Implications for patient follow-up of changes in inferior vena cava filter removal plan practices.

AIM: To assess the improvements during patient follow-up after implementing a proactive plan for retrieval of inferior vena cava (IVC) filters. MATERIALS AND METHODS: A retrospective study was undertaken including all patients who had a temporary IVC filter inserted over a 10-year period. Patient demographics, insertion dates, retrieval dates, retrieval rates, and complications were recorded. Patients were categorised into three groups as follows: group A, no intervention where retrieval was not suggested; group B, passive intervention where retrieval was suggested but no appointment made; and group C, proactive intervention where a retrieval date was booked by the radiologist. RESULTS: Five hundred and nine patients had a temporary IVC filter inserted at Royal Liverpool University Hospital over the study period. One per cent of patients in group C were lost to follow-up compared to 41% and 29% in groups A and B respectively (p<0.001). The number of patients who had an IVC retrieval attempt also increased to 80% in group C compared to 53% and 64% in groups A and B (p<0.001). CONCLUSION: Incorporation of a proactive retrieval booking system has significantly reduced the number of patients lost to follow-up to 1%, leading to an increased number of IVC filter retrieval attempts.

Variability in the perception and application of force used in IVC filter retrievals among interventional radiologists.

INTRODUCTION: A long dwell time is associated with higher inferior vena cava (IVC) filter retrieval complication rates. Manufacturers advise that "excessive force should not be used" during filter retrieval; however, the term "excessive" is subjective and is likely to lead to variability amongst operators. The aims of this study were to 1) ascertain what interventional radiologists consider to be excessive force during filter retrieval and 2) to understand the variability in interventional radiologists' perception of force. METHODS: The authors recruited interventional radiologists to perform a benchtop simulated filter retrieval. Participants were invited to pull on a modified force tester attached to a Gunther Tulip filter retrieval set (GTRS). The participants were asked to pull as if they were retrieving an IVC filter and stop when they felt it was clinically unsafe to apply greater force. They were then asked to replicate forces of 10N and 50N, respectively. Each of the three tasks was completed three times. Data were obtained on the clinical experience of the participants with specific questions focusing on their filter retrieval practices. RESULTS: The range of maximum forces applied during filter retrieval varied between 0.8 and 79.8N. When asked to replicate 10N and 50N, for attempt-1, the median forces produced were 23.5N and 38.1N, respectively. A trend analysis showed that those who overestimate 10N are more likely to apply a greater overall maximum force (rs = 0.622; P < 0.001). CONCLUSION: There is wide variation in what interventional radiologists consider to be the maximum safe force to apply during IVC filter retrieval. IMPLICATIONS FOR PRACTICE: Manufacturers and operators should consider methods in which only a safe range of forces can be applied during an IVC filter retrieval. Operators may wish to undertake 'personal' force calibration as part of training in interventional radiology.

Deformation and dynamic response of abdominal aortic aneurysm sealing.

Endovascular sealing is a new technique for the repair of abdominal aortic aneurysms. Commercially available in Europe since 2013, it takes a revolutionary approach to aneurysm repair through minimally invasive techniques. Although aneurysm sealing may be thought as more stable than conventional endovascular stent graft repairs, post-implantation movement of the endoprosthesis has been described, potentially leading to late complications. The paper presents for the first time a model, which explains the nature of forces, in static and dynamic regimes, acting on sealed abdominal aortic aneurysms, with references to real case studies. It is shown that elastic deformation of the aorta and of the endoprosthesis induced by static forces and vibrations during daily activities can potentially promote undesired movements of the endovascular sealing structure.

Estimating the error of CT-based measurements of aortic lumen volume used in endovascular planning.

