Imaging-Guided De Novo Retrograde Ureteral Access and Stent Placement without Cystoscopy in Women

PurposeTo evaluate the feasibility of a new technique for imaging-guided de novo retrograde ureteral double J (DJ) stent placement without cystoscopy in women.Materials and MethodsEighty-four women referred for ureteral stent placement between April 2019 and January 2022 were included. In all the patients, the initial attempt for stent placement was performed in a retrograde fashion. Successful ureteral catheterization and DJ stent placement were considered as technical success. The fluoroscopy time required to catheterize the ureter and that for the entire procedure were recorded. Factors affecting the technical success rate and fluoroscopy time were examined.ResultsA total of 108 ureteral stent placement procedures in 84 women, with a mean age of 57.5 years (range, 19–85 years), were performed. The most common underlying pathologies were cervical (n = 33, 31%) and ovarian (n = 32, 30%) carcinomas. The most commonly involved segments of the ureter were the lower half (n = 44, 40%) and trigone (n = 39, 36%). The technical success rate was 81.5%, and it reached 93% in the case of lower-half ureteral obstruction. Distorted trigonal anatomy caused by external compression of the bladder wall by a mass was associated with a higher rate of technical failure (90.6% vs 47.8%; P < .001). The use of ultrasound guidance to guide the sheath to the ureteral orifice allowed for a significant decrease in the fluoroscopy time for ureteral catheterization (4.6 minutes ± 3.91 vs 2.26 minutes ± 2.32; P = .003) and that for the entire procedure (9.42 minutes ± 4.95 vs 5.93 minutes ± 4.06; P = .001).ConclusionsImaging-guided de novo retrograde ureteral catheterization and stent placement can be successfully performed in a high percentage of patients within a reasonable fluoroscopy time without the need for cystoscopy in women.     

Transhepatic Placement of Metallic Biliary Stent for Internal Drainage of Persistent Liver Abscesses

Transhepatic placement of a metallic biliary stent for internal drainage of persistent liver abscesses was performed in 9 patients (males; median age, 65 years; range, 57–82 years) with refractory liver abscess. The median follow-up period was 2.8 months (range, 0.4–50.3 months). Technical success was achieved in all cases without any major complications. Clinical success, defined as the removal of the drainage tube without recurrent symptoms of infection, was achieved in 8 cases. Median duration until removal of the drainage tube from stent placement was 7 days (range, 0–36).     

Iatrogenic Portobiliary Fistula following Endoscopic Biliary Stent Placement: A Case Series and Review of the Literature

Iatrogenic portobiliary fistula is a rare adverse event following endoscopic biliary stent placement. Damage to the portal vein following endoscopic biliary stent placement has previously only been reported as single case reports. Management has ranged from conservative monitoring to surgery. Here, the authors present 4 cases of inadvertent endoscopic placement of a biliary stent into the portal vein. Interventional radiology was called to assist in the management of each of these cases. The experience presented here in conjunction with review of the previously reported cases helps shed light on potential management strategies if this adverse event is encountered in the future.     

Radiation-Free Thoracic Endovascular Aneurysm Repair with Fiberoptic and Electromagnetic Guidance: A Phantom Study

PurposeTo evaluate the feasibility and accuracy of a radiation-free implantation of a thoracic aortic stent graft employing fiberoptic and electromagnetic tracking in an anthropomorphic phantom.Materials and MethodsAn anthropomorphic phantom was manufactured based on computed tomography (CT) angiography data from a patient. An aortic stent graft application system was equipped with a fiber Bragg gratings and 3 electromagnetic sensors. The stent graft was navigated in the phantom by 3 interventionalists using the tracking data generated by both technologies. One implantation procedure was performed. The technical success of the procedure was evaluated using digital subtraction angiography and CT angiography (before and after the intervention). Tracking accuracy was determined at various anatomical landmarks based on separately acquired fluoroscopic images. The mean/maximum errors were measured for the stent graft application system and the tip/end of the stent graft.ResultsThe procedure resulted in technical success with a mean error below 3 mm for the entire application system and <2 mm for the position of the tip of the stent graft. Navigation/implantation and handling of the device were rated sufficiently accurate and on par with comparable, routinely used stent graft application systems.ConclusionsThe study demonstrates successful stent graft implantation during a thoracic endovascular aortic repair procedure employing advanced guidance techniques and avoiding fluoroscopic imaging. This is an essential step in facilitating the implantation of stent grafts and reducing the health risks associated with ionizing radiation during endovascular procedures.     

