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Arteriovenous Fistula Creation

Abstract

End stage renal disease is common in the United States. It is most commonly caused by diabetes and hypertension. Renal function progressively declines over an unpredictable period of months to years, such that the kidneys are no longer able to perform their function. If failing renal function is not corrected or aided, premature demise is certain. Fortunately, several reliable techniques exist for establishing durable vascular access, to aid in renal replacement therapy, specifically hemodialysis. Here we present the case of a middle aged male, with progressive renal failure who underwent arteriovenous fistula creation, for the purposes of aiding in renal replacement. We outline the scope of the problem, its natural history, preoperative care, selected intraoperative techniques, and relevant postoperative considerations for this process.

Case Overview

There is a growing burden of kidney disease worldwide. In the United States alone there are an estimated 20 million adults with chronic kidney disease (CKD).1 The incidence of disease has doubled since the beginning of the twenty-first century, growing most rapidly in adults older than sixty. The course of kidney disease is unpredictable with many sufferers progressing to end stage renal disease (ESRD) requiring dialysis. As of 2009 there were an estimated 871,000 people receiving treatment for ESRD.1

The patient with ESRD will require renal replacement therapy (RRT) in the form of hemodialysis, peritoneal dialysis, or renal transplant, to sustain life. The demand for donor kidneys is high, there are currently 100,791 people waiting for kidney transplants in the United States, with 3,000 new patients being added to the waiting list each month. The median wait time is 3.6 years, and while awaiting transplantation many patients become too ill to survive transplantation, or pass away prior to being offered an allograft.2 Alternatively there are 398,861 individuals in the United States receiving hemodialysis (HD) for their ESRD.1

In the United States, the easy availability of chronic HD as RRT enables it to serve, for some, as a safe and viable destination therapy; and for others, as a bridge to transplant. Surgical hemodialysis access in the form of an arteriovenous fistula (AVF) provides the best conduit for HD.3 AVFs are surgically created connections between the native arteries and veins, allowing for reliable HD access capable of achieving the necessary blood flow rates for effective filtration. We will discuss the necessary steps in preoperative evaluation, as well as the surgical technique for creating a common type of AVF.

Case Presentation

Our patient is a 56 year-old male with a history of obesity, type II diabetes, hypertension, hyperlipidemia, heart failure and progressive renal failure. He had been in satisfactory health prior to the procedure.

He had no prior extremity or chest surgery. His notable medications at the time of evaluation included aspirin, atorvastatin, isosorbide mononitrate, metoprolol and furosemide. His family history is notable for a sister with type II diabetes induced ESRD requiring renal transplantation. The patient is a social drinker, a previous five pack/year smoker having quit 17 years prior to evaluation. He did not engage in strenuous physical activity and was not employed at the time of evaluation.

Work up revealed an obese gentleman, with a heart rate of 51 beats per minute, blood pressures of 139/66 millimeters of Mercury (mmHg) in the left arm and 182/72mmHg in the right arm. His heart was regular with a grade II/VI systolic ejection murmur. His lungs had rales in the bases with deep inspiration. He had 1+ pitting bilateral lower extremity edema, and his jugular venous pulsation was noted 2 centimeters above the clavicle when reclining at forty-five degrees. A focused extremity exam was notable for right hand dominance. His left arm demonstrated a normal Allen's test and a palpable cephalic vein in the forearm. There were no overlying skin abnormalities noted.

Preoperative upper extremity vascular imaging was notable for a 3.8 millimeter (mm) cephalic vein and a 2.6 mm radial artery, at the lower forearm. Both vessels were patent and without pathology.

Typical Presentation

Typical signs and symptoms of progressive renal dysfunction are often protean. Therefore many patients do not present until their disease is in advanced stages. As the disease progresses, the patient will manifest progressive symptoms of declining renal endocrine function, filtration and excretion of electrolytes, metabolites, hormones and toxins; and failure to maintain a proper whole body fluid balance.

