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VOLume flow assistance for optimizing outcomes of dysfunctional autologous arteriovenous fistula Angioplasty: the VOLA Pilot Study
Abstract
Objectives
To investigate the feasibility of VF-assisted angioplasty (VFA) in dysfunctional AVF using sequential intraprocedural duplex ultrasound (DUS), to utilize intraprocedural VF as a quantifiable, functional endpoint in endovascular treatment.Methods
This prospective study included 20 consecutive patients (23 lesions; 16 men; mean age 67 ± 16 years) with dysfunctional AVF undergoing fluoroscopically guided balloon angioplasty between June 2019 and May 2020. Primary endpoints were quantification of outcome using sequential DUS VF analysis following each dilation, 6-month target lesion re-intervention (TLR)-free rate, standard technical success, procedural success (achievement of a postprocedural VF value equal (or 10% less) or superior to the baseline steady-state access), and correlation between procedural success and TLR-free rate. Secondary endpoints included 6-month lesion late lumen loss (LLL), correlation between balloon diameter used and intraprocedural VF values, and correlation between VF and LLL at 6 months follow-up.ResultsMean VF increase was 168.5% ± 102.5% (range: 24.24–493.33%). Procedural success was 80% (16/20 cases). VFA improved procedural success by 20% (4/20 cases) compared to standard assessment (< 30% residual stenosis and palpable thrill). TLR-free rate was 78.3% and 67.3% at 6 and 12 months. Significantly less TLR was noted in cases of procedural success (82.4% vs. 66.7% 6 months; p = 0.041). Unweighted linear regression showed a significant positive relationship between diameter of balloon and VF (146.9 ± 42.3 mL/min VF gain per mm of balloon diameter; p = 0.001, R2 = 0.23) and a significant negative relationship between LLL and VF decline at follow-up (102.0 ± 34.6 mL/min loss per mm of LLL; p = 0.01, R2 = 0.35). Optimal VF cutoff value and percentile increase to predict access failure were 720 mL/min (sensitivity 58.3%, specificity 71.4%) and 153% (sensitivity 66.7%, specificity 85.7%), respectively.Conclusion
Intraprocedural VF assessment could be used to optimize AVF angioplasty.Key Points
• A newly proposed functional endpoint of angioplasty in dysfunctional dialysis fistula was evaluated and angioplasty outcome was quantified using volume flow (VF) assessment with sequential intraprocedural DUS.
• Intraprocedural VF assessment improved immediate procedural success; increased balloon diameter was correlated with VF gain and late lumen loss with VF decline.
• Intraprocedural VF values ≥ to baseline steady-state values were correlated with less re-interventions.
Background
Doppler ultrasound (DUS) blood volume flow (VF) calculation is the most reliable method for demonstrating the success of endovascular treatment of dysfunctional radiocephalic arteriovenous fistula (AVF). Due to the difficulty of this method for the interventionalist, VF-correlated markers are required during the procedure.
Purpose
To investigate the relationship between intraprocedural anatomical markers (AMs) and changes in VF induced by percutaneous transluminal angioplasty (PTA).
Material and Methods
The study included 56 patients with dysfunctional radiocephalic AVF who underwent PTA between September 2020 and 2022. The VF of all patients was measured using DUS before and 1 h after PTA. AMs were determined from 10 images, five before and five after balloon angioplasty.
Results
The mean post-PTA VF was 637 ± 277 mL/min compared to baseline (151 ± 107 mL/min). Before and after balloon angioplasty, vein diameter (VD), artery diameter (AD), stenosis minimum luminal diameter (MLD), stenosis percentage (SP), and VF values were statistically significant ( P = 0.001). Spearman’s correlation analysis showed a positive strong linear relationship between VF and MLD ( r s = 0.850, P <0.001), and a negative strong linear relationship between VF and SP ( r s = 0.815). Receiver operating characteristic curve analysis showed that the sensitivity and specificity for VF ≥400 mL/min at cutoffs of SP <50% and MLD >2.5 mm were 81% and 82%, and 81% and 90%, respectively.
Conclusion
Among the AMs readily available during PTA, first MLD and then SP provided satisfactory results in predicting VF.
Background
To evaluate the implementation of routine surveillance using ultrasound on hemodialysis vascular access (VA) outcomes and determine the number and frequency of corrective, surveillance-guided procedures performed.
Methods
Multicenter, prospective, observational study that includes consecutive hemodialysis patients receiving therapy from native arteriovenous fistulae (AVF) or grafts (AVG). Participants were assigned to a routine VA Color Doppler ultrasound surveillance (DUS) protocol from January 2019 to December 2021. Patients were referred for corrective procedures (endovascular or surgical) based on clinical or DUS findings (pre-emptive procedures; PEP). Primary endpoint was the estimation of primary unassisted (PUP) and secondary patency (SP) rates. Secondary endpoints were the determination of the number and frequency of PEP and VA survival rates.
Results
In total, 223 patients with 243 VA (192 AVF and 51 AVG) were included. Access PUP and SP rates were 83% and 93% at 12 months, 75% and 88% at 24 months, and 72% and 83% at 36 months follow-up. Autologous fistulae PUP and SP were 89% and 96% at 12 months, 81% and 93% at 24 months, and 80% and 89% at 36 months, respectively. Graft PUP and SP were 56% and 80% at 12 months, 44% and 65% at 24 months, and 39% and 54% at 36 months, respectively. In total, 56 corrective procedures (38/56 PEP; 65.5%) were performed (0.13 procedures/year), of which 34 were in AVF patients (0.09 procedures/year) and 22 in AVG patients (0.40 procedures/year). Overall, 33 VA losses occurred (0.06 failures/year), 17 in AVF (0.04 failures/year), and 16 in AVG patients (0.20 failures/year).
Conclusion
The use of DUS resulted in the timely diagnosis of dysfunction, satisfactory overall VA survival, and patency rates, with a low PEP frequency. Randomized controlled trials are required to establish the value of DUS surveillance on access patency and whether DUS-guided interventions could improve VA outcomes.
