Thrombogenicity of a New Injectable Biocompatible Elastomer for Aneurysm Exclusion,Compared to Expanded Polytetrafluoroethylene in a Human Ex Vivo Model

ObjectivesCustomized Aortic Repair (CAR) is a new concept for endovascular aortic aneurysm repair in which a non-polymerised elastomer is injected to fill the aneurysm sac around a balloon catheter. Amongst other variables, the thrombogenicity of the elastomer should be tested, before further clinical experiments can take place. The aim of this human ex vivo study was to measure the thrombogenicity of the elastomer and to compare it to expanded polytetrafluoroethylene (ePTFE).Design and materialsIn a validated ex vivo model, non-anticoagulated blood was drawn from the antecubital veins of 10 healthy donors with a 19-gauge needle. It was drawn through elastomer tubes and through ePTFE Gore-Tex vascular grafts, both 60 cm long and with an inner diameter of 3 mm.MethodsFibrinopeptide A (FPA) and P-selectin expression was measured in blood samples, collected at the end of the grafts. After the experiments, the deposition of platelets and fibrin onto the grafts was visualised by scanning electron microscopy.ResultsFor these graft types, a progressive increase in FPA production was observed in time. No significant difference was observed between the elastomer and ePTFE grafts (p > 0.05). No increase in P-selectin expression, and thereby no platelet activation, was observed in the perfusate of either grafts (p > 0.05). By scanning electron microscopy, numerous platelet aggregates were observed on the ePTFE grafts, whereas just a few adhered platelets and no aggregates were observed in the elastomer grafts.ConclusionsThe elastomer in its current formulation has a low thrombogenicity, comparable to ePTFE, making it an ideal substance for endovascular aneurysm sac filling. Further research should clarify the feasibility of CAR in vivo.     

Morphological and Mechanical Changes in Juxtarenal Aortic Segment and Aneurysm Before and After Open Surgical Repair of Abdominal Aortic Aneurysms

ObjectiveThe aim of study was to assess how the ultrastructure of the wall of aortic aneurysms, sac and neck influences aortic wall distensibility and proximal dilatation 2 years after open repair.MethodsBiopsies for electron microscopy were taken from aneurysmal sac and neck of 30 patients. Patients were assessed by computed tomography (CT) and ultrasound for aneurysm diameter and distensibility (M-mode ultrasonography).ResultsPostoperative CT of the aortic stump distinguished two groups. Group I (n = 11) with little enlargement, median 1 mm (1–3 mm) and group II (n = 19) with significant aortic enlargement, median 5.2 mm (4–12 mm). In group II, changes in elastic fibres in the aneurysm neck were comparable to, but as extreme as in the aneurysm sac. For group I, the distensibility of the aneurysmal sac was significantly lower than in the neck or at the renal arteries. For group II, the distensibility in both the neck and sac was significantly lower than at the juxtarenal segment (p = 0.01). The biopsies of group II patients showed the extensive degeneration of normal architecture, which was associated with altered wall distensibility in both the aneurysmal neck and sac.ConclusionsDisorganisation and destruction of normal aortic architecture at the ultrastructural level are associated with decreasing aortic distensibility. Low aortic neck distensibility is associated with proximal aortic dilatation at 2 years postoperatively.     