Temporary Covered Metallic Ureteral Stent Placement for Ureteral Strictures following Kidney Transplantation: Experience in 8 Patients

This brief report presents 8 patients with silicone-covered metallic stent placement for ureteral strictures refractory to double-J stent placement, following kidney transplantation. Stent removal was successfully performed in 7 patients via antegrade (n = 4) or retrograde (n = 3) access 6 weeks to 6 months after stenting for elective removal (6-month interval, n = 3), urothelial hyperplasia (n = 2), or stent migration (n = 2), and their mean primary ureteral patency after stent removal was 15.4 months (range, 2–27 months). Hematuria (n = 2) and pain (n = 3) occurred, but resolved within 1 week. One stent was removed during reconstructive surgery. During follow-up of mean 22.6 months after stent removal, ureteral strictures recurred in 2 patients.     

Endovascular Treatment of Malignant Superior Vena Cava Syndrome through Upper-Limb Access: A Comparison between Venous-Dedicated and Conventional Stents

PurposeTo retrospectively evaluate the technical and clinical outcomes of superior vena cava (SVC) stent placement through upper-limb venous access in malignant SVC syndrome (SVCS) and compare the efficacy of different nitinol stent types.Materials and MethodsBetween 2006 and 2018, 156 patients (132 male; mean age, 62 y; age range, 33–81 y) underwent SVC stent placement for malignant obstructions through upper-limb venous access with 1 of 3 types of nitinol stent: 1 venous-dedicated (Sinus-XL stent) and 2 non–venous-dedicated (E-Luminexx Vascular Stent and Protégé GPS). Cases of common femoral vein access or non-nitinol stents were excluded from further analysis. The mean duration of follow-up was 8 mo.ResultsTechnical success was achieved in 99.3% of cases. One patient died during the procedure as a result of cardiac tamponade. Balloon predilation was performed in 10 patients and postdilation in 126. Mean procedural time was 34.4 min (range, 18–80 min). Overall survival rates were 92.3%, 57.3%, and 26.8%, and overall primary patency rates were 94.5%, 84.8% and 79.6%, at 1, 6, and 12 mo, respectively. There were no statistically significant differences in primary patency rates between venous- and non–venous-dedicated stents or among different Stanford SVCS grading groups (P > .05).ConclusionsSVC stent placement through an upper-limb approach is a safe, fast, and effective technique. There is no evident benefit of venous-dedicated vs non–venous-dedicated stents in the treatment of malignant SVCS.     

Single-Step Method for Pull-Type Gastrostomy Tube Placement

Single-step pull-type gastrostomy tube (PGT) placement is a method involving gastric puncture with a curved 18-gauge trocar needle allowing retrograde cannulation of the gastroesophageal junction without use of a sheath or snare. This retrospective review of 102 patients who underwent single-step PGT placement demonstrated 91% success in advancing the wire up the esophagus using only the curved trocar. Successful placement of a gastrostomy tube was 100%. Two major and 2 minor complications occurred within 30 days, all unrelated to the single-step technique. Mean fluoroscopy time for all patients was 5.1 min (range, 1.5–19.2 min). Single-step PGT placement is an effective, safe, fast, and equipment-sparing method for gastrostomy placement.     

Vascular Pathology and Impact of Stent Eccentricity for Stent Restenosis in Femoropopliteal Endovascular Therapy

