Poor Patency Research Articles

Poor mid-term functional patency and post-operative outcomes in diabetic patients who undergo arteriovenous graft creation.

Diabetes mellitus is a leading cause of renal failure in the US and has been associated with higher mortality when compared to nondiabetic patients. This remains true despite initiation of renal replacement therapy. As such, we were interested in identifying any potential differences in access durability and postoperative outcomes in diabetic patients who receive arteriovenous fistulas versus grafts for hemodialysis. Diabetic patients undergoing their first arteriovenous (AV) access creation surgery in the Vascular Quality Initiative from January 2011 to January 2022 were included in our study. After exclusions, the study included two groups: those receiving AV fistulas and those receiving AV grafts for hemodialysis. Demographic characteristics were summarized and compared between these two groups using chi-square analysis or unpaired t-test. After propensity score matching was conducted, the effect of procedure type on functional patency, along with secondary outcomes including wound infection were assessed using chi-square analysis. A total of 20,159 diabetic patients who used their hemodialysis access were included in our study; 16,205 received AV fistulas while 3954 received AV grafts. Patients receiving AV grafts were more likely to be older, female, and have higher pre-operative catheter usage. After propensity score matching, patients who received AV grafts had a shorter time-to-use their conduit (50 vs 166 days, p < 0.0001), however, patients who received AV fistulas were more likely to have longer functional patency use for hemodialysis when compared to those who received AV grafts (mean survival time: 3.3 vs 2.9 years, p < 0.0001). These results were consistent between diabetics with insulin-dependent or insulin-independent diabetes. Patients diagnosed with diabetes mellitus had an increased risk for significantly inferior clinical outcomes related to newly created AV grafts, including lower rates of mid-term functional patency and higher rates of worse post-operative outcomes when compared to diabetics who received AV fistulas.

Transjugular Intrahepatic Portosystemic Shunt: An Update.

It is more than 50 years since the concept of transjugular intrahepatic portosystemic shunt (TIPS) was first introduced as a percutaneous procedure for patients with refractory variceal bleeding and ascites. TIPS has become widely accepted in the management of complications of portal hypertension because it is less invasive than surgery. In the early days of TIPS, complications included the poor long-term patency of the stent and a high incidence of hepatic encephalopathy. In addition, an excessive shunt diameter after TIPS often resulted in severe hepatic encephalopathy. Although recent covered stents have significantly reduced shunt dysfunction, the development of hepatic encephalopathy and early liver failure remain to be crucial post-TIPS complications. This study reviews the current literature on the status of TIPS in the treatment of cirrhosis.

Bidirectional Elastic PTFE Small Diameter Artificial Blood Vessel Grafts and Surface Antithrombotic Functionalized Construction.

Expanded polytetrafluoroethylene (ePTFE) failed to achieve clinical application in the field of small-diameter blood vessels due to its lack of elasticity in the circumferential direction and high stiffness. Excellent multidirectional elasticity and dynamic compliance matching with natural blood vessels are important means to solve the problem of acute thrombosis and poor long-term patency. Herein, novel PTFE spinning blood vessels were prepared by the PTFE emulsion electrospinning process, which not only presented good bidirectional elasticity but also promoted the adhesion and proliferation of endothelial cells and induced the contractile expression of SMCs. And, a PTFE-shish and aminated polycaprolactone (PCL)-kebab structure has been developed that converted the chemically inert PTFE surface into a drug-loading platform for the multifunctionalization of PTFE vascular grafts. It provides novel preparation methods for the application of new bidirectional elastic small-diameter artificial blood vessels and their surface functionalization construction.

Development of small-diameter vascular grafts using PCL/PLA/gelatin/PVA/hyaluronic acid nanofibers containing VEGF/enoxaparin