Patients with advanced CKD, a glomerular filtration rate (GFR) of <25 mL/min calculated using the modification of diet in renal disease (MDRD) equation, should be referred to an access surgeon for preoperative evaluation for HD access.3 AV fistula access should be created as soon as possible to allow for the fistula to develop or “mature” appropriately and to perform any additional procedures prior to initiation of HD.3,4 The average maturation time for an autogenous fistula is 2 to 4 months, and data has suggested autogenous access construction 4 to 6 months prior to HD initiation and has been associated with a lower risk of complications including death and sepsis.3,4

Focused History

Given the wide reaching effects of ESRD, in preparation for AVF creation it is imperative to perform a thorough preoperative evaluation including a focused history and physical exam. This information will enable the access surgeon to provide a reasoned evaluation of the patient and offer an informed surgical assessment.

The evaluator should investigate for associated illnesses that are known to decrease the success of HD access creation. These include advanced age, female gender, diabetes mellitus, peripheral vascular disease and severe congestive heart failure.6,7 A history of stroke or extremity incapacitation, chronic infections, skin diseases, and any form of immunosuppression are important as these may all affect the type and location of access procedures.

A past surgical history should be obtained, with focus on prior access procedures, catheter placement; and procedures that utilize the venous system including pacemaker or defibrillator placement, chest surgery, or chest trauma.

The patient’s hand dominance should be established, as well as a work history, and any ongoing need to perform demanding manual tasks. Lastly a discussion should be had regarding the patient’s goals of care and long term outlook.

Physical Findings

Physical manifestations of CKD are often protean, and may not appear until very late in the course of the disease. A general physical exam is important to assess suitability for a surgical procedure.

With regard to AVF creation, the preferred first site of fistula creation is the non-dominant arm. If this is not possible, the exam can be extrapolated to the proposed location of AVF creation.

Evaluate for localized edema, overlying skin disease, prior surgical or traumatic scars, or extensive venous collaterals in the extremity. The extremity distal to the proposed site of AVF creation should be free from neurovascular compromise.

The relevant arterial vasculature should be palpable, soft, easily compressible and symmetric. Bilateral blood pressures should be obtained, and an Allen’s test should be performed to establish the presence of collateral flow distal to the proposed site of AVF creation. Alternatively, the Barbeau test has been noted to be more accurate and less subjective than Allen’s test.8

Imaging Studies

In preparation for AVF creation, an ultrasound (US) mapping of the commonly utilized arteries and veins is of utmost importance. This will allow for assessment of character and adequacy of the arteries and veins. It will provide information about vein diameter, patency, distensibility, depth, congenital variations, and unsuspected pathology.3 The minimum arterial diameter for successful AVF creation is 1.5-2mm, though we prefer a minimum diameter of 2mm.9,10 Regarding venous anatomy, it is important that the lumen be 2.5mm or greater, with unobstructed. Additionally it is ideal, though not imperative, that the selected segment be straight and <1cm from the skin surface.(uptodate fistula) Many of these characteristics can be assessed by clinical examination, although KDIGO guidelines recommend preoperative imaging.

Although operator dependent, and proper training is essential for effective study, US has many advantages. It is non-invasive and evaluates both the arteries and veins in one setting. Therefore, it is performed safely, quickly and easily in the physician’s office, and can be repeated in the perioperative holding area. Additionally, ultrasound study does not require administration of nephrotoxic iodinated contrast, as do other types of vascular imaging

Should there be further question of vascular disease, additional vascular studies including contrast venography, arteriography, computed tomography, or magnetic resonance angiography are available as adjunctive imaging techniques. These modalities must be utilized carefully given the toxic effects of various contrast media in the CKD patient.

Natural History

Progression of CKD is heterogeneous from patient to patient, and the determinants of progression are not well understood.11 Some factors such as HTN, diabetes, and proteinuria are understood, and further investigation is ongoing to elucidate additional influences. Drivers such as genetic predisposition, socioeconomic status and body habitus have been implicated.11 Despite the ongoing research, it is known that CKD is strongly associated with poor outcomes, increased morbidity, and a 5-year death rate that has been estimated to be up to 50%.11,12

Options for Treatment

There are three common types of vascular access that are used for HD:

1) Tunneled catheters
2) Arteriovenous fistulas created with synthetic or biologic material interposed (AV Graft)
3) Autogenous arteriovenous access created by anastomosing a native artery and vein to create a fistula (AVF).