INTRODUCTION: Planning of endovascular sealing of abdominal aortic aneurysms requires measurement of the aortic lumen volume. The aim of this study was to investigate mathematically the effect of intra- and inter-observer variability error, as well as cardiac cycle-related variability, on these measurements. METHODS: Mean (±2SD) intra- and inter-observer error in lumen measurements and mean (+2SD) cardiac cycle-related variability were obtained from published literature and added to the measurement of the flow lumen volume of a 57 mm abdominal aortic aneurysm to calculate average and extreme error possibilities. RESULTS: The aneurysm volume was measured at 165 ml. The calculated possible mean measurement error due to cardiac cycle variation, intra- and inter-observer variability was +11.0%, resulting in a potential measurement of 183.1 ml. The calculated extreme errors were +24.3% (if 2SD of all errors were added to the mean) and +3.5% (if 2SD of all errors, except cardiac cycle, were subtracted from the mean), resulting in potential measurements of 170.8 ml and 205.1 ml, respectively. When considering the errors combined, the proportion of patients who may have volume measurement errors of up to ±2.5 ml, ±2.6 to ±5.0 ml and ±5.1 to ±7.5 ml were 18%, 17% and 15%, respectively. CONCLUSION: Measurement of CT-based aortic lumen volumes in abdominal aortic aneurysms is imprecise. This has practical implications for the planning and the performance of complex endovascular therapies.

Long-term follow-up of fenestrated endovascular repair for juxtarenal aortic aneurysm.

BACKGROUND: Fenestrated endovascular aneurysm repair (FEVAR) is increasingly being used for juxtarenal aortic aneurysms. The aim of this study was to review long-term results and assess the importance of changing stent-graft design on outcomes. METHODS: This was a retrospective review of all patients who underwent FEVAR within a single unit over 12 years (February 2003 to December 2015). Kaplan-Meier analysis of survival, and freedom from target vessel loss, aneurysm expansion, graft-related endoleak and secondary intervention was performed. Comparison between outcomes of less complex grafts (fewer than 3 fenestrations) and more complex grafts (3 or 4 fenestrations) was undertaken. RESULTS: Some 173 patients underwent FEVAR; median age was 76 (i.q.r. 70-79) years and 90·2 per cent were men. Median aneurysm diameter was 63 (59-71) mm and median follow-up was 34 (16-50) months. The adjusted primary technical operative success rate was 95·4 per cent. The in-hospital mortality rate was 5·2 per cent; there was no known aneurysm-related death during follow-up. Median survival was 7·1 (95 per cent c.i. 5·2 to 8·1) years and overall survival was 60·1 per cent (104 of 173). There was a trend towards an increasing number of fenestrations in the graft design over time. In-hospital mortality appeared higher when more complex stent-grafts were used (8 versus 2 per cent for stent-grafts with 3-4 versus fewer than 3 fenestrations; P = 0·059). Graft-related endoleaks were more common following deployment of stent-grafts with three or four fenestrations (12 of 90 versus 6 of 83; P < 0·001). CONCLUSION: Fenestrated endovascular aneurysm repair for juxtarenal aneurysm is associated with few aneurysm-related deaths in the long term. Significant numbers of secondary interventions are required, but the majority of these can be performed using an endovascular approach.

Bilateral peroneal artery aneurysms.

True aneurysm of the tibial arteries is a rare clinical condition. We report the case of a 67-year-old man who presented with a gradual onset of right calf swelling and pain. Imaging revealed large aneurysms arising from the proximal peroneal arteries bilaterally, measuring 7.4cm and 4cm on the right and left respectively. A detailed medical history, clinical examination and laboratory investigations did not identify evidence of an underlying cause. A surgical reconstruction with an interposition vein graft was successfully performed. To our knowledge, this is the first reported case of primary aneurysm of the peroneal artery in the English literature. We undertook a systematic literature review to identify all reported cases of primary aneurysms of the tibial arteries. The clinical presentation, modes of investigation and interventional treatments are discussed.

A Comprehensive Review of In Situ Fenestration of Aortic Endografts.

