Midterm outcomes of arteriovenous fistula aneurysm repair with simultaneous inflow revision or outflow tract revascularization

OBJECTIVE

The aim of this study was to investigate the 2-year outcomes of extensive revisions aimed at simultaneously addressing arteriovenous fistula (AVF) aneurysms, outflow stenosis, and/or high flow volumes.

METHODS

This was a retrospective cohort study in a tertiary referral center. The study population comprised hemodialysis patients with aneurysmal AVFs requiring revision. Subjects were eligible if they were ≥18 years of age and had aneurysm repair associated with inflow revision or treatment of outflow lesions. Patients were followed-up for a minimum of 2 years, and the primary outcome measure was cumulative patency.

RESULTS

Our cohort comprised 93 patients with a mean age of 56 ± 12 years. The most frequent access type was brachiocephalic fistula (61%), and the median access age at the time of revision was 66 months (interquartile range, 46-93 months). The median access flow volume was 2300 ml/min (interquartile range, 1281-2900), and 31 subjects (33%) presented aneurysms associated with both high flow and venous obstruction. Aneurysm repair consisted of aneurysmorraphy in the overwhelming majority (95%). Inflow revision was performed in a total of 49 cases (53%), and outflow tract obstruction was treated in 71 patients (72%), with 27 patients (29%) receiving a simultaneous 3-component revision. At 2 years, the primary, primary assisted, and cumulative patencies were 60% ± 1%, 91% ± 3%, and 94% ± 3%, respectively. The most frequent indication for first-time reinterventions was outflow tract stenosis (24%). Aneurysm recurrence was observed in 13 subjects (14%) during the entire follow-up and was responsible for reinterventions in seven of them (8%), with a 2-year freedom from aneurysm-related reintervention rate of 95% ± 3%.

CONCLUSIONS

Extensive AVF revision with simultaneous aneurysm repair, inflow revision, and outflow tract revascularization is feasible, safe, and associated with favorable 2-year patency rates.

Safety of bilateral arm pressure measurements in the diagnostic workup of dialysis-associated steal syndrome

OBJECTIVE

Although bilateral brachial pressure measurement is routinely included in the diagnostic work-up of upper extremity ischemia, it is generally avoided in the presence of hemodialysis access due to fears of inducing access thrombosis. This study evaluated the safety of bilateral brachial pressure measurement in patients with clinical suspicion of dialysis-associated steal syndrome (DASS).

METHODS

Patients undergoing non-invasive testing for steal syndrome between September 2015 and December 2021 were included in this study. The diagnostic workup was performed by certified vascular sonographers in an outpatient vascular lab and consisted of bilateral brachial pressures, photoplethysmography, and duplex ultrasonography of the access. Interarm differential (IAD) was defined as systolic blood pressure (SBP) in the contralateral arm minus SBP in the access arm. The primary endpoint was immediate access thrombosis.

RESULTS

The study sample consisted of 331 subjects with a mean age of 61 ± 13 and a median access age of 9 months (3-31 months) with radiocephalic fistulas present in 29%. Many patients (68%) presented with paresthesia and 4% presented with tissue loss. The mean brachial systolic pressure was 152 ± 37 mmHg on the ipsilateral arm versus 143 ± 34 mmHg on the contralateral (p-value <0.001), with an inter-arm differential (IAD) of -8.4 ± 19 mmHg. A total of 16 subjects (5%) presented a differential ⩾20 mmHg. A positive thrill was noted in all the accesses immediately following blood pressure measurement and no occurrence of access thrombosis was noted at 30 days. Proximal arterial revascularization interventions were performed in 11 cases (3%). Subjects who presented an IAD ⩾20 mmHg had lower ipsilateral digital-brachial index (0.39 ± 0.18 vs 0.68 ± 0.26; p = 0.037), a higher tendency of being referred for angiograms (37.5% vs 10.5%, p = 0.006), and more proximal arterial revascularization procedures (25.0% vs 2.2%, p = 0.001).

CONCLUSION

Bilateral arm pressure measurement in the context of dialysis access-associated steal syndrome (DASS) appears safe and useful for identifying subjects whose symptoms are due to proximal arterial inflow disease. We therefore recommend this test be considered in the diagnostic algorithms of DASS.

Cardiovascular collapse during mechanical thrombectomy for acute pulmonary embolism and the role of extracorporeal membrane oxygenation in patient rescue

BACKGROUND

Driven by the ability to avoid thrombolytics and provide a one stop procedure with immediate hemodynamic improvement, there has been a dramatic increase in the use of mechanical thrombectomy (MT) devices for the treatment of intermediate-to-high risk pulmonary embolism (PE). This study investigated the incidence and outcomes of cardiovascular collapse during MT procedures and demonstrates the role of extracorporeal membrane oxygenation (ECMO) in salvaging patients.

METHODS

This single-center retrospective review included patients with PE undergoing MT with the FlowTriever device between 2017 and 2022. Patients presenting periprocedural cardiac arrest were identified and their perioperative characteristics and postoperative outcomes were evaluated.

RESULTS

A total of 151 patients with a mean age of 64 ± 14 years who presented with intermediate-to-high risk PE received LBAT procedures during the study period. The simplified PE severity score was ≥1 in 83% of cases and the average RV/LV ratio was 1.6 ± 0.5, with and elevated troponin in 84%. Technical success was achieved in 98.7% and a significant decrease in pulmonary artery systolic pressure (PASP) was observed (37 mm Hg vs 56 mm Hg; P < .0001). Intraoperative cardiac arrest occurred in nine patients (6%). These patients were more likely to present PASP of ≥70 mm Hg (84% vs 14%; P < .001), were more hypotensive upon admission (systolic of 94 ± 14 mm Hg vs 119 ± 23 mm Hg; P = .004), presented lower oxygen saturation levels (87 ± 6% vs 92 ± 6%; P = .023) and were more likely to present with a history of recent surgery (67% vs 18%; P = .004). Four patients were rescued successfully with ECMO and their residual PE was subsequently removed before discharge by surgical embolectomy in two of the four cases and repeat MT in the other two. All five patients (3%) who did not receive ECMO support expired intraoperatively. The overall 30-day mortality was 8% with no death occurring in patients who were salvaged with ECMO.