Simultaneous Operations for Combined Thoracic and Abdominal Aortic Aneurysms

Purpose. To assess whether simultaneous operations are appropriate for combined thoracic and abdominal aortic aneurysms.Methods. Simultaneous operations were performed for combined thoracic and abdominal aortic aneurysms in nine patients. The thoracic aortic aneurysm (TAA) was repaired first, followed by repair of the abdominal aortic aneurysm (AAA). Selective cerebral perfusion was used in eight patients, after the exception of one who underwent replacement of the ascending aorta under hypothermic circulatory arrest. The abdominal organs were perfused during distal anastomosis in surgery for Stanford type A aortic dissection or aortic arch aneurysm; via the femoral artery with an aortic balloon occlusion catheter in one patient, and via an occlusion catheter with a perfusion lumen in two patients.Results. All patients underwent planned simultaneous repair of the AAA. One of the patients who underwent simultaneous replacement of both the descending thoracic and abdominal aorta was left with paraplegia, and one patient died suddenly of massive hemoptysis and melena on the 29th postoperative day. Autopsy revealed that the bleeding had been caused by aorto-broncho-esophageal fistulae. The overall operative mortality was 11%.Conclusions. Simultaneous repair of combined TAA and AAA can be safely performed; however, the risk of paraplegia should be considered, especially with simultaneous repair of concomitant aneurysms of the descending thoracic and abdominal aorta.     

Tantalum-Dacron coknit stent for endovascular treatment of aortic aneurysms: A preliminary experimental study

Purpose: The purpose of this study was to evaluate the efficiency of intraluminal tantalum-Dacron coknit stents for the treatment of artificial aortic aneurysms in minipigs.Methods: Replacement of the infrarenal abdominal aorta with Dacron artificial aneurysm graft was performed in eight minipigs. After 2 weeks, balloon-expandable coknit stents were inserted through the femoral artery to the site of the artificial aneurysm in seven minipigs. One animal was kept as a control. Coknit stent/artificial aneurysm complexes were explanted at various intervals from 24 hours to 12 weeks and underwent gross examination, followed by scanning electron and light microscopy studies.Results: Aortography performed at the time of stent placement displayed immediate exclusion of the aneurysm in every case. In follow-up studies, all coknit stents remained patent until the time of explant. Scanning electron microscopy studies revealed apparent endothelialization of the entire coknit stent lumen at and after 6 weeks.Conclusion: Tantalum-Dacron coknit stents are efficient in the treatment of artificially created aneurysms in minipigs and facilitate the creation of an endothelialized new vascular wall. Clinical application of this coknit stent can be considered but necessitates retaining the same stent structure in diameters greater than 20 mm and the development of a suitable delivery system. (J VASC SURG 1994;19:698-706.)     

Pre-emptive nonselective perigraft aortic sac embolization with coils to prevent type II endoleak after endovascular aneurysm repair

ObjectivePre-emptive selective embolization of inferior mesenteric artery (IMA), lumbar arteries (LAs), and perigraft sac for prevention of type II endoleak (T2EL) has not been widely adopted. We perform pre-emptive nonselective perigraft aortic sac embolization with coils (PNPASEC) in patients at high risk for development of T2EL (four or more patent LAs, patent IMA ≥3 mm, and ≥30-mm aortic flow lumen). The goal of this study was to see whether PNPASEC decreases T2ELs requiring reinterventions.MethodsAll 266 patients undergoing elective endovascular aneurysm repair between September 1, 2007, and October 31, 2015, were retrospectively evaluated from a prospectively maintained database. Patients (N = 212; 211 men) with preoperative and postoperative contrast-enhanced computed tomography scans were included. Our PNPASEC technique involves leaving a wire in the sac after cannulation of the contralateral gate and inserting large (0.035-inch) coils into the sac after bifurcated graft deployment. T2EL and reintervention rates were compared between patients who underwent PNPASEC (group I) and those who met the criteria but did not have PNPASEC (group II) and those who did not meet the criteria (Group III).ResultsForty-seven (22.2%) patients were PNPASEC candidates and 165 (77.8%) patients (group III) were not. Among PNPASEC candidates, 16 (7.5%) underwent PNPASEC (group I) and 31 (14.6%) did not (group II). There were no significant differences between groups in terms of comorbidities, aneurysm size, and anatomic and neck characteristics. Mean number of patent LAs was similar between group I (4.5 ± 0.8) and group II (4.5 ± 0.9), which was significantly greater than in group III (1.9 ± 1.3; P < .001); 43.6% of group III patients had patent IMA. Mean follow-up was 44 ± 25 months. T2EL at 6 months was observed in 48.4% in group II, 3.0% in group III, and 6.3% in group I (P < .001). Sac diameter increase was seen in 38.7% in group II vs 6.1% in group III and 6.3% in group I (P < .001), with complete sac shrinkage in 23.3% in group II vs 23.8% in group III and 50.0% in group I (P = .09). T2EL-related interventions were performed in 29.0% in group II vs 1.2% in group III and 6.3% in group I (P < .001). Any endoleak at last follow-up was seen in 25.8% in group II vs 2.4% in group III and none in group I (P < .001).ConclusionsNonselective perigraft sac coil embolization in patients at high risk for T2EL (20% of patients undergoing endovascular aneurysm repair) is effective in preventing development of T2EL and is associated with decrease in sac size and reintervention rates.     

