Brachial Axillary AV Graft: Approaches and Hemodynamics

The brachial axillary arteriovenous (AV) graft is essential for patients needing long-term dialysis access. Understanding the approaches and hemodynamic considerations is vital for optimal outcomes. The choice of materials, procedures, and anatomical factors significantly impact AV graft success.

This article explores the complexities of brachial axillary AV grafts, covering aspects from vessel anatomy to alternative placement options, aiding healthcare professionals in creating effective vascular access.

Anatomy Of Brachial And Axillary Vessels

The brachial and axillary vessels form a network in the upper limb, facilitating blood flow between the heart and the arm. The axillary artery, continuing from the subclavian artery, becomes the brachial artery past the teres major muscle. This transition is key, as the brachial artery supplies the arm, forearm, and hand. Understanding the anatomical course and branching patterns of these vessels is critical for clinicians performing vascular access procedures.

The axillary artery is divided into three parts by its relation to the pectoralis minor muscle. Each part gives rise to branches supplying the shoulder and thoracic region, which also serve as collateral pathways in cases of vascular occlusion. The axillary vein, running parallel to the artery, provides venous return from the upper limb to the heart. Its proximity necessitates careful consideration during surgery to avoid complications.

As the axillary artery transitions into the brachial artery, it runs along the arm’s medial aspect, accompanied by the median nerve. The artery gives rise to several branches, ensuring adequate perfusion to the arm and forearm, even with vascular compromise.

Types Of Conduits

Selecting the appropriate conduit for a brachial axillary AV graft affects its long-term success and functionality. The choice of material influences hemodynamic properties, biocompatibility, and durability.

Polytetrafluoroethylene

Polytetrafluoroethylene (PTFE) is a synthetic polymer used in vascular grafts for its chemical inertness and resistance to degradation. PTFE grafts minimize thrombogenicity and promote laminar blood flow. A study in the “Journal of Vascular Surgery” (2020) highlighted their long-term patency rates. However, PTFE grafts can face complications like infection and pseudoaneurysm, requiring strict aseptic techniques and postoperative monitoring. PTFE is recommended for patients with limited autologous vein availability.

Biologic Options

Biologic conduits, such as autologous veins or bovine-derived grafts, offer advantages in biocompatibility and reduced infection rates. Autologous vein grafts, like the saphenous vein, have natural endothelial lining, reducing thrombosis risk. A meta-analysis in “The Lancet” (2019) showed superior patency and lower infection rates with autologous veins compared to synthetics. Bovine-derived grafts provide structural integrity and reduced immunogenicity, useful for patients contraindicated for synthetics. Despite benefits, biologic grafts may face availability issues and potential structural degradation.

Composite Materials

Composite materials combine synthetic and biologic elements to improve graft patency and reduce complications. An example is the heparin-bonded PTFE graft, incorporating an anticoagulant layer to reduce thrombosis risk. Clinical trials, such as in “Annals of Vascular Surgery” (2021), show promising results with composite grafts. These materials offer a tailored approach to vascular access and may become more prevalent in clinical practice.

Procedure Approaches

Procedural approaches for brachial axillary AV graft placement must be tailored to the patient’s anatomy and physiology. The approach influences immediate success and long-term functionality. Surgeons assess vascular anatomy using imaging modalities like duplex ultrasound or magnetic resonance angiography to guide incision site and graft routing.

The surgical approach involves creating an incision along the upper arm to access the brachial and axillary vessels. Precise dissection avoids damage to surrounding structures. Surgeons select the anastomosis site, ensuring adequate vessel diameter and flow. Guidelines recommend a minimum vessel diameter of 3 mm to optimize blood flow and reduce thrombosis risk. The choice between end-to-side or side-to-side anastomosis impacts hemodynamic outcomes.

Intraoperative monitoring of blood flow using Doppler ultrasound verifies anastomosis success. Postoperative care emphasizes monitoring for infection, graft occlusion, or stenosis. Regular surveillance using techniques like physical examination, duplex ultrasound, or fistulography detects early complications for prompt intervention.

Hemodynamic Factors

Hemodynamic factors are crucial for ensuring long-term graft functionality. Blood flow dynamics are influenced by vessel diameter, blood viscosity, and anastomosis geometry. These elements affect shear stress and pressure gradients, impacting patency and risks like thrombosis or stenosis.

Maintaining high flow velocities within the graft minimizes thrombus risk by reducing blood component contact with graft walls. Low flow velocities lead to turbulent flow, promoting endothelial damage and intimal hyperplasia, leading to graft failure.

Anastomosis Angles

The angle of vascular anastomosis significantly influences hemodynamic profiles. A well-executed anastomosis enhances laminar flow and reduces complications like intimal hyperplasia. Studies indicate that angles of 30 to 45 degrees are optimal for minimizing turbulent flow and maximizing shear stress alignment, promoting endothelial cell health and reducing neointimal proliferation.

The alignment of the graft relative to the host vessel impacts blood flow velocity. Acute angles can lead to flow separation and recirculation zones, increasing platelet aggregation and thrombus formation. More obtuse angles facilitate smoother transitions in flow, reducing adverse hemodynamic effects. The angle choice should be tailored to patient anatomy, with intraoperative assessments guiding decisions.

Alternative Placement Regions

When traditional brachial axillary AV graft placement is not feasible, alternative regions may be considered. Alternatives provide options for patients with complex vascular anatomy or previous failed grafts. The femoral region serves as a site, especially for patients with exhausted upper limb access. A review in “The Journal of Vascular Access” (2022) noted comparable patency rates to upper limb placements, though with higher infection risk due to groin proximity.

The chest wall is another viable site, where grafts can connect the axillary artery to the subclavian vein. This approach, while technically demanding, offers a solution for patients with limited access. Anatomical considerations in these sites require thorough preoperative evaluation, often using advanced imaging to map vascular structures. Postoperative monitoring is crucial to identify complications like thrombosis or stenosis. The choice of alternative sites should be guided by a multidisciplinary team, ensuring alignment of patient-specific factors and surgical expertise for optimal outcomes.