Purpose:
To investigate whether Doppler ultrasound (DUS) blood flow parameters could serve as quantifiable functional endpoints of peripheral endovascular arterial procedures for chronic limb-threatening ischemia (CLTI), influencing wound healing.
Methods:
This is a prospective single-center study investigating intraprocedural DUS parameters (pulsatility index [PI] and pedal acceleration time [PAT]) in quantifying immediate hemodynamic alterations in consecutive CLTI patients with wound, ischemia, and foot infection wound class ≥1 undergoing endovascular interventions. Primary endpoints were feasibility of preendovascular and postendovascular treatment measurements of PI/PAT, quantification of immediate PI/PAT modifications of the posterior and anterior foot circulation following revascularization, the correlation between PI and PAT, and 6-month complete wound healing. Secondary endpoints included the 6-month limb salvage (no major amputation) and complete and partial wound healing rates.
Results:
A total of 28 patients (75.0% male) were enrolled, and 68 vessels were treated. The overall mean PAT values significantly decreased from 154.15±70.35 ms preprocedural to 107.21±49.6 ms postprocedural (p<0.01), and the mean PI values significantly increased from 0.93±0.99 to 1.92±1.96 (p<0.01). Postprocedural PAT at the anterior tibial (r2=0.804; p=0.346) and the posterior tibial arteries (r2=0.784; p=0.322) had a strong correlation and postprocedural PI at the anterior tibial (r2=0.704; p=0.301) and the posterior tibial arteries (r2=0.707; p=0.369) had a good correlation with 6-month complete wound healing. The 6-month complete and partial wound healing rates were 38.1% and 47.6%, respectively. Limb salvage was 96.4% and 92.4% at 6 and 12 months of follow-up, respectively.
Conclusions:
Pedal acceleration time and PI accurately detected immediate hemodynamic changes of foot perfusion following revascularization and could serve as prognostic factors of wound healing in patients with CLTI.
Clinical impact:
Intraprocedural measurement of simple Doppler ultrasound blood flow parameters, Pulsatility Index (PI) and Pedal Acceleration Time (PAT), accurately detected immediate hemodynamic changes of foot perfusion following endovascular revascularization and could therefore serve as intraprocedural prognostic factors of wound healing in patients with chronic limb-threatening ischemia. This is the first time that PI has been proposed as a hemodynamic index of successful angioplasty outcome. The optimization of intraprocedural PAT and PI could be used to guide angioplasty and predict clinical success.
Purpose:
To present final, 2-year results of a randomized trial comparing paclitaxel-coated vs uncoated balloon angioplasty following vessel preparation with ultra-high-pressure percutaneous transluminal angioplasty (PTA) in hemodialysis arteriovenous fistulae (AVFs).
Materials and methods:
Twenty-three sites enrolled 285 subjects with dysfunctional AVFs located in the arm. Before 1:1 randomization, successful vessel preparation was achieved (full waist effacement, < 30% residual stenosis). Follow-up was clinically driven except for a 6-month office visit.
Results:
Ninety-six of 141 subjects in the drug-coated balloon (DCB) arm and 111 of 144 in the control arm completed the study. Target lesion primary patency (TLPP) rates for the DCB and control groups were 58% ± 4 vs 46% ± 4 (P = .02) at 9 months, 44% ± 5 vs 36% ± 4 (P = .04) at 12 months, 34% ± 5 vs 28% ± 4 (P = .06) at 18 months, and 27% ± 4 vs 24% ± 4 (P = .09) at 24 months, respectively. Mean time to TLPP event for subjects with an event was longer for DCBs (322 vs 207 d; P < .0001). Fewer interventions were needed to maintain target lesion patency in the DCB group at 9 months (P = .02) but not at 12 (P = .08), 18 (P = .13), or 24 months (P = .19). The noninferiority safety target was met at all intervals (P < .01). Mortality did not differ between groups (P = .27). Post hoc analyses showed equivalent DCB effect in all subgroups.
Conclusions:
Two-year results demonstrate long-term safety and variable efficacy of DCB angioplasty in AVFs.
Background:
Pulsatility is an important property of hemodialysis arteriovenous fistulas (AVF) and can be perceived by the fingers as a gradual decrease in strength downstream from the anastomosis along the main trunk of the fistula. The distance from the point at which the pulse becomes imperceptible to the anastomosis is termed the palpable pulsatility length (PPL); we considered this length may play a role in assessing the severity of inflow stenosis for hemodialysis fistulas.
Methods:
This study was performed by retrospective analysis of routinely collected data. Physical examinations and fistula measurements were performed in a selected population of 76 hemodialysis patients with mature fistulas during half a year. Fistula measurements included the PPL before and after treatment and the distance between the anastomosis and the arterial cannulation site (aPump length). The aPump index (API) was calculated by dividing the PPL by the aPump length. Angiograms were reviewed to determine the location and severity of stenosis. PPL and API were used to detect the critical inflow stenosis, which indicates severe inflow stenosis of an AVF.
Results:
Receiver operating characteristic analysis showed that the area under the curve was 0.895 for API and 0.878 for PPL. A cutoff value of API < 1.29 and PPL < 11.0 cm were selected to detect the critical inflow stenosis. The sensitivity was 96.0% versus 80.0% and specificity was 84.31% versus 84.31% for API and PPL, respectively.
Conclusions:
PPL and API are useful tools in defining the severity of pure inflow stenosis for mature AVFs in the hands of trained examiners with high sensitivity and specificity.
This review examines four imaging modalities; ultrasound (US), digital subtraction angiography (DSA), magnetic resonance imaging (MRI) and computed tomography (CT), that have common or potential applications in vascular access (VA). The four modalities are reviewed under their primary uses, techniques, advantages and disadvantages, and future directions that are specific to VA. Currently, US is the most commonly used modality in VA because it is cheaper (relative to other modalities), accessible, non-ionising, and does not require the use of contrast agents. DSA is predominantly only performed when an intervention is indicated. MRI is limited by its cost and the time required for image acquisition that mainly confines it to the realm of research where high resolution is required. CT’s short acquisition times and high resolution make it useful as a problem-solving tool in complex cases, although accessibility can be an issue. All four imaging modalities have advantages and disadvantages that limit their use in this particular patient cohort. Current imaging in VA comprises an integrated approach with each modality providing particular uses dependent on their capabilities. MRI and CT, which currently have limited use, may have increasingly important future roles in complex cases where detailed analysis is required.