Early sac shrinkage is a good surrogate marker of durable success after endovascular aneurysm repair in Japanese patients

ObjectiveThe applicability of early sac shrinkage as a predictor of a low risk of late complications after endovascular aneurysm repair (EVAR) in Asian populations has not been validated. This study aimed to analyze early sac shrinkage and its relationship with late complications in Asian people using a Japanese multicenter database. We also assessed the impact of endoleaks.MethodsA retrospective analysis of 697 patients who had undergone EVAR of abdominal aortic aneurysms from 2008 to 2015 and were followed up for at least 1 year was conducted. Late complications were defined as any aneurysm-related events occurring >1 year after EVAR, including >5-mm aneurysm sac enlargements and any reinterventions performed. Endoleaks without any evidence of sac enlargement or a requirement for additional treatment were not considered late complications.ResultsEarly sac shrinkage, defined as a >5-mm-diameter decrease within 1 year of EVAR, occurred in 335 patients (48.1%); type I endoleaks (T1ELs) and isolated type II endoleaks (iT2ELs; type II endoleaks without evidence of other endoleaks) were observed in 4.0% and 29.4%, respectively. During the mean follow-up period of 45.5 months, 93 late complications (13.3%) occurred. Kaplan-Meier curve and log-rank analyses showed that early sac shrinkage was a significant predictor for a lower risk of late complications (P < .001). Multivariate analysis revealed that early sac shrinkage was independently associated with a lower risk of late complications (adjusted hazard ratio, 0.425; P = .004). Conversely, T1ELs and iT2ELs were positively associated with late complication (adjusted hazard ratio, 11.774 and 5.137, respectively; both P < .001). Subsequent multivariate analysis demonstrated that T1ELs and iT2ELs were negatively associated with early sac shrinkage (adjusted odds ratio, 0.102 and 0.285, respectively; both P < .001).ConclusionsEarly sac shrinkage was associated with a low risk of late complications in Asian people and may be a good surrogate marker of durable success after EVAR. T1ELs and iT2ELs were negatively associated with early sac shrinkage and positively associated with late complications. Along with the high incidence of iT2ELs observed, T2ELs may be an important condition to consider after EVAR in the Asian population.     

Palliation of Abdominal Aortic Aneurysms in the Endovascular Era

ObjectivesTo establish outcome of patients with abdominal aortic aneurysm (AAA) deemed unfit for repair.DesignRetrospective non-randomised study.Materials and methodsIdentification of males with >5.5 cm or females with >5.0 cm AAA turned down for elective repair between 01/01/2006–24/07/2009 from a prospective database. Comorbidities, reasons for non-intervention, aneurysm size, survival, use of CPEX (cardio-pulmonary exercise) testing and cause of death were analysed. Although well-established at the time, patients unfit for open operation were not considered for endovascular repair.ResultsSeventy two patients were unsuitable for AAA repair. Aneurysm size ranged from 5.3 cm to 12 cm. Functional status, comorbidity and patient preference determined decision to palliate. Sixty percent of patients were alive at study close. Aneurysm rupture was cause of death in 46%. CPEX testing was performed in 54%, whose mortality was 28%, vs. 54% in the non-CPEX group (P < 0.05).Median survival of patients with 5.1–6.0 cm AAA was 44 months and 11% died of rupture. Between 6.1 and 7.0 cm median survival was 26 months and 20% died of rupture. However, with >7 cm aneurysms, survival was 6 months and 43% ruptured.ConclusionUnder half the deaths in our comorbid cohort were due to rupture. However, decision to palliate may be revisited as risk-benefit ratio changes with aneurysm expansion.     

