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1.
Health Technol Assess ; 26(6): 1-166, 2022 01.
Article in English | MEDLINE | ID: mdl-35094747

ABSTRACT

BACKGROUND: The management of chronic thoracic aortic aneurysms includes conservative management, watchful waiting, endovascular stent grafting and open surgical replacement. The Effective Treatments for Thoracic Aortic Aneurysms (ETTAA) study investigates timing and intervention choice. OBJECTIVE: To describe pre- and post-intervention management of and outcomes for chronic thoracic aortic aneurysms. DESIGN: A systematic review of intervention effects; a Delphi study of 360 case scenarios based on aneurysm size, location, age, operative risk and connective tissue disorders; and a prospective cohort study of growth, clinical outcomes, costs and quality of life. SETTING: Thirty NHS vascular/cardiothoracic units. PARTICIPANTS: Patients aged > 17 years who had existing or new aneurysms of ≥ 4 cm in diameter in the arch, descending or thoracoabdominal aorta. INTERVENTIONS: Endovascular stent grafting and open surgical replacement. MAIN OUTCOMES: Pre-intervention aneurysm growth, pre-/post-intervention survival, clinical events, readmissions and quality of life; and descriptive statistics for costs and quality-adjusted life-years over 12 months and value of information using a propensity score-matched subsample. RESULTS: The review identified five comparative cohort studies (endovascular stent grafting patients, n = 3955; open surgical replacement patients, n = 21,197). Pooled short-term all-cause mortality favoured endovascular stent grafting (odds ratio 0.71, 95% confidence interval 0.51 to 0.98; no heterogeneity). Data on survival beyond 30 days were mixed. Fewer short-term complications were reported with endovascular stent grafting. The Delphi study included 20 experts (13 centres). For patients with aneurysms of ≤ 6.0 cm in diameter, watchful waiting was preferred. For patients with aneurysms of > 6.0 cm, open surgical replacement was preferred in the arch, except for elderly or high-risk patients, and in the descending aorta if patients had connective tissue disorders. Otherwise endovascular stent grafting was preferred. Between 2014 and 2018, 886 patients were recruited (watchful waiting, n = 489; conservative management, n = 112; endovascular stent grafting, n = 150; open surgical replacement, n = 135). Pre-intervention death rate was 8.6% per patient-year; 49.6% of deaths were aneurysm related. Death rates were higher for women (hazard ratio 1.79, 95% confidence interval 1.25 to 2.57; p = 0.001) and older patients (age 61-70 years: hazard ratio 2.50, 95% confidence interval 0.76 to 5.43; age 71-80 years: hazard ratio 3.49, 95% confidence interval 1.26 to 9.66; age > 80 years: hazard ratio 7.01, 95% confidence interval 2.50 to 19.62; all compared with age < 60 years, p < 0.001) and per 1-cm increase in diameter (hazard ratio 1.90, 95% confidence interval 1.65 to 2.18; p = 0.001). The results were similar for aneurysm-related deaths. Decline per year in quality of life was greater for older patients (additional change -0.013 per decade increase in age, 95% confidence interval -0.019 to -0.007; p < 0.001) and smokers (additional change for ex-smokers compared with non-smokers 0.003, 95% confidence interval -0.026 to 0.032; additional change for current smokers compared with non-smokers -0.034, 95% confidence interval -0.057 to -0.01; p = 0.004). At the time of intervention, endovascular stent grafting patients were older (age difference 7.1 years; 95% confidence interval 4.7 to 9.5 years; p < 0.001) and more likely to be smokers (75.8% vs. 66.4%; p = 0.080), have valve disease (89.9% vs. 71.6%; p < 0.0001), have chronic obstructive pulmonary disease (21.3% vs. 13.3%; p = 0.087), be at New York Heart Association stage III/IV (22.3% vs. 16.0%; p = 0.217), have lower levels of haemoglobin (difference -6.8 g/l, 95% confidence interval -11.2 to -2.4 g/l; p = 0.003) and take statins (69.3% vs. 42.2%; p < 0.0001). Ten (6.7%) endovascular stent grafting and 15 (11.1%) open surgical replacement patients died within 30 days of the procedure (p = 0.2107). One-year overall survival was 82.5% (95% confidence interval 75.2% to 87.8%) after endovascular stent grafting and 79.3% (95% confidence interval 71.1% to 85.4%) after open surgical replacement. Variables affecting survival were aneurysm site, age, New York Heart Association stage and time waiting for procedure. For endovascular stent grafting, utility decreased slightly, by -0.017 (95% confidence interval -0.062 to 0.027), in the first 6 weeks. For open surgical replacement, there was a substantial decrease of -0.160 (95% confidence interval -0.199 to -0.121; p < 0.001) up to 6 weeks after the procedure. Over 12 months endovascular stent grafting was less costly, with higher quality-adjusted life-years. Formal economic analysis was unfeasible. LIMITATIONS: The study was limited by small numbers of patients receiving interventions and because only 53% of patients were suitable for both interventions. CONCLUSIONS: Small (4-6 cm) aneurysms require close observation. Larger (> 6 cm) aneurysms require intervention without delay. Endovascular stent grafting and open surgical replacement were successful for carefully selected patients, but cost comparisons were unfeasible. The choice of intervention is well established, but the timing of intervention remains challenging. FUTURE WORK: Further research should include an analysis of the risk factors for growth/rupture and long-term outcomes. TRIAL REGISTRATION: Current Controlled Trials ISRCTN04044627 and NCT02010892. FUNDING: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 26, No. 6. See the NIHR Journals Library website for further project information.


