Hemodialysis Access Interventions Research Articles

Complete stent graft relining of the hemodialysis access circuit for access salvage

Background: Stent grafts (SGs) are widely used in hemodialysis access procedures to maintain function and patency of the access circuit. There are no reports to date describing complete relining of the access circuit with SGs for extreme access salvage. Objective: To report outcomes and experience with complete SG relining of the hemodialysis access circuit. Methods: From April 2020 to May 2023, all hemodialysis salvage procedures that included complete relining of the access circuit with SGs were retrospectively analyzed from a prospectively collected database of 970 hemodialysis access interventions. SGs were placed for various pathologies including residual stenosis, perforation, aneurysm, and thrombosis. Follow up outcomes included primary patency, primary assisted patency, and secondary patency. Results: A total of 16 patients were included in the study. Average stented length was 30 cm. Average follow up was 283 days (range 38–647 days). The primary patency of the entire covered segment was 80% and 68% at 6 and 12 months, respectively. The primary assisted patency of the segment was 88% and 77% at 6 and 12 months, respectively. Secondary patency of the access circuit was 94% at both 6 and 12 months. There were no issues with SG cannulation and zero cases of SG fracture or infection. Conclusions: Salvage of failing hemodialysis access circuits by complete SG relining should be considered for a limited subgroup of patients where the access circuit would otherwise be deemed unsalvageable. Complete SG relining has both good immediate outcomes and 6- and 12-month patency rates.

Early experience with the Abre venous stent for central venous stenoses and occlusions in hemodialysis patients.

Hemodialysis patients are prone to stenoses and occlusions throughout the access circuit. Central venous stenoses or occlusions (CVO) can be particularly challenging. There are many different types of balloons and stents available for treatment, including a new generation of dedicated venous stents (VS). In this study, we report our experience and patency rates with the Abre VS in central venous lesions in hemodialysis patients. From April 2020 to May 2023, all procedures with Abre VSs placed for central venous lesions in hemodialysis patients were retrospectively analyzed from a prospectively collected database of 980 hemodialysis access interventions. Follow up outcomes were obtained from angiographic images on follow up angiography and included primary patency and primary assisted patency. Effective hemodialysis was considered a surrogate for access patency if no angiographic follow-up was available. A total of 15 patients with CVO were treated with the Abre VS. Technical success was 100%. All patients were able to achieve adequate hemodialysis after VS placement. Stents were placed across the thoracic inlet in 73% of patients. Post procedure primary patency at the target lesion site was 85% at 6 months and 70% at 12 months. Primary assisted patency of the circuit was 93% at 6 and 12 months. No stent fractures were observed. Treatment of CVO remains extremely challenging, especially when the lesion is located at the thoracic inlet. In these patients, VSs provide acceptable primary patency rates and allow patients to continue to receive effective hemodialysis. However, routine follow-up and re-interventions will likely be necessary to maintain patency in the long term.

The Results of The Interposition Graft-Technique in Treatment of High Flow Vascular Access

High-flow (HF) vascular access (VA) is a fearsome condition potentially responsible for cardiac or pulmonary complications, steal syndrome and hand ischemia. The present study was conducted to report the results achieved in a group of patients undergoing interposition-graft technique to treat HF. An analysis of clinical, ultrasound and echocardiography data collected from the review of medical charts was performed. Flow reduction, complications and need for secondary interventions were investigated. Among a total 498 hemodialysis access interventions performed during a 6-years period, 30 patients (n 15, 50% male, median age 63.5, range 42-91 years) presented with high-flow (median flow 1.9 L/min, range 1.5-4 L/min). 18 patients were asymptomatic (60%); 6 (20%) suffered from a severe distal hand ischemia; 5 (16.6%) developed signs of congestive heart failure and 1 patient (3.3%) presented with pulmonary hypertension. In twenty patients (66.7%) the access was preserved by the interposition of a 6 mm polytetrafluroethylene (PTFE) prosthesis. This approach was used as a primary flow reduction technique in 16 patients (80%) or the failure of a previously attempted procedure in 4 cases. No intraoperative complications were observed. Post-operative median VA flow was 1.1 L/min (range 0.900-2 L/min), with a median flow reduction of 0.770 L/min (range 0.100-2.8 L/min). At a median follow-up of 9 months (range 1-42), 95% (n 19) of patients were free from recurrences. In treatment of HF-VA graft interposition demonstrated satisfactory results at the mid-term follow-up. More data are needed to affirm this technique as the preferential one.