Of the commonly used methods, HD performed via autogenous AV access is superior with regard to patient morbidity and mortality, with the possible exception in the elderly population (>75 years of age).13,14,15 Autogenous access is also associated with lower rates of patient death, infection, and there are higher rates of graft patency.16 Additionally, initial AV access should ideally be located as far distally in the upper extremity as possible, in order to preserve more proximal locations for any future procedures.

Rationale for Treatment in this Case

A careful preoperative evaluation of our patient revealed satisfactory arterial and venous conduits for creation of a radio-cephalic AVF in the patient’s nondominant arm. We will focus our discussion on creation of the AV fistula, a common and reproducible technique for establishing HD access.

Special Considerations

Special considerations for this procedure include:

1) Ensuring that the patient is healthy enough to undergo surgical intervention, as this patient population can be quite ill at baseline.3 This would also influence the type of anesthesia used in these patients.
2) Ensuring that there is no overlying skin or soft tissue infection at the proposed site.17
3) The cephalic vein is preferred to other veins, given its ease of both access and dissection.
Additionally, the preferred arterial conduit is the radial artery due to its proximity to the cephalic vein in comparison to the ulnar artery.3
4) The surgeon ideally utilizes standard surgical magnification.

Step-by-Step Technique

A. Type of Anesthesia

This procedure is regularly performed under general anesthesia or monitored anesthesia care (MAC) with or without intravenous sedation. The approach is based on the patients baseline risks and ability to tolerate anesthesia. If performed under MAC, either local anesthesia or a peripheral nerve block is obtained in the holding area.

B. Patient Positioning

The patient is positioned supine with the operative arm abducted and resting comfortably on a specialized wide arm board designed for hand surgery. If this is not available, it is possible to have two standard sized arm boards placed next to each other.

C. Exposure and Surgical Approach

Determination of the location of the cephalic vein and radial artery must be made. This can be done with the aid of preoperative US and manual palpation. If the artery and vein are near to each other, a single curvilinear incision is acceptable. If the vessels are separate from each other, it is better to perform two parallel longitudinal incisions and create a subcutaneous tunnel through which to position the cephalic vein at the time of anastomosis. In our case the artery and vein were in close proximity.

D. Therapeutic Intervention

1) After injecting local anesthetic, a 5cm curvilinear incision is made over the artery and vein. It is important that the incision be made over the artery and vein, but with attention to bony, nerve, ligamentous and tendinous structures of the arm and hand. The proximal end of the incision should be closest to the vein, or directly superficial to it, in the event further proximal extension of the incision is necessary to mobilize the vein or ligate collateral branches.
2) The subcutaneous tissues and fat are carefully dissected with a combination of sharp dissection and electrocautery.
3) Identify the cephalic vein in the radial groove and dissect it proximally and distally to expose a 4cm segment that is of an appropriate diameter.
4) Ligate vein branches with braided suture.
5) Identify and palpate the radial artery, as it courses parallel to the cephalic vein and sharply dissect a 4cm portion that is of adequate caliber.
6) Place a vessel loops proximally and distally along the artery. These should be double looped, to be used for retraction and occlusion of the artery. This is less disruptive to the artery than vascular clamps, and does not crowd the small surgical field.
7) Ligate the cephalic vein at the distal most end of its course. Be sure to mobilize adequate length of the vein proximal, such that it will anastomose with the artery in a tension free manner. Then, spatulate the vein at an oblique angle to perform a larger anastomosis.
8) Flush the proximal end of the vein with heparinized saline solution; this will enable evaluation of vessel caliber as well as any side branches or iatrogenic vein injuries that may need repair. Place a Bulldog clamp proximal on the vein.
9) After proximal and distal control of the artery (with vessel loops), an arteriotomy is created, the length of which should be limited to 4-6mm to limit the risk of creating a vascular steal phenomenon. This is especially important with a small diameter artery. The size of the arteriotomy should roughly correspond to the spatulated diameter of the vein.
10) Create an end-to-side anastomosis between the cephalic vein and radial artery using 6-0 or 7-0 polypropylene suture in a continuous running fashion, as this will prevent enlarging of that anastomosis which may also lead to steal phenomena.
11) After completing the anastomosis release the clamp on the vein, followed by the vessel loops on the proximal and distal portions of the artery.
12) Palpate the newly created fistula to ensure that there is a palpable thrill indicating appropriate flow.