The aorta is the main artery that carries oxygen-rich blood from the heart to the body. An aneurysm is a swelling or bulging in a blood vessel, which usually occurs where the wall has become weak and has lost its elastic properties, which means that it does not return to its normal shape after the blood has passed through. A thoracic aortic aneurysm, or TAA for short, is an aneurysm in the section of the aorta in the chest (www.bhf.org.uk/informationsupport/conditions/thoracic-aortic-aneurysms). The Effective Treatments for Thoracic Aortic Aneurysms (ETTAA) study aimed to investigate aneurysm growth rates, patient outcomes, quality of life and costs, including those from surgery. Surgical treatments include open heart surgery, in which the section of the aorta that contains the aneurysm is removed and replaced by a new aorta made from a synthetic material, and stent grafting, in which tubes are inserted into arteries to allow blood to flow freely, using less invasive 'keyhole' surgery. The existing research evidence was reviewed, but data comparing the effectiveness of these two approaches were sparse or of limited quality, and outdated. Between 2014 and 2018, clinical experts were surveyed and 886 NHS patients with chronic thoracic aortic aneurysms (≥ 4 cm in diameter) were observed to monitor aneurysm growth and patient outcomes. If patients were unfit or unwilling to have surgery, they had conservative management with medication and lifestyle changes. For small aneurysms, experts recommended watchful waiting, with regular monitoring, until the aneurysm grew to about 6 cm in diameter. Open surgery was preferred for larger arch aneurysms and for descending aneurysms in patients with genetic disorders. Otherwise, stent grafting was preferred. The observational study recruited 321 women and 565 men with an average age of 71 years from 30 English hospitals. A total of 489 patients underwent watchful waiting and 112 received conservative management. Without surgery, death rates were higher for women and older patients, while the risk of dying doubled for each centimetre of aneurysm diameter at baseline. Of the remaining patients, 150 underwent stent grafting and 135 had open surgery. One-year overall survival was 83% after stent grafting and 79% after open surgery but the difference could be due to chance. The factors affecting survival after stent grafting or open surgery were aneurysm location, age, breathlessness and time waiting for a procedure. Small aneurysms are low risk, so blood pressure management and smoking cessation are recommended. For larger aneurysms, it is important that surgery is not delayed, as a longer waiting time to surgery means that outcomes are poorer. Only about half of patients who had surgery were considered suitable for both stent grafting and open surgery, which limited the ability to determine the best use of NHS resources. No comparative cost-effectiveness analysis was feasible. The main cost in a stent grafting procedure was the stent graft, and the main cost in an open surgery procedure was days in an intensive care unit.


Subject(s)
Aortic Aneurysm, Thoracic , Endovascular Procedures , Adolescent , Aged , Aged, 80 and over , Aortic Aneurysm, Thoracic/etiology , Aortic Aneurysm, Thoracic/surgery , Child , Cohort Studies , Cost-Benefit Analysis , Endovascular Procedures/methods , Female , Humans , Middle Aged , Prospective Studies , Quality of Life , Stents
2.
J Endovasc Ther ; 23(1): 229-32, 2016 Feb.
Article in English | MEDLINE | ID: mdl-26564914

ABSTRACT

PURPOSE: To report 2 cases of type IIIb endoleak with the Endurant stent-graft and postulate the cause for the events. CASE REPORT: A type IIIb endoleak was diagnosed at open conversion for a ruptured aneurysm 4 years after implantation of an Endurant stent-graft. In the other case, the endoleak was diagnosed at angiography 4 years after the Endurant stent-graft was implanted; the stent-graft was relined. In both cases the fabric hole was in the body of the stent-graft at the level of the top of the contralateral limb. CONCLUSION: The cause of the type IIIb endoleaks in these cases was fabric erosion likely due to interaction between the bare metal at the top of the contralateral limb and the fabric of the stent-graft body.