Purpose:
Patency after percutaneous transluminal angioplasty of native hemodialysis arteriovenous fistulae (AVFs) is highly variable. This study aimed to identify predictors of patency following angioplasty in native AVFs.
Materials and methods:
All endovascular procedures performed in native AVFs between 2005 and 2013 at two institutions were retrospectively reviewed. Clinical, anatomic, biochemical, and medication variables were subjected to univariate and multivariate Cox regression analysis to identify predictors of postintervention primary and secondary patency.
Results:
During the study period, 207 patients underwent first angioplasty of their AVF. Follow-up ranged from 14 days to 8 years, during which another 247 endovascular interventions were performed to maintain patency. Postintervention primary patency rates at 6, 12, and 24 months were 66%, 49%, and 29%, respectively. Postintervention secondary patency rates at 6, 12, and 24 months were 94%, 84%, and 79%, respectively. On multivariate adjusted Cox regression analysis, upper-arm AVFs (P = .00072), AVFs less than 6 months of age (P = .0014), presence of multiple stenoses (P = .019), and degree of initial stenosis (P = .016) were significantly associated with shorter postintervention primary patency. A previously failed AVF was the only significant predictor of postintervention secondary patency loss (P = .0053).
Conclusions:
Anatomic factors related to the AVF location, AVF age, and the extent of the lesion are important predictors of restenosis after balloon angioplasty. Traditional cardiovascular risk factors, metabolic and inflammatory markers, and medications were not associated with postintervention patency.
To determine the primary and secondary patency rates for fistulas treated with angioplasty, as well as clinical predictors of fistula patency after angioplasty.
The authors reviewed their institutional experience with autogenous fistulas from June 1997 to June 2002. A total of 104 men and 36 women were treated. Mean age +/- standard deviation of patient cohort was 62.4 years +/- 15.6. Patient age and sex, age of fistula at initial intervention, presence of diabetes, side and location of fistula, location of stenosis, and number of venous stenoses dilated were examined. Patency after angioplasty was estimated by using the Kaplan-Meier method, and predictors of patency were examined by using a Cox proportional hazards model.
One hundred fifty-one dysfunctional fistulas (94 radiocephalic and 57 brachiocephalic) were treated with angioplasty initially. Clinical success rate was 98.0% (297 of 303 interventions). At 3, 6, and 12 months, respectively, primary patency rates +/- standard errors of the estimate were 73% +/- 6, 51% +/- 7, and 39% +/- 7 for brachiocephalic fistulas and 85% +/- 4, 75% +/- 5, and 62% +/- 5 for radiocephalic fistulas; secondary patency rates were 96% +/- 2.4, 89% +/- 4, and 85% +/- 5 for brachiocephalic fistulas and 91% +/- 3, 88% +/- 3, and 86% +/- 4 for radiocephalic fistulas. For all time points, there was a significant difference in primary (P =.004) but not secondary (P =.45) patency between radiocephalic and brachiocephalic fistulas. Stenosis was most prevalent within 3 cm of the arteriovenous anastomosis in 74 (64%) of the 116 dysfunctional radiocephalic fistulas and at the cephalic arch in 22 (30%) of the 74 dysfunctional brachiocephalic fistulas. The clinical variables examined did not influence outcome. Complications occurred in seven (2.3%) of 303 interventions.
Patency after angioplasty in dysfunctional autogenous hemodialysis fistulas exceeds that observed in hemodialysis grafts. None of the clinical or anatomic variables examined affected patency outcome.
Background
Standard percutaneous transluminal angioplasty is the current recommended treatment for dysfunctional hemodialysis fistulas, yet long-term outcomes of this treatment are poor. Drug-coated balloons delivering the antirestenotic agent paclitaxel may improve outcomes.
Methods
In this prospective, single-blinded, 1:1 randomized trial, we enrolled 330 participants at 29 international sites. Patients with new or restenotic lesions in native upper-extremity arteriovenous fistulas were eligible for participation. After successful high-pressure percutaneous transluminal angioplasty, participants were randomly assigned to receive treatment with a drug-coated balloon or a standard balloon. The primary effectiveness end point was target-lesion primary patency, defined as freedom from clinically driven target-lesion revascularization or access-circuit thrombosis during the 6 months after the index procedure. The primary safety end point, serious adverse events involving the arteriovenous access circuit within 30 days, was assessed in a noninferiority analysis (margin of noninferiority, 7.5 percentage points). The primary analyses included all participants with available end-point data. Additional sensitivity analyses were performed to assess the effect of missing data.
Results
A total of 330 participants underwent randomization; 170 were assigned to receive treatment with a drug-coated balloon, and 160 were assigned to receive treatment with a standard balloon. During the 6 months after the index procedure, target-lesion primary patency was maintained more often in participants who had been treated with a drug-coated balloon than in those who had been treated with a standard balloon (82.2% [125 of 152] vs. 59.5% [88 of 148]; difference in risk, 22.8 percentage points; 95% confidence interval [CI], 12.8 to 32.8; P<0.001). Drug-coated balloons were noninferior to standard balloons with respect to the primary safety end point (4.2% [7 of 166] and 4.4% [7 of 158], respectively; difference in risk, −0.2 percentage points; 95% CI, −5.5 to 5.0; P=0.002 for noninferiority). Sensitivity analyses confirmed the results of the primary analyses.
Conclusions
Drug-coated balloon angioplasty was superior to standard angioplasty for the treatment of stenotic lesions in dysfunctional hemodialysis arteriovenous fistulas during the 6 months after the procedure and was noninferior with respect to access circuit–related serious adverse events within 30 days. (Funded by Medtronic; IN.PACT AV Access Study ClinicalTrials.gov number, NCT03041467.)
Background
Although percutaneous transluminal angioplasty has been established as a first-line therapy for access failure in dialysis, there are few reports on primary patency after percutaneous transluminal angioplasty. We investigated factors associated with primary patency following the first percutaneous transluminal angioplasty performed after vascular access construction in patients with arteriovenous fistula, including blood flow volume before and after percutaneous transluminal angioplasty and previously reported factors.
