Monitoring and surveillance of hemodialysis arteriovenous grafts to prevent thrombosis
- Michael Allon, MD
Michael Allon, MD
- Professor of Medicine
- University of Alabama at Birmingham
- Section Editors
- Jeffrey S Berns, MD
Jeffrey S Berns, MD
- Editor-in-Chief — Nephrology
- Section Editor — Dialysis
- Professor of Medicine
- Perelman School of Medicine at the University of Pennsylvania
- John F Eidt, MD
John F Eidt, MD
- Section Editor — Vascular and Endovascular Surgery
- Professor of Surgery
- University of South Carolina School of Medicine Greenville
- Joseph L Mills, Sr, MD
Joseph L Mills, Sr, MD
- Section Editor — Vascular and Endovascular Surgery
- Professor and Chief
- Division of Vascular Surgery and Endovascular Therapy
- Baylor College of Medicine
- David L Cull, MD
David L Cull, MD
- Section Editor — Arterial and Venous Access
- Clinical Professor, Department of Surgery
- University of South Carolina School of Medicine
Hemodialysis requires access to blood vessels capable of providing rapid extracorporeal blood flow. These requirements are currently best met by both primary arteriovenous (AV) fistulas and synthetic grafts. (See "Overview of chronic hemodialysis vascular access".)
Issues surrounding monitoring and surveillance of hemodialysis AV grafts in the attempt to prevent thrombosis and graft failure are presented in this topic review. Similar issues for hemodialysis AV fistulas are discussed separately. (See "Clinical monitoring and surveillance of the mature hemodialysis arteriovenous fistula".)
RATIONALE FOR MONITORING AND SURVEILLANCE OF ARTERIOVENOUS GRAFTS
The assessment of hemodialysis AV grafts for stenosis is performed using clinical monitoring and noninvasive surveillance methods. Unfortunately, the ability to detect stenotic lesions does not necessarily mean that clinical outcomes are improved, such as a decreased rate of thrombosis and/or improved graft survival .
More than 90 percent of thrombosed grafts have a stenotic lesion, suggesting that such an anatomic abnormality is required for graft thrombosis. Noninvasive monitoring methods have a relatively high positive predictive value for detecting >50 percent graft stenosis. A randomized, controlled trial  found that abnormalities detected by clinical monitoring had a 70 percent positive predictive value (PPV) for hemodynamically significant AV graft stenosis, compared with Duplex ultrasound, which had an 80 percent PPV. However, in general, fewer than half of grafts with >50 percent stenosis are destined to thrombose in the absence of preemptive angioplasty. Any type of program to preemptively identify and treat stenosis necessarily results in a substantial number of superfluous angioplasties. To complicate matters, the vascular injury resulting from angioplasty may actually stimulate neointimal hyperplasia and accelerate graft restenosis and potentially graft loss .
Clinical monitoring refers to assessments that can be performed by physical examination of the access or by using readily available information that is collected in the course of treating dialysis patients . A number of studies have observed that a hemodynamically significant (>50 percent) stenosis is present in approximately 70 to 90 percent of patients identified to have abnormalities of clinical monitoring [2,5-9]. The major advantages of clinical monitoring are: it is free, it does not require additional equipment or personnel, and it can be performed by multiple staff members.
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- RATIONALE FOR MONITORING AND SURVEILLANCE OF ARTERIOVENOUS GRAFTS
- CLINICAL MONITORING
- Intra-access blood flow monitoring
- Duplex ultrasonography
- Static venous dialysis pressure
- OUR APPROACH
- KDOQI RECOMMENDATIONS
- Indications for referral
- INFORMATION FOR PATIENTS
- SUMMARY AND RECOMMENDATIONS