Subject(s)
Aortic Aneurysm, Abdominal/surgery , Blood Vessel Prosthesis Implantation/instrumentation , Blood Vessel Prosthesis , Endoleak/etiology , Endovascular Procedures/instrumentation , Stents , Aged , Aged, 80 and over , Aortic Aneurysm, Abdominal/diagnosis , Aortography/methods , Blood Vessel Prosthesis Implantation/adverse effects , Endoleak/diagnosis , Endoleak/surgery , Endovascular Procedures/adverse effects , Humans , Male , Prosthesis Design , Reoperation , Tomography, X-Ray Computed , Treatment Outcome
3.
J Endovasc Ther ; 22(5): 734-44, 2015 Oct.
Article in English | MEDLINE | ID: mdl-26286073

ABSTRACT

PURPOSE: To report a systematic literature review of late rupture of abdominal aortic aneurysm (AAA) after endovascular aneurysm repair (EVAR) and the results of a pooled analysis of causes, treatment, and outcomes. METHODS: Electronic information sources and bibliographic reference lists were interrogated using a combination of free text and controlled vocabulary searches; 11 articles were ultimately identified that fulfilled the inclusion criteria. The articles reported a total of 190 patients who were included in the qualitative and quantitative synthesis. Mortality within 30 days or during the admission with aneurysm rupture was a primary endpoint; major perioperative morbidity was a secondary endpoint. A meta-analysis was performed for 30-day/in-hospital mortality using the random effects model. RESULTS: A total of 152 ruptures occurred after 16,974 EVAR procedures reported by 8 of the case series, giving an incidence of 0.9% [95% confidence interval (CI) 0.77 to 1.05]. The mean time to rupture was 37 months. Twenty-nine percent (95% CI 20 to 39) of the patients had at least one previous secondary endovascular intervention following the initial EVAR, and 37% (95% CI 30 to 45) were not compliant with surveillance. Type I and III endoleaks were the predominant causes of rupture. Open surgical treatment was undertaken in 61% (95% CI 53 to 68) of the patients who underwent treatment. The pooled estimate for perioperative mortality was 32% (95% CI 24 to 41). A significantly lower mortality was found with endovascular treatment than open surgical management (p=0.027). CONCLUSION: Graft-related endoleaks appear to be the predominant causes of late aneurysm rupture. Quality of and compliance with post-EVAR surveillance are important factors in late rupture; a large proportion of late ruptures are amenable to endovascular treatment.


Subject(s)
Aortic Aneurysm, Abdominal/surgery , Aortic Rupture/etiology , Blood Vessel Prosthesis Implantation/adverse effects , Endoleak/etiology , Endovascular Procedures/adverse effects , Aortic Aneurysm, Abdominal/diagnosis , Aortic Aneurysm, Abdominal/mortality , Aortic Rupture/diagnosis , Aortic Rupture/mortality , Aortic Rupture/therapy , Blood Vessel Prosthesis Implantation/mortality , Endoleak/diagnosis , Endoleak/mortality , Endoleak/therapy , Endovascular Procedures/mortality , Hospital Mortality , Humans , Risk Assessment , Risk Factors , Time Factors , Treatment Outcome
5.
J Endovasc Ther ; 21(5): 723-7, 2014 Oct.
Article in English | MEDLINE | ID: mdl-25290802

ABSTRACT

PURPOSE: To present confirmed cases of type IIIb endoleak in second and third-generation stent-grafts used for endovascular aneurysm repair (EVAR). CASE REPORTS: Four patients developed type IIIb endoleak caused by fabric tears between 4 and 13 years following their initial EVAR. Three patients presented with rupture and one with aneurysm expansion of unknown cause. In each case, the type IIIb endoleak was confirmed at open surgery after imaging proved non-diagnostic. Only one patient survived. Had the cause for the expansion or ruptures been found prior to open reintervention, relining of the stent-graft may have been possible. CONCLUSION: Type IIIb endoleak remains difficult to diagnose. Avoidance of the high mortality associated with open secondary intervention requires a high degree of suspicion and it should be considered in any post-EVAR aneurysm expansion without an obvious cause.


Subject(s)
Aortic Aneurysm, Abdominal/surgery , Blood Vessel Prosthesis Implantation/adverse effects , Endoleak/etiology , Endovascular Procedures/adverse effects , Prosthesis Failure , Aged , Aged, 80 and over , Aortic Aneurysm, Abdominal/diagnosis , Aortic Rupture/etiology , Blood Vessel Prosthesis , Blood Vessel Prosthesis Implantation/instrumentation , Device Removal , Endoleak/diagnosis , Endoleak/surgery , Endovascular Procedures/instrumentation , Fatal Outcome , Humans , Male , Prosthesis Design , Reoperation , Stents , Treatment Failure
6.
J Vasc Surg ; 60(2): 418-27, 2014 Aug.
Article in English | MEDLINE | ID: mdl-24657293

