basis of access thrombosis and discusses the currently available techniques for treatment.