Abstract No. 67 Spontaneous and assisted recanalization of hemodialysis access after prior failed thrombectomy and abandonment: the Lazarus phenomenon

To evaluate the occurrence of spontaneous and assisted recanalization of hemodialysis accesses following failed percutaneous mechanical thrombectomy and abandonment of the access A retrospective review was performed of a prospectively managed quality assurance database of all hemodialysis (HD) access interventions performed between March 2001 and September 2020. Of 11,266 hemodialysis access interventions, 3,137 thrombectomy procedures were performed. Successful thrombectomy procedures were performed in 2,891 cases for an overall success rate of 92.2%. A total of 246 failed thrombectomy procedures were identified. An access was considered abandoned if no further attempts at thrombectomy were planned. Cases in which thrombectomy was recorded as failure due to other issues such as procedure complication but not considered abandoned, with planned subsequent return for repeat attempt, were excluded from analysis. Retrospective review of all failed thrombectomy procedures was performed to evaluate for a subset of accesses deemed abandoned that demonstrated spontaneous or assisted recanalization. Of the 246 failed mechanical thrombectomy procedures, access types included 99 native fistulas, 120 grafts, 9 hybrid access, and 18 without documented access details. There were 14 accesses (5.7% of failures) that demonstrated recanalization enabling subsequent salvage of the access after failed thrombectomy and access abandonment; all accesses exhibited trace flow beyond the (arterial) anastomosis at the time of failed thrombectomy. Of these salvaged accesses, 9 occurred in fistulas, 4 in grafts, and 1 in a hybrid access. Secondary procedures were performed in 7 patients including repeat thrombectomy with angioplasty (n = 3), thrombectomy with stent (n = 1), angioplasty (n = 1) and stent (n = 1) to maintain access function. Seven of the cases demonstrated spontaneous recanalization with no required additional intervention. All 14 salvaged accesses were successfully used for hemodialysis within 30 days post spontaneous or assisted recanalization. Spontaneous recanalization of clotted hemodialysis accesses considered abandoned after failed mechanical thrombectomy can occur. Further characterization of this phenomenon is needed to determine whether an observation period of catheter HD is warranted in the subset of patients with trace flow beyond the anastomosis following failed thrombectomy.

Use of the Viabahn covered stent for the treatment of venous rupture during interventions of dysfunctional or thrombosed hemodialysis vascular access.

Angioplasty-related vessel rupture is a common complication of interventions. The effect of covered stents to treat venous rupture has been evaluated in smaller series, but should be further evaluated. To report the immediate outcomes and patency rates of a covered stent to rescue angioplasty-related venous rupture of hemodialysis vascular access. From January 2013 to December 2018, 113 procedures complicated with vessel ruptures were retrospectively analyzed from a prospectively collected database of 8146 hemodialysis access interventions. The strategies to salvage vessel ruptures were based on the discretion of the treating physicians. Follow-up outcomes were obtained via review of the angiographic images, procedural notes, and medical and dialysis records within 12 months after the index procedures. A total of 52 vessel ruptures (21 fistulas, 31 grafts) salvaged by using Viabahn covered stents were enrolled. Vessel ruptures developed in 28 (53.8%) thrombectomy procedures. Device success was achieved in all procedures (100%) and clinical success was achieved in 50 (96.2%). The primary patency of the stent area was 66.0% at 6 months and 50.0% at 12 months. The primary patency of the entire access circuit was 27.4% at 6 months and 16.0% at 12 months. The most common cause of access circuit primary patency loss was thrombotic occlusion for graft accesses and restenosis at stent area for native accesses. Eleven vascular accesses were abandoned within 12 months after vessel ruptures, and the secondary patency rate of the entire access circuit was 78.0% at 12 months. Treatment of angioplasty-induced vessel rupture of hemodialysis vascular accesses by using Viabahn covered stents has good immediate outcomes and patency results at the stent area. Nonetheless, the patency rate of entire access circuit was still below the threshold recommended by guidelines.