The extending demands for narrow-diameter vascular grafts to restore damaged arteries have captivated researcher's attention. The absence of appropriate vascular substitutes is due to the poor patency rate of small-caliber synthetic grafts caused by thrombosis and vessel hemodynamic mismatch that induce intimal hyperplasia. We developed small-diameter vascular grafts in two layers through electrospinning. The inner layer was fabricated by gelatin/polyvinyl alcohol (PVA)/hyaluronic acid/enoxaparin and vascular endothelial growth factor (VEGFs) and the outer layer was manufactured via polycaprolactone (PCL)/polylactic acid (PLA)/hyaluronic acid. The products were characterized by atomic force microscope (AFM), scanning electron microscope (SEM), water contact angle (WCA), attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR), swelling test, mechanical test, and release rate. Blood compatibility tests including blood clotting time, hemolysis, and human platelet sedimentation were measured. The interactions of human umbilical vein endothelial cells (HUVECs) and human endometrial stem cells (hEnSCs) with nanofibrous vascular grafts were detected by SEM, viability assay, and DAPI staining. The results exhibited the produced small-diameter vascular grafts had proper antithrombotic properties due to two factors of VEGF and enoxaparin. After two months of the subcutaneous implantation of the scaffolds on the back of rats, the tubular vascular grafts lacked any macroscopic and histological signs of acute inflammation and had appropriate degradation rates. Furthermore, lumen patency was observed after 2 months. Consequently, VEGF and enoxaparin improves cell and blood compatibility in the small-diameter vascular grafts.

Abstract 1152: Hydrodissection Facilitates Endoscopic Vein Harvesting Of The Great Saphenous Vein For Coronary Artery Bypass Grafting

Coronary Artery Disease is the primary cause of mortality in the United States (US), ranking as the third leading cause of death globally. Coronary Artery Bypass Grafting (CABG) with left internal mammary artery to the left anterior descending artery is the gold standard for CABG with a patency rate of 90% at 15 years. The great saphenous vein (GSV) harvested by endoscopic vein harvesting (EVH) is the second most common vascular conduit used for CABG in the US. This is despite the poor long-term patency of this conduit due to vein graft failure (VGF). VGF is the number one technical problem associated with CABG, with 15-year patency rates of only 30 to 50%. While the "no touch" harvesting technique avoids VGF, with 15-year patency rates of 86%, it is technically demanding and results in increased leg wound healing, and not widely used. With this in mind, we developed the Minimally Invasive No Touch (MINT) technique that incorporates the best features of EVH and no touch. This procedure employs hydro dissection, a process that utilizes fluid pressure to gently harvest the GSV with minimal trauma. This approach effectively addresses two significant issues associated with using the GSV in CABG, namely VGF resulting from impaired endothelial function and excessive trauma to the GSV during the extended learning curve needed to master EVH. To evaluate this, harvesting was conducted by a PA, with over 2,000 standard EVH procedures. Our preliminary studies looked to evaluate the quality of GSVs harvested from patients using 1) standard EVH, 2) “no touch” harvesting techniques or 3) the MINT harvesting procedure, focused on evaluating the quality of the vessels by measuring the endothelial nitric oxide synthase (eNOS) activity and nitric oxide (NO) bioavailability. eNOS activity assays across harvested GSVs revealed a 3.4-fold increase in NO generation across MINT harvested samples compared to EVH and “no touch” samples, respectively. This data suggests that the GSVs harvested by the MINT procedure result in a structurally intact vein with elevated eNOS activity and NO bioavailability consistent with a functionally intact endothelium. Additional studies are necessary to uncover the array of vascular benefits associated with MINT GSV harvesting for CABG procedures.

Heat transfer mechanism and performance optimization scheme of refractory oxide solid heat storage materials

Clean energy advances can drive solid heat storage technology. Because of their high-temperature, corrosion, and excellent thermal shock resistance properties, refractory oxides are widely used as solid heat storage materials. However, their applications are limited owing to their poor heat-transfer performance resulting from their multicomponent, multiphase, and complex nature and thus understanding their heat-transfer mechanism will be crucial for their performance optimization. In this study, the thermal properties and mechanisms of corundum, high-alumina, and magnesia bricks were characterized using heat-transfer theories and models. Macroscopic analysis of the bricks revealed that they are all “internal porosity” materials. By comparing the weighting parameter j, the multiphase high-alumina brick shows poor heat-transfer path patency and the measured thermal conductivity is the lowest at 3.55 W m−1 K−1. Microscopic analysis found that in contrast to the thermal conductivity of other materials, the thermal conductivity of high-alumina bricks was significantly affected by phonon intrinsic scattering. Moreover, corundum and magnesia bricks exhibited a wider range of ultimate heat-transfer performance than the high-alumina brick. Hence, the heat-transfer performance of refractory oxide can be enhanced by increasing their particle contact, reducing the negative effects of microcracks, phases, and impurities, and by reducing the number of defects on phonon heat transfer, thereby providing an optimization scheme for improving the heat-transfer performance of the materials.