Methods
We used medical records at six dialysis centers to retrospectively identify and analyze prognostic factors for primary patency after percutaneous transluminal angioplasty in 159 patients with arteriovenous fistula who underwent initial percutaneous transluminal angioplasty after vascular access construction.
Results
Multivariate analysis with the Cox proportional hazard model showed that primary patency after percutaneous transluminal angioplasty in patients with arteriovenous fistula was significantly associated with lesion length (hazard ratio, 1.76; 95% confidence interval, 1.01–3.07; P = 0.045), and blood flow volume after percutaneous transluminal angioplasty (hazard ratio, 0.71; 95% confidence interval, 0.60–0.84; P < 0.001). When blood flow volume after percutaneous transluminal angioplasty was classified into three categories, risks of outcome events defining the end of primary patency after percutaneous transluminal angioplasty were significantly lower for 400–630 mL/min (hazard ratio, 0.38; 95% confidence interval, 0.21–0.68; P = 0.001) and >630 mL/min (hazard ratio, 0.16; 95% confidence interval, 0.06–0.40; P < 0.001) compared with <400 mL/min.
Conclusion
Our study showed that blood flow volume after percutaneous transluminal angioplasty is an important prognostic factor for primary patency after percutaneous transluminal angioplasty in patients with arteriovenous fistula.
The National Kidney Foundation’s Kidney Disease Outcomes Quality Initiative (KDOQI) has provided evidence-based guidelines for hemodialysis vascular access since 1996. Since the last update in 2006, there has been a great accumulation of new evidence and sophistication in the guidelines process. The 2019 update to the KDOQI Clinical Practice Guideline for Vascular Access is a comprehensive document intended to assist multidisciplinary practitioners care for chronic kidney disease patients and their vascular access. New topics include the end-stage kidney disease “Life-Plan” and related concepts, guidance on vascular access choice, new targets for arteriovenous access (fistulas and grafts) and central venous catheters, management of specific complications, and renewed approaches to some older topics. Appraisal of the quality of the evidence was independently conducted by using a Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach, and interpretation and application followed the GRADE Evidence to Decision frameworks. As applicable, each guideline statement is accompanied by rationale/background information, a detailed justification, monitoring and evaluation guidance, implementation considerations, special discussions, and recommendations for future research.
Objective:
Percutaneous transluminal balloon angioplasty (PTA) is recommended as the first choice to treat stenosis of Brescia-Cimino arteriovenous fistulas (B-C AVFs). The ability to predict which B-C AVFs are at risk for recurrent stenosis post-PTA would allow closer monitoring of patients, and possibly result in surgical intervention rather than repeat PTA. The purpose of this study was to identify predictive factors of primary patency after PTA in B-C AVFs.
Methods:
Patients diagnosed with B-C AVF primary stenosis and treated by PTA between November 2013 and March 2018 were included in the study. Patient and stenotic lesion characteristics and PTA procedure factors were included in the analysis. The Kaplan-Meier method was used to analyze the primary patency rate. Cox proportional hazard regression analysis was used to identify factors predictive of decreased primary patency.
Results:
74 patients (35 males, 39 females) with a mean age of 61.68 ± 11.44 years (range, 36-84 years) were included in the study. The mean B-C AVF age was 16.34 ± 12.93 months (range, 2-84 months), and the median primary patency time was 7.79 ± 0.48 months. Cox proportional hazard regression analysis revealed stenosis location at the inflow artery [hazard ratio (HR)=3.83, 95% confidence interval (CI): 1.46-10.09] or anastomosis (HR = 1.90, 95% CI: 1.09-3.32), dilation >2 times during PTA (HR = 2.30, 95% CI: 1.22-4.34), and residual stenosis >30% (HR = 2.42, 95% CI: 1.26-4.63) were significantly associated with decreased patency.
Conclusion:
In conclusion, the primary patency rate of PTA for B-C AVF dysfunction is reduced by dilation >2 times, residual stenosis >30%, and stenosis located at the inflow artery or anastomosis. These results may help in tailoring surveillance programs, multiple PTA, or a proximal re-anastomosis surgery in patients with AVF dysfunction.
Advances in knowledge:
A number of studies have been conducted to examine the predictors of primary patency after PTA, however, no definitive conclusions have been reached. Our study revealed that stenosis location at the inflow artery or anastomosis, dilation >2 times during PTA, and residual stenosis >30% were the predictors of primary patency after PTA, which may help in tailoring surveillance programs, multiple PTA, or a proximal re-anastomosis surgery in patients with arteriovenous fistulas dysfunction.
Purpose:
To determine access blood flow (ABF) rate using 2D image sequences acquired with digital subtraction angiography (DSA) and fluoroscopy.
Materials and methods:
A total of 23 patients with known or suspected malfunctioning accesses were imaged using 2 filming modes: DSA at 3 or 6 frames/s (F/s), and fluoroscopy at 10 or 15 pulses/s (P/s). ABF rates were quantified using a bolus tracking method based on cross-correlation algorithm and compared with catheter-based thermal dilution (TD) flow measurements. The indicator-dilution curves were fitted with a gamma-variate (GV) curve fitting model to assess the effect on accuracy. Radiation doses were calculated to examine any increased susceptibility to tissue reactions and stochastic effects.
Results:
For DSA images, the absolute percent deviations (mean ± standard error of mean) in computed flow vs TD flow measurements at 3 F/s and 6 F/s were 34% ± 4.5% and 20% ± 4.7%, respectively, without curve fitting, and 31% ± 3.3% and 20% ± 4.1%, respectively, with curve fitting. For fluoroscopic images, the deviations at 10 P/s and 15 P/s were 44% ± 7.3% and 68% ± 10.7%, respectively, without curve fitting and 36% ± 6.4% and 48% ± 7.1%, respectively, with curve fitting. The mean peak skin dose and effective dose at 6 F/s were 3.28 mGy and 75 μSv, respectively.