PurposeTo explore the clinical features associated with stent eccentricity and reveal the impact of stent eccentricity on the risk of 1-year restenosis after femoropopliteal stent implantation for symptomatic atherosclerotic peripheral artery disease (PAD).Materials and MethodsThe clinical database of a multicenter prospective study was used. It registered 2,018 limbs of 1,766 patients in whom intravascular ultrasound (IVUS)-supported femoropopliteal endovascular therapy (EVT) for symptomatic atherosclerotic PAD was planned from November 2015 to June 2017. The study included 1,233 limbs of 1,088 patients implanted with a bare nitinol stent, drug-eluting stent (DES), or stent graft and administered ≥2 antithrombotic drugs. The stent eccentricity was evaluated using IVUS, calculated as [(maximum diameter) / (minimum diameter) ? 1] at the cross-sectional segment with the lowest lumen area after stent implantation.ResultsChronic total occlusion and bilateral arterial calcification (peripheral artery calcification scoring system Grades 3 and 4) were positively associated with stent eccentricity, whereas renal failure while receiving dialysis, DES use, and stent graft use were negatively associated with stent eccentricity (all P < .05). Stent eccentricity was associated with an increased risk of 1-year restenosis (odds ratio [OR], 1.18; 95% CI, 1.01–1.37; P = .034). However, after adjustment for lesion severity and implanted stent types, the association was no longer significant (OR, 1.07; 95% CI, 0.91–1.24; P = .43).ConclusionsStent eccentricity was not significantly associated with the risk of 1-year restenosis after femoropopliteal EVT.     

Comparison between Antegrade versus Retrograde Ureteral Stent Placement for Malignant Ureteral Obstruction

PurposeTo compare the technical success of antegrade uteral stent (AUS) and retrograde ureteral stent (RUS) placements in patients with malignant ureteral obstruction (MUO) and to determine the predictors of technical failure of RUS.Materials and MethodsThis study retrospectively included 61 AUS placements (44 patients) performed under fluoroscopic guidance and 76 RUS placements (55 patients) performed under cystoscopic guidance in patients with MUO from January 2019 to December 2020. Technical success rates of the 2 techniques were compared using inverse probability of treatment weighting (IPTW) analysis. Logistic regression was used to identify predictive factors for technical failures.ResultsTechnical success was achieved in 98.4% of the AUS group and 47.4% of the RUS group. After stabilized IPTW, the technical success rate was higher in the AUS group than in the RUS group (adjusted risk difference, 49.4%; 95% confidence interval [CI], 35.4%–63.1%). The independent predictors for technical failure of the RUS procedure were age of ≥65 years (odds ratio [OR], 5.56; 95% CI, 1.73–21.27), ureteral orifice invasion (OR, 4.21; 95% CI, 1.46–13.46), and extrinsic cancer (OR, 15.58; 95% CI, 2.92–111.81).ConclusionsThe technical success rate of AUS placement was higher than that of RUS placement in patients with MUO. RUS failure was associated with age of ≥65 years, cancer with ureteral orifice invasion, and extrinsic ureteral obstruction.     

Iliocaval Skip Stent Reconstruction Technique for Chronic Bilateral Iliocaval Venous Occlusion

PurposeTo report safety and efficacy of a skip stent technique using nitinol stents in patients with chronic bilateral iliocaval venous occlusions.Materials and MethodsA retrospective analysis of 48 consecutive patients (32 men; mean age, 40.7 years; age range, 18–68 years) with chronic bilateral iliocaval obstructions treated using a nonoverlapping stent technique was conducted at a single center. None of the patients had May-Thurner syndrome. Iliocaval confluence was treated by deploying a nitinol stent in inferior vena cava (IVC) and a nitinol stent in each common iliac vein close to the caval stent. Patency of stents was assessed by duplex US at 2 weeks, 3 months, and 6 months and yearly thereafter.ResultsRecanalization and stent reconstruction was technically successful in 47 (98%) patients. The sinus-XL venous stent was used to treat IVC (95 [100%]). Common iliac and external iliac veins were treated with sinus-Venous and VENOVO stents (80 [83%] and 16 [17%] limbs, respectively). External iliac and common femoral veins were treated with sinus-Venous and VENOVO stents (83 [92%] and 7 [18%] limbs, respectively). Early thrombosis (< 30 days) of the iliac vein with stent occurred in 2 limbs. Cumulative primary, assisted primary, and secondary patency rates at 30 months were 74%, 83%, and 97%.ConclusionsFindings of this study suggest that leaving a skipped lesion at the level of iliocaval confluence may not adversely affect stent patency. Patency rates were comparable with other reported techniques of stent reconstruction at the level of iliocaval confluence.     

Transhepatic Approach for Retrograde D2 Duodenal Stent Placement: New Technique and Case Series

Transhepatic duodenal stent placement may be a solution when endoscopy fails or when duodenal and biliary stents are needed simultaneously. This approach is usually not considered as an option when the duodenal stent must be deployed across the ampulla of Vater. The authors present a series of 10 patients who underwent a novel transhepatic technique to place a duodenal stent across the ampulla of Vater by establishing a wire scaffold from the liver toward the jejunum and then curving back on itself retrogradely through the duodenal tumor and out the mouth. Technical success was 90% with no associated mortality.     