An assessment of spiral flow graft patency rates in Hemodialysis (HD) patients

IntroductionVascular access for hemodialysis remains a challenge for end stage renal failure (ESRF) patients. Autogenous arterio-venous fistulae are the first choice, but synthetic grafts may be required. The Spiral Flow™ graft (SF) mimics physiological blood flow to minimize turbulence and neointimal hyperplasia. We analyzed patency of SF for hemodialysis at a vascular unit in Johannesburg, South Africa. MethodA retrospective review was performed of upper arm SF implanted between 2013and 2015. Primary and secondary patency rates were analyzed. ResultsEighty grafts were placed in 71 patients. The primary and secondary patency rates at 1 year were 54 % (95 % CI: 41 %-65 %) and 63 % (95 % CI: 43 %-78 %), respectively. Poor patency risks such as Black ethnicity, hypertension, diabetes and HIV, were present in 75 %, 61 %, 26 % and 19 %, respectively. ConclusionSFs were associated with acceptable patency rates in ESRF patients. Excessive comorbidities may affect patency rates.

Multicenter Registry of Common Femoral Artery Disease Treated With Endovascular Revascularization Using Interwoven Nitinol Stents: An Observational Retrospective Study.

Surgical thromboendarterectomy has been the gold standard treatment for common femoral artery (CFA) disease. However, endovascular therapy (EVT) is conducted in certain patients with CFA lesions because of multiple comorbidities. The interwoven nitinol stent (IWS) has been developed to prevent stent fracture. Thus, this study aimed to evaluate the feasibility of EVT using IWS for CFA lesions in clinical practice. This retrospective multicenter registry analyzed patients who had symptomatic lower-extremity artery disease due to CFA lesions and underwent EVT using IWS between 2019 and 2021. The primary endpoint was restenosis 2 years after EVT. This study enrolled a total of 177 patients with 196 CFA lesions. The 2-year estimate of freedom from restenosis was 88.0%. The 2-year freedom rates from the target-lesion revascularization, major amputation, and all-cause death were 92.9%, 99.0%, and 75.2%, respectively. The clinical features significantly associated with restenosis risk were the reference vessel diameter (RVD, per 1.0 mm, hazard ratio [HR], 0.24 [0.08-0.70]; p=0.009), external iliac artery (EIA) involvement (HR=4.03 [1.56-10.4]; p=0.004), superficial femoral artery (SFA) involvement (HR=3.05 [1.00-9.25]; p=0.049), body mass index (BMI; per 1.0, HR=0.85 [0.73-0.99]; p=0.032), occlusion of deep femoral arteries (DFAs) at baseline (HR=7.89 [2.04-30.5]; p=0.003), and chronic limb-threatening ischemia (CLTI, HR=2.63 [1.02-6.78]; p=0.045). Their significant association was also confirmed by the random survival forest analysis. During a median follow-up of 12.0 months, guiding sheaths were inserted via CFAs implanted IWSs in 73 cases (37.2%), and no patients had cannulation-related complications, such as failed hemostasis, fracture of IWS, and stent occlusion. Endovascular therapy using IWS in CFA lesions showed acceptable 2-year patency rates at 88.0% and might preserve the arterial access via the ipsilateral CFAs. Small RVD, involving EIA and SFA lesions, emaciation, occluded DFA, and CLTI are associated with poor 2-year patency rates following EVT, thus, IWS implantation in CFA lesions may be an option for patients unsuitable for surgical revascularization. This retrospective multicenter registry enrolled 177 patients with 199 CFA lesions treated with EVT using interwoven nitinol stents, because surgical thromboendarterectomy was difficult due to their multiple comorbidities. The 2-year estimate of freedom from restenosis was acceptable at 88.0%. The 2-year freedom rate from major amputation was also high at 99.0%. Moreover, during a median follow-up of 12.0 months, guiding sheaths were inserted via CFAs implanted IWSs in 73 cases, and no patients had cannulation-related complications such as failed hemostasis, fracture of IWS, and stent occlusion.

Small-Diameter Blood Vessel Substitutes: Biomimetic Approaches to Improve Patency.