Mortality analysis of endovascular aneurysm sealing versus endovascular aneurysm repair

BackgroundEndovascular aneurysm sealing (EVAS), using the Nellix endovascular aneurysm sealing system, has been associated with high reintervention and migration rates. However, prior reports have suggested that EVAS might be related to a lower all-cause mortality compared with endovascular aneurysm repair (EVAR). In the present study, we examined the 5-year all-cause mortality trends after EVAS and EVAR.MethodsWe compared the 333 EVAS patients in the EVAS-1 Nellix U.S. investigational device exemption trial with 16,497 infrarenal EVAR controls from the Vascular Quality Initiative, treated between 2014 and 2016, after applying the exclusion criteria from the investigational device exemption trial (ie, hemodialysis, creatinine >2.0 mg/dL, rupture). As a secondary analysis, we stratified the patients by aneurysm diameter (<5.5 cm and ≥5.5 cm). We calculated propensity scores after adjusting for demographics, comorbidities, and anatomic characteristics and applied inverse probability weighting to compare the risk-adjusted long-term mortality using Kaplan-Meier and Cox regression analyses.ResultsAfter weighting, the EVAS group had experienced similar 5-year mortality compared with the controls from the Vascular Quality Initiative (EVAS vs EVAR, 18% vs 14%; hazard ratio [HR], 1.1; 95% confidence interval [CI], 0.71-1.7; P = .70). The subgroup analysis demonstrated that for patients with an aneurysm diameter of <5.5 cm, EVAS was associated with higher 5-year mortality compared with EVAR (19% vs 11%; HR, 2.4; 95% CI, 1.7-4.7; P = .013). In patients with an aneurysm diameter of ≥5.5 cm, EVAS was associated with lower mortality within the first 2 years (2-year mortality: HR, 0.29; 95% CI, 0.13-0.62; P = .002). However, compared with EVAR, EVAS was associated with higher mortality between 2 and 5 years (HR, 1.9; 95% CI, 1.2-3.0; P = .005), with no mortality difference at 5 years (18% vs 17%; HR, 0.82; 95% CI, 0.4-1.4; P = .46).ConclusionsWithin the overall population, EVAS was associated with similar 5-year mortality compared with EVAR. EVAS was associated with higher mortality for those with small aneurysms (<5.5 cm). For those with larger aneurysms (≥5.5 cm), EVAS was initially associated with lower mortality within the first 2 years, although this advantage was lost thereafter, with higher mortality after 2 years. Future studies are required to evaluate the specific causes of death and to elucidate the potential beneficial mechanism behind sac obliteration that leads to this potential initial survival benefit. This could help guide the development of future grafts with better proximal fixation and sealing that also incorporate sac obliteration.     

Patient-specific hemodynamic analysis of small internal carotid artery-ophthalmic artery aneurysms