Conclusions:
Digital subtraction angiography images obtained at 6 F/s offered the highest accuracy for dialysis access blood flow quantification.
The National Kidney Foundation’s Kidney Disease Outcomes Quality Initiative (KDOQI) has provided evidence-based guidelines for all stages of chronic kidney disease (CKD) and related complications since 1997. The 2015 update of the KDOQI Clinical Practice Guideline for Hemodialysis Adequacy is intended to assist practitioners caring for patients in preparation for and during hemodialysis. The literature reviewed for this update includes clinical trials and observational studies published between 2000 and March 2014. New topics include high-frequency hemodialysis and risks; prescription flexibility in initiation timing, frequency, duration, and ultrafiltration rate; and more emphasis on volume and blood pressure control. Appraisal of the quality of the evidence and the strength of recommendations followed the Grading of Recommendation Assessment, Development, and Evaluation (GRADE) approach. Limitations of the evidence are discussed and specific suggestions are provided for future research.
The native arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis because of the lower incidence of complications and longer survival in comparison to grafts and central venous catheters. The use of color-Doppler sonography in the surgery of vascular accesses has increased the number of patients that are eligible for AVF as it allows to optimize the search for vessels suitable for surgical intervention (preoperative vascular mapping). Furthermore, color-Doppler imaging (CDI) has improved the survival of native AVF by increasing the early diagnosis of complications (postoperative surveillance). CDI is the only imaging technique able to provide both morphological and functional information about native vascular access and it is the only tool directly available to the nephrologist. This aspect is undoubtedly an additional value. Here we present a survey of the applications of CDI in the surgery and followup of AVF, with particular reference to preoperative mapping, AVF maturation and surveillance.
To quantify the effect of central venous percutaneous transluminal angioplasty (PTA) on blood flow within hemodialysis access circuits in patients with symptomatic central venous stenosis (CVS).
This prospective study enrolled 30 adults with symptoms attributable to CVS ipsilateral to their access. Five subjects were deregistered because of a lack of CVS (n = 1), untreatable lesion (n = 1), or improper flow measurement timing (n = 3); 25 completed the study (15 men and 10 women; mean age, 62 y; age range, 33-87 y). There were 7 fistulae, 15 grafts, and 3 hybrid access circuits. Mean access age was 675 days (range, 16-3,039 d). Mean CVS symptom duration was 37 days (range, 3-120 d). Peripheral stenoses, if present, were treated first. Intraaccess flow was measured immediately before and immediately after CVS treatment (PTA, stent).
Eleven patients had only CVS, whereas 14 had at least 1 peripheral lesion in addition to CVS. All stenoses underwent PTA. Mean flow rates were 1,424 mL/min (range, 565-2,765 mL/min) before PTA and 1,535 mL/min (range, 598-2,545 mL/min) afterward, yielding a mean increase of 111 mL/min ± 456 or 15% ± 34 (range, -70% to +100%; 95% confidence interval, 1%-29%). Flow was decreased in 9 patients (36%). CVS symptoms were reduced in 24 patients (96%) and recurred in 14 (58%) within a mean of 110 days (range, 7-459 d) after initial PTA. Mean follow-up was 371 days (range, 17-592 d).
CVS symptoms were observed to occur over a wide range of blood flow rates. On average, central venous PTA only mildly increased flow yet reduced symptoms regardless of flow change.
Copyright © 2015 SIR. Published by Elsevier Inc. All rights reserved.
To report 1-year results of a single-center randomized controlled trial comparing paclitaxel-coated balloon (PCB) versus high-pressure plain balloon angioplasty for the treatment of failing arteriovenous fistulae (AVFs).
Forty patients (26 men; mean age, 61 y ± 14.63) were randomized at 1:1 to undergo PCB (n = 20) or high-pressure balloon (HPB; n = 20) angioplasty of dysfunctional AVFs. There were no significant differences in baseline demographics between groups. Enrollment required a clinical diagnosis of a dysfunctional AVF attributed to a single stenotic lesion verified with digital subtraction angiography. Primary endpoints included device success, anatomic success, clinical success, and target lesion revascularization (TLR)-free survival. Secondary endpoints included dialysis circuit primary patency and procedure-related complication rates.
Device success rates were 100% in the HPB group and 35% in the PCB group (P < 0001): further dilation with an HPB was needed to achieve anatomic success in 13 of 20 cases in the PCB group (65%). Anatomic and clinical success rates were 100% in both groups. TLR-free survival (PCB, 308 d; HPB, 161 d; hazard ratio [HR], 0.478; 95% confidence interval [CI], 0.236-0.966; P = .03) and access circuit primary patency (PCB, 270 d; HPB, 161 d; HR, 0.479; 95% CI, 0.237-0.968; P = .04) were significantly in favor of PCB angioplasty. No minor or major procedure-related complications occurred.
In this single-center study, the use of PCBs resulted in superior TLR-free survival and dialysis access circuit primary patency of dysfunctional AVFs. However, additional HPB postdilation was required in the majority of cases.
Copyright © 2014 SIR. Published by Elsevier Inc. All rights reserved.
Objectives
This study sought to report the results of a prospective randomized controlled trial comparing paclitaxel-coated balloons (PCB) versus drug-eluting stents (DES) in long infrapopliteal lesions.
Background
DES have an established role in the treatment of short infrapopliteal lesions, whereas there is increasing evidence for the use of PCB in longer below-the-knee lesions.
Methods
Inclusion criteria were patients with Rutherford classes 3 to 6 and angiographically documented infrapopliteal disease with a minimum lesion length of 70 mm. The primary endpoint was target lesion restenosis >50% assessed by digital angiography at 6 months. Secondary endpoints included immediate post-procedure stenosis and target lesion revascularization.