Small-dimeter blood vessels (<6 mm) are required in coronary bypass and peripheral bypass surgery to circumvent blocked arteries. However, they have poor patency rates due to thrombus formation, intimal hyperplasia at the distal anastomosis, and compliance mismatch between the native artery and the graft. This review covers the state-of-the-art technologies for improving graft patency with a focus on reducing compliance mismatch between the prosthesis and the native artery. The focus of this article is on biomimetic design strategies to match the compliance over a wide pressure range.

Predictors of amputation-free survival and wound healing after infrainguinal bypass with alternative conduits

ObjectiveInadequate vein quality or prior harvest precludes use of autologous single segment greater saphenous vein (ssGSV) in many patients with chronic limb-threatening ischemia (CLTI). Predictors of patient outcome after infrainguinal bypass with alternative (non-ssGSV) conduits are not well-understood. We explored whether limb presentation, bypass target, and conduit type were associated with amputation-free survival (AFS) after infrainguinal bypass using alternative conduits. MethodsA single-center retrospective study (2013-2020) was conducted of 139 infrainguinal bypasses performed for CLTI with cryopreserved ssGSV (cryovein) (n = 71), polytetrafluoroethylene (PTFE) (n = 23), or arm/spliced vein grafts (n = 45). Characteristics, Wound, Ischemia, and foot Infection (WIfI) stage, and outcomes were recorded. Multivariable Cox proportional hazards and classification and regression tree analysis modeled predictors of AFS. ResultsWithin 139 cases, the mean age was 71 years, 59% of patients were male, and 51% of cases were nonelective. More patients undergoing bypass with cryovein were WIfI stage 4 (41%) compared with PTFE (13%) or arm/spliced vein (27%) (P = .04). Across groups, AFS at 2 years was 78% for spliced/arm, 79% for PTFE, and 53% for cryovein (adjusted hazard ratio for cryovein, 2.5; P = .02). Among cases using cryovein, classification and regression tree analysis showed that WIfI stage 3 or 4, age >70 years, and prior failed bypass were predictive of the lowest AFS at 2 years of 36% vs AFS of 58% to 76% among subgroups with less than two of these factors. Although secondary patency at 2 years was worse in the cryovein group (26% vs 68% and 89% in arm/spliced and PTFE groups; P < .01), in patients with tissue loss there was no statistically significant difference in wound healing in the cryovein group (72%) compared with other bypass types (72% vs 87%, respectively; P = .12). ConclusionsIn patients with CLTI lacking suitable ssGSV, bypass with autogenous arm/spliced vein or PTFE has superior AFS compared with cryovein, although data were limited for PTFE conduits for distal targets. Despite poor patency with cryovein, wound healing is achieved in a majority of cases, although it should be used with caution in older patients with high WIfI stage and prior failed bypass, given the low rates of AFS.

Abstract 14961: Revitalizing Graft Patency: Intravascular Lithotripsy in Calcified Saphenous Vein Graft to Left Anterior Descending Artery Stenosis

A 73-year-old man with coronary artery disease (CAD), coronary artery bypass graft, heart failure [EF 25%] &amp; hypertension presented with Non-ST Segment Myocardial Infarction. Angiography revealed multivessel CAD with chronic total occlusion (CTO) of mid-left anterior descending (LAD) after a large first diagonal branch, CTO of mid-left circumflex &amp; distal right coronary artery. Saphenous vein graft (SVG) to obtuse marginal was patent. SVG-diagonal &amp; SVG-ramus intermedius were occluded. Mid SVG-LAD showed severe calcified stenosis (Fig. 1A). Native LAD beyond the SVG provided left to right collaterals to right posterior descending artery. Complex high-risk coronary intervention was performed on the SVG-LAD with mechanical circulatory support (MCS; Impella CP). SVG-LAD had a balloon undilatable lesion despite high pressure inflation with 4.0 mm cutting balloon (Fig. 1B). Intravascular ultrasound (IVUS) revealed severe stenosis with extensive circumferential calcification (Fig. 1C). Subsequently, intravascular lithotripsy (IVL) with 4.0 mm Shockwave balloon followed by high pressure balloon angioplasty with 4.5 mm noncompliant (NC) balloon was performed with significant luminal gain and fractures in calcium (Fig. 1D). The lesion was treated with 5.0 mm drug eluting stents that were post dilated with 5.0 mm NC balloon with excellent angiographic and IVUS result (Figs. 1E &amp; F). MCS was successfully removed at the end of the case.SVG grafts are associated with poor long-term patency compared to arterial grafts. PCI to SVG has a high failure rate and PCI of native vessel is often preferable. High risk SVG interventions with atherectomy have been recently reported, though data is limited. IVL has been safely used in heavily calcified native coronary arteries, however, its use in SVG disease is rare. We report the first off-label use IVL of SVG-LAD with MCS for treatment of a last-remaining conduit. Additional studies to assess IVL efficacy in vein grafts are warranted.