BackgroundProphylactic treatment of unruptured small brain aneurysms is still controversial due to the low risk of rupture. Distinguishing which small aneurysms are at risk for rupture has become important for treatment. Previous studies have indicated a variety of hemodynamic properties that may influence aneurysm rupture. This study uses hemodynamic principles to evaluate these in the context of ruptured and unruptured small aneurysms in a single location.MethodsEight small internal carotid artery-ophthalmic artery (ICA-Oph) aneurysms (<10 mm) were selected from the University of California, Los Angeles, database. We analyzed rupture-related hemodynamic characteristics including flow patterns, wall shear stress (WSS), and flow impingement using previously developed patient-specific computational fluid dynamics software.ResultsMost ruptured aneurysms had complicated flow patterns in the aneurysm domes, but all of the unruptured cases showed a simple vortex. A reduction in flow velocity between the parent artery and the aneurysm sac was found in all the cases. Inside the aneurysms, the highest flow velocities were found either at the apex or neck. We also observed a trend of higher and more inhomogeneous WSS distribution within ruptured aneurysms (10.66 ± 5.99 Pa) in comparison with the unruptured ones (6.31 ± 6.47 Pa) (P < .01).ConclusionA comparison of hemodynamic properties between ruptured and unruptured small ICA-Oph aneurysms found that some hemodynamic properties vary between small aneurysms although they are similar in size and share the same anatomical location. In particular, WSS may be a useful hemodynamic factor for studying small aneurysm rupture.     

Factors Affecting the Regression of Surgically Replaced Abdominal Aortic Aneurysms

Purpose After endovascular therapy for abdominal aortic aneurysms, aneurysm sac shrinkage is considered to be the best marker of successful treatment. Such shrinkage, however, is infrequent and the rate of shrinkage is variable because of endoleaks. To investigate the factors that influence such contraction, the aneurysm sac regression after a conventional surgical replacement of the abdominal aortic aneurysm in an inclusion fashion was studied. Methods Abdominal aortic aneurysms that measured 5 cm in diameter or larger were studied in 35 patients who underwent surgical replacement. The aneurysm sac was closed anterior to the prosthesis. Of the 35 cases, 4 aneurysms were inflammatory and 10 had aneurysm wall circumferential calcification of greater than 40%. Computed tomography was performed preoperatively, and at 1 week, and then 3 months postoperatively. Results The maximum major and minor diameters of the aneurysmal sac decreased significantly from 1 week to 3 months after surgery (major diameter: 49 ± 12 to 32 ± 8 mm and minor diameter: 39 ± 10 to 26 ± 7 mm). In inflammatory aneurysms, the maximum major and minor diameters were significantly larger at 3 months postoperatively, in comparison to nonspecific aneurysms. Among the 31 patients with nonspecific aneurysms, the maximum major diameter was significantly larger in those with aneurysmal calcification of greater than 40% of its circumference at 3 months postoperatively, in comparison to noncalcified aneurysms. Conclusions The surgically repaired abdominal aortic aneurysm contraction tends to develop over 3 months, and inflammation, thickening, and calcification of the aneurysm wall are all considered to influence the regression of the aneurysm.     

Abdominal Aortic Aneurysm Rupture is not Associated with an Up-regulation of Inflammation within the Aneurysm Wall

BackgroundThe nature of the inflammatory change within ruptured AAA has not been extensively reported. The aim of this study was to compare the inflammatory response in non-ruptured and ruptured aneurysms with emphasis on the site of rupture.MethodsNon-rupture site biopsies were taken from the anterior aneurysm sac of non-ruptured (n = 31) and ruptured AAA (n = 20). In 12 ruptured AAA, a further biopsy was taken from the rupture site. Enzyme-linked immunosorbent assay was used to quantify IL-6, IL-1beta and TNF-alpha. Quantitative immunohistochemistry was undertaken for generic lymphocytes, T-cells, and B-cells.ResultsComparing biopsies in non-ruptured AAA versus a non-rupture site biopsy from ruptured AAA; there was no significant difference in IL-6, IL-1β, TNF-alpha, generic lymphocytes, T-cell or B-cell content. Comparing ruptured AAA – non-rupture site with rupture site; IL-6 and TNF-alpha were unchanged. By contrast IL-1β and lymphocytes were lower at the rupture site compared to the non-rupture site (IL-1β 1.39 ng/mg [0.97–2.29] vs. 1.92 ng/mg [1.46–2.57], p = 0.027; generic lymphocytes 2.89% [0.51–5.51] vs. 4.73% [2.27–12.40], p = 0.018; T-cells 0.28% [0.04–1.18] vs. 0.82% [0.40–1.36], p = 0.027; B-cells 0.16% [0.04–1.14] vs. 1.30% [0.32–5.40], p = 0.021).ConclusionsThese findings suggest the biological events leading to AAA rupture may not be dependent on an up-regulation in the inflammatory process.     