OBJECTIVE: Despite technical advances of fenestrated and branched endografts, endovascular exclusion of aneurysms involving renal, visceral, and/or supra-aortic branches remains a challenge. In situ fenestration (ISF) of standard endografts represents another endovascular means to maintain perfusion to such branches. This study aimed to review current indications, technical descriptions, and results of ISF. METHOD: A review of the English language literature was performed in Medline databases, Cochrane Database, Web of Science, and Scopus using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Sixty-seven relevant papers were selected. Thirty-three papers were excluded, leaving 34 articles as the basis of the present review. RESULTS: Most experimental papers evaluated ISF feasibility and assessed the consequences of ISF on graft fabric. Regarding clinical papers, 73 ISF procedures have been attempted in 58 patients, including 26 (45%) emergent and three (5%) bailout cases. Sixty-five (89%) ISF were located at the level of the arch, and eight (11%) in the abdominal aorta. Graft perforation was performed by physical, mechanical, or unspecified means in 33 (45%), 38 (52%), and two vessels (3%), respectively. ISF was technically successful in 68/73 (93%) arteries. At 30 days, two (3.4%) patients died in the setting of an aorto-bronchial fistula and an aorto-oesophageal fistula, respectively. No post-operative death, major complication, or endoleak was described as secondary to the ISF procedure. With follow-up between 0 and 72 months, four (6.9%) late deaths were noted, unrelated to the aorta. One (1.7%) LSA stent was stenosed without symptoms. CONCLUSIONS: Although there may be publication bias, multiple techniques were described to perform ISF with satisfactory short-term results. Long-term data remain scarce. Aortic endograft ISF is an off-label procedure that should not be used outside emergent bailout techniques or investigational studies. A comparison with alternative techniques of preserving aortic side branches is needed.

Medical device adverse incident reporting in interventional radiology.

AIM: To investigate the current situation concerning adverse incident reporting by members of the British Society of Interventional Radiology (BSIR). MATERIALS AND METHODS: A survey of the members of the BSIR was conducted between November 2012 and January 2013. The survey contained questions on the reporting of adverse incidents and attitudes to the reading of "Instructions for Use" for new devices. RESULTS: The majority of the 119 members who completed the survey had experienced an adverse incident relating to the use of a device. Around 75% of respondents reported adverse incidents locally with only 42% reporting directly to the Medicines and Healthcare products Regulatory Agency (MHRA), which was explained by both a lack of time and a lack of awareness regarding mechanisms of reporting directly to the MHRA. CONCLUSION: Adverse incidents related to the unexpected failure of medical devices have been experienced by the majority of interventional radiologists. The majority of these are reported, but there is significant confusion as to where and how these should be reported. Improvements in the number and quality of adverse incidents reported requires better education, avoidance of duplication of work, and improved feedback after reports have been made to ensure the delivery of high-quality, safe patient care.

How secure is the anastomosis between the proximal and distal body components of a fenestrated stent-graft?

OBJECTIVES: To examine the longitudinal migratory force required to cause disconnection of the bifurcated distal body component from the tubular proximal body of a fenestrated stent-graft. METHODS: Using a previously reported mathematical model distal distraction forces were calculated prior to performing in vitro pullout testing. The top end of the proximal body and the iliac limbs of the distal body were attached to the grips of a tensile tester via plastic sealing plugs and pneumatic clamps. Channels within the plugs allowed pressurisation of the inside of the stent-graft. Pullout tests were conducted in the vertical plane. Force and displacement data were recorded and tests repeated 8 times at room temperature with the stent-grafts either dry or wet and unpressurized, at 100 mmHg or at 120 mmHg. RESULTS: The median maximum pullout force was 2.9 N (2.6-4.1) when dry, 3.9 N (3.5-5.4) when wet and unpressurized, 6.3 N (4.8-8.3) when wet and pressurized at 100 mmHg and 6.5 N (4.8-7.2) when wet and pressurized at 120 mmHg. There was a significant difference between pressurized and unpressurized conditions (P < 0.01). CONCLUSIONS: The force required to distract the distal bifurcated component of a fenestrated stent graft is much lower than the reported proximal fixation strength of both a standard and fenestrated Zenith stent graft. Although this helps protect the fenestrated proximal body from the effects of longitudinal migration forces in vivo the current strength of the body overlap zone may actually be unnecessarily weak and requires careful surveillance in follow up.