Obesity drives secondary procedures to achieve access maturation in end-stage renal disease

BackgroundEstablishing long-term arteriovenous access is an important component in the long-term care of a patient with end-stage renal disease. The increasing frequency of obesity is reported to impact the access management of end-stage renal disease patients. This study aims to evaluate the outcomes of arteriovenous fistulae (AVF) in obese and nonobese patients. MethodsA retrospective review of all patients over ten years with primary autogenous AVF (radiocephalic, brachiocephalic, and brachial-basilic) was undertaken at a single center. Patients were subcategorized by body mass index into nonobese, class I, II, and III obesity. Outcomes of maturation (successful progression to hemodialysis), reintervention, functional dialysis (continuous hemodialysis for 3 consecutive months), and patency were examined. ResultsFrom January 1999 to December 2019, 2311 patients (67% female; mean age, 61 ± 15 years) underwent primary AVF placement (12% radiocephalic, 53% brachiocephalic, and 35% brachial basilic). Forty-one percent were nonobese, 29% had class I obesity, 19% had class II obesity, and 11% had class III obesity. The majority of patients were diabetic and Hispanic. The 30-day major adverse cardiovascular event rate was elevated in class II (0.20%) and class III (0.50%) obesity compared with class I obesity (0.15%) and nonobese (0.05%). The 30-day morbidity rate was higher in all classes of obesity (0.5% vs0.3% vs 0.2% vs 0.05% for class III vs class II vs class I obesity and nonobese, respectively). Early thrombosis was significantly increased in class II (9%) and class III obesity (12%) compared with class I obesity (5%) and nonobese (3%). There was a two-fold increase in procedures to effect maturation in class II (51%) and class III (74%) obesity compared with class I obesity (22%) and nonobese (34%). Secondary patency at 3 years was significantly lower in class III (62 ± 4%) and class II (79 ± 3%) compared with class I obesity (87 ± 2%) and nonobese (93 ± 4%). All classes of obesity required significantly more secondary Interventions per year compared with nonobese (3.9 vs 3.1 vs 2.5 vs 1.4 secondary interventions per year for class III vs class II vs class I obesity and nonobese, respectively). ConclusionsAdvancing obesity class is associated with an increased number of procedures to achieve AVF maturation and is associated with poorer patency and functionality as the category of obesity advances.

A Comparative Study of Continuous Versus Interrupted Suturing Technique in Creating a Vascular Access for Hemodialysis: An Institutional-Based Experience.

Background Arteriovenous fistulas (AVFs) are considered the first and best access for patients with end-stage renal disease who need permanent vascular access for hemodialysis over arteriovenous grafts and central venous catheters for reasons that have been well-established. Poor early patency rates pose the biggest challenge in creating vascular access as they cause increased morbidity and economic/psychological concerns among patients. To minimize such effects, it is critical to use a patient-centered approach and carefully choose patients for AVF access creation. This study aimed to compare the primary patency of distal vascular access provided by continuous suturing versus that provided by interrupted suturing. Methodology This prospective study was conducted in the urology department of a superspecialty, tertiary care center from November 2021 to November 2022. Patency was assessed immediately after surgery (on the table), one month later, and six months later by palpating thrill and auscultating bruit. A total of 50 patients between the ages of 18 and 70 years who met the inclusion criteria were randomly assigned to two groups of 25 each. Results The baseline characteristics of both groups were comparable. At six months (p = 0.09), the continuous suturing group was observed to be somewhat better than the interrupted suturing group, with no significant difference in immediate and one-month patency rates. When compared to the continuous suturing group, the primary patency failure rate was significantly higher in the interrupted suturing group. Conclusions Thus, under appropriate circumstances, continuous sutures can be performed with greater ease, resulting in anastomosis that is as patent as that performed with interrupted sutures.