Performance of a Modified Rabbit Model of Abdominal Aortic Aneurysm Induced by Topical Application of Porcine Elastase: 5-Month Follow-up Study

ObjectivesTo modify the method for creating an abdominal aortic aneurysm in rabbits, and to study its performance.Materials and methodsA total of 24 New Zealand white rabbits were induced topically with 10 μl of porcine elastase (0, 0.1, 5 and 10 units μl^?1) to define the optimal concentration (groups A–D). Twelve aneurysms were induced with 10 units μl^?1 of 10 μl elastase to serve as a follow-up group (group E) to serve as a follow-up. A 1.5-cm aortic segment was isolated and induced with elastase solution for 30 min.ResultsAll animals in groups D and E developed AAA by day 5. Aneurysms in Group E were stable over 100 days. Partial destruction to disappearance of elastic lamellae and smooth muscle cells (SMCs) was seen in elastase-treated animals by day 5. Regenerated elastin and proliferated SMCs were present in group E. Matrix metalloproteinases 2 and 9 and RAM11 showed strong expression in group D, but expression decreased in group E after day 15.ConclusionsThe rabbit AAA model induced via topical application of porcine elastase at 10 units μl^?1 for 30 min appears easy and simple, with shorter induction and more rapid aortic dilation. The model is stable over 100 days and is useful to study the formation and progress of AAAs.     

Significance of Initial Aortic Aneurysm Pressure Sensor Readings Varies with Aortic Endograft Design

Background  

The differences in implantable pressure sensor aneurysm sac readings were compared following endovascular aneurysm repair (EVAR) among three different stent grafts.     

Aorto-enteric Fistula After Endovascular Abdominal Aortic Aneurysm Repair: Case Report and Review

ObjectiveTo report a case and to review previous publications regarding the rare complication of aorto-enteric fistula following endovascular aortic aneurysm repair.MethodsWe report the case of a stent-graft infection secondary to an aorto-enteric fistula 14 months after uncomplicated endovascular treatment of an infra-renal aortic aneurysm.ResultsThe surgical treatment involved the removal of the infected graft and in situ aortic replacement by cryopreserved allograft. There have been no major complications noted during the 2-month follow-up after surgery.ConclusionsAn aortojejunal fistula is a possible long-term complication of endovascular treatment of abdominal aortic aneurysm. An explantation of the infected graft and aortic replacement by a cryopreserved allograft is a valuable surgical treatment.     

Biomechanical Rupture Risk Assessment of Abdominal Aortic Aneurysms: Model Complexity versus Predictability of Finite Element Simulations

ObjectiveInvestigation of the predictability of finite element (FE) models regarding rupture risk assessment of abdominal aortic aneurysms (AAAs).Materials and materialsPeak wall stress (PWS) and peak wall rupture risk (PWRR) of ruptured (n = 20) and non-ruptured (n = 30) AAAs were predicted by four FE models of different complexities derived from computed tomography (CT) data. Two matching sub-groups of ruptured and non-ruptured aneurysms were used to investigate the usability of different FE models to discriminate amongst them.ResultsAll FE models exhibited a strong positive correlation between PWS and PWRR with the maximum diameter. FE models, which excluded the intra-luminal thrombus (ILT) failed to discriminate between ruptured and non-ruptured aneurysms. The predictability of all applied FE models was strengthened by including wall strength data, that is, computing the PWRR. The most sophisticated FE model applied in this study predicted PWS and PWRR 1.17 (p = 0.021) and 1.43 (p = 0.016) times higher in ruptured than diameter-matched non-ruptured aneurysms, respectively.ConclusionsPWRR reinforces PWS as a biomechanical rupture risk index. The ILT has a major impact on AAA biomechanics and rupture risk, and hence, needs to be considered in meaningful FE simulations. The applied FE models, however, could not explain rupture in all analysed aneurysms.     

