Holding Pressure AVF/AVG Creation Show Notes
Name of Surgery: AVF/AVG Creation
Gowri Gowda, Tulane University School of Medicine, MS3
Daniela Medina, Penn State College of Medicine, MS4
Dr. Gerry Victor, LSU Health New Orleans, PGY1
- Rutherford's Vascular and Endovascular Therapy 9th Edition Chapter# 175,176,178,179
- Landmark paper: benefits of regional vs local anesthesia on AV fistula outcomes titled“Effect of regional versus local anesthesia on outcome after arteriovenous fistula creation: a randomized controlled trial” by Aitken et. al found that regional brachial plexus block anesthesia results in greater vasodilation and increased short-term blood flow was associated with higher primary patency at 3 months compared to local anesthesia.
- SVS reporting standards for HA access: reference for surgical dialysis access placement and revision
- VSITE Review - Vascular Access
Underlying disease featured in episode
- Pathophysiology/etiology: Chronic Kidney Disease (CKD) is defined as decreased kidney function (estimated as an eGFR<60) for three or more months or the presence of kidney damage indicated by a urinary albumin excretion of ≥30 mg/day).
· Pathophysiology: The pathophysiology of CKD is variable based on the underlying condition. Two common etiologies are diabetic nephropathy and hypertensive nephropathy. Diabetic nephropathy is a result of chronic hyperglycemia which results in the glycosylation of the basement membrane and plasma hyperfiltration. This ultimately results in glomerular damage. Hypertensive nephropathy is a result of long standing arterial hypertension and increased capillary hydrostatic pressure in the glomeruli as well as ischemic glomerular damage.
· Etiology: Conditions that can cause chronic kidney disease include diabetic nephropathy, hypertensive nephropathy, glomerulonephritis, and polycystic kidney disease. CKD stage is used to guide the management and risk stratify for major complications of CKD such as all-cause mortality, cardiovascular mortality, and progression of kidney disease. . Appropriate staging includes cause of disease, eGFR level, and category of albuminuria. Decline in kidney function is typically asymptomatic. However, when a patient reaches ESRD (eGFR<15) they may show signs such as uremia, electrolyte imbalances, volume overload, and bone disease.
· Epidemiology: With an aging population and a rise in the incidence of diabetes, CKD and ESRD are becoming increasingly prevalent diagnoses in the United States. The prevalence of ESRD reached 746,557 in 2017 with an increase in incidence by 2.3% from 2017 to 2018. Data from the United States Renal Data System reported a rise in ESRD patients receiving hemodialysis from 84,537 to 112,818 between the years of 2000-2018. Medicare spending for ESRD patients increased from $36.1 billion in 2009 to $38.7 billion in 2018.
- Patient Presentation
· Case: Our patient is a 60 year old right-hand dominant female with a past medical history of diabetes, hypertension, hyperlipidemia, and CKD with an eGFR of 20. She has no surgical history and has a family history of heart failure and diabetes. She does not currently work, drinks around 2 glasses of wine a week, and quit smoking 10 years ago. Her current medications include atorvastatin, lisinopril, and aspirin.
· History: H&P of a patient referred for access creation should elicit hand dominance and work history because they can affect where the fistula or graft should be positioned. It is especially important to note any previous access procedures, prior central lines, pacemakers, thoracic surgeries, or other venous system procedures. A history of chronic infections, immunosuppression, skin diseases, history of stroke, and extremity weaknesses may also affect choice of procedure.
· Physical Exam and Imaging: discussed in preop assessment section.
- Treatment (Medical/Surgical)
· Non-temporary treatment options include kidney transplantation and dialysis (requires AV Fistula creation, AV graft creation, or peritoneal dialysis access placement).
- Indications for surgery:
· The treatment of choice for ESRD is kidney transplantation as it provides a higher quality of life and a lower mortality risk for patients when compared with dialysis.
· Patients who are unable to receive a transplant have a choice between hemodialysis through a hemodialysis catheter, AV Fistula, AV graft, or peritoneal dialysis based on various patient-specific factors.
· The SVS’s clinical practice guidelines and the National Kidney Foundation - Kidney Disease Outcomes Quality Initiative (NFK-KDOQI) guidelines align in their recommendation to refer patients to a vascular access surgeon for permanent hemodialysis access when their creatinine drops below 25 mL/min. So for our patient, her GFR of 20 warranted a referral to vascular surgery.