Building a Scaffold for Arteriovenous Fistula Maturation: Unravelling the Role of the Extracellular Matrix

Vascular access is the lifeline for patients receiving haemodialysis as kidney replacement therapy. As a surgically created arteriovenous fistula (AVF) provides a high-flow conduit suitable for cannulation, it remains the vascular access of choice. In order to use an AVF successfully, the luminal diameter and the vessel wall of the venous outflow tract have to increase. This process is referred to as AVF maturation. AVF non-maturation is an important limitation of AVFs that contributes to their poor primary patency rates. To date, there is no clear overview of the overall role of the extracellular matrix (ECM) in AVF maturation. The ECM is essential for vascular functioning, as it provides structural and mechanical strength and communicates with vascular cells to regulate their differentiation and proliferation. Thus, the ECM is involved in multiple processes that regulate AVF maturation, and it is essential to study its anatomy and vascular response to AVF surgery to define therapeutic targets to improve AVF maturation. In this review, we discuss the composition of both the arterial and venous ECM and its incorporation in the three vessel layers: the tunica intima, media, and adventitia. Furthermore, we examine the effect of chronic kidney failure on the vasculature, the timing of ECM remodelling post-AVF surgery, and current ECM interventions to improve AVF maturation. Lastly, the suitability of ECM interventions as a therapeutic target for AVF maturation will be discussed.

In-vivo evaluation of silk fibroin small-diameter vascular grafts: state of art of preclinical studies and animal models.

Autologous vein and artery remains the first choice for vascular grafting procedures in small-diameter vessels such as coronary and lower limb districts. Unfortunately, these vessels are often found to be unsuitable in atherosclerotic patients due to the presence of calcifications or to insufficient size. Synthetic grafts composed of materials such as expanded polytetrafluoroethylene (ePTFE) are frequently employed as second choice, because of their widespread availability and success in the reconstruction of larger arteries. However, ePTFE grafts with small diameter are plagued by poor patency rates due to surface thrombogenicity and intimal hyperplasia, caused by the bioinertness of the synthetic material and aggravated by low flow conditions. Several bioresorbable and biodegradable polymers have been developed and tested to exploit such issues for their potential stimulation to endothelialization and cell infiltration. Among these, silk fibroin (SF) has shown promising pre-clinical results as material for small-diameter vascular grafts (SDVGs) because of its favorable mechanical and biological properties. A putative advantage in graft infection in comparison with synthetic materials is plausible, although it remains to be demonstrated. Our literature review will focus on the performance of SF-SDVGs in vivo, as evaluated by studies performing vascular anastomosis and interposition procedures, within small and large animal models and different arterial districts. Efficiency under conditions that more accurately mime the human body will provide encouraging evidence towards future clinical applications.

Less Is More: Developments in Nanotechnology for Antirestenosis Therapies.

Despite recent advancements in vascular disease treatments, thrombosis and poor long-term vessel patency remain significant barriers to effective endovascular intervention. Current balloon angioplasty and stenting techniques effectively restore acute blood flow in occluded vessels but have persistent limitations. Damage to the arterial endothelium caused by injury during catheter tracking triggers neointimal hyperplasia and the release of proinflammatory factors leading to increased risk of thrombosis and restenosis. Antirestenotic agents commonly delivered on angioplasty balloons and stents have lowered arterial restenosis rates, but the absence of cell type selectivity significantly delays critical endothelium repair. Targeted delivery of biomolecular therapeutics, coupled with engineered nanoscale excipients, has the potential to redefine cardiovascular interventions by improving long-term efficacy, limiting off-target effects, and reducing costs compared with conventional clinical standards of care. This review analyzes current forms of localized vascular drug delivery, emerging nanoscale therapeutic and excipient strategies, and provides recommendations for future areas of study to advance the treatment of vascular disease through innovations in nanotechnology.

Brachial-Brachial Fistulas Are Highly Morbid and Associated with Poor Maturation and Patency

Brachial-Brachial Fistulas Are Highly Morbid and Associated with Poor Maturation and Patency

Temperature change of epidural space by radiofrequency use in biportal endoscopic lumbar surgery: safety evaluation of radiofrequency.