Retrospective Analysis of 77 Hemodialysis Patients Shows No Cases of Steal Syndrome from Graft Taper Reduction

PurposeTo review the immediate flow response and incidence of steal syndrome after taper reduction of tapered dialysis grafts. Material and MethodsThis was a retrospective review of a quality assurance database of all hemodialysis access interventions performed between 2005 and 2017. It identified 77 patients who underwent a taper reduction procedure, involving angioplasty of the arterial limb of the graft and the arterial anastomosis for graft thrombosis/poor flow. A subset of patients underwent 5-, 6-, or 7-mm balloon taper reduction angioplasty coupled with intravascular direct flow measurement (n = 15 with 16 dialysis grafts). A two-tailed Wilcoxon matched-pairs signed-rank test was used to compare pre- and post-taper reduction flows. Mean duration of follow-up was 3.5 years (range, 0–12.5 years). ResultsMean access survival after taper reduction was 20.2 months (range, 0.10–94.4 months). Pre- and post-taper reduction access flows (mean Qb ± standard deviation) were 574 ± 315 ml/min and 929 ± 352 ml/min, respectively (P < .0001). The mean ratio of post- to pre-taper reduction flows was 1.6 (range, 1.1–10.2). No patients developed steal syndrome within 6 months after taper reduction. ConclusionsDialysis graft arterial anastomotic taper reduction did not result in the development of steal syndrome within 6 months. In the subset of patients who underwent flow measurements, taper reduction was associated with nearly a 2-fold improvement in access flow, which is a key predictor of access function.

The usefulness and feasibility of placing a clinch knot with a guidewire to achieve temporary hemostasis in arteriovenous dialysis access interventions.

To evaluate the usefulness and feasibility of using a reversible clinch knot with a guidewire in place rather than eliminating the access route during an arteriovenous hemodialysis access (AV access) intervention using the facing sheath technique. From July 2016 to June 2019, we retrospectively studied 78 sessions performed as interventional treatment for arteriovenous (AV) hemodialysis (HD) access using the "facing-sheath technique." In all sessions, all antegrade sheaths were removed while a 0.035-inch guidewire remained in place with purse-string suture and the clinch knot. Seventy-two sessions were performed in patients with thrombosed AV accesses (69 arteriovenous grafts [AVGs] and three arteriovenous fistulas [AVFs]), and six sessions were carried out to treat non-thrombosed AV accesses (four AVGs and two AVFs). We evaluated whether proper hemostasis and successful reinsertion of the sheath over the wire into the clinch knot was achieved. Clinical success was defined as achieving prompt restoration of blood flow for AV access, and the postintervention primary and secondary patency were also evaluated. In all 87 clinch knots created in 78 total sessions, proper hemostasis was achieved. All clinch knots that required reversal for additional procedures were successfully reopened (55 clinch knots in 50 sessions). The postintervention primary patency rates at 1, 3, and 6 months, and at 1 year were 77.8%, 68.9%, 55.6%, and 33.3%, respectively. The postintervention secondary patency rates at 1, 3, and 6 months, and also at 1 year were 93.3%, 91.1%, 86.7%, and 86.7%, respectively. Our AV access intervention which used a clinch knot with purse-string suture while the guidewire remained in place was both useful and feasible for maintaining temporary hemostasis.

Abstract No. 443 Radiation reduction techniques in dialysis patients undergoing arteriovenous fistulograms

In an effort to reduce radiation exposure to patients, this study aims to evaluate the efficacy of initiating the procedure using 3 versus 1 frame per second (fps) fluoroscopy rates in patients undergoing hemodialysis access interventions for dysfunctional dialysis access. This is prospective, comparative analysis of 46 patients (22 M and 24 F, 39-83 years) who previously underwent fistulogram procedure and underwent a second, identical procedure for recurrent symptoms of dysfunction. The prospective studies were initiated on half dose fluoroscopy, reducing the frame rate for digital recording from 3 per second (standard technique) to 1 per second. The operator changed to the standard exposure rate if image quality was subjectively suboptimal, but only total procedural exposure was tracked. Radiation exposure and contrast amount were evaluated for the two procedures comparing the same patient as an internal control. Both the patient’s fistulograms had identical procedural elements and were successful. Initiating the procedure with 1 versus 3 fps fluoroscopy rate resulted in a significant reduction in radiation dose (16.9 ± 20.2 mGy vs. 8.03 ± 5.8 mGy, P <0.05). There was no significant difference in the quantities of contrast utilized during the procedures between the standard vs. reduced radiation dose between the two groups (74.7 ± 24.4 mL vs. 66.8 ± 18.4 mL; P >0.05). Statistical analysis performed after excluding outlier data (determined by the interquartile range method) demonstrated the same results, increasing the validity of the results. Implementing this simple radiation sparing strategy can dramatically reduce radiation exposure without impacting the diagnostic or therapeutic quality of the procedure. Encouragingly, even if the procedure started with the reduced exposure mode and was later changed to a higher dose for maintenance of image guidance, overall radiation exposure was still reduced by 50%. These findings are important, as these patients require multiple fluoroscopically guided interventions over the course of years to maintain a functioning hemodialysis access.