CONCLUSIONS

Large-bore aspiration thrombectomy for acute PE is associated with favorable technical outcomes, but the concern for acute cardiac decompensation is non-negligible in patients presenting with high-risk features and a PASP of ≥70 mm Hg. ECMO can help to salvage some of these patients and should be considered in the treatment algorithms of patients deemed at high risk.

Surgical creation of upper extremity arteriovenous fistula and grafts: a narrative review

Background and Objective

Surgical creation of arteriovenous fistulas (AVF) and grafts (AVG) continues to be the mainstay access for hemodialysis (HD). Avoidance of dependence on dialysis catheters continues to be a worldwide mission in dialysis access. Importantly, there is no one-size-fits-all approach to hemodialysis access and each patient should undergo access creation that is patient-centered. The aim of this paper is to review the literature, current guidelines, and discuss the common types of upper extremity hemodialysis access and their reported outcomes. We will also share our institutional experience regarding the surgical creation of upper extremity hemodialysis access.

Methods

The literature review incorporates twenty-seven relevant articles from 1997 to present and one case report series from 1966. Sources were gathered from electronic databases including PubMed, EMBASE, Medline, and Google Scholar. Only articles written in the English language were considered and study designs varied from current clinical guidelines, systematic and meta-analyses, randomized controlled trials, observational studies, and two main vascular surgery textbooks.

Key Content and Findings

This review exclusively focuses on the surgical creation of upper extremity hemodialysis accesses. Creating a graft versus fistula ultimately is decided by the existing anatomy, and is centered around the need of the patient. Preoperatively, the patient should undergo a thorough history and physical exam, with special attention to any previous central venous access, as well as, delineating the vascular anatomy with ultrasound imaging. The major tenets of access creation are choosing the most distal site of the non-dominant upper extremity whenever possible; and ideally creation of an autogenous access is preferred over a prosthetic graft. Described in this review are multiple surgical approaches for upper extremity hemodialysis access creation and associated institutional practices performed by the surgeon author. In the postoperative period, follow up care and surveillance are imperative to preserve a functioning access.

Conclusions

The most recent guidelines regarding hemodialysis access still favor arteriovenous fistula as the primary goal for patients with suitable anatomy. Preoperative evaluation including patient education, intraoperative ultrasound assessment, meticulous technique, and careful postoperative management are all paramount for successful access surgery. Dialysis access remains quite challenging, but with diligence the great majority of patients can be dialyzed without catheter dependence.

Dynamic, Time-Resolved CT Angiography After EVAR: A Quantitative Approach to Accurately Characterize Aortic Endoleak Type and Identify Inflow Vessels

PURPOSE

Our purpose was to study the accuracy of dynamic computed tomography angiography (d-CTA) in characterizing endoleak type, inflow vessels as compared with digital subtraction angiography (DSA) using qualitative and quantitative analysis.

METHODS

Between March 2019 and January 2021, all patients who underwent d-CTA imaging after EVAR were retrospectively reviewed. Two blinded independent reviewers qualitatively reviewed d-CTA and DSA images. Quantitative region of interest (ROI) analysis was performed by measuring time-resolved contrast enhancement within the aorta and endoleak lesion(s) in the aneurysm sac. Differences between time-to-peak enhancement (Δ TTP) across different ROIs were quantified.

RESULTS

A total of 48 patients underwent d-CTA during the study period, of whom 24 patients had abdominal EVAR and DSA imaging for comparison. Qualitative review of DSA imaging showed type I (n=4), type II (n=16), and type III (n=2) and no endoleak (n=2). In 23 of 24 patients (95.8%), d-CTA findings correlated with DSA findings for endoleak type. One patient had a type III endoleak that was demonstrated only in d-CTA (arising from defect in polymer sealing ring of Ovation stent graft) imaging. In type II endoleak cases, d-CTA identified more inflow vessels than DSA imaging (33 vs 21 vessels, p=0.010). Quantitative analysis showed mean (±SD) Δ TTP values for type I endoleak as 1.8 (±1.8) seconds, type II as 9.6 (±3.5) seconds, and for type III endoleak as 5.6 (±1.3) seconds.

CONCLUSION

Dynamic CTA can accurately characterize aortic endoleak type, inflow vessels as compared with DSA imaging. Quantitative parameters such as Δ TTP enhancement can help better differentiate endoleak types and provide an objective approach to endoleak diagnosis.

Advanced intraoperative imaging guidance for inside-out central venous recanalization using a novel catheter access system

BACKGROUND

The novel Surfacer Inside-Out recanalization technique facilitates right-sided central venous access in occluded vessels but carries a risk of arterial and pleural injuries. This article demonstrates how an advanced intraoperative imaging protocol can help to avoid these potential complications.

METHODS

This retrospective review included patients undergoing the Surfacer Inside-Out central venous recanalization procedure between December 2017 and October 2021. The study sample comprised patients included in the SAVE-US trial at our site as well as patients treated after US Food and Drug Administration approval of the device. All procedures were performed using intraoperative cone-beam computed tomography (CBCT) angiography to map out the trajectory of the device through the mediastinum and supraclavicular space with fusion imaging for guidance. Procedures were aborted if CBCT findings predicted injury to arterial or respiratory structures. The intraoperative coronal and sagittal orientation of the device was compared to preoperatively predicted trajectory.

RESULTS

A total of 17 procedures were performed in 16 patients with end-stage renal disease and a mean age of 61 ± 11 years. Most patients presented a type 3 central venous occlusion (9/15). Successful recanalization was achieved in 14 of the 17 cases (82.4%) with no intraoperative complications. The procedure had to be aborted in 3 of the 17 cases based on intraoperative CBCT findings, which projected the device to perforate the right pleural space in one patient, the trachea and right subclavian artery in another, and the innominate artery in the third patient. The total radiation dose per procedure was 753 ± 346 mGy and the mean procedural time was 101.6 ± 29.7 minutes. A median of 2 (range, 1-5) intraoperative CBCT scans were performed per patient and accounted for 70% of the total radiation dose. Statistical analysis showed intraoperative CBCT findings to differ significantly from preoperative predicted values.