· Early access placement, ideally more than 4 months before the initiation of dialysis, decreases the risk of sepsis and death. This has been attributed to a decreased need for the use of central venous catheters for temporary hemodialysis access.
- Preop Preparation:
- The first step in a successful permanent AV access placement is a thorough preop evaluation.
- Comorbid conditions impacting access patency rates include age, diabetes, peripheral vascular disease, smoking, hyperparathyroidism, and anemia.
· Age, Diabetes, and Smoking have been more extensively studied than others. Retrospective observational studies have shown that smoking increases both early and late failure of AV access. ESRD patients who are smokers should be counseled on smoking cessation and referred to a tobacco cessation program before their AV access procedure.
· Studies regarding age and its effects have also been largely retrospective observational studies but with conflicting results. A meta-analysis of 13 studies by Lazarides et al. looked at dialysis outcomes in elderly patients and found a higher rate of radiocephalic AV access failure in elderly patients compared with the non elderly. Additionally this analysis found a statistically significant higher rate of brachiocephalic AVF patency compared to radiocephalic access and no statistically significant difference in AVG placement within the elderly population. In conclusion, for elderly patients, upper arm brachial-cephalic AVF or AVG is the preferable access placement site when compared to a distal radial-cephalic AVF.
· For patients with DM, studies have suggested an increased long term risk of thrombosis and arterial steal. Taking inflow as distal as possible decreases the risk of steal syndrome.
- Surgical steps (relevant images can be found in Rutherford Chapter 175):
Autogenous Access Steps
- The selected artery and vein are identified and dissected.
- The distal end of the vein is transected. Side branches are identified and ligated to maximize flow into the vein and prevent delayed maturation.
- Prior to clamping the artery, systemic heparin may be considered. Alternatively, the artery may be clamped and flushed with heparinized saline.
- An arteriotomy of 4 to 6 mm is made. Limiting the length decreases the incidence of arterial steal
- An end to side AV anastomosis between the end of the vein and side of the artery is performed using a 6-0 or 7-0 monofilament nonabsorbable (prolene) suture. The anastomosis is flushed just prior to completion. An end to side vs side to side anastomosis has been shown to decrease the risk of venous hypertension.
- After the anastomosis is completed, remaining side venous branches are identified and ligated through the main incision. Depending on practice style, stable incisions may be done to ligate additional venous branches not accessible through the main incision. This final step increases flow into the main venous segment and promotes maturation.
Autogenous Access with a Transposition
- If a transposition is required, a one-stage or two-stage technique may be utilized. The benefit of a one-stage technique is the need for only one procedure. The benefit of the two stage procedure is being able to assess whether the vein will mature and be usable. Two stage procedures are recommended for small veins <4 mm.
- If a two stage procedure is selected, the first stage consists of creating the arterio-venous fistula.
- The second stage , the transposition, is performed 4 to 6 weeks later. A superficial tunnel is created. The venous limb of the fistula is transected and passed through the tunnel. A new anastomosis is created between the two ends of the venous limb of the fistula.
- Alternatively, a superficialization of the fistula may be performed. The vein is exposed, side branches ligated, and the vein is mobilized superficially by approximating the subcutaneous tissue below the vein. The vein is transected and mobilized proximal to the anastomosis. A tunnel is created in the subcutaneous tissue. The vein is then passed through the tunnel and once again
- A 6 mm PTFE graft is the graft of choice for an AV graft creation. A tapered graft (4-6mm) should be considered to decrease risk of steal
- The artery and vein selected for use are identified and dissected.
- Subcutaneous tunnel is created using Gore Sheath, the Noon, or the Kelly-Weck tunneler.
- The graft is first anastomosed to the vein in an end-to side fashion using a 6-0/7-0 monofilament suture. The venotomy should ideally be made to optimize venous outflow and prevent any turning or twisting of the vein. Systemic heparin is administered to prevent arterial occlusion. The inflow artery is clamped and arterial anastomosis is completed in a similar fashion. Unlike the autogenous access procedure, the arteriotomy does not need to be strictly limited to 4 to 6 mm as the graft size will limit arterial steal.
- Postoperative care: Postop Care and Evaluation of fistulas and grafts revolve around assessing maturation
· AV fistulas generally can take up to 12 weeks to mature whereas AV grafts are ready in 2 weeks.