Articles evaluating radiofrequency (RF) safety are insufficient. Thus, the purpose of this study was to investigate RF safety during biportal endoscopic lumbar decompressive laminotomy by measuring epidural temperature after RF use. Both in vitro cadaveric study and in vivo study were performed. The epidural temperature was measured at epidural space after RF use in three cadavers. The epidural temperature was measured and analysed according to RF mode, RF power, RF usage time, and saline irrigation patency. In the in vivo study, the epidural temperature was measured after biportal endoscopic surgery. Epidural temperatures were measured around ipsilateral and contralateral traversing nerve roots after 1-s use of RF. In the in vivo study, epidural space temperature was increased by 0.31 ± 0.16°C ipsilaterally and 0.29 ± 0.09° contralaterally after RF use in coagulation mode 1. The epidural temperature of epidural space was increased by 0.21 ± 0.13°C ipsilaterally and 0.15 ± 0.21°C contralaterally after RF use in high mode 2. In the in vitro study, epidural temperature was significantly increased with a long duration of RF use and a poor patency of irrigation fluid. The use of RF in biportal endoscopic spine surgery might be safe. In order to reduce indirect thermal injuries caused by RF use, it might be necessary to reduce RF use time and maintain continuous saline irrigation patency well.

Choosing the right treatment for the right lesion, part I: a narrative review of the role of plain balloon angioplasty in dialysis access maintenance.

The majority of patients with end-stage renal disease (ESRD) requiring hemodialysis (HD) do so via an arteriovenous fistula (AVF) or graft. Both of these accesses are complicated by dysfunction related to neointimal hyperplasia (NIH) and subsequent stenosis. Percutaneous balloon angioplasty using plain balloons is the first line treatment for clinically-significant stenosis, with excellent initial response rates, however, with poor long-term patency and need for frequent reintervention. Recent research has sought to improve patency rates utilizing antiproliferative drug-coated balloons (DCBs), however, their role in treatment has not yet been fully determined. In part one of this two-part review, we aim to provide a comprehensive overview of the mechanisms of arteriovenous (AV) access stenosis, the evidence behind their treatment with high-quality plain balloon angioplasty techniques, and treatment considerations for specific stenotic lesions. An electronic search was performed on PubMed and EMBASE to identify relevant articles from 1980 to 2022. The highest available level of evidence regarding stenosis pathophysiology, angioplasty techniques, and approaches to treating different types of lesions within fistulas and grafts were included as part of this narrative review. NIH, and subsequent stenoses, develop via a combination of upstream events, causing vascular damage, and downstream events, representing the subsequent biologic response. The large majority of stenotic lesions can be treated utilizing high-pressure balloon angioplasty, with the addition of ultra-high pressure balloon (UHPB) angioplasty for resistant lesions and prolonged angioplasty with progressive balloon upsizing for elastic lesions. Additional treatment considerations must be taken into account when treating specific lesions, including cephalic arch and swing point stenoses in fistulas and graft-vein anastomotic stenoses in grafts, amongst others. High-quality plain balloon angioplasty, performed utilizing the available evidence-basis regarding technique and considerations for specific lesion locations, is successful in treating the large majority of AV access stenoses. While initially successful, patency rates remain non-durable. Part two of this review will discuss the evolving role of DCBs, which seek to improve angioplasty outcomes.

Role of stenting for maintenance of the extremity fistula/graft overview.

Dialysis access interventions have undergone significant developments over the last few decades. Angioplasty has been the mainstay of therapy since the early interventions in the 1980s and 1990s, but poor long-term patency and early loss of access has led investigators to assess other devices to treat stenoses associated with dialysis access failure. Multiple retrospective studies of stents for treatment of stenoses that did not respond to angioplasty demonstrated that the long-term outcomes were not improved over angioplasty alone. Cutting balloons have been studied in a prospective randomized fashion but also showed no long-term improvement over angioplasty alone. Prospective randomized trials have demonstrated that stent-grafts have superior primary patency of the access and the target lesions than angioplasty. The purpose of this review is to summarize the current state of knowledge regarding stent and stent graft use in dialysis access failure. We will discuss the early observational data related to stent use in dialysis access failure including the earliest reports of stent use in dialysis access failure. This review will then focus the review on the prospective randomized data that supports the use of stent-grafts in specific areas of access failure. These include venous outflow stenosis related to grafts, cephalic arch stenoses, native fistula intervention, and the use of stent-grafts to revise in-stent restenosis. Each of these applications will be summarized and the current status of the data will be reviewed.