CONCLUSIONS

The nonsteerable and penetrating nature of the Surfacer device may lead to serious complications when performed under fluoroscopic guidance alone. Intraoperative CBCT with fusion overlay enhances the safety and effective use of this device and inside out crossing technique.

Dynamic CT angiography is more accurate in diagnosing endoleaks than standard triphasic CT angiography and enables targeted embolization

PURPOSE

The primary objective was to compare the accuracy of dynamic CT angiography (d-CTA) with standardized triphasic contrast enhanced CT angiography (t-CTA) in diagnosing endoleak type after endovascular aortic repair (EVAR) using digital subtraction angiography (DSA) as reference standard. The secondary objective was to study the impact of d-CTA on image-fusion guided endoleak embolization.

MATERIALS AND METHODS

Retrospective review of patients who underwent d-CTA imaging after EVAR between March 2019 and July 2021 was performed. De-identified images were independently reviewed by two-two blinded readers to document endoleak type and target vessels. Impact of d-CTA-guided embolization was evaluated by number of planning angiograms, radiation exposure and accuracy of target vessel overlay.

RESULTS

During the study period, 52 patients underwent d-CTA, 19 had all three modalities available for analysis. DSA imaging confirmed 4(21.0%) type-I, 14(73.7%) type-II and 1(5.3%) type-III endoleak. Findings from d-CTA matched with DSA in 19/19 cases (100%), whereas t-CTA matched in 14/19 cases (73.7%). In type-II endoleaks, number of target vessels identified by d-CTA, t-CTA and DSA were 23, 17 and 16 respectively. Mean dose-length product from d-CTA and t-CTA was 1445±551 and 1612±530 mGy*cm (p=0.26). Nine patients underwent d-CTA-guided type-II endoleak embolization, using a median of 1(range:1-4) planning angiogram before embolization utilizing 21.6(±8.7)% of total procedural radiation dose. Target vessel overlay was accurate in 9/9(100%) cases.

CONCLUSION

Dynamic, time-resolved CTA is more accurate compared to standardized triphasic contrast enhanced CTA in diagnosing endoleak type after EVAR. In type-II endoleak, d-CTA better identified target vessels and enabled safe, targeted embolization.

Downregulation of the endothelial histone demethylase JMJD3 is associated with neointimal hyperplasia of arteriovenous fistulas in kidney failure

Jumonji domain-containing protein-3 (JMJD3), a histone H3 lysine 27 (H3K27) demethylase, promotes endothelial regeneration, but its function in neointimal hyperplasia (NIH) of arteriovenous fistulas (AVFs) has not been explored. In this study, we examined the contribution of endothelial JMJD3 to NIH of AVFs and the mechanisms underlying JMJD3 expression during kidney failure. We found that endothelial JMJD3 expression was negatively associated with NIH of AVFs in patients with kidney failure. JMJD3 expression in endothelial cells (ECs) was also downregulated in the vasculature of chronic kidney disease (CKD) mice. In addition, specific knockout of endothelial JMJD3 delayed EC regeneration, enhanced endothelial mesenchymal transition, impaired endothelial barrier function as determined by increased Evans blue staining and inflammatory cell infiltration, and accelerated neointima formation in AVFs created by venous end to arterial side anastomosis in CKD mice. Mechanistically, JMJD3 expression was downregulated via binding of transforming growth factor beta 1-mediated Hes family transcription factor Hes1 to its gene promoter. Knockdown of JMJD3 enhanced H3K27 methylation, thereby inhibiting transcriptional activity at promoters of EC markers and reducing migration and proliferation of ECs. Furthermore, knockdown of endothelial JMJD3 decreased endothelial nitric oxide synthase expression and nitric oxide production, leading to the proliferation of vascular smooth muscle cells. In conclusion, we demonstrate that decreased expression of endothelial JMJD3 impairs EC regeneration and function and accelerates neointima formation in AVFs. We propose increasing the expression of endothelial JMJD3 could represent a new strategy for preventing endothelial dysfunction, attenuating NIH, and improving AVF patency in patients with kidney disease.

A systematic review of management of superficial reflux in the setting of deep venous obstruction

BACKGROUND

Due to fear of obliterating collateral outflow path and thus worsening venous hypertension, many physicians believe that deep venous obstruction is a contraindication for treatment of superficial venous reflux. This review will present the available clinical data in this important group of patients.

METHODS

A literature search was performed on PubMed, Web of Science and Google scholar to identify clinical research studies between 1991 and 2021 evaluating the concomitant management of superficial reflux and deep venous obstruction. Studies were excluded if they reported on less than 5 patients, did not specify interventions to treat superficial reflux or had no follow-up data available. All studies included were observational, and their quality assessed using the Newcastle-Ottawa scale.

RESULTS

Ten retrospective cohort studies were included, encompassing a total of 2476 limbs in 2428 patients out of which concurrent superficial venous reflux (SVR) and deep venous obstruction (DVO) or a known history of DVT were managed in 944 limbs. Eight of the studies were comparative. The level of deep venous obstruction was supra-inguinal when specified in most cases. The mean age ranged between 42 and 65 years, and 1432 patients (59%) were female and advanced CVD (i.e. CEAP C4-6) was present in 614 limbs (70%) with two studies reporting uniquely on C6 patients. Out of the 944 limbs treated for concomitant SVR and DVO, a combination of saphenous vein ablative procedures and deep venous stenting (DVS) was carried out in 483 limbs (51.2%), saphenous vein ablative procedures alone in 293 limbs (31%) and DVS alone in 168 (17.8%). Out of the five studies comparing different treatment strategies of concurrent SVR and DVO, four reported better outcomes after a combined deep venous stenting and saphenous vein ablation compared to ablation alone. Studies comparing the outcomes of saphenous ablation in patients with reflux alone versus patients with concurrent reflux and DVO did not find any significant difference in clinical improvement and postoperative complication rates.

CONCLUSION

Current evidence is weak owing to limited number of studies and small sample size but suggests that ablation of superficial venous reflux is safe in patients with concurrent deep venous obstruction. Patients with advanced venous disease and iliac vein obstruction have better results when superficial reflux ablation is combined with treatment of iliac vein obstruction. Additional contemporary studies are needed to confirm the safety and specifically investigate the efficacy of superficial reflux ablation in relieving symptoms in patients with concurrent infrainguinal obstruction.