ABSTRACT

BACKGROUND: Meta-analysis supports patch angioplasty after carotid endarterectomy (CEA); however, studies indicate considerable variation in practice. The hemodynamic effect of a patch is unclear and this study attempted to elucidate this and guide patch width selection. METHODS: Four groups were selected: healthy volunteers and patients undergoing CEA with primary closure, trimmed patch (5 mm), or 8-mm patch angioplasty. Computer-generated three-dimensional models of carotid bifurcations were produced from transverse ultrasound images recorded at 1-mm intervals. Rapid prototyping generated models for flow visualization studies. Computational fluid dynamic studies were performed for each model and validated by flow visualization. Mean wall shear stress (WSS) and oscillatory shear index (OSI) maps were created for each model using pulsatile inflow at 300 mL/min. WSS of <0.4 Pa and OSI >0.3 were considered pathological, predisposing to accretion of intimal hyperplasia. The resultant WSS and OSI maps were compared. RESULTS: The four groups comprised 8 normal carotid arteries, 6 primary closures, 6 trimmed patches, and seven 8-mm patches. Flow visualization identified flow separation and recirculation at the bifurcation increased with a patch and was related to the patch width. Computational fluid dynamic identified that primary closure had the fewest areas of low WSS or elevated OSI but did have mild common carotid artery stenoses at the proximal arteriotomy that caused turbulence. Trimmed patches had more regions of abnormal WSS and OSI at the bifurcation, but 8-mm patches had the largest areas of deleteriously low WSS and high OSI. Qualitative comparison among the four groups confirmed that incorporation of a patch increased areas of low WSS and high OSI at the bifurcation and that this was related to patch width. CONCLUSIONS: Closure technique after CEA influences the hemodynamic profile. Patching does not appear to generate favorable flow dynamics. However, a trimmed 5-mm patch may offer hemodynamic benefits over an 8-mm patch and may be the preferred option.


Subject(s)
Angioplasty , Carotid Arteries/surgery , Carotid Artery Diseases/surgery , Endarterectomy, Carotid , Hemodynamics , Wound Closure Techniques , Adult , Aged , Aged, 80 and over , Angioplasty/adverse effects , Angioplasty/instrumentation , Blood Flow Velocity , Carotid Arteries/diagnostic imaging , Carotid Arteries/physiopathology , Carotid Artery Diseases/diagnosis , Carotid Artery Diseases/physiopathology , Computer Simulation , Equipment Design , Female , Humans , Male , Middle Aged , Models, Cardiovascular , Pulsatile Flow , Regional Blood Flow , Reproducibility of Results , Stress, Mechanical , Treatment Outcome , Ultrasonography , Wound Closure Techniques/adverse effects
7.
J Endovasc Ther ; 20(3): 345-9, 2013 Jun.
Article in English | MEDLINE | ID: mdl-23731307

ABSTRACT

PURPOSE: To report an initial experience of concomitant endovascular repair of abdominal aortic aneurysms (AAA) and cardiac surgery. METHODS: Records for 10 consecutive patients (all men; median age 68 years, range 60-79) with AAA treated by a multidisciplinary team at a tertiary specialist center were retrospectively reviewed. Each patient had independent indications for surgical correction of their cardiac disease and AAAs. The patients underwent endovascular aneurysm repair (EVAR) followed by cardiac surgery under the same anesthesia. Eight patients had concomitant coronary artery bypass grafting (CABG; 4 off-pump), 1 patient had CABG and left ventricular aneurysmectomy, and 1 patient required aortic root replacement. RESULTS: All combined procedures were performed successfully under a single general anesthesia and took a median of 508 minutes (range 425-625). Median intensive care stay was 3 days (range 2-4), while hospital stay was 8 days (range 7-21) days. There were no deaths in-hospital or within 30 days. Complications were minor and self-limiting; there were no instances of renal failure. At a median follow-up of 29 months (range 14-38), no EVAR-related secondary interventions were required. CONCLUSION: Concomitant EVAR and cardiac surgery delivered by a multidisciplinary team is feasible, appears safe, and eliminates the risk associated with staged operations. Improved patient satisfaction and efficient use of resources are potential advantages.


Subject(s)
Aortic Aneurysm, Abdominal/complications , Aortic Aneurysm, Abdominal/surgery , Coronary Artery Bypass , Coronary Artery Disease/complications , Coronary Artery Disease/surgery , Endovascular Procedures , Aged , Humans , Male , Middle Aged , Retrospective Studies
8.
J Vasc Surg ; 57(6): 1543-52, 2013 Jun.
Article in English | MEDLINE | ID: mdl-23541544