Anchoring barbs and balloon expandable stents: what is the risk of perforation and failed stent deployment?

PURPOSE: Balloon expandable stents may on occasion be deployed in close proximity to the anchoring barbs of endovascular grafts. The aim of this study was to determine the risk and effect of balloon perforation by anchoring barbs and to assess whether these risks are different if the balloon is protected by a covered stent mounted upon it. METHODS: A bench-top model was developed to mimic the penetration of anchoring barbs into the lumen of medium sized blood vessels. The model allowed variation of angle and depth of vessel penetration. Both bare balloons and those with covered stents mounted upon them were tested in the model to determine whether there was a risk of perforation and which factors increased or decreased this risk. RESULTS: All combinations of barb angle and depth caused balloon perforation but this was most marked when the barb was placed perpendicular to the long axis of the balloon. When the deployment of covered stents was attempted balloon perforation occurred in some cases but full stent deployment was achieved in all cases where the perforation was in the portion of the balloon covered by the stent. The only situation in which stent deployment failed was where the barb was intentionally placed in the uncovered portion of the balloon. This resulted in only partial deployment of the stent. CONCLUSIONS: Balloon rupture is a distinct possibility when deploying balloon-expandable stents in close proximity to anchoring barbs. Care should be taken in this circumstance to ensure that the barb is well away from the uncovered portion of the balloon.

Off label use of devices and drugs in interventional radiology.

AIM: To establish how often off-label device and drug use occurs in interventional radiology (IR) in a UK tertiary referral hospital and consider the wider implications for the interventional radiologist. MATERIALS AND METHODS: Prospective data were collected during interventional procedures for 1 working week in a university hospital. Out-of-hours procedures and procedures outside the department were excluded. Operators were asked to record the drugs and devices used, the indication, and method of use. The instructions for use/summary of product characteristics were then studied for each device/drug used to assess if the use was on or off-label. RESULTS: During the study period 52 cases were performed and data were available on 26 cases (50%). In 22 of the 26 cases (84%) there was evidence of off-label use of devices or drugs. Off-label use of drugs included treatment of venous malformations with Fibrovein(©) (sodium tetradecyl sulphate), which is licensed for the treatment of varicose veins in the leg, and intra-arterial injection of heparin, which is licensed for intravenous and subcutaneous use. Off-label device use included placing vascular sheaths in the urinary tract, using angiographic catheters to guide wires in the urinary tract, using sheaths for thrombosuction, reshaping of the tip of most guidewires, and using angioplasty balloons to dislodge the arterial plug at fistula thrombectomy. CONCLUSION: Off-label device and drugs use is common in a UK tertiary hospital IR department and literature suggests this is common in the wider IR community. There are important clinical and legal implications for off-label use for patients and physicians.

Surveillance after EVAR based on duplex ultrasound and abdominal radiography.

INTRODUCTION: Computed tomography angiography (CTA) is considered the gold standard imaging technique for surveillance following endovascular aneurysm repair (EVAR). Limitations of CTA include cost, risk of contrast nephropathy and radiation exposure. A modified surveillance protocol involving annual duplex ultrasound (DUS) and abdominal radiography (AXR) was introduced, with CTA performed only if abnormalities were identified or DUS was undiagnostic. METHODS: Prospective records were maintained on patients undergoing infra-renal EVAR at a UK, tertiary referral centre. All patients enrolled with at least one-year follow-up were reviewed. Primary outcomes identified were aneurysm rupture and aneurysm-related complications. Secondary outcomes included number of CTAs avoided and cost. RESULTS: Median follow-up was 36 months (range 12-57) for 194 patients. The total number of sets of surveillance imaging was 412 of which 70 (17%) required CTA. Abnormalities were found in 30 patients, 18 confirmed by CTA. Eleven patients required secondary intervention, three initially identified by AXR, three by DUS, three by both DUS and AXR, and two by CTA following undiagnostic DUS. No patient presented with rupture or aneurysm-related complications not identified by modified surveillance. Mean annual savings were €223. CONCLUSION: EVAR surveillance based on DUS and AXR is feasible and safe. The complimentary nature of AXR and DUS is demonstrated.