Evaluation of a Novel System for RFID Intraoperative Cardiovascular Analytics

Objective: To evaluate a novel technology for real time tracking of RF-Identified (RFID) surgical tools (Biotic System), providing intraoperative data analytics during simulated cardiovascular procedures. Ineffective asset management in the Operating Room (OR) leads to inefficient utilization of resources and contributes to prolonged operative times and increased costs. Analysis of captured data can assist in quantifying instrument utilization, procedure flow, performance and prevention of retained instruments. Methods & Results: Five surgeons performed thirteen simulated surgical cases on three human cadavers. Procedures included (i) two abdominal aortic aneurysm (AAA) repairs, (ii) three carotid endarterectomies (CE), (iii) two femoropopliteal (fem-pop) bypasses, (iv) thoracic aortic aneurysm repair, (v) coronary artery bypass graft, (vi) aortic valve replacement, (vii) ascending aortic aneurysm repair, (viii) heart transplants, and (ix) mitral valve replacement. For each case an average of 139 surgical instruments were RFID-tagged and tracked intraoperatively. Data was captured and analyzed retrospectively. Of the 139 instruments tracked across each of the 13 cases, 55 instruments (39.5%) were actually used, demonstrating a high level of redundancy. For repeat cases (i.e. CE/AAA/fem-pop): (i) average instrument usage was 41 ± 3.6 (8.8% variation) for CE (n=3); (ii) average instrument usage was 69 ± 4.0 (5.8% variation) for AAA (n=2); and (iii) average instrument usage was 48 ± 2.5 (5.3% variation) for fem- pop (n=2). Results also showed a reduction in end-of-procedure instrument counting times of 58-87%. Conclusions: We report on a method for collecting intraoperative data analytics regarding instrument usage via RFID technology. This system will help refine instrument selection, quantitate instrument utilization and prevent inadvertent retention in a patient. This should help increase efficiency in packaging and sterilization and let surgeons make objective decisions in the composition of surgical trays. Clinical and Translational Impact Statement—Intraoperative analytics of surgical tools and associated equipment may ultimately lead to safer more efficient surgeries that increase patient outcomes while decreasing the cost of care.

Cone-Beam CT and Image Fusion-Guided Percutaneous Recanalization of Occluded Central Venous Stent

We describe an 81-year-old man with end-stage renal disease and central venous occlusion who was referred for dialysis access creation. This case illustrates a novel percutaneous image fusion–guided recanalization of an occluded right subclavian vein and brachiocephalic vein stent in a patient with limited remaining dialysis access sites. (Level of Difficulty: Advanced.)

Novel technique of stent retrieval after migration to the right heart

Central venous obstruction in the symptomatic patient is often treated with endovascular stenting. A rare, but serious, complication of this treatment is migration of the stent from the original site of deployment. Treatment of this complication requires either open or endovascular retrieval of the displaced stent. To treat a rare, but potentially devastating, complication, we have presented an effective endovascular method for migrated stent retrieval using a combination of a large bore sheath, balloon, and snare.

PATENCY-2 trial of vonapanitase to promote radiocephalic fistula use for hemodialysis and secondary patency

OBJECTIVE

Arteriovenous fistulas created for hemodialysis often fail to become usable and are frequently abandoned. This prospective trial evaluated the efficacy of vonapanitase, a recombinant human elastase, in increasing radiocephalic fistula use for hemodialysis and secondary patency.

METHODS

PATENCY-2 was a randomized, double-blind, placebo-controlled trial in patients on or approaching the need for hemodialysis undergoing radiocephalic arteriovenous fistula creation. Of 696 screened, 613 were randomized, and 603 were treated (vonapanitase n = 405, placebo n = 208). The study drug solution was applied topically to the artery and vein for 10 min immediately after fistula creation. The primary endpoints were fistula use for hemodialysis and secondary patency (fistula survival without abandonment). Other efficacy endpoints included unassisted fistula use for hemodialysis, primary unassisted patency, fistula maturation and unassisted maturation by ultrasound criteria, and fistula procedure rates.

RESULTS

The proportions of patients with fistula use for hemodialysis was similar between groups, 70% vonapanitase and 65% placebo, (p = 0.33). The Kaplan-Meier estimates of 12-month secondary patency were 78% (95% confidence interval [CI], 73-82) for vonapanitase and 76% (95% CI, 70-82) for placebo (p = 0.93). The proportions with unassisted fistula use for hemodialysis were 46% vonapanitase and 37% placebo (p = 0.054). The Kaplan-Meier estimates of 12-month primary unassisted patency were 50% (95% CI, 44-55) for vonapanitase and 43% (95% CI, 35-50) for placebo (p = 0.18). There were no differences in the proportion of patients with fistula maturation or in fistula procedure rates. Adverse events were similar between groups. Vonapanitase was not immunogenic.

CONCLUSIONS

Vonapanitase treatment did not achieve clinical or statistical significance to meaningfully improve radiocephalic fistula surgical outcomes. Outcome in the placebo group were better than in historical controls. Vonapanitase was well-tolerated and safe.

TRIAL REGISTRATION

clinicaltrials.gov: NCT02414841 (https://clinicaltrials.gov/ct2/show/NCT02414841).

PDGFRA in vascular adventitial MSCs promotes neointima formation in arteriovenous fistula in chronic kidney disease

Chronic kidney disease (CKD) induces the failure of arteriovenous fistulas (AVFs) and promotes the differentiation of vascular adventitial GLI1-positive mesenchymal stem cells (GMCs). However, the roles of GMCs in forming neointima in AVFs remain unknown. GMCs isolated from CKD mice showed increased potential capacity of differentiation into myofibroblast-like cells. Increased activation of expression of PDGFRA and hedgehog (HH) signaling were detected in adventitial cells of AVFs from patients with end-stage kidney disease and CKD mice. PDGFRA was translocated and accumulated in early endosome when sonic hedgehog was overexpressed. In endosome, PDGFRA-mediated activation of TGFB1/SMAD signaling promoted the differentiation of GMCs into myofibroblasts, extracellular matrix deposition, and vascular fibrosis. These responses resulted in neointima formation and AVF failure. KO of Pdgfra or inhibition of HH signaling in GMCs suppressed the differentiation of GMCs into myofibroblasts. In vivo, specific KO of Pdgfra inhibited GMC activation and vascular fibrosis, resulting in suppression of neointima formation and improvement of AVF patency despite CKD. Our findings could yield strategies for maintaining AVF functions.

