The Role of Duplex Ultrasound in Assessing AVF Maturation
Yana Etkin, MD, Sonia Talathi, MD, Amit Rao, MD, Merideth Akerman, Martin Lesser, Gregg Landis, MD.
Northwell Health, Lake Success, NY, USA.
Objectives
We examined the utility of postoperative color duplex ultrasound (CDU) in assessing AVF maturation and determining the need for balloon assisted maturation (BAM).
Methods 633 patients underwent AVF creation at a single institution from 2014-2016. 339 patients had a postoperative CDU assessment, which included vein diameter, volume flow (VF), presence of ≥50% stenosis at the anastomosis or in the fistula, and stealing branches. Outcome variables examined included functional status of AVFs, CDU findings and timing when CDUs were performed. Fistulas were considered mature when they were successfully cannulated on dialysis.
A Generalized Linear Mixed Model (GLMM) was created to analyze duplex criteria associated with AVF maturation, by comparing CDU findings of AVFs used on HD to those that thrombosed or needed further intervention. The validity of CDU was analyzed by comparing their findings to corresponding fistulography images.
Results608 CDUs were performed in 339 patients. 408 studies correlated with functional status of AVFs, i.e. maturation (N=174), need for BAM (N=201), or failure (N=33). The remaining 200 studies were inconclusive and subsequent CDUs were performed at a later date. The conclusive studies were performed at a median time of 7.86 weeks post-operatively as compared to inconclusive studies performed at 2.14 weeks (P <0.001).
Univariate analysis was performed to compare CDU findings based on functional status of AVFs. Duplex results in AVFs requiring BAM and those that failed to mature were similar and were combined (Table 1). Based on GLMM analysis, the probability of AVF maturation increases if the vein diameter is ≥6 (OR=38.7), there is no stenosis in the fistula (OR=35.6), there are no stealing branches (OR=21.6) and there is a VF ≥675 (OR=5.0).
195 fistulography images were available for review. Vein diameter, presence of stealing branches and stenosis in the fistula were compared to CDU findings. Sensitivity, specificity and accuracy were determined: vein diameter (84.3%, 28.6%, 72.3%), fistula stenosis (59.3%, 78.8%, 69.2%), stealing branches (20.7%, 92.7%, 71.3%).
ConclusionsRoutine CDU surveillance of AVFs is valid and should be performed 6-8 weeks postoperatively to identify and correct small vein diameters, low VF, flow-limiting stenosis and stealing branches to help assure AVF maturation.
| Matured AVFs(N=174) | AVFs requiring BAM/failed AVFs(N=234) | P value | |
| Median vein diameter (mm) | 7.0 (4.6-12.4) | 5.0 (1.6-8.5) | <0.0001 |
| Median VF (ml/min) | 986 (328-3327) | 561 (170-2924) | <0.0001 |
| Presence of ≥50% stenosis at the anastomosis (%) | 42.2% | 46.3% | 0.43 |
| Presence of ≥50% stenosis in thefistula (%) | 4.6% | 39.1% | 0.0001 |
| Presence of stealing branches (%) | 1.7% | 12.3% | 0.0001 |
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