Overview
Definition:
An arteriovenous (AV) fistula is a surgically created connection between an artery and a vein, typically in the arm, to provide adequate blood flow for chronic hemodialysis
This increased flow causes the vein to enlarge and thicken, becoming suitable for repeated needle cannulation
The brachiocephalic fistula, created by connecting the radial artery to the cephalic vein, is a common and preferred type due to its patency and ease of use.
Epidemiology:
End-stage renal disease (ESRD) affects millions globally, with a significant portion requiring renal replacement therapy
AV fistulas are the preferred initial access for hemodialysis in most guidelines due to lower complication rates compared to grafts or central venous catheters
In India, the incidence of ESRD is rising, making proficiency in AV fistula creation crucial for surgical residents preparing for DNB and NEET SS examinations.
Clinical Significance:
Adequate and durable vascular access is paramount for successful hemodialysis
AV fistulas offer the best long-term outcomes, reducing morbidity and mortality associated with infection, thrombosis, and stenosis
Understanding the principles and techniques of AV fistula creation is fundamental for surgeons managing patients with chronic kidney disease, directly impacting patient survival and quality of life
Mastery of this procedure is a key learning objective for surgical trainees aiming for DNB and NEET SS certification.
Indications
Indications For Creation:
Chronic kidney disease requiring long-term hemodialysis
Failure or contraindication for peritoneal dialysis
Need for durable vascular access
Patients with suitable anatomy (adequate arterial supply and venous diameter).
Patient Assessment:
Thorough vascular mapping of the upper limb is essential
This includes assessing the diameter and depth of cephalic and basilic veins, and the patency of the radial and ulnar arteries
Palpation for a thrill and auscultation for a bruit are key physical findings
Avoidance of previous cannulation sites or dominant arm for fistula creation.
Timing Of Creation:
Fistulas are typically created 3-6 months before the anticipated need for hemodialysis to allow for maturation
Early referral to a vascular surgeon is critical for optimal planning and timely creation
Delayed creation can lead to reliance on temporary catheters, increasing infection risk.
Preoperative Preparation
Informed Consent:
Detailed discussion with the patient regarding the procedure, risks (e.g., bleeding, infection, thrombosis, steal syndrome, nerve injury), benefits, and alternatives
Operative consent must be obtained after understanding.
Anesthesia:
Local anesthesia with sedation is often preferred for outpatient procedures
General anesthesia may be used for complex cases or if the patient cannot tolerate local anesthesia
Anesthesia selection depends on patient factors and surgeon preference.
Imaging And Mapping:
Preoperative duplex ultrasonography (Doppler) is gold standard for vascular mapping
It assesses venous diameter (minimum 2.5 mm for cephalic, 3 mm for basilic), depth (less than 6 mm), and patency
Arterial assessment confirms adequate inflow
Angiography may be considered in cases of prior surgery or suspected vascular disease.
Pharmacological Management:
Antibiotic prophylaxis (e.g., first-generation cephalosporin) is administered within 60 minutes prior to incision
Patients on anticoagulants or antiplatelets may require specific perioperative management strategies as advised by their nephrologist or cardiologist.
Procedure Steps
Surgical Technique:
The most common technique is the side-to-side brachiocephalic fistula
An incision is made over the cephalic vein in the forearm or antecubital fossa
The cephalic vein is dissected, and its patency confirmed
The radial artery is then identified and dissected proximally
A side-to-side anastomosis is created between the radial artery and the cephalic vein using fine monofilament sutures (e.g., 6-0 or 7-0 Prolene).
Arterial Anastomosis:
The anastomosis is performed meticulously to ensure a tension-free, watertight seal
The artery is typically anastamosed to the side of the vein, allowing outflow into the vein and distal arterialization of the venous system.
Hemostasis And Closure:
Meticulous hemostasis is achieved
The wound is irrigated with saline
Subcutaneous tissues are closed with absorbable sutures, followed by skin closure using non-absorbable sutures or staples
A sterile dressing is applied.
Intraoperative Assessment:
Immediately after creation, patency of the fistula is assessed by palpation for a thrill and auscultation for a continuous bruit
Doppler ultrasound can confirm flow and rule out anastomotic stenosis or thrombosis
The limb should be kept elevated postoperatively.
Postoperative Care
Early Monitoring:
Close monitoring for bleeding, hematoma formation, signs of infection, and development of a thrill and bruit
Palpation and auscultation should be performed regularly by nursing staff and physicians
Limb color, temperature, and sensation are assessed for signs of ischemia or compromise.
Maturation Process:
The fistula requires 4-6 weeks to mature for cannulation
During this period, the vein dilates and thickens due to increased arterial flow and venous hypertension
Patients are advised to perform regular squeezing exercises with a rubber ball to promote venous dilation.
Medications:
Anticoagulation is generally not required postoperatively unless there is a specific indication
Pain management is provided with analgesics
Antibiotics are discontinued unless signs of infection develop.
Patient Education:
Patients are educated on fistula care, including daily examination for the thrill and bruit, monitoring for swelling or pain, avoiding constrictive clothing or jewelry on the arm, and protecting the fistula arm from injury
They are instructed on when to contact their healthcare provider.
Complications
Early Complications:
Bleeding and hematoma formation at the anastomosis site
Thrombosis of the fistula or vein
Infection of the surgical wound
Arterial steal syndrome (ischemia of the hand due to excessive diversion of arterial blood)
Nerve injury causing numbness or weakness.
Late Complications:
Steal syndrome (can develop later as fistula matures)
Aneurysm or pseudoaneurysm formation at cannulation sites
Stenosis of the fistula or inflow/outflow veins
Infection (access site infection, bacteremia)
Venous hypertension in the distal limb
Congestive heart failure due to high-flow state.
Prevention Strategies:
Meticulous surgical technique, appropriate patient selection, pre-operative vascular mapping, and avoiding cannulation of immature fistulas
Regular monitoring for signs of complications and prompt intervention
Patient education on fistula care is crucial
Use of ultrasound for diagnosis and intervention.
Key Points
Exam Focus:
Indications for AV fistula
Preferred access type (fistula vs graft vs catheter)
Brachiocephalic (Cimino-Brescia) vs
other types of fistulas
Surgical techniques (side-to-side, end-to-side, loop)
Maturation time
Complications and their management
Steal syndrome pathogenesis and treatment
Role of ultrasound in vascular mapping.
Clinical Pearls:
Always assess both arms and distal veins for fistula creation
Cephalic vein is preferred for its superficial location
Consider basilic vein if cephalic is inadequate
Ensure adequate arterial inflow
Avoid tension on the anastomosis
Educate patients thoroughly on fistula care and signs of complications
Early referral to vascular access specialists is key.
Common Mistakes:
Inadequate pre-operative vascular mapping
Creating fistulas in veins that are too small or too deep
Poorly constructed anastomosis leading to early failure
Cannulating an immature fistula
Ignoring signs of steal syndrome or infection
Lack of comprehensive patient education
Delay in referral for access creation.