Radial Artery–Cephalic Vein and Brachial Artery–Cephalic Vein Arteriovenous Fistula




Historical Background


Although Kolff and colleagues reported the development of a hemodialysis machine for renal replacement therapy in 1944, maintenance hemodialysis did not become a reality for another 2 decades because of a lack of reliable vascular access. Simple venipuncture was initially employed, but peripheral veins would not support the flow rates necessary for dialysis. The Scribner-Quinton shunt was the earliest solution proposed and consisted of a cannulated artery and vein connected by an external Teflon tube. At the time of dialysis the Teflon tube could be disconnected so that the artery and vein extensions could be connected directly to the hemodialysis system. The Scribner-Quinton shunt was prone to infection, thrombosis, and dislodgement, and as an exteriorized shunt, it provoked patient apprehension.


The ability to achieve reliable arteriovenous access was solved in 1966 when Cimino and Brescia, two nephrologists at the Bronx Veterans Affairs Hospital’s chronic dialysis unit, reported the successful dialysis of 13 patients by repeated venipuncture of arteriovenous fistulas constructed between the radial artery and the cephalic vein by Appel. They theorized that a surgically created arteriovenous fistula would provide durable venous access with reliable flow rates without high-output heart failure or hand ischemia.


Unfortunately, many patients lack a cephalic vein suitable for creation of an arteriovenous fistula at the wrist, because repeated venipunctures often render the forearm cephalic vein unusable. Alternative fistula constructions, including the anastomosis of the cephalic vein to the brachial artery at the elbow, have since been described. Although a number of options for hemodialysis access, including large-bore central catheters, ports, and synthetic bridge grafts, are in wide use, the radiocephalic or Cimino arteriovenous fistula and the brachiocephalic arteriovenous fistula remain the preferred options for access.




Indications


As outlined in Kidney Disease Outcomes Quality Initiative (KDOQI), every patient with chronic kidney disease (CKD) should have a functioning arteriovenous fistula ready for use when dialysis is initiated. Most surgeons and nephrologists prefer to wait a minimum of 6 weeks between the creation of a fistula and its use. This interval allows time for fistula maturation, which Saad succinctly defines as “a general term used to refer to multiple processes that occur from the time of surgical fistula construction until the time the arteriovenous fistula becomes a functional hemodialysis access. The desired end result of the maturation process is a high-flow, large-caliber, superficial vessel with robust wall structure suitable for reliable repeated dialysis needle access.”


Most nephrologists refer patients to a surgeon when they anticipate a need for dialysis within 1 year to allow time for preoperative planning, scheduling of the procedure, maturation of the fistula, and necessary revisions to the fistula. Typically, a patient will likely require dialysis within 1 year when serum creatinine is 4 mg/dL or greater and creatinine clearance is less than 25 mL/min. The initiation of maintenance hemodialysis is driven by multiple factors, including uremic symptoms, hyperkalemia, and fluid overload.




Preoperative Preparation





  • History. A successful arteriovenous fistula requires an artery with adequate “inflow” and a vein of adequate size and “outflow.” Thus the history and physical should be directed toward identifying a suitable vein, as well as arterial or venous lesions that might limit flow. Arteriovenous fistulas are preferentially placed in the nondominant extremity if the upper extremity vessels are equally suitable. Given the advanced age and increased comorbidities of patients with chronic renal disease, a history of central venous catheters or cardiac devices with transvenous wires, such as pacemakers or defibrillators, is not uncommon. Patients with a history of such devices are at increased risk for central venous stenoses that may compromise outflow, especially when the subclavian vein has been used. Finally, the patient must be asked whether there is prior history of arm trauma or surgery, including prior attempts at hemodialysis access that might compromise flow or complicate the dissection.



  • Physical examination. On physical examination, both radial and brachial pulses are assessed and blood pressure is measured in both arms. Allen’s test can identify the rare patient whose palmar arch depends on radial artery flow, although this does not preclude its use for access. Visual inspection of the neck and chest often reveals evidence of pacemakers, defibrillators, scarring, or venous collaterals consistent with a history of central venous devices. Similarly, examination of the arms can reveal scars from previous injuries or surgical procedures.



