What are the indications for a fistulogram in a dialysis patient with a fistula presenting with bruit and thrill?

Indications for Fistulogram in Dialysis Patients with Functioning Fistula

Despite the presence of bruit and thrill indicating a functioning fistula, a fistulogram is indicated when there are clinical signs of access dysfunction or abnormal hemodynamic parameters that suggest underlying stenosis or other complications. 1

Primary Indications for Fistulogram in Patients with Bruit and Thrill

Clinical Indicators of Dysfunction

• Changes in the quality or intensity of the access thrill or bruit (even if still present)
• Prolonged bleeding after needle removal post-dialysis
• Arm swelling ipsilateral to the access site
• Development of collateral veins
• Difficulty with cannulation despite apparent maturation

Hemodynamic Indicators

• Reduction in dialysis vascular access blood flow rate (Qa)
• Abnormal access recirculation measurements
• Elevated dialysis venous pressure during treatment
• Inadequate dialysis delivery despite adequate treatment time

Diagnostic Value of Fistulogram

Fistulography is considered the reference standard for imaging dysfunctional dialysis access due to:

• High diagnostic accuracy - up to 90% of accesses with abnormal physical examinations will have clinically significant findings on imaging 1
• Ability to perform percutaneous endovascular interventions during the same procedure
• Comprehensive evaluation of the entire vascular access circuit from arterial anastomosis to central veins

When to Proceed with Fistulogram Despite Presence of Bruit and Thrill

1. Suspected Underlying Stenosis: Even with a functioning fistula, stenosis may be developing that could eventually lead to thrombosis

2. Surveillance Abnormalities: When device-based surveillance methods detect problems despite clinical signs of patency

3. Central Venous Stenosis: When there is swelling of the extremity ipsilateral to the access site with or without development of venous collaterals 1

4. Failure to Mature: If an arteriovenous fistula fails to develop adequately within 2 months after creation despite presence of bruit and thrill 1

5. Vascular Steal Syndrome: When patient experiences ischemic symptoms in the extremity despite a functioning access 1

Importance of Early Detection and Intervention

Early identification and treatment of access stenosis through fistulogram can:

• Decrease fistula thrombosis rates threefold compared to waiting for complete dysfunction 2
• Improve assisted primary patency rates (4.84 months with revision vs. 2.9 months without) 3
• Preserve long-term access viability and reduce the need for catheter placement

Pitfalls to Avoid

• Relying solely on physical examination: While bruit and thrill indicate patency, they don't exclude significant stenosis that may progress to thrombosis
• Waiting for complete loss of thrill: By this point, access thrombosis has likely occurred, requiring more complex intervention
• Overlooking subtle changes: Gradual changes in the quality of bruit or thrill may indicate developing problems
• Limited sensitivity of fistulogram alone: In some cases, fistulogram may not detect all abnormalities and should be supplemented with other imaging when clinical suspicion remains high 4

Remember that while the presence of spiral laminar flow (often associated with a thrill) is supportive of successful fistula maturation 5, it does not exclude the development of stenosis that could compromise the access over time.