Open bilateral common femoral and popliteal vein aneurysm repair

Although venous aneurysms are rare, typically asymptomatic, and most commonly found incidentally on imaging studies, patients with this pathology can develop pulmonary emboli owing to these aneurysms acting as a nidus for thrombus formation. There is no clear consensus regarding conservative management with anticoagulation vs operative intervention as the best treatment of deep venous aneurysms. We report the clinical course and surgical treatment of a patient presenting with both bilateral common femoral vein and bilateral popliteal venous aneurysms who had a known history of prior symptomatic pulmonary emboli.

Efficacy and safety associated with the use of the Surfacer® Inside-Out® Access Catheter System: Results from a prospective, multicenter Food and Drug Administration-approved Investigational Device Exemption study

Purpose:

Thoracic central venous obstruction is commonly associated with the use of central venous catheters. The Surfacer System to Facilitate Access in Venous Occlusions Study was an Food and Drug Administration–approved US Investigational Device Exemption study designed to evaluate the performance and safety of the Surfacer System when used to facilitate central venous access in patients with thoracic central venous obstruction.

Methods:

Thirty patients were enrolled in this prospective, multicenter, single-arm study between December 2017 and May 2019. Device performance and adverse events were collected peri-procedurally and at discharge. Enrollment included 15 female and 15 male subjects with a mean age of 55.5 ± 12.9 (range: 30–79) years. Twenty-eight patients (93.3%) required central venous access for hemodialysis access. Locations of thoracic central venous obstruction were graded from 1 to 4 based on severity and extension of venous occlusions. Seven patients (23.3%) had type 1, 6 (20.0%) type 2, 16 (53.3%) type 3, and 1 (3.3%) type 4 obstruction.

Results:

Successful central venous catheter placement was achieved in 27 of 30 patients (90.0%). The procedure was discontinued in three (10.0%) due to tortuous anatomy discovered intraprocedurally. All 27 patients with successful CVC placement achieved adequate catheter patency and tip positioning with a mean overall procedural time and time to achieve central venous access with the Surfacer System being 44.1 ± 30.6 and 19.1 ± 25.1 min, respectively. There were no device-related adverse events or catheter malposition.

Conclusion:

The results of the SAVEUS Study confirm the safety and efficacy of the Surfacer System and the Inside-Out procedure when used for the placement of right-sided central venous access in patients with thoracic central venous obstruction.

Early cannulation of the Hemodialysis Reliable Outflow graft

OBJECTIVE

In complex dialysis patients, central venous stenosis may preclude additional upper extremity access options. The Hemodialysis Reliable Outflow graft (Merit Medical Systems, Inc.) can bypass this stenosis providing patients with an additional upper extremity long-term access option. We report our experience with early-cannulation Hemodialysis Reliable Outflow grafts and compare them to traditional Hemodialysis Reliable Outflow grafts.

METHODS

We retrospectively reviewed all patients undergoing Hemodialysis Reliable Outflow graft placement from 1 January 2013 through 15 August 2017 at our institution and compared those undergoing placement of traditional Hemodialysis Reliable Outflow grafts and simultaneous tunneled dialysis catheter insertion to those undergoing Hemodialysis Reliable Outflow graft placement using an early-cannulation Hemodialysis Reliable Outflow graft without a tunneled dialysis catheter.

RESULTS

A total of 88 patients had 98 Hemodialysis Reliable Outflow grafts inserted throughout this time period. Of these, 61 (62%) were early-cannulation Hemodialysis Reliable Outflow grafts, while 37 (38%) were traditional Hemodialysis Reliable Outflow grafts. Primary, primary-assisted, and secondary patency rates at 1 year were higher for the traditional Hemodialysis Reliable Outflow graft cohort (53.1% vs 25.2%, p < 0.01; 70.1% vs 30.5%, p < 0.01; and 80.4% vs 55.4%, p = 0.07, respectively). There was no difference in the rate of postoperative hematoma, seroma, pseudoaneurysm formation, steal syndrome, or overall graft thrombosis between the two cohorts. Early-cannulation Hemodialysis Reliable Outflow grafts required earlier reintervention for thrombosis and earlier reintervention for any cause when compared to traditional Hemodialysis Reliable Outflow grafts (146 ± 184 days vs 417 ± 272 days, p < 0.01, and 123 ± 169 days vs 401 ± 311 days, p < 0.01, respectively).

CONCLUSION

In complex dialysis patients, early-cannulation Hemodialysis Reliable Outflow grafts have significantly lower 1-year primary and primary-assisted patency rates and require earlier reintervention to maintain this patency compared to traditional Hemodialysis Reliable Outflow grafts.

Notch signaling in bone marrow-derived FSP-1 cells initiates neointima formation in arteriovenous fistulas

Neointima formation is a major contributor to arteriovenous fistula (AVF) failure. We have previously shown that activation of the Notch signaling pathway contributes to neointima formation by promoting the migration of vascular smooth muscle cells (VSMCs) into the venous anastomosis. In the current study we investigated the mechanisms underlying the dedifferentiation and migration of VSMCs, and in particular the role of bone marrow-derived fibroblast specific protein 1 (FSP-1)⁺ cells, another cell type found in models of vascular injury. Using VSMC-specific reporter mice, we found that most of the VSMCs participating in AVF neointima formation originated from dedifferentiated VSMCs. We also observed infiltration of bone marrow-derived FSP-1+ cells into the arterial anastomosis where they could interact with VSMCs. In vitro, conditioned media from FSP-1+ cells stimulated VSMC proliferation and phenotype switching. Activated Notch signaling transformed FSP-1⁺ cells into type I macrophages and stimulated secretion of cytokines and growth factors. Pretreatment with a Notch inhibitor or knockout of the canonical downstream factor RBP-Jκ in bone marrow-derived FSP1⁺ cells decreased FSP1⁺ cell infiltration into murine AVFs, attenuating VSMC dedifferentiation and neointima formation. Our results suggest that targeting Notch signaling could provide a new therapeutic strategy to improve AVF patency.