Fascial closure following percutaneous endovascular aneurysm repair.

INTRODUCTION: There are potential benefits of percutaneous over open femoral access for endovascular aneurysm repair (EVAR). Subsequent arterial closure using percutaneous devices is costly, whilst open repair risks potential wound complications and delayed discharge. The technique of fascial closure has perceived advantages but its efficacy is unclear. The aim of this study was to assess the safety and durability of fascial closure after EVAR. METHODS: Patients undergoing EVAR using devices up to 24 French were considered. Exclusion criteria included morbid obesity, high bifurcation, previous surgery, inadvertent high puncture, arteries < 5 mm and surgeon preference. The primary outcome measure was immediate technical success. All patients were followed-up clinically and with duplex at one and twelve months to determine secondary complications. RESULTS: Over a one-year period fascial closure of 69 common femoral arteries was attempted in 38 patients undergoing EVAR. Nine primary failures were due to haemorrhage in eight arteries and thrombosis in one artery; all had immediate, uncomplicated open revision. Of the 60 (87%) successful procedures, all had duplex surveillance at one month. Four pseudoaneurysms were identified, all treated conservatively. At one year, 61 fascial closures (88%) were imaged, four patients had died and two were lost to follow-up. Three of the pseudoaneurysms had resolved, the fourth patient had died (unrelated). No other complication attributable to fascial closure was found at either one or twelve months. CONCLUSION: Fascial closure is a safe, durable and cost-effective method of arterial closure following EVAR. Success and complication rates are comparable to other techniques.

Audit of the use of IVC filters in the UK: experience from three centres over 12 years.

AIM: To audit the use of inferior vena cava (IVC) filter insertions at three UK centres over 12 years to assess whether trends in filter use in the UK mirrored those seen elsewhere. MATERIALS AND METHODS: Radiology department databases were interrogated for IVC filter insertions and removals between 1994 and 2006. Reports for these interventions, along with prior and subsequent imaging reports, were analysed. Follow-up data were obtained when available. RESULTS: Five hundred and sixteen filters were placed with a significant year-on-year trend towards increasing use. Fifty-seven percent of filters placed were for absolute indications and 37% for relative indications. The filters were used for prophylaxis in 6% of patients in the absence of proven pulmonary embolism (PE) or deep vein thrombosis (DVT). A retrievable filter was used in 74% of cases with retrieval attempted in 40% of these and no evidence of an increasing rate of retrieval over time. A significant complication related to insertion or retrieval was encountered in 0.4 and 1% of procedures, respectively. Mean 24 h and 30 day mortalities were 1 and 8%, respectively. There was an absence of organized follow-up at all three centres. CONCLUSION: IVC filter use in the UK is increasing. The use of retrievable filters has not resulted in increased filter retrieval. Filter insertion and retrieval is associated with a low risk of significant complication, but lack of systematic follow-up limits conclusions regarding safety and efficacy.

Wholly endovascular repair of thoracoabdominal aneurysm.

BACKGROUND: The aim was to evaluate a wholly endovascular approach to the repair of thoracoabdominal aortic aneurysm (TAAA). METHODS: Six patients (median age 71 years) underwent wholly endovascular repair of TAAA (maximum diameter 56-85 mm) employing individually customized endografts. Procedures were performed under general anaesthesia, with spinal drainage in five patients. Patients were followed by serial computed tomography, plain radiography and duplex imaging for a median of 17 (range 8-44) months. RESULTS: All grafts were deployed as intended, with preservation of all target vessels. There were no postoperative deaths, strokes or paraplegia. One patient suffered a silent myocardial infarction. In two patients a persistent paraostial endoleak was treated by further balloon dilatation of the stent within the endograft fenestration. Imaging before discharge confirmed aneurysm exclusion in all patients. Two patients required late secondary intervention to abolish endoleaks due to side-branch disconnection. One patient suffered late occlusion of the coeliac axis without clinical sequelae, and late occlusion of a solitary renal artery in another resulted in dependence on dialysis. There have been no late deaths and all aneurysms remain excluded. CONCLUSION: Wholly endovascular TAAA repair is relatively safe, but long-term follow-up is required to establish its durability.