ABSTRACT

OBJECTIVE: This article reports the incidence, timing, and related sequelae for proximal and distal migration of the Zenith Fenestrated AAA Endovascular Graft (Cook Medical, Bloomington, Ind) used to treat abdominal aortic aneurysms. METHOD: A prospectively maintained database at a tertiary referral hospital was used to identify 83 patients who underwent endovascular repair using the Zenith fenestrated stent graft. Inclusion criteria included a postoperative computed tomography (CT) scan within 6 weeks of implantation and at least one additional follow-up CT scan (>5 months) available electronically at our institution. Eligible patients underwent assessment of stent graft migration using a CT-based central luminal line (CLL) technique. The proximal and distal margins of the stent graft were measured using CLLs relative to vascular landmarks on all available follow-up CT scans. Migration was defined as stent graft movement ≥4 mm. RESULTS: Fifty-five patients were included in this study, mean age was 74 ± 7 years, and 89% were men. Mean preoperative aneurysm diameter was 67 ± 9 mm. In these 55 patients, fenestrations were applied to 162 target vessels with the commonest design accommodating two renal arteries (RAs) and the superior mesenteric artery (SMA). Median follow-up was 24 (range, 5-97) months; 80% of patients (n = 44) had both the proximal and two distal attachment sites assessed for evidence of migration. Twelve iliac limbs in 11 patients were excluded from analysis due to occlusion of one internal iliac artery precluding CLL assessment (n = 7), or image quality issues (n = 5). Using CLLs and based on those patients who exhibited migration, the median proximal and distal migration distances were +5.0 (range, +4.0 to +8.1) mm and -5.0 (range, -4.3 to -21.3) mm, respectively. Kaplan-Meier analysis for proximal migration revealed migration rates of 14% and 22% at 12 and 36 months, respectively. Distal migration rates were lower at 3% and 8%, respectively. There have been no incidences of late rupture or open conversion. Of the patients with proximal migration, two patients lost a single target vessel (two RAs) and three patients were reported to have target vessel stenosis (two SMAs, one RA). These cases did not require reintervention. CONCLUSIONS: Both suprarenal fabric extension and visceral artery stenting are known to provide additional fixation for fenestrated aortic stent grafts. Despite this, minor proximal migration still occurs in up to one quarter of fenestrated endovascular repair patients by 4 years. We believe this is mainly due to the engagement of the barbs of the anchoring stent. Distal migrations occur with lower frequency.


Subject(s)
Aortic Aneurysm, Abdominal/surgery , Foreign-Body Migration/etiology , Stents/adverse effects , Aged , Female , Foreign-Body Migration/complications , Foreign-Body Migration/epidemiology , Humans , Incidence , Male , Prospective Studies , Prosthesis Design
9.
J Vasc Surg ; 55(4): 895-905, 2012 Apr.
Article in English | MEDLINE | ID: mdl-22264930

ABSTRACT

PURPOSE: This study evaluated the accuracy of central luminal line (CLL) measurements in quantifying stent graft migration. The bias of the CLL technique together with observer variability were assessed. METHODS: Stent grafts were deployed in plastic aortic phantoms at fixed locations from two side branches. Each phantom was filled with iodinated contrast, and a 2-mm multislice computed tomography (CT) scan was performed. The stent graft was then displaced caudally, its new location determined, and again, a CT scan performed. This created a series of 15 cases with known stent graft migration. CLLs were used to measure stent graft position on the CT scans and calculate migration (3 observers). In vivo stent graft migration was then evaluated in a similar manner using a series of follow-up CT scans from nine patients (2 observers). All CLL measurements were performed independently and were repeated on a separate occasion. RESULTS: The mean difference in CLL migration between the actual and observed measurements (bias) in the aortic phantoms was <1 mm. The 95% confidence intervals for the bias were within the interval (-1 and 1 mm), and the 95% limits of agreement were within -3 mm and +3 mm. The 95% limits of agreement for measurements within and between observers were -4 to 2 mm and -2 to 2 mm, respectively. The phantom study generated a coefficient of repeatability (RC) of 1 mm for within-observer measurements. Clinically, CLLs generated 95% limits of agreement within and between observers of -3 to 4 mm (RC, 2 mm) and -3 to +3 mm, respectively. CONCLUSIONS: Bias from CLL-determined migration is small and insignificant from a practical point of view. A small amount of measurement variability within and between observers does exist; it should be feasible to detect changes in stent graft position that are ≥4 mm.