Site of service influence on stent use for hemodialysis access interventions

ObjectiveWith rising health care spending in the United States, the Centers for Medicare and Medicaid Services (CMS) in recent years attempted to use reimbursement rates to influence use of less expensive care sites for covered patients, such as ambulatory surgery centers (ASCs) and office-based laboratories (OBLs), in lieu of hospital service sites. It has been suggested that cost savings have not been realized because of more procedures being performed by physicians with ownership interests in nonhospital facilities. CMS adopted massive reimbursement changes for 2019 OBL and ASC-based procedures, which reduced dialysis access angioplasty reimbursement in the ASC setting by 50%, whereas facility reimbursement for stenting increased by 33% above prior levels. The clinical utility of adjunctive stenting in treating dialysis access stenosis remains controversial and highly discretionary. As a vascular group performing such procedures in both a hospital and nonhospital facility in which we have equity interest, we reviewed our use of stents in dialysis access procedures both in the hospital and in the ASC/OBL to determine whether site of service affected stent use. MethodsA retrospective review of a prospectively maintained database was performed from 2014 to 2018. All patients undergoing dialysis access angiography with angioplasty and adjunctive stent placement at our OBL (later ASC) and our primary hospital were included in the study. ResultsThere were 961 angioplasty or stent procedures performed for dialysis accesses between the two sites, 564 (58.7%) in the hospital setting and 397 (41.3%) at the OBL/ASC. There was a significant difference in race and age between the two sites, with younger, minority patients more frequently being treated in the hospital and older, white patients more likely to be treated in the ambulatory setting; 153 (27.1%) underwent adjunctive stent placement in the hospital and 127 (32.0%) in the ambulatory setting (P = .09). ConclusionsWhereas financial incentives have not yet had an appreciable influence on stent use for dialysis access within previous reimbursement paradigms, the dramatic changes recently adopted by CMS may well alter this dynamic and could lead to substantially higher overall costs without proven clinical advantage. Interventionalists may be incentivized to add stents when performing balloon angioplasty in ASCs. With high failure and reintervention rates and increasingly expensive adjuncts (drug-coated balloons and stents, covered stents), the cost implications of attempts to incentivize interventionalists toward a specific type of procedure or site of care are substantial, and unintended negative consequences are likely to occur.

Clinical Practice Patterns of Interventional Radiologists by Gender.

OBJECTIVE. Given recent specialty attention to workforce diversity, we aimed to characterize potential gender differences in the practice patterns of interventional radiologists (IRs). MATERIALS AND METHODS. Using Medicare claims data, we identified IRs on the basis of the distribution of their billed clinical work effort and descriptively characterized practice patterns by gender. RESULTS. Women represented 8.2% (241/2936) of all IRs identified nationally. Female representation varied geographically (≤ 2% in nine states, ≥ 20% in three states) and by career stage (9.4% among early-career IRs and 6.4% among late-career IRs; 18.8% among early-career IRs in the Northeast). For both female IRs and male IRs, interventional case mixes were similar across service categories (e.g., venous and hemodialysis access, arterial and venous interventions, biopsies and drainages) and by procedural complexity (e.g., 5.7% vs 4.3% for low-complexity procedures and 59.5% vs 61.3% for high-complexity procedures). Average patient complexity scores were also similar for female (2.7 ± 12 [SD]) and male (2.8 ± 12) IRs. Female IRs spent slightly lower portions of their work effort rendering invasive services (66.5% vs 70.0%, respectively) and noninvasive diagnostic imaging (19.0% vs 22.2%) than male IRs but spent more time in evaluation and management clinical visits (14.5% vs 7.9%). Both female IRs and male IRs rendered a majority of their services to female patients (53.4% vs 53.1%). CONCLUSION. Although women remain underrepresented in interventional radiology, female IRs' interventional case composition, procedural complexity, and patient complexity are similar to those of their male colleagues. Female IRs' higher proportion of evaluation and management clinical visits supports the specialty's increased focus on longitudinal care so that interventional radiology will thrive alongside other clinical specialties.

