Type I and III endoleaks following endovascular aneurysm repair (EVAR) can lead to catastrophic events that require major re-interventions. We reviewed our experience with aortic endograft ...re-interventions for type I and III endoleaks and other serious failures among different devices.
We retrospectively reviewed patients with a prior EVAR who underwent open conversion (OC) or major endovascular intervention (MEI) (re-lining, cuff/limb extension, parallel graft) for type I/III endoleaks at our institution from 2002 to 2019. Baseline characteristics, procedural details, re-interventions, and outcomes were collected.
A total of 229 patients (194 men) underwent re-interventions for type I and III endoleaks after EVAR (90 OC, 139 MEI) for devices implanted between 1997 and 2019. Average age at re-intervention was 78±8.5 years. A total of 135 (59%) were implanted at our institution, whereas 93 (41%) were referred. Median time to re-intervention was 4 years with 25% to 75% interquartile range (IQR) of 2.2-6.6 years. There was no significant difference in baseline demographics or type of re-interventions (OC/MEI) between device types. 42/229 (18%) presented with ruptured aneurysms, 20/229 (9%) were symptomatic, whereas the rest presented with asymptomatic radiographic findings. Type 1A endoleak was present in 146/229 (63.8%-72 with proximal migration), type IB in 46/229 (20.1%), type IIIA in 37/229 (16.6%), type IIIB in 15/229 (6.5%), and persistent aneurysm sac growth with no radiographic evidence of an endoleak in 6/229 (2.6%). Devices included most commercial products: AFX, Excluder, AneuRx, Ancure, Endurant, and Zenith. A smaller number of investigational devices accounted for the rest. Type 1A endoleak was the most common indication for re-intervention among all devices except for AFX and ancure devices, proximal migration was a frequent presentation with AneuRx. AFX devices more frequently presented with a type III and ancure devices more frequently presented with a type IB endoleak.
Serious failure modes after EVAR differ between endografts and occur throughout the follow-up period. This is important to guide targeted interrogation of surveillance studies and follow-up schedules, even for discontinued devices, as well as comparisons between various series and estimation of EVAR failure rates.
Surveillance after EVAR is critical for long term success of the repair, understanding of the differential modes of failure of every graft available is important in the longitudinal evaluation of these endografts. Equally important is the understanding of the modes of failure of legacy endografts that are no longer on the market but still being followed, in order to be able to tailor a surveillance regiemn and the evntual repair if needed.
Objective To identify patient-related and device-specific predictors of challenging and failed inferior vena cava (IVC) filter retrievals. Methods Retrospective single center review of consecutive ...retrievable IVC filters placed between 2004 and 2009. Retrieval was defined as challenging when it was unsuccessful owing to reported technical failure or when adjunctive endovascular maneuvers or access sites were recruited. Data regarding patient- and filter-specific information were collected. Logistic regression models were used to identify predictors of the reported outcomes. Statistical significance was set at p < .05. Results Four hundred and one patients underwent retrievable IVC filter placement—the majority indicated for prophylaxis (67%). Two hundred and fifty-nine retrievals were attempted and 237 filters were successfully retrieved (overall retrieval rate: 59.1%). Eleven out of 259 (4.2%) attempts were aborted owing to significant thrombus within the filter and 11 (4.2%) were technically unsuccessful. In 142 patients no attempt for filter retrieval was made—the major reason being physician oversight (44.3%). Thirty-eight out of 248 (15.3%) non-aborted filter retrievals were recorded as challenging. Failed retrievals were predicted by prolonged dwell time (96.9 ± 111.9 vs. 29.5 ± 25.1 days, odds ratio OR 1.034, 95% confidence interval CI 1.016–1.053, p < .001), therapeutic indication (OR 5.197, 95% CI 1.200–22.511, p = .028), and filter wall apposition (OR 11.857, 95% CI 2.069–67.968, p = .006). Challenging retrievals were predicted by dwell time (51.1 ± 69.8 vs. 29.1 ± 24.5 days, OR 1.017, 95% CI 1.005–1.029, p = .007), filter tilt (OR 2.607, 95% CI 1.045–6.508, p = .040) and filter wall apposition (OR 6.149, 95% CI 2.398–15.763, p = <.001). Conclusions Physician oversight leads to poor IVC filter retrieval rates. Retrievals can be challenging or fail when the dwell time is >50 days and >90 days, respectively, and when the filter hook apposes the caval wall. Filter tilt increases retrieval difficulty but not failure rates.
