Complications - Dialysis access surgery: Brescia-Cimino (radiocephalic) fistula – Vascular surgery

• Selected vein (cephalic or basilic vein) not suitable unexpectedly (e.g., partial thrombosis) or marked arteriosclerosis of the radial artery
• Depending on the situation, fallback procedures, e.g., direct antecubital fistula , Collier fistula (axillo-axillary), or fashioning a loop fistula on the forearm or upper arm 

Peripheral stenoses

Evidence of progressive obstruction:

• Changes in the thrill of the shunt
• Changes in the auscultation murmur (extreme case: "seagull cry" in high-grade stenosis)
• Fistula with local bulging
• Inadequate fistula performance for dialysis ("failing fistula")

Diagnostic work-up: color-coded duplex ultrasonography, possibly angiography

• Blood flow reduced by more than 25% or fallen below an absolute limit of 300 ml/min for antebrachial AV fistulas (AVFs) or 600 ml/min in grafts.
• Evaluation of the anastomosis
• Evidence of stenosis
• In central stenosis: angiography

In up to 75% of stenoses in radiocephalic fistulas, the stenoses are present in the immediate vicinity of the anastomosis. In approximately 50% of stenoses in brachial fistulas (cephalic and basilar vein), the stenoses are present in the ostial region of the fistula vein (subclavian and axillary vein).

Fistula occlusion – Mickley classification*

*Mickley V (2004) Stenosis and thrombosis in hemodialysis fistulae and grafts: the surgeon`s point of view. Nephrol Dial Transplant 19:309–311

Management

• Early intervention even in a "failing fistula", do not wait for full-blown stenosis
• Stenoses near the anastomosis in the forearm: Proximalization of the anastomosis
• Stenoses in the venous part of the fistula: percutaneous balloon angioplasty
• Recurrent stenosis: surgical intervention; short stenosis → patch plasty, long stenosis → bridge conduit

Central venous stenoses

Cause

• Often late sequelae of central venous catheters, gradual development

Presentation

• Cardinal symptom: edematous increase in arm circumference!
• Possibly also increased venous markings in the upper arm and thoracic aperture
• Complete occlusion with absence of collateral blood flow: hand necrosis

Diagnostic work-up

• MR-phlebography
• Angiography with stand-by for intervention

Management

• Catheter-based intervention
• 1-year patency rate in PTA of up to 43% (70% when combined with stenting).
• Mechanical problems with stenting of subclavian vein between clavicle and 1st rib → resection of 1st rib might become necessary
• One-year patency rate in patch plasty and bypass surgery almost 90%
• Viable option: Bypass from axillary vein to internal jugular vein

Fistula thrombosis

Cause

• Most often preexisting stenosis

Diagnostic work-up

• Medical history: initial signs, e.g., documented prior stenoses, previous balloon dilations.
• Clinical examination: aneurysmatic dilation near the stenosis suggests narrowing
• Color-coded duplex ultrasonography is of lesser importance, but useful nonetheless: extent of thrombosis, run-in problem upstream, impaired central run-off

Management

• Emergency in case of native AV fistulae because of impending vessel wall injury due to thrombophlebitic inflammatory reaction
• Prompt intervention also in synthetic grafts, however, successful recanalization even after 1 week is usually possible
• Fogarty catheter thrombectomy, in synthetic grafts also catheter-based thrombectomy
• Patch angioplasty, moving the arterial anastomosis more proximally or transposing the venous anastomosis, or bridge grafting may also be required
• Immediate intraoperative monitoring required: Flow measurement, angiography, or color-coded duplex ultrasonography
• Local lysis has lost its importance

Recurrent fistula occlusion without tangible morphological cause

• External compression (e.g., during sleep)
• Low cardiac output
• Hypotension
• Elevated hematocrit (post-dialysis)
• Undiagnosed coagulopathy

Aneurysm

Morphology

• Extended bulging with thin vessel wall combined with high blood flow or stenosis

Cause

• Vessel wall destruction through repeated punctures (at the same site) and replacement by scar tissue.
• Degeneration of the material in PTFE grafts
• Rare: Infection

Management

While shunt aneurysms per se do not require surgery, they:

• require intervention if complications are imminent, e.g., mural thrombi, thrombophlebitis, infection, impending perforation, cardiac overload
• also require intervention when dialysis is mandatory and ideal placement of the cannula is no longer possible; aneurysmatic bulging should not be punctured on principle because it is often partially thrombosed.