Subject(s)
Aortic Aneurysm/diagnostic imaging , Foreign-Body Migration/diagnostic imaging , Multidetector Computed Tomography/methods , Prosthesis Failure , Stents , Adult , Aged , Aortic Aneurysm/therapy , Blood Vessel Prosthesis Implantation/adverse effects , Blood Vessel Prosthesis Implantation/methods , Cardiac Catheterization/methods , Female , Humans , Male , Middle Aged , Models, Anatomic , Observer Variation , Phantoms, Imaging , Sensitivity and Specificity
10.
J Endovasc Ther ; 18(6): 797-801, 2011 Dec.
Article in English | MEDLINE | ID: mdl-22149229

ABSTRACT

PURPOSE: To measure the stiffness of commonly used "stiff" guidewires in terms of their flexural modulus, an engineering parameter related to bending stiffness. METHODS: Eleven different intact stiff guidewires were selected to undergo a 3-point bending test performed using a tensile testing machine. Testing was performed on 3 new and intact specimens of each guidewire at 10 locations along the wire's length, excluding the floppy tip. The flexural modulus (in gigapascals, GPa) was calculated from the results of the bending test. RESULTS: The flexural modulus of the plain Amplatz wire was 9.5 GPa compared to 11.4 to 14.5 GPa for the "heavy duty" wires. Within the Amplatz family of guidewires, the flexural modulus was 17 GPa for the "stiff," 29.2 GPa for the "extra stiff," 60.3 GPa for the "super stiff," and 65.4 GPa for the "ultra stiff." The Backup Meier measured 139.6 GPa and the Lunderquist Extra Stiff 158.4 GPa. CONCLUSION: The Instructions for Use of some endovascular devices specify a wire type selected from a range of undefined "stiffness" descriptors. These descriptors have little correlation with the measured flexural modulus. Two guidewires with the description "extra stiff" can have a 5-fold difference in flexural modulus. We recommend that guidewire catalogues and packaging include the flexural modulus and that device manufacturers amend their Instructions for Use accordingly.


Subject(s)
Endovascular Procedures/instrumentation , Materials Testing , Pliability , Blood Vessel Prosthesis
11.
J Endovasc Ther ; 18(4): 569-75, 2011 Aug.
Article in English | MEDLINE | ID: mdl-21861749

ABSTRACT

PURPOSE: To quantify the compression force acting on target vessel stents as a consequence of the misalignment between the native aortic anatomy and the fenestrated stent-graft owing to measuring errors during the design of the device. METHODS: The material properties of a fenestrated Zenith stent-graft were determined using a standardized tensile testing protocol. Aortic anatomy was modeled using fresh porcine aortas that were subjected to tensile testing. The net force acting on a target vessel stent due to incremental discrepancy between the target vessel ostia and the stent-graft fenestrations was calculated as the difference in wall tension between the aorta and the stent-graft in diastole and systole. The change in diameter between diastole and systole was set to 8%. RESULTS: Using the diastole model, underestimation of circumferential target vessel position by 15°, 22.5°, and 30° resulted in net forces on the target vessel stent of 0.6, 0.8, and 1.1 N, respectively. Overestimation of target vessel position by the same increments resulted in net forces of 0.3, 0.6, and 0.9 N, respectively. With the systolic model, underestimating target vessel position by 30° resulted in a 2.1-N maximum force on the stent, which potentially threatened the seal. In the longitudinal direction, underestimating target vessel separation by up to 10 mm resulted in a maximal force on the stent of 6.1 N, while overestimating target vessel separation did not result in any additional force on the stent due to fabric infolding. CONCLUSION: The magnitude of the forces generated solely due to mismatch between stent-graft design and native anatomy is modest and is unlikely to cause significant deformation of target vessel stents. Mismatch, however, may cause loss of seal.


Subject(s)
Aorta/surgery , Blood Vessel Prosthesis Implantation/instrumentation , Blood Vessel Prosthesis , Endovascular Procedures/instrumentation , Hemodynamics , Stents , Animals , Aorta/anatomy & histology , Biomechanical Phenomena , Blood Vessel Prosthesis Implantation/adverse effects , Elasticity , Endovascular Procedures/adverse effects , Friction , Materials Testing , Models, Animal , Prosthesis Design , Stress, Mechanical , Swine , Tensile Strength
13.
J Endovasc Ther ; 17(3): 402-7, 2010 Jun.
Article in English | MEDLINE | ID: mdl-20557184

ABSTRACT

PURPOSE: To evaluate intra- and interobserver agreement of target vessel measured from computed tomography (CT) scans with 2 measuring techniques used in planning fenestrated endovascular aneurysm repairs (FEVAR): multiplanar reconstruction (MPR) and semi-automated central lumen line (CLL). METHODS: CT datasets from 25 FEVAR patients were independently analyzed by 2 experienced observers according to a standardized protocol using the MPR (Leonardo workstation) and CLL (Aquarius workstation) techniques for each patient. Longitudinal vessel separation and clock-face position of the visceral aortic branches were measured twice. The repeatability coefficient (RC) was calculated using the Bland and Altman method to measure intra- and interobserver variability. Differences between groups were examined by paired t test (continuous data) or chi-squared analysis (categorical). Clock-face discrepancy >30 minutes was considered significant. RESULTS: Intraobserver mean difference was insignificant regardless of the measurement technique: the observer and workstation-specific RCs varied between 3.9 and 4.9 mm. Paired measurements differed by >3 mm in 8%. Interobserver variability was greater: observer and workstation-specific RC varied between 5.6 and 7.4 mm, with a tendency toward consistency using MPR, although the mean difference was insignificant. Paired measurements differed by >3 mm in 18%. There was no significant intraobserver variation in clock-face measurement, while interobserver variation was significant in 12% of measurements using the Aquarius workstation and 6% using the Leonardo workstation (p = 0.19). CONCLUSION: Subjective interpretation of anatomical landmarks is more important than measurement techniques or workstations used in the generation of measurement inconsistencies. Introduction of consensus regarding interpretation of anatomical detail and development of fenestrated stent-grafts tolerant of measurement errors might ameliorate some of the problems encountered in FEVAR.


