What are the indications, complications, and types of arteriovenous (AV) access for dialysis, including arteriovenous fistula (AVF), arteriovenous grafts (AVGs), and central venous catheters (CVCs)?

Arteriovenous Access for Hemodialysis: Indications, Types, and Complications

Arteriovenous fistulas (AVFs) should be the first choice for vascular access in hemodialysis patients due to their superior long-term patency rates, lower infection rates (1-4%), and significantly reduced mortality risk compared to other access types. 1

Types of Vascular Access

1. Arteriovenous Fistula (AVF)

• Definition: Direct surgical connection between an artery and vein
• Indications: First-line access for most hemodialysis patients
• Advantages:
  • Lowest infection rates (1-4%)
  • Best long-term patency (4-5 year survival)
  • Lowest mortality risk
  • Lowest intervention rates (47-52 per 100 patient-years)
  • Supports adequate blood flow for dialysis
• Locations:
  • Wrist (radial-cephalic) - first choice when vessels are adequate
  • Elbow (brachial-cephalic) - second choice if wrist not feasible
• Complications:
  • Failure to mature (20-60%)
  • Thrombosis (<0.25 episodes per patient-year)
  • Steal syndrome
  • Aneurysm formation
  • Infection (lowest among access types)

2. Arteriovenous Graft (AVG)

• Definition: Synthetic tube connecting artery and vein
• Indications: When native vessels are inadequate for AVF creation
• Advantages:
  • Can be used sooner than AVF (2-3 weeks vs. 3-4 months)
  • Option for patients with poor vessels
• Complications:
  • Higher infection rates (11-20%)
  • Higher thrombosis rates (<0.5 episodes per patient-year)
  • More frequent interventions (91-158 per 100 patient-years)
  • 1.47 times greater mortality risk than AVF
  • Shorter lifespan than AVF

3. Central Venous Catheter (CVC)

• Definition: Catheter inserted into central vein (typically internal jugular)
• Indications:
  • Temporary access while AVF/AVG matures
  • Urgent need for dialysis
  • Failed AVF/AVG with no other options
  • Limited life expectancy
• Complications:
  • Highest infection rates
  • Central venous stenosis
  • Thrombosis
  • Inadequate blood flow
  • 2.3 times greater mortality risk than AVF
  • Compromised dialysis adequacy

Indications for Specific Access Types

AVF Indications:

• First-line access for most patients
• Adequate vessels on preoperative ultrasound mapping
• Sufficient time for maturation (3-4 months before dialysis needed)
• Life expectancy >1 year

AVG Indications:

• Failed AVF attempts
• Inadequate vessels for AVF creation
• Need for earlier access use than AVF allows
• Elderly patients with poor vessels

CVC Indications:

• Immediate need for dialysis
• Bridge to AVF/AVG maturation
• Multiple failed AV accesses with no feasible options
• Severe arterial occlusive disease
• Non-correctable central venous outflow occlusion
• Limited life expectancy

Complications and Management

Thrombotic Complications

• Primary cause of access loss
• Rates: AVF (<0.25 episodes/patient-year) < AVG (<0.5 episodes/patient-year) < CVC
• Prevention through surveillance and monitoring:
  • Physical examination (changes in thrill/bruit)
  • Flow measurements
  • Doppler ultrasound
• Treatment: endovascular interventions (angioplasty, thrombectomy) or surgical revision

Infectious Complications

• Rates: AVF (1-4%) < AVG (11-20%) < CVC (highest)
• Prevention:
  • Strict aseptic technique
  • Access site care
  • Avoidance of unnecessary manipulations
• Treatment: antibiotics, possible access removal in severe cases

Non-thrombotic Flow-related Complications

• Steal syndrome (limb ischemia)
• Aneurysm formation
• High-output cardiac failure
• Venous hypertension

Access Planning Algorithm

1. Early referral to nephrology/vascular surgery (at least 6 months before anticipated dialysis)
2. Vessel assessment with ultrasound mapping
3. Access creation priority:
   • First: Wrist (radial-cephalic) AVF
   • Second: Elbow (brachial-cephalic) AVF
   • Third: AVG if AVF not feasible
   • Fourth: CVC only if immediate dialysis needed or no other options

Quality Metrics for Dialysis Access

• Less than 10% of chronic maintenance hemodialysis patients should be on catheters as permanent access 2
• AVF thrombosis rate should be <0.25 episodes per patient-year 2
• AVG thrombosis rate should be <0.5 episodes per patient-year 2
• Centers should track access-related complications as part of quality improvement

Common Pitfalls and Caveats

1. Delayed referral for access creation often results in catheter dependence and worse outcomes
2. Ignoring patient-specific factors when selecting access type
3. Inadequate monitoring for access dysfunction
4. Overreliance on catheters due to convenience or patient preference despite higher complication rates
5. Failure to consider vessel adequacy before attempting AVF creation
6. Neglecting regular surveillance to detect access dysfunction before thrombosis

The KDOQI guidelines have evolved from a strict "Fistula First" approach to a more individualized "Patient Life-Plan" approach that considers patient circumstances, vessel characteristics, comorbidities, and patient preferences when selecting the optimal access type 2. However, when all factors are equal, the evidence strongly supports AVF as the access with lowest morbidity and mortality risks.