Treatment options

• Resection of the aneurysm with direct anastomosis
• Resection of the aneurysm with bridge graft
• Aneurysmorrhaphy (resected material can be used for patch plasty)
• Fashioning of a new AV fistula

·         Pseudoaneurysm (spurious aneurysm)

Pathophysiology

• Puncture site of the fistula is occluded by local thrombus and secured above it by connective tissue
• If the above mechanism fails, or there is also superinfection of the perivascular hematoma or pressure injury to the skin with necrosis -> imminent rupture with possible massive bleeding

Management

Swift intervention in expanding or infected pseudoaneurysm

• In case of active (massive) bleeding -> compression bandage, brachial tourniquet
• Bridging graft: Synthetic graft, biograft, venous bridge graft in exceptional cases
• Do not place the graft in the same wound bed as the affected fistula  section, but tunnel around it akin to an over-bypass.
• After anastomosis of the bridge graft, remove the defective and possibly infected segment of the fistula
• Stent grafting only if bacterial colonization has been reliably ruled out; "covered stents" shorten the length of the fistula available for puncture

Early-onset infection (≤ 30 days postoperatively)

Incidence

• For native shunts (AV fistulae), approx. 0.5–3.5%
• For synthetic grafts 5–8%
• 20-35% of patient deaths in dialysis are attributable to infections

Cause

• Usually infected hematomas
• Most common pathogens: S. aureus, MRSA, enterococci

Presentation/diagnostic work-up

• Warming, swelling
• Possibly fever
• Laboratory panels: Leukocytosis, elevated CRP, possibly positive blood cultures

Management

Native AV fistula

• Hematoma evacuation, microbiology, drainage, antibiotics
• Fistula can usually be saved

Synthetic graft

• Most cases require graft removal
• Autologous or xenogeneic patch to cover the arterial defect
• Swabs and tissue samples from various sites
• Open wound treatment
• Antibiotics according to antimicrobial susceptibility testing
• Dialysis via a temporary central venous catheter
• Fashioning of a new fistula only after the inflammation parameters have subsided and the skin conditions have consolidated; usually after 4 weeks at the earliest, possibly with the fistula on the contralateral arm

Differential diagnosis of abacterial perigraft reaction

• Occasionally seen after implantation of PTFE grafts
• Patients are usually afebrile
• Wound sutures are unremarkable
• Clinical course and laboratory parameters with spontaneous return to normal

Prevention of infection

• Atraumatic surgery
• Painstaking hemostasis
• Avoid incisions over the course of the graft, if possible

Late-onset infection (>30 days postoperatively)

Presentation

• Septicemia of unknown etiology
• Suspicious skin conditions in the shunt region
• Puncture-related infectious local complications

Diagnostic work-up

• Color-coded duplex ultrasonography, CT, MRI: periprosthetic fluid lining
• Possibly also leukocyte scintigraphy or positron emission tomography (PET): Evidence of periprosthetic leukocyte colonies
• Evidence of infected pseudoaneurysms

Management

• See pseudoaneurysm

Steal syndrome

The run-off of blood at the AV anastomosis into the venous low-pressure system always reduces the pressure in the distal arterial limb and in the periphery. The magnitude of this pressure drop depends on the peripheral resistance of the afferent artery (diameter and length) and the shunt volume. The higher the shunt volume and the higher the arterial resistance, the higher the peripheral pressure drop.

General background

• In up to 80% of cases, fashioning of such a fistula alters the peripheral perfusion
• Symptomatic limb ischemia of 1% in Cimino fistulae (radial artery → cephalic vein) and ≥10% in antecubital fistulae, with a mean of 6-8% in all dialysis patients
• Women are affected more often than men
• Risk factors: PAOD, diabetes, advanced age, previous AV shunt surgery

High flow and low flow AV fistulae

• Ischemia resulting from high volume flow (>1000–1500 ml/min, so called high flow fistulae)
• Ischemia with normal volume flow, reduced peripheral perfusion due to local changes in the vascular bed, classical steal phenomenon

Classical steal phenomenon

Low peripheral perfusion caused by:

• Retrograde blood flow distal to AV anastomosis via collaterals toward the fistula vessel
• Stenosis in the arterial run-in
• Rarefaction of the peripheral arterial vascular bed

Steal syndrome – clinical classification

Management

High flow fistulae → flow reduction by banding

• In native fistulae by gathering sutures or synthetic patch plasty
• In synthetic grafts (also an option in native fistulae), bridging of a "tapered prosthesis" with an increase in lumen from 4 to 6 mm

Classical steal phenomenon → improvement of peripheral perfusion

• In Cimino fistulae, stopping retrograde blood flow into the fistula vein by ligating the radial artery distal to the AVF is recommended → usually exacerbates the ischemia of the hand! 
• In brachial fistulae, run-off perfusion is usually inadequate despite ligation; therefore, additional bypass to the vascular tree distal to the ligation (DRIL = distal revascularization with interval ligation)
• Proximalization of the AVF enlarges the vascular bed, which can supply more collaterals distad
• More distal location of the anastomosis (RUDI = "revision using distal inflow"), better peripheral perfusion by leaving the ulnar/radial artery as part of the circulation
• Stenosed run-in vessel → catheter-based intervention
• Exceptions: Undoing the fistula and fashioning a new one on contralateral arm, peritoneal dialysis