Mar 24, 2022
Holding Pressure AVF/AVG Creation Show
Notes
Name of Surgery: AVF/AVG Creation
Authors:
Gowri Gowda, Tulane University School of Medicine, MS3
Daniela Medina, Penn State College of Medicine, MS4
Dr. Gerry Victor, LSU Health New Orleans, PGY1
Editor:
Yasong Yu
Reviewers:
Amanda Fobare
Farooq Usmani
Core Resources:
- Rutherford's Vascular and Endovascular Therapy 9th Edition
Chapter# 175,176,178,179
Additional Resources:
- 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.
- Diagnosis
-
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.
- Comorbidities:
-
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
Prosthetic Access
- 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.
- Patency:
- 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.
- Complications:
- 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).
Patency Measure
|
Autogenous Access
|
AV graft
|
1-year Primary Patency
|
43%-85%
|
40%-54%
|
2-year Primary Patency
|
40%-69%
|
18%-30%
|
1- year Secondary Patency
|
46%-90%
|
59%-65%
|
2-year Secondary Patency
|
62%-75%
|
40%-60%
|
- 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.
References:
-
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
-
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.
-
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
-
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.
-
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.
-
Woo, K. Arteriovenous fistula creation for hemodialysis and its
complications. InUpToDate. UpToDate, Waltham, MA.
(Accessed on February 22, 2022)
-
Woo, K. Arteriovenous graft creation for hemodialysis and its
complications. In T. Post (Ed.),UpToDate. UpToDate,
Waltham, MA. (Accessed on February 22, 2022).
-
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
-
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
-
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
-
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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