Results
Fifty patients were randomized to undergo infrapopliteal PCB angioplasty (25 arteries in 25 limbs; PCB group) or primary DES placement (30 arteries in 27 limbs; DES group). Immediate residual post-procedure stenosis was significantly lower in DES (9.6 ± 2.2% vs. 24.8 ± 3.5% in PCB; p < 0.0001). At 6 months, 5 patients died (2 in PCB vs. 3 in DES; p = 1.00) and 3 suffered a major amputation (1 in PCB vs. 2 in DES; p = 1.00). In total, 44 angiograms were evaluable with quantitative vessel analysis. Binary (>50%) angiographic restenosis rate was significantly lower in DES (7 of 25 [28%] vs. 11 of 19 [57.9%] in PCB; p = 0.0457). There were no significant differences with regard to target lesion revascularization (2 of 26 [7.7%] in DES vs. 3 of 22 [13.6%] in PCB; p = 0.65). Positive vessel wall remodeling was observed in 3 cases in the PCB arm (3 of 19 [(15.8%)] vs. 0 of 19 [0%] in DES; p = 0.07).
Conclusions
Compared with PCB in long infrapopliteal lesions, DES are related with significantly lower residual immediate post-procedure stenosis and have shown significantly reduced vessel restenosis at 6 months. PCB may produce positive vessel remodeling. (Infrapopliteal Drug-Eluting Angioplasty Versus Stenting [IDEAS-I]; NCT01517997)
Purpose:
Increased vascular access flow after percutaneous transluminal angioplasty (PTA) for central venous stenosis and occlusion (central venous disease, CVD) can affect cardiac function in hemodialysis (HD) patients. We evaluated the cardiac function, etiology, and treatment in HD patients with CVD.
Methods:
HD patients with CVD treated by PTA between June 2006 and February 2013 were studied.
Results:
Of the 26 patients, 22 had left arteriovenous fistulas (AVFs), 1 left arteriovenous graft (AVG), 2 right AVFs, and 1 right AVG. CVD sites were the left brachiocephalic vein (LBCV; n=13), left subclavian vein (LSCV; n=7), both LBCV and LSCV (n=3), right BCV (n=2), and right SCV (n=1). Computed tomography findings indicated a high extrinsic compression rate for the LBCV (91%) and LSCV (50%). The success rate of PTA was 96%. The primary patency rates at 3, 6, 9, and 12 months were 81%, 73%, 65%, and 57%, respectively. The post-PTA brachial artery flow volume was significantly increased compared with the pre-PTA volume (1306 vs. 957 ml/min; p=0.005). The post-PTA left ventricular ejection fraction and expiration inferior vena cava diameter were the same as the pre-PTA values (57% versus 60%, p=0.2 and 17 versus 17 mm, p=0.9, respectively).
Conclusions:
Our findings suggest that increased vascular access flow after PTA for CVD has no relation to cardiac function.
Purpose:
To investigate retrospectively the use of catheter-based intraaccess blood flow measurements as an adjunct to physical examination and fistulography in hemodialysis access interventions.
Materials and methods:
Among 1,540 dialysis interventions performed at a single institution in a 2.5-year period, 104 qualifying catheter-based flow measurements were made in 70 mature native fistula interventions in 55 patients and 34 graft interventions in 31 patients. The flow rate threshold prompting intervention was generally 600 mL/min, but some variation existed depending on the clinical setting.
Results:
The most common indication for measurement of blood flow was to determine the hemodynamic significance of a fistula inflow stenosis (n = 25), of which only four had subsequent intervention. Other common indications included decision-making resulting in further angioplasty or stent implantation of noninflow lesions (fistulas, n = 10; grafts, n = 23) versus termination of the procedure (n = 23), problem-solving in cases in which there was no visible lesion to explain the clinical indicator of access failure (n = 17), evaluation for high-flow-related cardiac risk in aneurysmal fistulas (n = 13), suboptimal evaluation of the inflow (n = 8), and suboptimal physical examination (n = 6). Overall, flow measurements supported a decision to perform angioplasty (n = 11) or stent placement (n = 3) in 17% of fistula interventions and 35% of graft interventions.
Conclusions:
The major benefit of flow measurement was to support a decision to withhold further angioplasty or stent placement.
Purpose:
The success of percutaneous interventions on stenotic hemodialysis prosthetic grafts and autogenous fistulas is assessed by comparing vessel diameter before and after treatment. These changes do not correlate with gold standard access blood flow (ABF) measurements obtained during hemodialysis. The AngioFlow (AngioDynamics, Inc, Queensbury, New York) calculates real-time blood flow through access circuits and may provide more physiologically relevant data in the interventional suite. This study compares angiographic vessel diameter and access circuit flow rates obtained with the AngioFlow Meter before and after percutaneous interventions on stenotic hemodialysis prosthetic grafts and autogenous fistulas ABF measurements obtained during hemodialysis.
Materials and methods:
Angiographic images and AngioFlow measurements for 76 procedures in 35 patients undergoing hemodialysis with arteriovenous grafts or fistulas were analyzed retrospectively. Correlations between ABF, fistulography, and AngioFlow measurements before and after treatment were computed. Regression analyses of AngioFlow measurements and measurements after ABF were performed to account for confounding factors. Time to failure of treatment was modeled in first-time patients stratified by AngioFlow values obtained after treatment. Only patients with ABF measurements obtained within 5 weeks of intervention were included.
Results:
Correlations between initial ABF and fistulography measurement (ρ = 0.781), initial ABF and AngioFlow (ρ = 0.675), and final AngioFlow and ABF measurement (ρ = 0.798) were statistically significant. The correlation between final ABF and AngioFlow was significantly stronger than final ABF and fistulography (difference = 0.418, 95% bootstrap confidence interval [CI] [0.054, 0.914]). AngioFlow values and access survival after treatment did not show significant correlation.
Conclusions:
AngioFlow measurements performed after treatment correlate more strongly with hemodialysis ABF values than fistulography measures. Further studies are needed to determine the target AngioFlow value obtained after treatment that is associated with the greatest survival benefit for access circuits.
Radial-cephalic fistulas (RCFs) perianastomotic stenoses (PASs) are on and around the fistula anastomosis. This group of lesions encompasses juxta-anastomotic stenosis (stenosis located on the venous side within 3 cm away from the anastomosis), anastomotic, and arterial stenosis. The purpose of our study was to assess the postintervention primary patency and assisted postintervention primary patency (APP) rates for surgery and angioplasty when treating these stenoses. The secondary endpoint was to identify factors that might influence the procedure's patency rates.