· Patients who receive an AV fistula should be assessed by the vascular surgeon 2 weeks post-op, for patency and any early surgical complications such as infection, nerve compression, ischemia, steal syndrome, or extremity swelling.
· Around 4-6 weeks, the fistula should be evaluated for maturity by using a duplex ultrasound to assess diameter, depth, flow through the fistula, and length of access.
· Physical examination for maturity should include feeling for a thrill and pulse, evaluation of the body with the optimal length being 6 to 10 cm, and evaluation of the depth ideally within 1 cm of the skin surface.
- Primary patency is the interval from time of access placement to any intervention required to maintain or reestablish patency.
- Primary assisted patency is the interval time from access placement to maintenance of access patency and includes surgical or endovascular interventions needed to maintain functionality of a patent access as long as it is not occluded.
- Once a conduit gets occluded, you move on to measuring secondary patency, which is the interval time from time of access placement to access abandonment. To learn more about this, listeners can check out the section “time of measurement of patency” in the SVS reporting standards for hemodialysis access.
- The DOPPS study indicated an improvement in AVG primary patency with calcium channel blockers, AVG secondary patency with aspirin, decreased AVG primary patency with warfarin, and improvement in AVF secondary patency with ACE inhibitors.
- There are a multitude of complications that can arise and affect the patency of the AV fistula or graft. In fact, a large portion of the rise in costs during the transition from CKD to ESRD can be attributed to hospitalizations for AV access failures, revision procedures, repeated access placements, and thrombectomies.
- Primary AVF failure is defined as an AVF that fails within three months of use or has never been usable for dialysis. Radio-cephalic fistulas have the highest failure rate and are commonly caused by anatomic problems or lesions that were preexisting or arose after the procedure.
- Thrombosis: Hemodynamic changes and flow disturbances can cause intimal hyperplasia primarily at the outflow anastomosis in an AVG and anywhere along the outflow vein in an AVF. Another factor that can contribute to intimal hyperplasia is repeated puncture of the fistula or graft. Intimal hyperplasia can ultimately lead to stenosis and thrombosis.
- Infection: Infection is the second most common cause of loss of access patency, accounting for 20% of cases. Some of the risk factors for infection include the presence of AV grafts, diabetes, increased age, and repeated cannulation.
- Pseudoaneurysm: Repeated cannulation in the same area of access can result in the formation of a pseudoaneurysm which is a disruption of the vessel wall with a collection of blood contained by fibrous tissue. Pseudoaneurysms have a risk of rupture and infection.
- Dialysis Access Steal Syndrome: Due to the increased blood flow through the AV access, there can develop a decrease in blood flow to the distal extremity. Clinical features of steal syndrome include hand pain, diminished sensory or motor function, or coolness. Risk factors include previous access procedures, diabetes, PAD, CAD, a history of steal syndrome, and female gender. Steal syndrome can lead to permanent neurological damage to the extremity if not dealt with in an expeditious manner.
- Venous Hypertension: Venous HTN commonly occurs due to central venous stenosis primarily caused by chronic endothelial trauma from a previous catheter placement. Venous HTN impacts access patency and function and can lead to severe edema.
- Top Asked Questions:
- What are the rules of 6’s?
- The rule of 6s is an easy way to evaluate the maturity of a fistula. Six weeks after the AV fistula is created, the fistula should be able to support a blood flow of 600ml/min, be at a maximum of 6mm from the surface, and have a diameter greater than 6mm
- What are the indications for choosing an AV graft vs. an AV fistula vs a temporary catheter?
- Indications for choosing AVF:
· Preferred over AVGs due to their superior patency rates if the patient's vascular anatomical characteristics such as diameter and depth are deemed appropriate through physical examination and vascular mapping via ultrasound.
· Less chances of infection compared to AVGs and temporary catheter.
- Indications for choosing AVGs:
· Once native fistulas in the non dominant arm have been exhausted you move on to the consideration of AVGs.
· If a patient’s vascular anatomy is inadequate for AVF placement.
· If a patient requires an expedited catheter removal, AVGs can be considered to avoid longer maturation time of AVF
· Older age and smaller vein size have been associated with appropriateness of using AVG or AVF
- Indications for choosing temporary catheters include the following:
· Patient is in need of dialysis but has not yet received an AVF/AVG or their AVF/AVG is not ready for use
· AVF/AVG/Peritoneal Dialysis with complications and temporarily not able to be utilized
· Patient requires dialysis but has a transplant confirmed in <90 days
· Acute need of dialysis without indications for permanent HA access placement
- How long do AV Fistulas and AV grafts typically last?