Evaluation of a Novel Spun Polytetrafluoroethylene Stent Graft in an Ovine External Iliac Artery Model

PurposeTo evaluate the patency, cellular response, and thrombogenicity of a novel vascular stent graft.Materials and MethodsTest stent grafts, incorporating luminal spun polytetrafluoroethylene and a nonpermeable fluoropolymer layer, and control stent grafts, constructed of permeable expanded polytetrafluoroethylene, were implanted in the external iliac arteries of 14 adult sheep with a median weight of 73.4 kg ranging from 60.6–86.8 kg for 30 (n = 4), 90 (n = 4), and 180 (n = 6) days. Angiographic patency and percent diameter stenosis (%DS) were assessed at termination. Excised stent grafts were fixed and stained for histopathologic analysis, including neointimal coverage (NC) assessment.ResultsTest and control device migration occurred in 1 animal, resulting in test device thrombosis. Both devices were excluded from analysis. Mean %DS in test and control implants was 4.6% and 8.2% (P = .563), 2.0% and 10.9% (P = .363), and 2.1% and 10.3% (P = .009) at 30, 90, and 180 days, respectively. Median NC scores at 30, 90, and 180 days were significantly lower in middle test device sections (P < .05). Proximal and distal test and control sections exhibited similar median NC scores at all time periods (P > .05). When present, test and control devices exhibited no neointimal detachment from the graft surface. Except for the migrated test device, no thrombus was observed. Transgraft cellular migration was absent in test devices but present in control devices with tissue accumulation around the stent struts.ConclusionsTest and control devices demonstrated excellent patency in an ovine model. Compared to the control, test devices exhibited significantly lower %DS values at 180 days and significantly lower mid-device NC scores at 30, 90, and 180 days.     

Utilization of and Outcomes Associated with Intravascular Ultrasound during Deep Venous Stent Placement among Medicare Beneficiaries

PurposeTo evaluate temporal trends, practice variation, and associated outcomes with the use of intravascular ultrasound (US) during deep venous stent placement among Medicare beneficiaries.Materials and MethodsAll lower extremity deep venous stent placement procedures performed between January 1, 2017, and December 31, 2019 among Medicare beneficiaries were included. Temporal trends in intravascular US use were stratified by procedural setting and physician specialty. The primary outcome was a composite of 12-month all-cause mortality, all-cause hospitalization, or repeat target vessel intervention. The secondary outcome was a composite of 12-month stent thrombosis, embolization, or restenosis.ResultsAmong the 20,984 deep venous interventions performed during the study period, 15,184 (72.4%) utilized intravascular US. Moderate growth in intravascular US use was observed during the study period in all clinical settings. There was a variation in the use of intravascular US among all operators (median, 77.3% of cases; interquartile range, 20.0%–99.2%). In weighted analyses, intravascular US use during deep venous stent placement was associated with a lower risk of both the primary (adjusted hazard ratio, 0.72; 95% confidence interval [CI], 0.69–0.76; P < .001) and secondary (adjusted hazard ratio, 0.32; 95% CI, 0.27–0.39; P < .001) composite end points.ConclusionsIntravascular US is frequently used during deep venous stent placement among Medicare beneficiaries, with further increase in use from 2017 to 2019. The utilization of intravascular US as part of a procedural strategy was associated with a lower cumulative incidence of adverse outcomes after the procedure, including venous stent thrombosis and embolization.     

Percutaneous Access of the Modified Hutson Loop for Retrograde Cholangiography,Endoscopy, and Biliary Interventions