This retrospective study included 73 consecutive patients treated for lack of maturation PASs between January 1999 and December 2005 in two interventional centers. Patients' mean age was 65 years old. Stenoses were treated by surgery (n = 21) or percutaneous transluminal angioplasty (PTA; n = 52). Surgery meant creation of a new anastomosis excluding the area of stenosis. Preoperative characteristics including the patient's age, gender, comorbidities, stenosis location, and length were not statistically different between the two groups. The mean follow-up was 39 months for PTA and 49 months for surgery.
Anatomical and clinical success rates were 86% and 90% for surgery, and 75% and 92% for PTA. At 1 year, the primary patency rates were 71 ± 10% for surgery and 41 ± 6% for PTA, respectively (P < .02). There was no significant difference between the two groups with respect to assisted primary patency (95% vs 92%). In the PTA group, stenosis location at the anastomosis itself was a risk factor of early recurrence (P = .047). The complication rate was similar between surgery and PTA.
Our results suggest that the treatment of anastomotic stenoses should be surgical rather than endovascular. Angioplasty and surgery have shown similar results when used to treat other perianastomotic stenoses, but repeat procedures were more frequent with angioplasty.
We evaluated native coronary arteries treated by directional coronary atherectomy or balloon-expandable stent placement in an effort to derive a quantitative geometric model relating the luminal diameter immediately after intervention to that present 6 months later. The minimal luminal diameter of each lesion was measured before and immediately after intervention in 102 single Palmaz-Schatz stents and 134 directional atherectomies, 192 (81%) of which had repeat angiographic measurement of minimal luminal diameter 6 months after the intervention. The immediate enlargement in luminal diameter produced by the intervention (acute gain) and the subsequent reduction in luminal diameter from the time of intervention to 6 months of follow-up (late loss) were calculated.
Luminal diameter increased from 0.69 +/- 0.40 mm to 3.11 +/- 0.64 mm (acute gain, 2.41 +/- 0.64 mm) after intervention, providing an immediate postprocedure residual stenosis of 1 +/- 14% relative to a reference diameter of 3.13 +/- 0.65 mm. At 6-month follow-up, the late luminal diameter was 1.97 +/- 0.92 mm (late loss, 1.13 +/- 0.89 mm), yielding a late diameter stenosis of 36 +/- 26%. The restenosis rate (according to the traditional definition of diameter stenosis > or = 50%) was 30%. Multivariable analysis demonstrated that late luminal diameter (p = 0.02), late percent stenosis (p = 0.04), and restenosis (according to a > 50% definition, p = 0.04) were each strongly associated with the luminal diameter present immediately after the procedure. Whereas late luminal diameter was also influenced by reference artery size and the vessel treated (left anterior descending versus right coronary artery), reference vessel size was rejected by the multivariable models of late percent stenosis and binary restenosis after they were adjusted for the effect of postprocedure luminal diameter. Once adjusted for postprocedure luminal diameter, neither late luminal diameter nor late loss was found to be independently determined by which device was used (atherectomy versus stents). Rather, late loss was determined independently by the immediate postprocedure luminal diameter (p = 0.005) and the postprocedure percent stenosis (p = 0.02). Although late loss thus increased with acute gain, the net beneficial effect of increased acute gain was maintained: Late loss was only a fraction (0.47) of acute gain, so the ability of a larger postprocedure luminal diameter to reduce the probability of subsequent restenosis was preserved.
This quantitative model demonstrates that the late coronary lumen diameter and the probability of restenosis after Palmaz-Schatz stenting or directional atherectomy are influenced strongly by the lumen diameter present immediately after the procedure rather than by the specific device used. Although the influence of a larger acute result on reduced restenosis appears to be well established in this treatment population, the interplay among the multiple other biological influences on restenosis limits the ability to predict the probability of restenosis for the individual patient based on a large acute result alone. Future studies of restenosis, however, can further refine this multivariable quantitative model by adjusting for the effects of other clinical variables, mechanical interventions, or drug therapies in addition to the clear effect of postprocedure luminal diameter.
To assess patency after percutaneous treatment of dysfunctional and thrombosed native arteriovenous fistulas and to examine predictors of patency after intervention.
A cohort of 65 consecutive patients with dysfunctional (n = 53) or occluded (n = 12) native fistulas who underwent 96 percutaneous interventions over an 18-month period was retrospectively analyzed. Fistula locations were radiocephalic (n = 37), brachiocephalic (n = 10), or brachiobasilic (n = 18). Primary interventions consisted of angioplasty (n = 50), stent placement (n = 3), or percutaneous thrombolysis/thrombectomy (n = 12). Additional interventions during follow-up consisted of angioplasty (n = 22), stent placement (n = 6), or percutaneous thrombolysis/thrombectomy (n = 3). Duration of fistula function was assessed clinically and examined as a function of anatomic and clinical variables with use of Cox hazards models and the Kaplan-Meier method.
Clinical success with resumption of at least one session of normal dialysis occurred in 94% (90 of 96) of interventions. The 30-day morbidity rate was 2.1%; no procedure-related deaths occurred. Primary, assisted primary, and secondary patency rates (+/- SE) of dysfunctional fistulas after intervention at 12 months were 26% +/- 11%, 80% +/- 6%, and 82% +/- 6%. Occluded fistulas after intervention had 3-month primary, assisted primary, and secondary patency rates of 60% +/- 15%, 60% +/- 15%, and 80% +/- 13%. Lesions 2.0 cm or more in length were five times more likely to have loss of patency than lesions smaller than 2.0 cm. The presence of at least one comorbid factor--diabetes, coronary artery disease, or peripheral vascular disease--was associated with nearly twice the risk of patency loss after any intervention.
Despite modest primary patency rates in our experience, high assisted and secondary patency rates can be achieved with percutaneous intervention in native arteriovenous fistulas. These findings emphasize the need for close surveillance of native fistulas and a low threshold for diagnostic fistulography after initial intervention. The most detrimental determinant of outcome was lesion length > or =2 cm.
The ratio of intragraft venous limb pressure (VLP) to systemic pressure (S) has been proposed to help determine the endpoint of hemodialysis access interventions. It was hypothesized that physical examination of the access could be used in the same way and these techniques were compared as predictors of outcome.
