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The treatment of vascular access graft dysfunction: a nephrologist's view and experience
1Austin Diagnostic Clinic, TX, USA.
Insights
Expanded polytetrafluoroethylene grafts used for hemodialysis are prone to venous stenosis and thrombosis. Pharmacomechanical thrombolysis (PMT) offers a safe and effective treatment for thrombosed grafts, combining mechanical clot removal with pharmacological agents.
Area of Science:
- Nephrology
- Vascular Surgery
- Interventional Radiology
Background:
- Chronic hemodialysis relies on expanded polytetrafluoroethylene grafts for vascular access.
- These grafts are susceptible to venous stenosis and thrombosis, compromising dialysis efficiency and graft longevity.
- Current screening for venous stenosis lacks an optimal test, making patient selection for treatment crucial.
Purpose of the Study:
- To evaluate treatment options for venous stenosis and thrombosis in hemodialysis grafts.
- To assess the efficacy and safety of percutaneous transluminal angioplasty (PTA) and pharmacomechanical thrombolysis (PMT).
Main Methods:
- Review of percutaneous transluminal angioplasty (PTA) for venous stenosis.
- Analysis of pharmacomechanical thrombolysis (PMT) for thrombosed grafts, involving pharmacological and mechanical clot removal.
- Comparison with pharmacological thrombolysis and mechanical thrombolysis using saline.
Main Results:
- PTA is a safe and reasonably effective treatment for venous stenosis, preserving access sites.
- Pharmacomechanical thrombolysis (PMT) is a practical, quick, effective, and safe treatment for thrombosed grafts.
- PMT integrates angiography, thrombolysis, and angioplasty in a single procedure.
- Mechanical thrombolysis using saline demonstrated equal effectiveness and safety compared to PMT.
Conclusions:
- Venous stenosis and thrombosis are significant complications of expanded polytetrafluoroethylene grafts in hemodialysis.
- Pharmacomechanical thrombolysis (PMT) and mechanical thrombolysis are effective endovascular strategies for managing thrombosed grafts.
- PTA remains a valuable option for treating venous stenosis, with surgical revision potentially offering better long-term patency.
Abstract:
Chronic hemodialysis, as it is practiced today, is heavily dependent on the use of the expanded polytetrafluoroethylene graft for vascular access, although it is prone to the problem of venous stenosis and its sequela, thrombosis. The natural history of untreated venous stenosis is to decrease the efficiency of dialysis and to limit the life expectancy of the graft. Prospective treatment of venous stenosis has been advocated and percutaneous transluminal angioplasty (PTA) has been shown to be safe and reasonably effective for this purpose. Because there is no optimum screening test for venous stenosis, patient selection for PTA is particularly important. The use of a group of clinical indicators that serve to indicate a significant degree of graft dysfunction has been recommended for this purpose. Long-term patency may be better when venous stenosis is surgically revised; however, PTA has a number of advantages, especially the preservation of potential vascular access sites. Endovascular metallic stents have been used to preserve patency following PTA with disappointing results except in selected cases with central lesions. Three types of percutaneous thrombolysis have been studied for the treatment of thrombosed access grafts. The technique of pharmacological thrombolysis in which a lytic enzyme is infused into the clotted graft has proven to be unsatisfactory. The more recently developed technique of pharmacomechanical thrombolysis (PMT) has proven to be practical for use in the dialysis patient. This procedure consists of two components, a pharmacological phase in which lytic enzyme is administered and a mechanical phase in which the residual clot is macerated and removed to restore flow. This technique offers the benefits of being quick, effective, and safe. Additionally, it combines angiographic evaluation of the access, thrombolysis, and angioplasty of stenotic lesions. Mechanical thrombolysis, performed in a manner identical to PMT except that saline is used in place of the lytic enzyme, has been shown to be equally effective and safe.