Dialysis: Graphs and Fistula

Key Topics

• Differences between AV Fistula and Graft
• Duplex findings of a normal AV fistula
• Upper extremity venous and arterial anatomy
• Venous Doppler findings in axillary veins
• Positioning for imaging a radio-cephalic fistula
• Quantifying stenosis degree based on Doppler findings

Background

• Chronic Kidney Disease (CKD) and End-Stage Renal Disease (ESRD)
  • Increasing incidence in the US
  • Arteriovenous access aims for long-term hemodialysis with low reintervention and complication rates

AV Fistula

• Autogenous Fistula
  • Preferred due to superior patency rates and lower complications
  • Created as distally as possible in the non-dominant arm
  • Allows the patient to maintain normal daily activities
  • Lower maturation rate, higher early thrombosis rate compared to synthetic grafts
• Preoperative Evaluation
  • Essential for successful creation and maturation
  • Includes vein mapping for suitability
  • Duplex assessment pre-dialysis or post-other access procedures

Imaging and Assessment

• Vessels in the Arm
  • Radial artery connected to cephalic vein
• Patient History Documentation
  • Medical history, trauma, medications, and previous access procedures
  • Dominant arm determination for fistula placement
  • Contraindications such as central venous catheter, pacemaker, defibrillator
• Physical Assessment
  • Blood pressure and pulse check
  • Allen test for palmar arch integrity
  • Tourniquet use for vein assessment
• Imaging Procedures
  • Use of high-frequency transducer
  • Color and spectral Doppler
  • Evaluation of arterial and venous systems (arteries >2mm diameter)
  • Assessment of superficial venous system with tourniquet

Criteria and Measurements

• Arterial System
  • Direct imaging and physiologic tests
  • Evaluation for diameter, calcification, stenosis, compliance
• Venous System
  • Assessment for compressibility, thrombus, calcifications
  • Vein diameter, patency, wall thickness documentation
• Fistula Maturity
  • Defined by palpable, usable fistula with >350 ml/min flow rate

Types of Access and Interventions

• Types of Fistulas
  • Brescia-Cimino (cephalic vein to radial artery)
  • Basilic vein transposition and juxtaposition
  • Lower extremity use if upper unsuitable (less common)
• Maturation and Follow-Up
  • Takes 8-12 weeks
  • Low maturation rates with suboptimal veins
  • Follow-up for stenosis, pseudoaneurysm, hematoma, arterial steal syndrome

Doppler and Flow Measurements

• Doppler Use
  • Evaluate patency and identify stenosis
  • Measure velocities within the fistula and native artery
• Flow Volume Measurements
  • Useful for assessing access function
  • Large sample volume recommended

Arterial Steal Syndrome

• Check Retrograde Flow
  • Assess flow direction with and without graft compression

The lecture continues with further details on imaging and assessment techniques. The notes provide a comprehensive summary of the creation, assessment, and monitoring of arteriovenous fistulas for hemodialysis.