Purpose: Abdominal aortic aneurysm (AAA) rupture is believed to occur when the mechanical stress acting on the wall exceeds the strength of the wall tissue. Therefore, knowledge of the stress ...distribution in an intact AAA wall could be useful in assessing its risk of rupture. We developed a methodology to noninvasively estimate the in vivo wall stress distribution for actual AAAs on a patient-to-patient basis. Methods: Six patients with AAAs and one control patient with a nonaneurysmal aorta were the study subjects. Data from spiral computed tomography scans were used as a means of three-dimensionally reconstructing the in situ geometry of the intact AAAs and the control aorta. We used a nonlinear biomechanical model developed specifically for AAA wall tissue. By means of the finite element method, the stress distribution on the aortic wall of all subjects under systolic blood pressure was determined and studied. Results: In all the AAA cases, the wall stress was complexly distributed, with distinct regions of high and low stress. Peak wall stress among AAA patients varied from 29 N/cm2 to 45 N/cm2 and was found on the posterior surface in all cases studied. The wall stress on the nonaneurysmal aorta in the control subject was relatively low and uniformly distributed, with a peak wall stress of 12 N/cm2. AAA volume, rather than AAA diameter, was shown by means of statistical analysis to be a better indicator of high wall stresses and possibly rupture. Conclusion: The approach taken to estimate AAA wall stress distribution is completely noninvasive and does not require any additional involvement or expense by the AAA patient. We believe that this methodology may allow for the evaluation of an individual AAA's rupture risk on a more biophysically sound basis than the widely used 5-cm AAA diameter criterion. (J Vasc Surg 2000;31:760-9.)
Purpose: Our previous computer models suggested that intraluminal thrombus (ILT) within an abdominal aortic aneurysm (AAA) attenuates oxygen diffusion to the AAA wall, possibly causing localized ...hypoxia and contributing to wall weakening. The purpose of this work was to investigate this possibility. Methods: In one arm of this study, patients with AAA were placed in one of two groups: (1) those with an ILT of 4-mm or greater thickness on the anterior surface or (2) those with little (< 4 mm) or no ILT at this site. During surgical resection but before aortic cross-clamping, a needle-type polarographic partial pressure of oxygen (Po2) electrode was inserted into the wall of the exposed AAA, and the Po2 was measured. The probe was advanced, and measurements were made midway through the thrombus and in the lumen. Mural and mid-ILT Po2 measurements were normalized by the intraluminal Po2 measurement to account for patient variability. In the second arm of this study, two AAA wall specimens were obtained from two different sites of the same aneurysm at the time of surgical resection: group I specimens had thick adherent ILT, and group II specimens had thinner or no adherent ILT. Nonaneurysmal tissue was also obtained from the infrarenal aorta of organ donors. Specimens were subjected to histologic, immunohistochemical, and tensile strength analyses to provide data on degree of inflammation (% area inflammatory cells), neovascularization (number of capillaries per high-power field), and tensile strength (peak attainable load). Additional specimens were subjected to Western blotting and immunohistochemistry for qualitative evaluation of expression of the cellular hypoxia marker oxygen-regulated protein. Results: The Po2 measured within the AAA wall in group I (n = 4) and group II (n = 7) patients was 18% ± 9% luminal value versus 60% ± 6% (mean ± SEM; P <.01). The normalized Po2 within the ILT of group I patients was 39% ± 10% (P =.08 with respect to the group I wall value). Group I tissue specimens showed greater inflammation (P <.05) compared with both group II specimens and nonaneurysmal tissue: 2.9% ± 0.6% area (n = 7) versus 1.7% ± 0.3% area (n = 7) versus 0.2% ± 0.1% area (n = 3), respectively. We found similar differences for neovascularization (number of vessels/high-power field), but only group I versus control was significantly different (P <.05): 16.9 ± 1.6 (n = 7) vs 13.0 ± 2.3 (n = 7) vs 8.7 ± 2.0 (n = 3), respectively. Both Western blotting and immunohistochemistry results suggest that oxygen-regulated protein is more abundantly expressed in group I versus group II specimens. Tensile strength of group I specimens was significantly less (P <.05) than that for group II specimens: 138 ± 19 N/cm2 (n = 7) versus 216 ± 34 N/cm2 (n = 7), respectively. Conclusion: Our results suggest that localized hypoxia occurs in regions of thicker ILT in AAA. This may lead to increased, localized mural neovascularization and inflammation, as well as regional wall weakening. We conclude that ILT may play an important role in the pathology and natural history of AAA. (J Vasc Surg 2001;34:291-9.)
Acute type B aortic dissection is a life threatening disease process, which remains a clinical dilemma despite advances in technology, surgical technique and postoperative management. The variability ...of presenting symptoms, lack of a consensus on indications for treatment and differing opinions about the optimal timing for repair have added to the management confusion. Medical management has been the standard of care for acute uncomplicated type B dissection. Surgical repair and endovascular intervention are reserved for those who present with, or subsequently develop, dissection-related complications. Complicated dissections occur in 25% of cases and may include organ malperfusion, aortic rupture, periaortic hematoma, and uncontrolled hypertension. In the past decade thoracic endovascular aortic repair (TEVAR) has gained widespread acceptance as the modality of choice for the treatment of complicated type B dissection. This transition is representative of advances in technology, physician experience with aortic endografts and lower morbidity and mortality rates associated with TEVAR. The best medical therapy remains the standard of care for uncomplicated dissection, however this strategy fails to prevent long-term aortic-related morbidity and mortality. Recent data suggest that early TEVAR lowers aortic-related events and improves long-term aortic specific survival by covering the entry tear, promoting false lumen thrombosis and inducing aortic wall remodeling. The paucity of supporting data has created controversy surrounding the optimal treatment strategy for acute type B dissection. Nonetheless, recent healthcare trends show a paradigm shift towards the utilization of early TEVAR in acute type B dissection.