- Autogenous AV access has better primary and secondary patency rates compared to prosthetic AV access (refer to patency paragraph #9 above for definitions of patency).
1-year Primary Patency
2-year Primary Patency
1- year Secondary Patency
2-year Secondary Patency
- Apart from an AV Graft and AV Fistula, what is another method of permanent dialysis?
- Peritoneal dialysis (PD) is an alternative method of dialysis that utilizes the peritoneum as a membrane for fluid dissolution and exchange.
- PD is as effective as hemodialysis access (HA) with the only absolute contraindication being a lack of peritoneal membrane. However, there are other factors to consider when choosing between PD and HA for dialysis access. Medical considerations include previous peritoneal scarring, adhesions, or hernias. Additionally, because PD is performed by the patient and not in a dialysis center, it is vital to assess any patient specific factors (physical, social, environmental) that could prevent them from adhering to their dialysis regimen.
- When working up a patient for dialysis access, PD should be considered as a potential option. If a patient is deemed suitable for PD, it can provide a much higher quality of life than HA. PD can be performed from the home relieving the patient of visits to a dialysis center multiple days during the week. PD can also be performed overnight while the patient is asleep and does not require needle sticks.
1. Misskey, J., & Hsiang, Y. (2015). The First Arteriovenous Fistula: A History of Hemodialysis Access and a Forgotten Pioneer. In Journal of Vascular Surgery (Vol. 61, Issue 6, p. 81S). Elsevier BV. https://doi.org/10.1016/j.jvs.2015.04.156
2. Polo JR. Kenneth Charles Appell, M.D.: the surgeon who performed the first radiocephalic fistulas for hemodialysis. Am Surg. 2006 Feb;72(2):172-3. PMID: 16536251.
3. Annual data report. USRDS. (n.d.). Retrieved February 21, 2022, from https://adr.usrds.org/2020/end-stage-renal-disease/1-incidence-prevalence-patient-characteristics-and-treatment-modalities
4. Chopra, V. Central venous access devices and approach to device and site selection in adults. In T. Post (Ed.). UpToDate, Waltham, MA (accessed on February 20, 2022): UpToDate.
5. Oliver, M., Quinn, R. Approach to the adult patient needing vascular access for chronic hemodialysis. In T. Post (Ed.). UpToDate, Waltham, MA (accessed on February 20, 2022): UpToDate.
6. Woo, K. Arteriovenous fistula creation for hemodialysis and its complications. In UpToDate. UpToDate, Waltham, MA. (Accessed on February 22, 2022)
7. Woo, K. Arteriovenous graft creation for hemodialysis and its complications. In T. Post (Ed.), UpToDate. UpToDate, Waltham, MA. (Accessed on February 22, 2022).
8. Aitken, E., Jackson, A., Kearns, R., Steven, M., Kinsella, J., Clancy, M., & Macfarlane, A. (2016). Effect of regional versus local anaesthesia on outcome after arteriovenous fistula creation: a randomised controlled trial. Lancet (London, England), 388(10049), 1067–1074. https://doi.org/10.1016/S0140-6736(16)30948-5
9. Lazarides, M. K., Georgiadis, G. S., Antoniou, G. A., & Staramos, D. N. (2007). A meta-analysis of dialysis access outcome in elderly patients. Journal of vascular surgery, 45(2), 420–426. https://doi.org/10.1016/j.jvs.2006.10.035
10. Pisoni, R. L., Gillespie, B. W., Dickinson, D. M., Chen, K., Kutner, M. H., & Wolfe, R. A. (2004). The Dialysis Outcomes and Practice Patterns Study (DOPPS): design, data elements, and methodology. American journal of kidney diseases : the official journal of the National Kidney Foundation, 44(5 Suppl 2), 7–15. https://doi.org/10.1053/j.ajkd.2004.08.005
11. Sidawy AN, Gray R, Besarab A, Henry M, Ascher E, Silva M Jr, Miller A, Scher L, Trerotola S, Gregory RT, Rutherford RB, Kent KC. Recommended standards for reports dealing with arteriovenous hemodialysis accesses. J Vasc Surg. 2002 Mar;35(3):603-10. doi: 10.1067/mva.2002.122025. PMID: 11877717.
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