E. Closure of Wound

13) Close the subcutaneous tissue over the fistula using a running 3-0 braided stitch. Close the skin in a single layer using a 4-0 monofilament stitch. Single layer skin closure is also adequate in cases with minimal subcutaneous tissue.

F. Immediate Post-operative Care

Place a standard postoperative occlusive dressing. Some pressure dressing may be necessary in the event that the patient is at elevated risk of raw surface or other postoperative venous bleeding. This should not be placed proximal to the incision to avoid pressure on the proximal vein and occlusion of it. Postoperative pain should be minimal; patients often do not require opiate pain medication. Upon discharge the patient should receive instructions for hand exercises to start 1-2 days postoperatively. These exercises should increase blood flow through the venous system, which in turn will aid in maturation of the AV fistula.

G. Post-operative Restrictions, Plan for Follow-up

Postoperatively activity is minimized for the immediate postoperative period. The patient is instructed to avoid lifting heavy objects for 14 days postoperatively. Additionally they are instructed to palpate their newly created fistula every day, and should a thrill be absent to contact their surgeon immediately. The patient will follow up in the surgical clinic approximately two weeks postoperatively, to assess healing and fistula patency, and again six to eight weeks postoperatively to evaluate for fistula maturation.

Discussion

Here we present the case of a 56 year-old male with type II diabetes leading to ESRD. He underwent an uncomplicated left forearm radio-cephalic AV fistula creation and recovered without complication. He was seen in follow up eight weeks after surgery and found to be in satisfactory health, though his GFR has continued to decline such that he is requiring increasing doses of furosemide to maintain a euvolemic state. On exam, his left forearm, over the site of the AV fistula, had an excellent palpable thrill and auscultatable bruit, though it had not yet matured to the point that could be accessed for HD. He will continue to meet with his outpatient nephrologist to assess maturation of the fistula and plan for eventual initiation of HD.

Over the past ten years, more than one million patients in the United States have initiated hemodialysis. This process has almost become routine, counseling patients that this is a “minor” procedure. This is made possible largely through increased safety and simplification of vascular access creation, and is no small feat when considering that the patient population inherently has a diminished baseline secondary to comorbid disease.18

When chosen appropriately and monitored carefully it is possible to safely perform this procedure with relatively low risk of complication. Of the available methods, arteriovenous fistula creation remains the most reliable method for providing RRT in patients with ESRD. However, outcomes studies of AV fistula creation note that primary failure of the fistula remains a major issue.20 There is no clear consensus on predictors of this phenomena, however it is thought that arterial diameter was most strongly associated with failure. The mean initial arterial diameters for patent brachiocephalic, brachiobasilic and radiocephalic AV fistulae were 4.7 ± 1.0, 4.4 ± 1.2, and 2.9 ± 1.2 mm, respectively.

When compared with other means of obtaining vascular access, AV fistulae present lower risks of morbidity in the form of infection and technical complications.18,19 Additionally, the rates of cardiovascular and infection related mortality after AV fistula creation is 3.1% versus 9.7% after catheter placement or 4.8% after graft placement.18 These estimates are amplified in the older and increasingly more comorbid patient. This morbidity and mortality risks are not trivial when considering the large number of people who will require RRT as a bridge or destination therapy.

With this burden in mind, multiple studies are underway to further refine the discussion of AV fistula creation and further optimize patient outcomes. It will be important to define testing modalities to ensure adequate extremity perfusion after fistula creation. Further work is ongoing to further refine alternative techniques of access creation such as catheter placement or AV graft placement, in an effort to minimize burdensome complications. Most importantly, work continues to better characterize biologic determinates of renal failure, as well as its progression towards ESRD requiring RRT.

Disclosures

None

Statement of Consent

Consent for the use of clinical history, radiology, and intraoperative video was obtained from the patient and providers involved in compilation of this case report and filming.

Citations

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