Accurate estimation of the wall stress distribution in an abdominal aortic aneurysm (AAA) may prove clinically useful by predicting when a particular aneurysm will rupture. Appropriate constitutive ...models for both the wall and the intraluminal thrombus (ILT) found in most AAA are necessary for this task. The purpose of this work was to determine the mechanical properties of ILT within AAA and to derive a more suitable constitutive model for this material. Uniaxial tensile testing was carried out on 50 specimens, including 14 longitudinally oriented and 14 circumferentially oriented specimens from the luminal region of the ILT, and 11 longitudinally oriented and 11 circumferentially oriented specimens from the medial region. A two-parameter, large-strain, hyperelastic constitutive model was developed and used to fit the uniaxial tensile testing data for determination of the material parameters. Maximum stiffness and strength were also determined from the data for each specimen. Scanning electron microscopy (SEM) was conducted to study the regional microstructural difference. Our results indicate that the microstructure of ILT differs between the luminal, medial, and abluminal regions, with the luminal region stronger and stiffer than the medial region. In all cases, the constitutive model fit the experimental data very well (R2>0.98). No significant difference was found for either of the two material parameters between longitudinal and circumferential directions, but a significant difference in material parameters, stiffness, and strength between the laminal and medial regions was determined (p<0.01). Therefore, our results suggest that ILT is an inhomogeneous and possibly isotropic material. The two-parameter, hyperelastic, isotropic, incompressible material model derived here for ILT can be easily incorporated into finite element models for simulation of wall stress distribution in AAA.
The Ancure endografting system (Guidant Cardiac and Vascular Division, Menlo Park, Calif) features a unibody, nonsupported woven polyester graft designed to treat abdominal aortic aneurysms. It is ...constructed in tube, bifurcated, and aortoiliac configurations. The attachment system consists of a frame with four independent V-shaped double hooks that penetrate the arterial wall for fixation. There are separate attachment systems at the proximal and distal ends of the endoprosthesis. In September 1999, the Food and Drug Administration (FDA) approved the tube and bifurcated devices for general use. The aortoiliac device is under present consideration of the FDA. Phase II and III clinical trials of the system enrolled over 870 patients from the end of 1995 to the summer of 1999. The device was deployed successfully in 90% to 96% of cases, depending on the configuration and the phase of the trial. Mortality rates were similar to those of concurrent open surgical control rates, but serious morbidity was reduced. Long-term follow-up of the bifurcated group from phase II showed only one migration and no ruptures. Aneurysm size reduction in this group was noted in 51.3% of patients at 1 year and 68.5% at 2 years. In the same subset, type I endoleaks were noted in 2.7% at 1 year and 1.3% at 2 years. All postoperative imaging studies were reviewed by a core laboratory facility. The advantages of the ancure system include solid fixation, flexibility in accommodating morphologic changes, and excellent long-term clinical performance. The disadvantages include a large introducer system and the potential for limb obstruction by compression or angulation. However, limb compromise responds well to intraluminal stenting. The expected FDA approval of the aortoiliac device and a larger variety of graft sizes should expand the number of patients who can be treated with this system. (J Vasc Surg 2001;33:S129-34.)
In-stent restenosis is the primary failure mode of endovascular treatment of occlusive disease in the femeropopliteal segment. Cryoplasty has been proposed to reduce intimal hyperplasia through ...induction of apoptosis. We sought to evaluate the efficacy of cryoplasty for treatment of in-stent restenosis compared to conventional balloon angioplasty (CBA). After IRB approval, a retrospective record review was performed of reinterventions for in-stent restenosis by a single vascular surgery group at a university hospital. Reinterventions involving cryoplasty and CBA were evaluated at 1, 3, 6 and 12 months after intervention with duplex imaging to identify significant recurrent stenosis utilizing established velocity criteria. Data collected included basic demographic information and comorbidities as well as time to restenosis. Statistical analysis was performed using Kaplan–Meier survival curves with the log rank test, Wilcoxon rank test, and Cox proportional hazards models. From December 2004 to November 2007, 76 reinterventions were performed using CBA (n = 39) or cryoplasty (n = 37) for in-stent restenosis without placement of additional stents. Periprocedural technical success (>30% residual stenosis) was 100% for both groups, with no complications. The two cohorts were statistically similar in mean age, gender, comorbidities, tobacco use and use of statins, aspirin and Plavix. However, the mean lesion length was significantly longer in the cryoplasty cohort (CBA: 140.9 mm, Cyro: 191.7 mm; P = 0.032). The mean time to recurrent stenosis or need for additional secondary intervention was significantly shorter for the cyroplasty cohort than for the CBA, 4.09 and 10.79 months, respectively (P = .0001). Recurrent stenosis-free survival was significantly lower in the cyroplasty cohort at 3 months (CBA: 96.9%, Cyro: 88.9%) and 6 months (CBA: 84.0%, Cyro: 43.8%; P = .0089). Cyroplasty as a modality for treatment of in-stent stenosis in the femoropopliteal segment offers no benefit over CBA.
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