Superior Vena Cava Reconstruction Using Femoropopliteal Vein as a Panel Graft

There has been an increase in superior vena cava (SVC) syndrome secondary to the growing use of indwelling catheters and pacemaker wire insertions. These 2 factors can account up to 74% cases of benign SVC syndrome. Endovascular therapy is considered the first line of treatment. Surgery is an excellent option and is generally reserved for SVC syndrome not amenable to traditional endovascular procedures. We report a case of central venous reconstruction including an SVC reconstruction using the femoropopliteal vein as a panel graft in a patient with SVC syndrome due to pacemaker wires who failed multiple endovascular interventions.

Stent Grafts Can Convert Unusable Upper Arm Arteriovenous Fistulas into a Functioning Hemodialysis Access: A Retrospective Case Series

Introduction

Not all newly created arteriovenous fistulas (AVFs) successfully mature and develop into a functioning access for hemodialysis. Percutaneous transluminal angioplasty (PTA) and balloon-assisted maturation (BAM) have been utilized to either treat flow-limiting stenoses or to promote and accelerate maturation. We hypothesized that unusable upper arm AVFs can be rescued by conversion to a functional access using the percutaneous placement of a stent graft (SG).

Methods

Clinical data on 12 patients with an early non-usable upper arm AVF underwent percutaneous revision using SGs. There were six brachial–cephalic, three brachial–basilic, and three brachial–brachial vein transposition AVFs.

Results

All patients had either at least two or more stenoses (>2 cm) within the fistula conduit, or a long segment stenosis (>4 cm) in combination with shorter segment stenoses. Nine patients had failed PTA. Three patients had failed BAM at outside access centers. All patients were referred for failure to achieve access cannulation and concomitant hemodialysis through the AVF. SGs were placed retrograde toward the arterial anastomoses and ranged in diameter (6, 7, and 8 mm in four, seven, and one patients, respectively). The average length of the SG was 10 cm (range 5–15 cm). All SGs were post-balloon dilated at the time of placement. All AVFs were salvaged, and patients were able to maintain functional use of their access with cannulation occurring through the SG. The primary patency rate at 6 and 12 months was 91% [95% confidence interval (CI), 56–98%] and 65% (95% CI, 32–87%), respectively (n = 11 and 5 at risk, respectively). The secondary patency rate at 6 and 12 months was 100 and 72% (95% CI, 46–93%), respectively (n = 11 and 7 at risk, respectively).

Conclusion

This report outlines a successful initial experience using SGs to rescue, preserve, and convert an unusable upper arm AVF into a functioning hemodialysis access.

Establishing patient-specific criteria for selecting the optimal upper extremity vascular access procedure

OBJECTIVE

The Kidney Disease Outcome Quality Initiative and Fistula First Breakthrough Initiative call for the indiscriminate creation of arteriovenous fistulas (AVFs) over arteriovenous grafts (AVGs) without providing patient-specific criteria for vascular access selection. Although the U.S. AVF rate has increased dramatically, several reports have found that this singular focus on increasing AVFs has resulted in increased AVF nonmaturation/early failure and a high prevalence of catheter dependence. The objective of this study was to determine the appropriateness of vascular access procedures in clinical scenarios constructed with combinations of relevant factors potentially influencing outcomes.

METHODS

The RAND/UCLA Appropriateness Method was used. Accordingly, a comprehensive literature search was performed and a synthesis of results compiled. The RAND/UCLA Appropriateness Method was applied to 2088 AVF and 1728 AVG clinical scenarios with varying patient characteristics. Eleven international vascular access experts rated the appropriateness of each scenario in two rounds. On the basis of the distribution of the panelists' scores, each scenario was determined to be appropriate, inappropriate, or indeterminate.

RESULTS

Panelists achieved agreement in 2964 (77.7%) scenarios; 860 (41%) AVF and 588 (34%) AVG scenarios were scored appropriate, 686 (33%) AVF and 480 (28%) AVG scenarios were scored inappropriate, and 542 (26%) AVF and 660 (38%) AVG scenarios were indeterminate. Younger age, larger outflow vein diameter, normal or obese body mass index (vs morbidly obese), larger inflow artery diameter, and higher patient functional status were associated with appropriateness of AVF creation. Older age, dialysis dependence, and smaller vein size were associated with appropriateness of AVG creation. Gender, diabetes, and coronary artery disease were not associated with AVF or AVG appropriateness. Dialysis status was not associated with AVF appropriateness. Body mass index and functional status were not associated with AVG appropriateness. To simulate the surgeon's decision-making, scenarios were combined to create situations with the same patient characteristics and both AVF and AVG options for access. Of these 864 clinical situations, 311 (36%) were rated appropriate for AVG but inappropriate or indeterminate for AVF.

CONCLUSIONS

The results of this study indicate that patient-specific situations exist wherein AVG is as appropriate as or more appropriate than AVF. These results provide patient-specific recommendations for clinicians to optimize vascular access selection criteria, to standardize care, and to inform payers and policy. Indeterminate scenarios will guide future research.

Arteriovenous fistula patency in the 3 years following vonapanitase and placebo treatment

OBJECTIVE

This study explored the long-term outcomes of arteriovenous fistulas treated with vonapanitase (recombinant human elastase) at the time of surgical creation.

METHODS

This was a randomized, double-blind, placebo-controlled trial of 151 patients undergoing radiocephalic or brachiocephalic arteriovenous fistula creation who were randomized equally to placebo, vonapanitase 10 μg, or vonapanitase 30 μg. The results after 1 year of follow-up were previously reported. The current analysis occurred when the last patient treated was observed for 3 years. For the current analysis, the primary end point was primary patency; the secondary end points included secondary patency, use of the fistula for hemodialysis, and rate of procedures to restore or to maintain patency.