PurposeThe purpose of this study was to present the institutional experience of performing endoscopy, cholangiography, and biliary interventions through the modified Hutson loop by interventional radiology.Materials and MethodsA total of 61 of 64 modified Hutson loop access procedures were successful. This single-center retrospective study included 61 successful procedures of biliary interventions using existing modified Hutson loops (surgically affixed subcutaneous jejunal limb adjacent to biliary anastomosis or anastomoses) for diagnostic or therapeutic purposes in 21 patients. Seventeen of 21 patients (81%) had undergone liver transplantation. Indications included biliary strictures (n = 18) and biliary leaks (n = 3). The clinical success and complications were evaluated.ResultsThere were 3 of 26 modified Hutson loop retrograde biliary intervention failures (12%) before introduction of endoscopy and no failures (0 of 38 [0%]) subsequently (P = .06). Endoscopy or cholangioscopy was performed in 19 procedures by interventional radiologists. Retrograde biliary interventions included diagnostic cholangiography (n = 26), cholangioplasty (n = 25), stent placement (n = 29), stent retrieval (n = 25), and biliary drainage catheter placement (n = 5). No procedure-related mortality occurred. There was 1 major complication (duodenal perforation) (1.6%) and 12 minor complications (19%). In the 9 patients undergoing therapeutic interventions for biliary strictures, there was a significant decrease in median alkaline phosphatase (288.5 to 174.5 U/L; P = .03). There was a trend toward decrease in median bilirubin levels (1.7 to 1 mg/dL; P = .06) at 1 month post-intervention.ConclusionsThe modified Hutson loop provided interventional radiologists a safe and effective alternative access to manage biliary complications in patients with biliary-enteric anastomoses. Introduction of the endoscope in interventional radiology has improved the success rate of these procedures.     

Weighted Tip Extensions Result in Fewer Gastrojejunostomy Tube Migrations and Increase Tube Lifespan

PurposeTo investigate the safety and efficacy of attaching a weighted extension to the distal aspect of prefabricated gastrojejunostomy (GJ) tubes, and to determine whether this alteration reduces the occurrences of tip reflux into the esophagus or stomach.Materials and MethodsThis retrospective 1-way crossover study included 64 GJ tubes in 15 patients placed by multiple operators in the interventional radiology department at a single institution from July 1, 2019, to December 1, 2021. Patients were selected for a weighted tip extension if they required a GJ tube exchange because of the distal tip refluxing into the stomach or esophagus and were aged ≥18 years. These modified GJ tubes were prepared by cutting the distal end of a nasojejunal tube to a length of 10–15 cm and suturing to the distal aspect of the GJ tube.ResultsOf the 64 tubes studied, 37 had a weighted tip extension. The unmodified GJ tubes had a mean lifespan of 34.3 days, which was significantly shorter than the weighted tips (92.8 days; t test P = .001). There was 1 limited adverse event of abdominal pain and spasms that resolved after exchange with a shorter weighted extension.ConclusionsThis study suggests that for patients who require a GJ tube replacement because of the tip refluxing proximally into the stomach or esophagus, the addition of a 10–15-cm weighted extension to the distal end of the GJ tube is safe and significantly improves the lifespan of the enteric tube.     

Grasp-and-Fold Technique for Complex Inferior Vena Cava Filter Retrieval

This study evaluated the use of the grasp-and-fold technique for complex forceps retrieval of inferior vena cava (IVC) filters. A retrospective study of 14 patients (12 women and 2 men) who had either deeply tip-embedded or severely distorted IVC filters was performed at a single institution over 10 years. In this technique, endobronchial forceps were used to fold the filter in half to remove it through the sheath because the filter tip could not be accessed by dissection. The grasp-and-fold technique successfully removed all 14 filters. One patient had retained filter struts, which were present before the procedure. One mild and 5 moderate adverse events (AEs), including fracture fragment embolization requiring retrieval and self-limited IVC extravasation, occurred. No severe AEs occurred. In this small patient cohort, the grasp-and-fold forceps technique successfully retrieved deeply tip-embedded or distorted IVC filters with inaccessible tips.     

Irreversible Electroporation for Hepatic Tumors: Protocol Standardization Using the Modified Delphi Technique