Site of Service Influence on Stent Utilization for Hemodialysis Access Interventions

With unsustainably rising health care spending in the United States, the Centers for Medicare and Medicaid Services (CMS) has in recent years attempted to use reimbursement rates to influence utilization of less expensive care sites for covered patients, such as ambulatory surgery facilities and office-based interventions in lieu of hospital service sites. It has been suggested that cost savings have not been realized because of an increase in procedure numbers performed by physicians with ownership interests in nonhospital facilities. CMS has proposed massive reimbursement changes for 2019 that will reduce access angioplasty reimbursement in the ambulatory surgery center setting by 75.9%, whereas stenting would be increased by 12.1% over current levels. The clinical utility of adjunctive stenting in treating access stenosis remains controversial and highly discretionary. Our group performs such procedures in both a hospital and a nonhospital facility in which we have equity interest. We reviewed the prevalence of stent deployment in patients in both settings since 2014 to determine whether site of service affected stent utilization. Between 2014 and 2018, there were 739 total angioplasty or angioplasty with stenting procedures performed by our group; 599 were done in the hospital setting, whereas 140 were performed in an ambulatory facility, initially as a physician office site of service and since 2018 as an ambulatory surgery center. Patients’ demographics and variables were compared. There was no difference in any clinical or demographic variable between the hospital and nonhospital groups, other than a higher incidence of Medicaid patients in the hospital setting (P < .001). In hospital-treated patients, 190 of 599 procedures included adjunctive stenting (33.2%), whereas in the non-hospital-treated patients, 45 of 140 had stents (32.1%), despite financial incentives for both professional and facility reimbursement in favor of stenting (P = .94). Whereas financial incentives have not yet had an appreciable influence in stent utilization within previous reimbursement paradigms, the dramatic changes proposed by CMS may well alter this dynamic and lead to substantially higher overall costs without proven clinical advantage. With very high failure and reintervention rates and increasingly expensive adjuncts (drug-coated balloons and stents, covered stents), the cost implications of attempts to incentivize interventionalists toward a specific site of care are substantial, and unintended negative consequences are likely to occur.

Drug Coated Balloon Angioplasty in Failing AV Fistulas: A Randomized Controlled Trial.

Restenosis remains a problem in hemodialysis access interventions. Paclitaxel-coated balloons have shown promise in reducing access-related restenosis in small trials. The primary hypotheses for our multicenter trial were superior effectiveness at 180 days and noninferior safety at 30 days of a drug-coated balloon compared with conventional angioplasty for treatment of dysfunctional arteriovenous fistulas. This randomized trial enrolled 285 patients with dysfunctional arteriovenous fistulas at 23 centers. Grafts, central venous stenoses, thrombosed fistulas, and immature fistulas were excluded. All patients received angioplasty of the lesion responsible for access dysfunction. After successful angioplasty (≤30% residual stenosis), lesions were treated with either a paclitaxel-coated balloon or an uncoated control balloon of similar design to the drug-coated balloon. Access function during follow-up was determined per centers' usual protocols; reintervention was clinically driven. The primary efficacy outcome assessment was done at 6 months, and the safety assessment was done within 30 days of the procedure. Prespecified secondary end points included assessment of postintervention target lesion primary patency and access circuit primary patency at 6 months. The 180-day end point was not met with target lesion primary patency (71%±4% for the drug-coated balloon and 63%±4% for control; P=0.06), representing a difference of 8%±6% (95% confidence interval, -3% to 20%). Access circuit primary patency did not differ between groups. Interventions to maintain target lesion patency were fewer for the drug-coated balloon at 6 months (0.31 versus 0.44 per patient; P=0.03). The primary safety noninferiority end point was met and did not differ between groups (P=0.002). Paclitaxel-coated balloon-assisted angioplasty did not meet the primary effectiveness end point at 180 days compared with conventional angioplasty. Both arms showed equivalent safety (ClinicalTrials.gov number NCT02440022).

TCTAP A-144 Thrombophilia Is Associated with Early Thrombosis After Percutaneous Hemodialysis Access Intervention.