RESULTS

There was no significant difference in the risk of primary patency loss with vonapanitase 10 μg or 30 μg vs placebo. When seven initial patency loss events related to cephalic arch and central vein balloon angioplasty were excluded, the risk of patency loss was reduced with vonapanitase overall (hazard ratio [HR], 0.63; P = .049) and 30 μg (HR, 0.51; P = .03). In patients with radiocephalic fistulas (n = 67), the risks of primary and secondary patency loss were reduced with 30 μg (HR, 0.37 [P = .02] and 0.24 [P = .046], respectively). The rate of procedures to restore or to maintain fistula patency was reduced with 30 μg vs placebo (0.23 vs 0.72 procedure days/patient/year; P = .03) and also reduced in patients with radiocephalic fistulas with 30 μg vs placebo (0.17 vs 0.85 procedure days/patient/year; P = .048).

CONCLUSIONS

In this study, vonapanitase did not significantly improve primary patency in the primary analysis but did significantly improve primary patency in an analysis that excluded patency loss due to cephalic arch and central vein balloon angioplasty. In patients with radiocephalic fistulas, 30 μg significantly improved primary and secondary patency. Vonapanitase 30 μg decreased the rate of procedures to restore or to maintain patency in the analysis that included all patients and in the subset with radiocephalic fistulas.

Laser Atherectomy for Lower Extremity Revascularization: An Adjunctive Endovascular Treatment Option

Excimer laser atherectomy (LA) employs precision laser energy control (shallow tissue penetration) and safer wavelengths (ultraviolet as opposed to the infrared spectra in older laser technology), which decreases perforation and thermal injury to the treated vessels. Though extensively used by cardiologists for severe obstructive coronary artery disease, peripheral interventionalists have not accepted LA as a routine adjunctive technique for stenotic or occluded vessels. We report herein the technical and clinical outcomes with LA for complex peripheral vascular disease in patients deemed high-risk for conventional surgical revascularization. Over a 6-month period, 19 lesions in 15 high-risk patients (mean age 72 ±10 years) were treated with LA (308-nm spectral wavelength) followed by balloon angioplasty for limb-threatening ischemia (n=10) and severe disabling claudication (n=5). The lesions were located at the superficial femoral artery (n=8), popliteal artery (6), and/or tibial vessels (5). The mean occlusion length was 10.3 ±2.3 cm. Laser catheter choice ranged from 1.4 to 2.5 mm depending on the target vessel diameter. Clinical examination, duplex ultrasound, and ankle-brachial indices were performed in follow-up visits. Immediate technical success was achieved in 16 (84%) lesions. In the 3 technical failures, inability to cross the lesion with a wire (n=2) or vessel perforation (n=1) precluded successful LA. Overall, primary patency as assessed by duplex was 57% (superficial femoral artery 71%, popliteal 60%, tibial vessels 25%). Clinical improvement was seen in 10 lesions (77%) that were successfully treated initially. One patient required below-knee amputation. At an average of 2-year follow-up, 6 patients who were initially successfully treated were alive (46%), including 3 patients (50%) with stable symptoms without the need for major amputation. Laser atherectomy is a useful adjunctive revascularization technique for high-risk patients with limb-threatening ischemia. This technique is especially beneficial in the treatment of ostial lesions, which may be prone to distal embolization, as well as total occlusions that can be traversed by a guide wire but not a balloon. Vascular surgeons should add LA to their endovascular armamentarium for the treatment of complex peripheral vascular disease in the high surgical risk patients. Further study of clinical outcome measures and comparison to other interventional techniques are warranted.

Bioengineered human acellular vessels for dialysis access in patients with end-stage renal disease: two phase 2 single-arm trials

BACKGROUND

For patients with end-stage renal disease who are not candidates for fistula, dialysis access grafts are the best option for chronic haemodialysis. However, polytetrafluoroethylene arteriovenous grafts are prone to thrombosis, infection, and intimal hyperplasia at the venous anastomosis. We developed and tested a bioengineered human acellular vessel as a potential solution to these limitations in dialysis access.

METHODS

We did two single-arm phase 2 trials at six centres in the USA and Poland. We enrolled adults with end-stage renal disease. A novel bioengineered human acellular vessel was implanted into the arms of patients for haemodialysis access. Primary endpoints were safety (freedom from immune response or infection, aneurysm, or mechanical failure, and incidence of adverse events), and efficacy as assessed by primary, primary assisted, and secondary patencies at 6 months. All patients were followed up for at least 1 year, or had a censoring event. These trials are registered with ClinicalTrials.gov, NCT01744418 and NCT01840956.

FINDINGS

Human acellular vessels were implanted into 60 patients. Mean follow-up was 16 months (SD 7·6). One vessel became infected during 82 patient-years of follow-up. The vessels had no dilatation and rarely had post-cannulation bleeding. At 6 months, 63% (95% CI 47-72) of patients had primary patency, 73% (57-81) had primary assisted patency, and 97% (85-98) had secondary patency, with most loss of primary patency because of thrombosis. At 12 months, 28% (17-40) had primary patency, 38% (26-51) had primary assisted patency, and 89% (74-93) had secondary patency.

INTERPRETATION

Bioengineered human acellular vessels seem to provide safe and functional haemodialysis access, and warrant further study in randomised controlled trials.

FUNDING

Humacyte and US National Institutes of Health.