Subject(s)
Aortic Aneurysm/diagnostic imaging , Aortic Aneurysm/surgery , Aortography/methods , Blood Vessel Prosthesis Implantation/instrumentation , Blood Vessel Prosthesis , Radiographic Image Interpretation, Computer-Assisted , Stents , Tomography, X-Ray Computed , Chi-Square Distribution , England , Humans , Observer Variation , Patient Selection , Predictive Value of Tests , Prosthesis Design , Reproducibility of Results
14.
J Endovasc Ther ; 17(1): 108-14, 2010 Feb.
Article in English | MEDLINE | ID: mdl-20199276

ABSTRACT

PURPOSE: To determine whether the introduction of a policy of adjunctive stent insertion based on preoperative CT assessment or completion angiography reduced the incidence of limb occlusion after stent-graft implantation for endovascular aneurysm repair (EVAR). METHODS: A tertiary referral unit's endovascular database was retrospectively interrogated to compare the incidence of endograft limb occlusion in Zenith grafts following the introduction of a policy of selective adjunctive stent insertion. Group A included 288 limbs at risk in 146 patients (134 men; mean age 74+/-8 years) treated prior to August 2005 in whom adjunctive stents were inserted on an ad hoc basis only. Group B included 293 limbs at risk in 149 patients (127 men; mean age 76+/-7 years) treated after this date in whom a more aggressive adjunctive stenting strategy was adopted. Kaplan-Meier analysis was employed to compare outcomes. RESULTS: In total, 295 patients underwent EVAR involving 581 iliac vessels, of which 11 (1.8%) occluded at a median of 24 months (0-27). Of 65 limbs extended into the external iliac segment, 5 (7.6%) subsequently occluded; in the remaining 516 limbs, there were 6 (1.1%) occlusions (p = 0.004). Across the study group, 38 (6.5%) adjunctive stents were deployed in limbs deemed at risk; 1 (2.6%) of these occluded. In the remaining 543 unstented limbs, 10 (1.8%) occlusions occurred (p = 0.15). There were 11 occlusions in group A, in which 5 (1.7%) adjunctive stents had been deployed, but none in group B, which had received 33 (11.2%) stents (p<0.0001). Kaplan-Meier survival curves identified primary patency rates at 36 months of 96% and 100%, respectively (p = 0.001). CONCLUSION: Adjunctive stenting significantly reduces the risk of postoperative stent-graft limb occlusion without obvious compromise to the aneurysm repair.


Subject(s)
Aortic Aneurysm, Abdominal/surgery , Blood Vessel Prosthesis Implantation/instrumentation , Blood Vessel Prosthesis , Graft Occlusion, Vascular/prevention & control , Iliac Artery/surgery , Stents , Aged , Aged, 80 and over , Aortic Aneurysm, Abdominal/diagnostic imaging , Aortography/methods , Blood Vessel Prosthesis Implantation/adverse effects , Chi-Square Distribution , Female , Graft Occlusion, Vascular/etiology , Humans , Iliac Artery/diagnostic imaging , Kaplan-Meier Estimate , Male , Middle Aged , Prosthesis Design , Retrospective Studies , Risk Assessment , Risk Factors , Time Factors , Tomography, X-Ray Computed , Treatment Outcome
15.
J Endovasc Ther ; 16(3): 373-9, 2009 Jun.
Article in English | MEDLINE | ID: mdl-19642797

