From the Guidelines
Arteriovenous fistulas steal blood flow from distal tissues due to the creation of an abnormal low-resistance connection between arteries and veins, leading to compromised perfusion and ischemia, as described in the 2020 update of the KDOQI clinical practice guideline for vascular access 1. This abnormal connection diverts blood away from the normal capillary networks that supply oxygen and nutrients to downstream tissues, resulting in a range of signs and symptoms, including mild numbness to severe motor impairment or skin ulceration to gangrene necessitating major amputation, as outlined in the study 1. The key factors contributing to this phenomenon include:
- The pressure gradient created by the fistula, which pulls blood through the abnormal connection rather than allowing it to continue through the normal arterial pathway to distal tissues
- The resulting tissue ischemia, which triggers inflammatory responses as cells release cytokines and other mediators in response to oxygen deprivation
- The increased vascular permeability caused by inflammation, allowing fluid to leak from blood vessels into surrounding tissues and contributing to edema formation
- The venous hypertension caused by increased blood flow through the fistula, which impairs normal venous return and further promotes fluid accumulation in distal tissues, as noted in the context of steal syndrome 1. The combination of reduced arterial inflow and compromised venous outflow can lead to tissue necrosis, particularly in patients with pre-existing vascular disease or diabetes, highlighting the importance of careful management and monitoring of arteriovenous fistulas to prevent these complications.
From the Research
Arteriovenous Fistulas and Blood Flow
- Arteriovenous fistulas (AVFs) can steal blood flow from distal tissues, potentially leading to ischemia and further contributing to edema through inflammatory responses 2, 3, 4, 5.
- The creation of AVFs can lead to Hemodialysis Access-Induced Distal Ischemia (HAIDI), characterized by ischemia in extremities due to reduced capillary perfusion, potentially leading to severe outcomes such as tissue necrosis and digital amputations 2.
- High-flow AVFs, defined by excessive blood flow that disrupts overall circulatory dynamics, pose another significant challenge, particularly in patients with cardiovascular compromise 2.
Complications and Management
- The management of AVF complications is complex and often requires specialized techniques to preserve the AVF and avoid its closure 2, 3, 6.
- Techniques discussed in the literature include vein approach like ligation, plication, banding, prosthetic graft interposition, and various arterial interventions like distal radial artery ligation and embolization 2, 3.
- Endovascular methods, such as coil embolization and percutaneous glue embolization, can be used to manage AVF complications, including steal syndrome and high-flow AVFs 3, 6.
- A thorough preoperative workup and careful postoperative monitoring can minimize steal syndrome and prevent permanent impairment 4.
Individualized Approach to Therapy
- The choice of intervention for AVF complications should be based upon the clinical features presented by that individual patient; the clinical condition and prognosis of the patient, stage of the disease, location of the arterial anastomosis, and the level of blood flow within the access 5.
- An individualized, physiologic approach to managing AVF complications is crucial to relieve ischemia and preserve the access 5.