Early Experience With a Novel Hybrid Vascular Graft for Hemodialysis Access Creation in Patients With Disadvantaged Anatomy

Purpose: To describe the use of the Hybrid vascular graft in disadvantaged anatomy for hemodialysis access creation and compare outcomes to standard-wall polytetrafluoroethylene (PTFE) grafts. Methods: In a retrospective analysis, 25 patients (mean age 65±14 years; 13 men) who received the Hybrid graft were compared with 35 contemporaneous patients (mean age 63±12 years; 20 men) who received a standard PTFE graft for hemodialysis access over a 2-year period. Criteria for Hybrid graft placement were (1) exhausted or inadequate peripheral veins for arteriovenous fistula (AVF) creation and concomitant small target veins that precluded conventional PTFE graft placement, (2) previous graft anastomosis or a stent in the venous target at the level of the axilla, or (3) failed brachial-basilic or brachial-brachial upper arm transposition AVF with a small target vein at the axilla. Efficacy, anatomic and clinical considerations, and technique were reviewed; patency rates, complications, and reinterventions were examined. Results: Technical success was achieved in all cases, and all grafts were usable for hemodialysis. Seven of 25 Hybrid patients required stent-graft extensions and 3 patients required angioplasty to improve venous outflow at the time of Hybrid graft insertion. Three of 35 standard PTFE graft patients required angioplasty to improve venous outflow at the time of graft insertion. There was no perioperative mortality or procedure-related morbidity in either group. Median follow-up was 21 months. The patient survival estimate was 66% at 2 years. Estimated primary patency (24% vs 18%, p>0.05), assisted primary patency (34% vs 28%; p>0.05), and secondary patency rates (40% vs 38%, p≥0.05) at 24 months were equivalent for Hybrid vs PTFE grafts, respectively. Venous hypertension was not a complication following Hybrid graft implantation but was seen in 2 patients with the standard PTFE graft. Conclusion: The Hybrid graft offers a safe, technically effective alternative for patients with disadvantaged anatomy requiring hemodialysis access and has comparable outcomes to standard PTFE grafts. Further clinical experience and long-term data are required for determining the proper utility of this device in chronic dialysis-dependent patients.

Open arterial revascularization of the critically ischemic foot using arterial homograft

BACKGROUND

Revascularization alternatives for patients with critical limb ischemia and without adequate autogenous vein remain challenging. We reviewed our experience with the use of arterial homograft as a conduit for limb salvage in patients with limb ischemia and active lower extremity infections.

METHODS

A retrospective review of patients who underwent open arterial revascularization of the lower extremity with cryopreserved femoral artery homograft for the treatment of symptomatic critical limb ischemia (i.e., foot ulceration, infection, or gangrene) during an 18-month period was performed. Relevant clinical variables and treatment outcomes were analyzed. Clinical success was defined as limb salvage for one year, patency of the reconstruction, and wound healing.

RESULTS

Thirteen patients (5 men; average age 71 +/- 83 years, range 51-87 years) were treated during this study period. Treatment indications included 10 (77%) foot ulcerations, 2 (15%) critically ischemic limbs without ulceration, and 1 (8%) infected polytetrafluoroethylene bypass graft with acute occlusion and limb ischemia. A femoral below-the-knee popliteal bypass was performed in 4 (1%), femoral to anterior tibial artery in 4 (31%), femoral to posterior tibial artery in 3 (23%), and femoral to peroneal artery in 2 (15%). All 13 limbs were preserved. Minor amputations were performed in 6 patients, 2 underwent toe amputations and 4 patients had a trans-metatarsal amputation. The cumulative patency rate at 6, 9, and 18 months was 92.3%, 70.3%, and 58.6%, respectively.

CONCLUSION

Open arterial revascularization with arterial femoral homograft is an acceptable treatment method in patients with critical limb ischemia and active infection in whom autogenous vein is not available or the use of a synthetic conduit is not possible.

Application of human type I pancreatic elastase (PRT-201) to the venous anastomosis of arteriovenous grafts in patients with chronic kidney disease

PURPOSE

To explore the safety and efficacy of PRT-201 applied to the outflow vein of a newly created arteriovenous graft (AVG).

METHODS

Randomized, double-blind, placebo-controlled, single-dose escalation study of PRT-201 (0.01 to 9 mg) applied to the graft-vein anastomosis and adjacent outflow vein immediately after AVG placement. The primary outcome measure was safety. The efficacy measures were intraoperative increases in outflow vein diameter and blood flow rate, primary unassisted patency, and secondary patency by dose groups (placebo, low, medium, high and All PRT-201).

RESULTS

A total of 89 patients were treated (28 placebo and 61 PRT-201). There were no significant differences in the proportion of placebo and PRT-201 patients reporting adverse events. Intraoperative outflow vein diameter increased 5% (p=0.14) in the placebo group compared with 13% (p=0.01), 15% (p=0.07) and 12% (p<0.001), in the low, medium and high groups, respectively. The comparison between the high and placebo groups was marginally statistically significant (p=0.06). The intraoperative blood flow did not change in the placebo group, and increased in the low, medium and high groups by 19% (p=0.34), 36% (p=0.09) and 46% (p=0.02), respectively. The low group had the longest primary unassisted and secondary patency and the fewest procedures to restore or maintain patency; however, the differences between groups were not statistically significant.

CONCLUSIONS

PRT-201 was well tolerated and increased AVG intraoperative outflow vein diameter and blood flow. Low dose tended to increase secondary patency and decrease the rate of procedures to restore or maintain patency. Larger studies with these doses will be necessary to confirm these results.

Evaluating and treating venous outflow stenoses is necessary for the successful open surgical treatment of arteriovenous fistula aneurysms

BACKGROUND

Arteriovenous fistula (AVF) aneurysms (AVFAs) can lead to skin erosion, bleeding, difficult access while on hemodialysis, and poor cosmetic appearance. We reviewed our experience in treating patients with aneurysmal dilatation of their AVF.

METHODS

We reviewed clinical data of 48 patients (37 men; overall mean age, 55 years; range, 28-85 years) with an AVFA who underwent treatment during a 30-month period. Relevant clinical variables and treatment outcomes were analyzed.

RESULTS

All patients underwent a fistulogram, and 90% required percutaneous angioplasty to improve outflow. Fifty-six percent of patients had one stenotic outflow lesion, and 44% had at least two tandem outflow stenoses that required treatment. Open repair with aneurysmorrhaphy was performed in one stage in 64% of patients and in two stages in 36%. A tunneled hemodialysis catheter was required in 11 patients (23%) until the surgically repaired AVF was ready for use again, comprising 10 patients treated with single-stage surgery and only one patient in the staged group. All AVFAs were effectively treated, and patients were able to maintain functional use of their access when healed.

CONCLUSIONS

There is a high association of venous outflow stenoses and AVFA. Comprehensive therapy should encompass treatment of any venous outflow stenoses before open AVFA repair. A two-stage repair may decrease tunneled hemodialysis catheter use in patients with multiple aneurysms.