Forearm Loop Graft and Brachial Artery–Axillary Vein Interposition Graft




Historical Background


Kolff’s development of hemodialysis in the 1930s led to a series of advances in the care of patients with end-stage renal disease (ESRD). Although native arteriovenous fistulas and homografts were initial cannulation options for dialysis access, the availability of prosthetic grafts in the 1970s afforded a number of new access sites. Nonetheless, this new type of access generated a new set of complications and expenditures to the health care system, with economic costs of ESRD in the United States at more than $26 billion in 2006.




Indications


The National Kidney Foundation’s Kidney Disease Outcomes Quality Initiative guidelines promote initial fistula formation in the nondominant extremity. The “fistula first” initiative would suggest creating autogenous access on the dominant upper extremity once native fistula options have been exhausted on the nondominant side. However, a common practice is to remain on the ipsilateral nondominant limb and proceed with a forearm loop or upper arm brachial artery–to–axillary vein arteriovenous graft (AVG).




Preoperative Preparation





  • History and physical examination. The decision to implant a forearm loop or brachial-axillary AVG depends on the existing arterial and venous anatomy. A thorough past medical history and a physical examination of the extremities and sites of previous vascular access should be obtained to preserve the greatest number of sites for future access ( Fig. 64-1 ). A strong palpable pulse is required to provide adequate inflow, and a weak pulse may indicate a proximal defect of the artery or heavily calcified vessels, neither of which allows ample flow to support hemodialysis and both of which may predispose the patient to arterial steal syndrome.




    Figure 64-1


    An algorithm to guide the sequence of access site selection. AVF, Arteriovenous fistula; AX-AX, axillary-axillary DA, dominant arm; HD, hemodialysis; NDA, nondominant arm.



  • Venous imaging. Determining target vein patency and the quality of venous outflow is essential to careful planning ( Fig. 64-2 ). Venous duplex mapping is limited to determining the adequacy of venous outflow in the antebrachium, antecubital fossa, and axilla, but venography is required to effectively evaluate the central veins, if it is deemed clinically necessary because of a history of prior interventions. Magnetic resonance venography is an alternative to conventional venography, but images are less dynamic and patients with severe renal dysfunction are at risk of nephrogenic systemic fibrosis. However, recent advances in imaging and contrast technology allow for the use of Feraheme as a contrasting agent, which can safely be used in ESRD patients.




    Figure 64-2


    B-mode ultrasound is used to visualize the cephalic vein in the longitudinal view ( A ) and the basilic vein in the transverse view ( B ) with compression (right) and without compression (left).



  • Preoperative dialysis. Patients taking hemodialysis require dialysis the day before or the morning of surgery.





Pitfalls and Danger Points





  • Selection of adequate inflow and outflow sites. Inflow arteries must be relatively soft and amenable to clamping. Outflow veins should be greater than 3 mm in diameter and free from prior traumatic injury, thrombus, scar, or occlusion.



  • Arterial and nerve injury. Distraction performed too forcefully on neurovascular structures can lead to injury, including arterial dissection or neuropraxia.



  • Graft tunneling. Tunneling the graft too deeply can lead to difficulties in accessing the graft. Care must also be taken to prevent conduit twisting or kinking, which may occur when tunneling too tight of a loop for a forearm graft. When placing a brachial-axillary AVG, the preference is to position the graft posterior to the median nerve to avoid kinking, which can occur if the graft is draped anteriorly over the nerve.



  • Anastomosis. The anastomosis must be constructed at an appropriate angle and beveled to avoid kinking of the hood. Likewise, excessive tension can lead to tenting of the back wall of the artery at the anastomosis.



  • Central venous stenosis. A long-standing tunneled dialysis catheter may increase the risk of a central venous stenosis. Likewise, this catheter may need to be relocated before the placement of the access graft to minimize the risk of postoperative arm edema.





Operative Strategy


Selection of an Arteriovenous Graft


Once native fistula possibilities in the nondominant extremity have been exhausted, placement of a forearm AVG may be considered. A brachial-axillary AVG is a more proximal option usually reserved after failure of a forearm graft without the possibility for endovascular or surgical revision. Additional options include axillary artery–to–axillary vein grafts, chest wall grafts, or the hemodialysis reliable outflow (HeRO, Hemosphere, Eden Prairie, Minn.) “graft catheter” device.


Selection of Sites for Venous Outflow and Arterial Inflow


Potential venous outflow options for a forearm loop AVG include the median antebrachial, median cubital, basilic, cephalic, and brachial veins, but their utilization limits future use for fistula creation. Options for arterial inflow include the brachial, proximal ulnar, and radial arteries. A palpable brachial pulse or use of the proximal radial or ulnar artery decreases the incidence of steal syndrome.


Potential venous outflow options for a brachial-axillary arteriovenous graft include the proximal brachial or basilic veins or the distal axillary vein. As in the loop graft, options for arterial inflow include the brachial, proximal radial, and ulnar arteries. If these arteries are too small, then an axillary-axillary teardrop AVG should be considered (see Fig. 64-1 ).




Operative Technique


Forearm Loop Graft


Incision


A forearm graft requires control of the brachial artery and antecubital veins through a transverse incision approximately 2 cm distal from the antecubital fossa. The vessels are dissected free from the surrounding tissue and encircled with vessel loops for control. In some cases it may be necessary to use the most proximal aspect of the radial or ulnar artery for inflow. Similarly, options for venous outflow can vary considerably. Common choices include the brachial, median antebrachial, median cubital, cephalic, and basilic veins. A minimal touch technique is used to dissect the vein with silicone elastomer (Silastic) vessel loops used for gentle distraction and manipulation of the vein.


Tunneling of the Graft


A tunneling device is used to place the graft in the subdermal space, thus facilitating cannulation, and a counterincision in the distal forearm is required for tunneling. The tunneler is passed from the counterincision in the distal forearm to the antecubital incision, and as the graft is pulled back through the tunnel, avoidance of twisting or kinking of the conduit must be maintained ( Fig. 64-3 ). The tunneling device is then passed from the antecubital incision to the counterincision to pull the graft back through and complete the loop.


Mar 13, 2019 | Posted by in VASCULAR SURGERY | Comments Off on Forearm Loop Graft and Brachial Artery–Axillary Vein Interposition Graft
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