Thrombophilia has been proposed to be an important risk factor hemodialysis vascular access thrombosis. Nonetheless, the role of thrombophilia on post-angioplasty thrombosis remained unknown. From Jan 2015 to Dec 2015, a nested case-control study was performed in patients who received endovascular

TCTAP A-086 Salvage of Venous Rupture by Stent Graft During Percutaneous Intervention of Dialysis Vascular Access

Percutaneous transluminal angioplasty (PTA) -induced venous rupture is a common complication of hemodialysis access intervention. Various management strategies have been reported but the patency outcome was poor. We aim to report the immediate and patency results with a self-expandable stent graft

Preprocedure Evaluation of a Dysfunctional Dialysis Access

Given the many different types of hemodialysis access and the various problems that can occur in each, a structured approach should be taken in the preprocedure evaluation of patients referred for hemodialysis access intervention. Abnormalities detected on surveillance or monitoring trigger referrals for evaluation and intervention in hopes of preventing thrombosis or underdialysis. Familiarity with surveillance and monitoring findings not only facilitates better communication with nephrologists but also helps the interventionalist surmise where the site of stenosis might be and which stenoses are clinically relevant. Additionally, knowing where stenoses are prone to occur (eg, the cephalic arch in brachiocephalic fistulas) and facility with performing and interpreting an on-table ultrasound are important in preprocedure planning.

Cardiovascular implantable electronic devices in hemodialysis patients: prevalence and implications for arteriovenous hemodialysis access interventions.

Cardiovascular implantable electronic devices (CIEDs) are frequently utilized in hemodialysis patients. CIED leads are typically implanted via the subclavian vein resulting in stenosis and venous hypertension. We studied 1235 chronic hemodialysis patients under the care of our nephrology practice. For each, we determined the presence of a CIED, indication for implantable cardioverter-defibrillator (ICD), and type of hemodialysis access. Records were reviewed to identify all interventions performed on the access circuit and the central veins specifically. A CIED was present in 129 patients (10.5%), including ICDs in 75 (6.1%) and pacemakers in 54 (4.4%). The access circuit intervention rate was 1.48/access year (AY) and was similar when a CIED was ipsilateral (1.53/AY) or contralateral (1.44/AY) to arteriovenous access (p = 0.477). The rate of central venous interventions was greater in the ipsilateral (0.59/AY) versus contralateral group (0.28/AY), (p < 0.001). Fifty-four of 59 patients with ipsilateral access and CIED required <2 interventions per AY, but six failed angioplasty and required access ligation. None had superior vena cava stenosis requiring intervention. We conclude that there is a high prevalence of CIEDs in our HD patients. Ipsilateral CIED and arteriovenous access results in higher central venous intervention rates compared with contralateral cases; overall access circuit intervention rates are similar.

Medical Emergencies and Cardiopulmonary Arrests in Interventional Radiology

To evaluate the circumstances and determine the outcomes of medical emergencies (MEs) and cardiopulmonary arrests (CPAs) in patients undergoing interventional radiology (IR) procedures. Retrospective review of all MEs and CPAs that occurred between July 2006 and December 2011 was performed. Procedure type, technical outcome, complications, etiology and location of ME/CPA, event outcome, and postevent mortality were collected. A total of 58 events occurred during 38,927 procedures (0.15%). Complete records were available for 55 events (43 MEs, 12 CPAs) in 53 patients (mean age, 63 y; 58.5% male) during 37 inpatient (27 MEs, 10 CPAs) and 18 outpatient (16 MEs, two CPAs) encounters. Seven events (13%; six MEs, one CPA) occurred before the start of the procedure, and 18 (33%; 16 MEs, two CPAs) occurred in the periprocedural holding area. Thirty-five procedures (64%) were completed successfully. Forty-two patients (76%) were alive at discharge, 37 (67%) at 1 month, 26 (47%) at 3 months, and 23 (42%) at 1 year. Procedural complications were attributed as the main cause of 22 MEs (51%) and one CPA (8%; P = .018). The relative risk (RR) of an ME or CPA occurring during a hemodialysis access case versus all other cases was 5.2 (95% confidence interval = 3.02-8.95; P < .0001). Although the incidence of MEs/CPAs in patients undergoing IR procedures is low, the 1-year mortality rate following these events is high. MEs are significantly more likely than CPAs to be directly attributed to a procedural complication. The RR of MEs/CPAs is significantly higher in hemodialysis access interventions.