Fenestrated endovascular repair for juxtarenal aortic aneurysm.

BACKGROUND: The outcome of fenestrated endovascular aneurysm repair (F-EVAR) was evaluated. METHODS: Between February 2003 and December 2006, 45 patients (median age 73 (range 53-85) years) underwent primary (41) or secondary (four) F-EVAR for an abdominal aortic aneurysm with infrarenal neck anatomy unsuitable for a standard stent-graft. Median aneurysm diameter was 68 (range 55-100) mm and median infrarenal aortic neck length was 6 (range 0-13) mm. Customized fenestrated Zenith stent-grafts were employed in all procedures, incorporating fenestrations to preserve flow into renal (80), superior mesenteric (35) and coeliac (two) arteries. Eighty-two target vessels were stented (61 bare metal, 21 covered). RESULTS: All aneurysms were isolated successfully, with preservation of the target vessels. One accessory renal artery was lost. One patient died after 5 days from myocardial infarction, and another at 3 months from multiorgan failure secondary to atheroembolism. At median follow-up of 24 (range 1-48) months, all aneurysms were stable or shrinking, with no late ruptures or graft-related endoleaks. Six patients required a secondary intervention. The primary vessel patency rate was 96.6 per cent. There were four late deaths, unrelated to the aneurysm. CONCLUSION: F-EVAR enabled successful treatment of juxtarenal aortic aneurysm with a low complication rate.

TIPSS in the treatment of ectopic variceal bleeding.

BACKGROUND/AIMS: Bleeding from ectopic varices is a well recognized life-threatening complication of portal hypertension but the optimal treatment of this problem is yet to be established. METHODOLOGY: We retrospectively reviewed patients with ectopic variceal bleeding who underwent transjugular intrahepatic portosystemic shunting for recurrent bleeding not responding to conservative management. RESULTS: Over an eleven-year period we identified ten patients who underwent TIPSS for ectopic variceal hemorrhage. Six patients bled from rectal varices and four from stomal varices. TIPSS was successful in nine patients. The Childs-Pugh grade of the patients was A=3, B=3 and C=4. The follow-up period ranged from 7 days to 1380 days. Rebleeding occurred in three patients, two of whom died. The remaining patient had a blocked TIPSS and successfully underwent repeat stenting which re-established patency. Four patients (Childs B=2, Childs C=2) died within 60 days. All three patients with Childs A liver disease were alive at one year. CONCLUSIONS: TIPSS can be used effectively to treat ectopic variceal bleeding. Patients with Childs grade A liver disease appear to do well with TIPSS. Those with advanced liver disease (Childs B & C) have a uniformly poor outcome. In these patients ectopic variceal hemorrhage is likely to represent a terminal event.

Late complications after ligation and bypass for popliteal aneurysm.

BACKGROUND: Ligation and bypass is standard treatment for popliteal aneurysm. This technique does not abolish collateral circulation to the aneurysm, which may continue to expand and/or rupture. This study assessed whether complete thrombosis of the aneurysm sac occurs after operation and examined the long-term clinical outcome. METHODS: The records of all patients who underwent popliteal aneurysm repair in a university hospital over 10 years were reviewed. Patients who had undergone ligation and bypass were recalled for clinical and ultrasonographic examination to determine the fate of the aneurysm sac. RESULTS: Persistent blood flow in the aneurysm sac was present in 12 of 36 legs a median of 48 months after operation. This was associated with symptomatic enlargement of the aneurysm in six patients. The incidence of sac enlargement was lower in bypassed aneurysms with no intrasac flow on duplex examination. CONCLUSION: Ligation and bypass does not always abolish blood flow in the sac of a popliteal aneurysm. It may be associated with continued expansion and late complications.