PurposeA consensus study of panelists was performed to provide a uniform protocol regarding (contra) indications, procedural parameters, perioperative care, and follow-up of irreversible electroporation (IRE) for the treatment of hepatic malignancies.Materials and MethodsInterventional radiologists who had 2 or more publications on IRE, reporting at least 1 patient cohort in the field of hepatobiliary IRE, were recruited. The 8 panelists were asked to anonymously complete 3 iterative rounds of IRE-focused questionnaires to collect data according to a modified Delphi technique. Consensus was defined as having reached 80% or greater agreement.ResultsPanel members’ response rates were 88%, 75%, and 88% in rounds 1, 2, and 3, respectively; consensus was reached on 124 of 136 items (91%). Percutaneous or intraoperative hepatic IRE should be considered for unresectable primary and secondary malignancies that are truly unsuitable for thermal ablation because of proximity to critical structures. Absolute contraindications are ventricular arrhythmias, cardiac stimulation devices, and congestive heart failure of New York Heart Association class 3 or higher. A metal stent outside the ablation zone should not be considered a contraindication. For the only commercially available IRE device, the recommended settings are an inter-electrode distance of 10–20 mm and an exposure length of 20 mm. After 10 test pulses, 90 treatment pulses of 1500 V/cm should be delivered continuously, with a pulse length of 70–90 μs. The first post-procedural follow-up should take place 1 month after IRE and thereafter every 3 months, using cross-sectional imaging plus tumor marker assessment.ConclusionsThis article provides recommendations, created by a modified Delphi consensus study, regarding patient selection, workup, procedure, and follow-up of IRE treatment for hepatic malignancies.     

Percutaneous Cystic Duct Interventions and Drain Internalization for Calculous Cholecystitis in Patients Ineligible for Surgery

PurposeTo evaluate the feasibility, effectiveness, and outcomes of percutaneous cholecystostomy drain internalization in patients with calculous cholecystitis who were not surgical candidates.Materials and MethodsPercutaneous cystic duct interventions were attempted in 17 patients (with the intent to place dual cholecystoduodenal stents) who were deemed unfit for surgery and had previously undergone percutaneous cholecystostomies for acute calculous cholecystitis. Baseline demographics, technical success, time from percutaneous cholecystostomy to internalization (dual cholecystoduodenal stent placement), stent patency duration, and adverse event rates were evaluated.ResultsFifteen (88%) of 17 procedures to cross the cystic duct were technically successful. Of these 17 patients, 13 (76%) underwent successful placement of dual cholecystoduodenal stents. Two of these 13 patients (who had successful dual cholecystoduodenal stent placement) needed repeat percutaneous cholecystostomy drains (1 patient had stent migration leading to recurrent cholecystitis, and the other had a perihepatic biloma). The 1-year patency rate was 77% (95% CI, 47%–100%).ConclusionsDual cholecystoduodenal stent placement in nonsurgical patients is a technically feasible treatment option with the goal to remove percutaneous cholecystostomy drains.     

The Effects of Protrusion into the Outflow Vein on Outcomes of Stent Grafts Used to Treat Cephalic Arch Stenoses in Dysfunctional Brachiocephalic Fistulae

PurposeTo assess long-term patency rates of cephalic arch stent grafts in brachiocephalic fistulae and the importance of device position.Materials and MethodsThis retrospective study reviewed 152 patients with dysfunctional brachiocephalic fistulae and cephalic arch stenosis treated with stent grafts (Viabahn; W. L. Gore) at a single tertiary center between 2012 and 2021. The median age was 67.5 years (range, 25–91 years), and the median follow-up period was 637 days (range, 3–3,368 days). A grading system of protrusion was applied: (a) Grade 0, no protrusion; (b) Grade 1, perpendicular; and (c) Grade 2, in-line protrusion. Subsequent fistulograms were available in 133 (88%) of the 152 patients and were assessed for central vein stenosis within 10 mm of the stent graft. Clinical records were assessed for sequelae of stent graft protrusion. Stent graft primary and cumulative circuit patencies were calculated using the Kaplan-Meier method.ResultsProtrusion was documented in 106 (70%) stent grafts—56 Grade 1 and 50 Grade 2. Central vein stenosis was seen in 1 (2%) case of no protrusion (Grade 0) and 38 (40%) cases of protrusion (P < .0001). There was no significant difference in stenosis between Grade 1 and 2 protrusion (P = .15). No adverse clinical sequelae occurred in 147 (97%) patients. Eight patients had a new access subsequently formed in the same arm, and 3 of these 8 patients developed symptoms due to the previous stent graft protrusion (all Grade 2). The primary patency rates of the stent-grafts at 6 and 12 months were 73% and 50%, respectively. The cumulative access circuit patency rates at 1, 2, and 5 years were 84%, 72%, and 54%, respectively.ConclusionsThis study demonstrated that protrusion of a cephalic arch stent graft into the central vein is safe and only clinically relevant when a subsequent ipsilateral access is created.