Abstract No. 281 - Medical emergencies and cardiopulmonary arrests in interventional radiology

Purpose To characterize the circumstances and outcomes of medical emergencies (ME) and cardiopulmonary arrests (CPA) in patients undergoing IR procedures. Materials and Methods Retrospective review of all ME/CPAs occurring between July 2006 and Dec. 2011 was performed. Procedure type, technical outcome, complications, etiology and location of ME/CPA, event outcome, and post-event mortality were all collected. Frequency of CPA/ME by procedure type and relative risk (RR) of ME/CPA were calculated. Results 58 events occurred during 38,927 procedures. Complete records were available for 55(12 CPA, 43 ME) occurring in 53 patients (mean age 63yrs, 58.5% M) during 37 inpatient (10 CPA, 27 ME) and 18 outpatient (2CPA, 16ME) encounters. Frequency and location of ME/CPA are summarized in the Table. Seven events (13%) occurred before start of the procedure. 18 ME/CPA (33%) occurred in the holding area. 35 procedures (64%) were completed successfully. All patients survived the event. From the time of the event, 42 patients (76%) were alive at discharge, 37 (67%) at 1 month, 26 (47%) at 3 months, and 23 (42%) at 1 year. Procedural complications were attributed as the cause of 22 ME (51%) and 1 CPA (8%, p=0.018). Of the 12 CPAs, 9 occurred in hemodialysis (HD) access cases (75%). The RR of a ME/CPA occurring during HD access case compared to all other cases was 5.2 (CI=3.02-8.95). Conclusion Incidence of ME/CPAs in patients undergoing IR procedures is low, yet 1-year mortality following these events is high. Vigilant observation of patients in the holding area is warranted given frequency of ME/CPAs in this location. MEs are significantly more likely to be directly attributed to a procedural complication then CPAs. The RR of ME/CPAs is significantly higher in HD access interventions.

Abstract No. 331 - Outcomes of interventions in hybrid hemodialysis access

Purpose Fistulae and grafts respond differently to percutaneous interventions, with fistulae generally yielding longer patency. Failing fistulae, whether due to aneurysm or refractory stenosis, may be treated surgically with interposition grafting, creating a “hybrid” access. The purpose of this study was to determine the outcomes of percutaneous interventions in hybrid accesses. Materials and Methods We retrospectively reviewed patient records from a prospectively collected database containing more than 6,000 hemodialysis interventions conducted over a 10-year period. From this database, patients identified as having hybrid access were included; those without follow-up were excluded. The main outcomes investigated were the intervals of primary and secondary patency after percutaneous interventions to maintain or restore function, as defined by SIR guidelines. A sample of synthetic and native hemodialysis access interventions from the same database served as control. Results Of 40 patients with hybrid access, 29 met inclusion criteria. Mean access age for fistulae, grafts, and hybrids was 232±257, 176±232, and 918±953 days respectively. 77 interventions were performed in this group, 737 in the fistula control group, and 603 in the graft control group. Median post intervention primary patency in hybrids was similar to fistulae (166 vs 133 days, P=0.7) and longer than grafts (79 days, P Conclusion Our data suggest that interposition grafting in fistulae to form a hybrid access does not compromise post-intervention patency.

Blood Pressure Recordings During Hemodialysis Access Interventions: Implications for Acute Management

A retrospective study evaluating the pattern of blood pressure and its related complications before, during, and after percutaneous hemodialysis interventions was performed in patients presenting with asymptomatic hypertension. Hemodialysis patients undergoing percutaneous interventions including tunneled hemodialysis catheter insertion, percutaneous balloon angioplasty and thrombectomy procedure, and stage II hypertension (systolic blood pressure ≥160 mmHg) were included in this analysis. Blood pressure medications were not used while midazolam and fentanyl were routinely administered. Patients were followed for up to 4 weeks to monitor any complications. The mean blood pressure before, during, and after the procedures were 185 ± 18/96 ± 14, 172 ± 22/92 ± 15, and 153 ± 25/87 ± 14, respectively. There was a statistically significant difference between the blood pressure readings before and after the procedure (before = 185 ± 18/96 ± 14, after = 153 ± 25/87 ± 14; p = 0.001). None of the patients had a stroke, myocardial infarction, or acute pulmonary edema before, during, or after the procedure or during the 4-week follow-up period. A significant reduction in blood pressure was observed after the procedure without the administration of any antihypertensive medication. These results suggest that the reduction in blood pressure observed after percutaneous dialysis access interventions (particularly in the presence of midazolam and fentanyl) may make it unnecessary to treat asymptomatic hypertension prior to these procedures.