With use of a quality-assurance database, records from 117 hemodialysis access interventions were retrospectively reviewed. Only interventions in grafts were included. The database included physical examination (to establish thrill, thrill with slight pulsatility [TSP], pulse with slight thrill [PST], and pulse) at three locations along the graft (proximal, midportion, and distal), normalized pressure ratio calculated with S from a blood pressure cuff (S(cuff)) and S within the graft with outflow occluded (S(direct)), graft configuration and location, indication, operator, and time to next intervention (outcome of primary patency). Only procedures with complete follow-up data were included in the analysis (n = 97; declotting, n = 51; prophylactic percutaneous transluminal angioplasty [PTA], n = 46). Statistical analysis was performed with use of Cox proportional-hazards regression.
Graft configuration, location, side, VLP, S(direct), and S(cuff) did not affect outcomes. An operator effect was noted for two physicians and was adjusted for in all analyses. Pressure ratios were weak predictors of outcome (VLP/S(direct), P =.07; VLP/S(cuff), P =.08) and suggested that patency increased with increasing pressure ratio, contrary to earlier studies. Procedure type predicted outcome (declotting, median patency of 50 days; PTA, median patency of 105 days; P =.01). Thrill at distal physical examination was predictive of outcome (P =.04) and even more so when thrill and TSP combined were compared with PST and pulse combined (P =.03). Similar but less-pronounced effects were seen at midportion and proximal physical examinations.
The presence of a thrill or slightly pulsatile thrill at the distal (venous) end of a dialysis graft is the best predictor of outcome after percutaneous intervention. Based on the present study, the authors believe that physical examination of dialysis access should supplant pressure measurements as an endpoint of intervention and should serve as an essential component of quality assurance of access interventions.
To determine if intragraft blood flow measurements correlate with the anatomical characteristics of stenoses found during diagnostic fistulography.
This investigation was a retrospective review of 40 patients with decreased intragraft blood flow (<600 mL/min) in patent polytetrafluoroethylene hemodialysis grafts who underwent diagnostic fistulography and angioplasty. Intragraft blood flow was measured with the ultrasonic dilution technique. The fistulogram images were reviewed and the anatomic characteristics of all stenoses were measured and recorded. These characteristics were correlated with the intragraft blood flow values.
The mean intragraft blood flow was 476 mL/min (range, 270-600 mL/min). Fistulography revealed a total of 71 stenoses and all 40 patients had at least one lesion with > 50% stenosis. There was no correlation between the intragraft blood flow and the location, length, or number of stenoses. There was a moderate inverse correlation between the intragraft blood flow and the degree of stenosis (P =.08). Fifty-nine stenoses were treated with angioplasty. The mean postangioplasty blood flow was 796 mL/min (range, 470-1565 mL/min). The mean change in blood flow after angioplasty was 311 mL/min (range, 15-1154 mL/min) There was no association between the change in blood flow after angioplasty and the number, length, or degree of residual stenosis.
Intragraft blood flow < 600 mL/min is an excellent predictor of the presence of at least one significant (>/=50%) stenosis. There was an inverse correlation between intragraft blood flow and the degree of stenosis. There was no association between the intragraft blood flow and the location, length, or number of stenosis.
Objective:
Several imaging modalities are available for the evaluation of dysfunctional hemodialysis shunts. Color Doppler ultrasonography (CDUS) and digital subtraction angiography (DSA) are most widely used for the detection of access stenoses, and contrast-enhanced magnetic resonance angiography (CE-MRA) of shunts has recently been introduced. To date, no study has compared the value of these three modalities for stenosis detection in dysfunctional shunts. We prospectively compared CDUS and CE-MRA with DSA for the detection of significant (> or = 50%) stenoses in failing dialysis accesses, and we determined whether the interventionalist would benefit from CDUS performed before DSA and endovascular intervention.
Methods:
CDUS, CE-MRA, and DSA were performed of 49 dysfunctional hemodialysis arteriovenous fistulas and 32 grafts. The vascular tree of the accesses was divided into three to eight segments depending on the access type (arteriovenous fistula or arteriovenous graft) and the length of venous outflow. CDUS was performed and assessed by a vascular technician, whereas CE-MRA and DSA were interpreted by two magnetic resonance radiologists and two interventional radiologists, respectively. All readers were blinded to information from each other and from other studies. DSA was used as reference standard for stenosis detection.
Results:
DSA detected 111 significant (> or = 50%) stenoses in 433 vascular segments. Sensitivity and specificity of CDUS for the detection of significant stenosed vessel segments were 91% (95% CI, 84%-95%) and 97% (95% CI, 94%-98%), respectively. We found a positive predictive value of 91% (95% CI, 84%-95%) and a negative predictive value of 97% (95% CI, 94%-98%). The sensitivity, specificity, positive predictive value, and negative predictive value of MRA were 96% (95% CI, 90%-98%), 98% (95% CI, 96%-99%), 94% (95% CI, 88%-97%), and 98% (95% CI, 96%-99%), respectively. CDUS and CE-MRA depicted respectively three and four significant stenoses in six nondiagnostic DSA segments. The interventionalist would have chosen an alternative cannulation site in 38% of patients if the CDUS results had been available.
Conclusions:
We suggest that CDUS be used as initial imaging modality of dysfunctional shunts, but complete access should be depicted at DSA and angioplasty to detect all significant stenoses eligible for intervention. CE-MRA should be considered only if DSA is inconclusive.
National Kidney Foundation KDOQI Clinical Practice Guideline for Hemodialysis Adequacy: 2015 update
- J T Daugirdas
- T A Depner
- J Inrig
- JT Daugirdas
National Kidney Foundation. KDOQI clinical practice guideline for vascular access: 2019 update
- C E Lok
- T S Huber
- T Lee
- CE Lok
Society of Interventional Radiology Standards of Practice Committee. Quality improvement guidelines for percutaneous image-guided management of the thrombosed or dysfunctional dialysis circuit
- S R Dariushnia
- T G Walker
- J E Silberzweig
- SR Dariushnia