  • Duplex ultrasound. Visual inspection and palpation of the cephalic vein is often sufficient. However, many patients, especially those who are obese, may have a cephalic vein of suitable caliber that cannot be seen or palpated. Furthermore, even a cephalic vein of adequate size on physical examination may be compromised proximally. Therefore duplex ultrasound “vein mapping” should be used to accurately assess the diameter of the arm veins before surgery. Preoperative duplex ultrasound can also reveal a central venous stenosis or occlusion. A cephalic vein measuring at least 3 mm in diameter without tourniquet placement and less than 1 cm deep by duplex ultrasound usually matures to a usable fistula. Noninvasive arterial studies are used selectively for patients in which there is the suspicion of arterial occlusive disease.



  • Assessment of comorbidities. Preoperative medical clearance may occasionally be indicated, because patients presenting for access frequently have significant comorbidities. Fortunately, the creation of a fistula is a relatively minor procedure that can usually be completed under local anesthesia. Electrolytes should be routinely assessed before the procedure.





Pitfalls and Danger Points





  • Failure of the cephalic vein to mature. A cephalic vein with an insufficient diameter or without the ability to dilate may fail to mature. The vein should measure a minimum of 3.5 mm and preferably 4 mm to interrogation with a coronary dilator.



  • Anastomotic tension. Inadequate dissection of a sufficient length of distal cephalic vein will limit the ability of the vein to reach the artery without tension.



  • Vein kinking. Proximal “skeletonization” of the cephalic vein is necessary to avoid kinking in the subcutaneous space.



  • Vein twisting. Failure to maintain proper orientation of the cephalic vein causes twisting and stenosis.



  • Inadequate arterial inflow. Poor choice of inflow vessel due to size or because of the presence of a stenosis or occlusion of the proximal inflow vessel may lead to steal or access occlusion.



  • Nerve or vessel injury. Injury to the nerve or vessel may occur because of traction or through use of electrocautery.





Operative Strategy


Selection of a Fistula Site


If a suitable cephalic vein is found at the wrist, the first choice is to perform a radiocephalic fistula, because it is the simplest fistula to construct and preserves more proximal veins as future access sites. If vein size at the wrist is borderline in size, the vein can be explored through a small incision and an attempt made to pass a dilator. If the vein accommodates a 3.5-mm dilator, the incision is extended and the fistula is created. A brachiocephalic fistula at the elbow is performed if a radiocephalic fistula does not prove feasible. The presence of an internal jugular venous catheter in a patient already receiving dialysis is not a contraindication to access placement when suitable veins are found in the ipsilateral arm.


Alternatives in the Absence of Suitable Cephalic Vein


For patients without adequate cephalic vein, the best alternatives are either a basilic vein transposition or a synthetic arteriovenous graft, which are described in subsequent chapters. The basilic vein transposition requires a significantly larger incision and dissection, whereas a synthetic bridge graft is associated with higher rates of infection and thrombosis.


Anesthesia


In the operating room, light sedation or anxiolytics are administered, along with local anesthesia.


Operative Field


The entire arm, including the hand, is prepared circumferentially up to the shoulder and chest to allow easy mobilization of the operative site during the procedure. The entire hand is prepared to allow evaluation of hand perfusion at the conclusion of the case and prevent contamination from sudden and unexpected patient movement. Care must be taken to allow adequate exposure up into the axilla when the patient has consented for possible basilic vein transposition. Magnifying surgical loupes are routinely used.


Heparinization


Regional rather than systemic heparinization is preferred.




Operative Technique


Radiocephalic (Cimino) Arteriovenous Fistula


Incisions


Although separate incisions for the radial artery and cephalic vein exposures are described, a single, oblique incision extending from the cephalic vein distally to the radial artery pulse proximally is preferred ( Fig. 63-1 ). This orientation facilitates mobilization of the vein to the artery. When the cephalic vein is appreciable only with duplex ultrasound, it can be initially identified through a smaller incision that is then extended to the radial pulse.


Mar 13, 2019 | Posted by in VASCULAR SURGERY | Comments Off on Radial Artery–Cephalic Vein and Brachial Artery–Cephalic Vein Arteriovenous Fistula
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