ABSTRACT

PURPOSE: To determine if oblique angulation of the image intensifier is adequate to image the entire length of the common iliac artery during endovascular aneurysm repair or if additional caudal tilt is necessary. METHODS: Using a 3D workstation, the apparent level of the iliac bifurcation (distal limit of the stent-graft) was determined on computed tomographic angiography by profiling the common iliac segment in oblique angulation only and repeated with a combination of oblique angulation and caudal tilt. Two independent observers measured twice the apparent length of the iliac segment in both profiles for 50 patients according to a set protocol. Intra- and interobserver variability was calculated using the Bland and Altman method; the differences between the two different profiles were tested using paired t tests. RESULTS: Of the 50 CTA datasets reviewed, 2 datasets were excluded owing to extensive calcification of the iliac system that prevented accurate interpretation of the image. Of the 96 segments studied, the iliac segments appeared longer (better profiled) with a combination of caudal tilt and oblique angulation in 80%, with an average discrepancy of 9 mm for observer 1 (range -1 to +28) and 7 mm for observer 2 (0 to +26). The effect of caudal tilt was statistically significant for individual observers (p = 0.001 and 0.024, respectively). Forty-six percent of iliac segments measured by observer 1 and 35% by observer 2 showed that the addition of caudal tilt resulted in improved profiling by at least 10 mm. Although inter- and intraobserver variation was significant, the gain in apparent iliac length with the addition of caudal tilt was preserved. CONCLUSION: When profiled with oblique angulation alone, the location of the iliac bifurcation may appear higher than its true location, resulting in underutilization of the iliac segment by >10 mm in over a third of the patients. The problem is corrected by employing additional caudal tilt.


Subject(s)
Angiography , Aortic Aneurysm, Abdominal/diagnostic imaging , Aortic Aneurysm, Abdominal/surgery , Iliac Artery/diagnostic imaging , Imaging, Three-Dimensional , Tomography, X-Ray Computed , Angioplasty, Balloon , Blood Vessel Prosthesis Implantation , Humans , Observer Variation , Retrospective Studies , Stents
16.
Ann R Coll Surg Engl ; 90(7): 554-6, 2008 Oct.
Article in English | MEDLINE | ID: mdl-18831866

ABSTRACT

INTRODUCTION: The aim of this study was to review the information available to the public regarding the treatment of varicose veins on dedicated UK-based websites. PATIENTS AND METHODS: Websites were identified by using the Google search engine. All identified websites were examined, noting the range of treatments explained and their stated potential complications. Website ownership was also recorded. RESULTS: A total of 49 websites were identified, belonging to individual physicians (21), private clinics or groups (15), national institutions (4) and device/drug manufacturers (4). Five websites were simply redirecting portals and, hence, were excluded from further analysis. Treatment methods discussed were conventional surgery (32), endovenous laser [EVLA] and/or radiofrequency ablation [RFA] (31), and ultrasound-guided foam sclerotherapy [UGFS] (27). Only 19 websites (43%) discussed all treatment methods. Complications mentioned following surgery were: cutaneous nerve damage (56%), recurrence (56%), infection (53%), bleeding (41%) and venous thrombo-embolism (38%). Complications following EVLA/RFA were: cutaneous nerve damage (42%), recurrence (42%), venous thrombo-embolism (39%) and burns (35%). Complications following UGFS were: pigmentation (59%), venous thrombo-embolism (48%), ulceration (41%), recurrence (41%), allergy (26%) and visual disturbance (26%). CONCLUSIONS: Over 50% of the websites examined did not mention all the management methods now available for varicose veins. More importantly, the majority of the websites did not warn of the common complications of intervention. Currently, information on the Internet cannot be relied upon to supplement informed consent and may actually generate unrealistic patient expectations.


Subject(s)
Information Dissemination/methods , Internet/standards , Patient Education as Topic/standards , Varicose Veins/therapy , Humans , United Kingdom
17.
J Endovasc Ther ; 14(1): 59-61, 2007 Feb.
Article in English | MEDLINE | ID: mdl-17291146

ABSTRACT

PURPOSE: To report the recanalization of an occluded common iliac artery (CIA) to allow endovascular repair of an abdominal aortic aneurysm (AAA) with a bifurcated stent-graft. CASE REPORT: A 76-year-old man with a 75-mm infrarenal AAA and an occluded right CIA was successfully treated with a Zenith bifurcated stent-graft. The right CIA was recanalized allowing access, delivery, and deployment of the stent-graft. Follow-up computed tomography at 9 months showed no evidence of endoleak; maximum aneurysm diameter was reduced to 72 mm, and the iliac vessels were patent. CONCLUSION: Bifurcated stent-graft repair of an AAA can be performed following recanalization of an occluded CIA. This option may be preferable to an open repair or an aortomonoiliac stent-graft with extra-anatomical bypass in some patients. Long-term surveillance will be necessary to ensure freedom from iliac-related secondary intervention.


Subject(s)
Aortic Aneurysm, Abdominal/complications , Aortic Aneurysm, Abdominal/surgery , Arterial Occlusive Diseases/surgery , Blood Vessel Prosthesis Implantation , Iliac Artery/surgery , Stents , Aged , Aortic Aneurysm, Abdominal/diagnostic imaging , Arterial Occlusive Diseases/complications , Arterial Occlusive Diseases/diagnostic imaging , Humans , Iliac Artery/diagnostic imaging , Male , Radiography, Interventional , Tomography, X-Ray Computed , Treatment Outcome
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