Complications]

Transluminal endovascular stent grafts placement has recently been introduced as a promising alternative to surgical treatment of aortic aneurysms, but complications can occur. Mortality, aneurysm rupture, massive microembolization, paraplegia, endoleaks, and graft migration are significant problems associated with endovascular aneurysm repair. An endoleak, defined as persistence of blood flow within the aneurysm sac outside the lumen of the stent graft, is among the most common complications and is a major problem because it may permit aneurysm expansion and rupture. Endoleaks are caused by inadequate hemostatic sealing at the proximal or distal attachment site or by retrograde sac perfusion through patent aortic branch vessels; the reported incidence varies from 10-40%. In the treatment of thoracic aortic aneurysms, the occurrence of paraplegia is considered to be the Achilles heel of this technique, because reconstruction of intercostal arteries is impossible. Coverage of the intercostal artery, which is thought to be important for distal spinal cord blood supply, with stent grafts should be avoided. Although we consider this exciting new technique holds great promise for aortic aneurysm repair, further advances in device technology are necessary to minimize the risk of complications with this procedure.     

Pipeline flow diversion with adjunctive coil embolization for internal carotid artery aneurysms following an intradural component: results in 46 consecutive aneurysms from a Japanese single-center experience

In the treatment of an intracranial aneurysm with the flow diverter, the combined use of coil embolization can help promote subsequent progressive thrombosis within the aneurysm sac and reduce the risk of delayed aneurysm rupture. This study retrospectively reviewed outcomes of patients who had undergone the Pipeline Embolization Device (PED) with adjunctive coil embolization (PED/coil) at a single center to determine its safety and efficiency. Patients with internal carotid artery aneurysms following an intradural component were selected for PED/coil between 2015 and 2020. All patients were premedicated with dual antiplatelet therapy of aspirin plus clopidogrel or prasugrel. A minimal number of PEDs were deployed, with coils inserted using a stent-jail technique, avoiding dense packing. A total of 46 aneurysms (43 patients; median dome size, 11.6 mm; median neck width, 6.3 mm) were treated with PED/coil. The median volume embolization ratio was 14.8%. The degree of angiographic filling at the 6-month and latest angiography showed complete occlusion in 60.5% (26/43) and 70.5% (31/44), respectively. Small (<?10 mm) aneurysms achieved a higher complete occlusion rate in the early period; a lower cumulative incidence of aneurysm occlusion was observed in large and giant (≥?10 mm) aneurysms (P?=?.024). The median clinical follow-up was 22 months, and no aneurysm ruptures occurred. Favorable clinical outcomes were achieved, with permanent neurological morbidity of 4.7% and no mortality. PED/coil demonstrated a high angiographic occlusion rate at an early stage. Loosely packed coils are sufficient to obliterate aneurysms effectively.

     

Noninvasive measurement of aortic aneurysm sac tension with vibrometry

OBJECTIVE: Currently, the risk of aneurysm sac rupture after endovascular abdominal aortic aneurysm repair (EVAR) is estimated by using a group of anatomic variables. Available techniques for pressure monitoring include either direct measurement using catheter-based techniques or indirect measurement requiring implantation of a pressure sensor during aneurysm repair. None of these methods is without limitations. Radiation pressure, such as that generated by a modulated ultrasound (US) beam, can induce surface vibration at a distance. The velocity of the resulting surface waves depends on the tensile stress of the vibrated surface. By measuring the change in wave velocity, it is possible to detect the change in tensile stress and calculate the pressure through the vibrated surface. We tested this concept in an in vitro aneurysm model. METHODS: Rubber tubes and explanted porcine abdominal aortas were used to model an aneurysm sac. The surface of the model was vibrated with an amplitude-modulated US beam. The resulting motion was detected either by reflected laser light or by Doppler US. The phase of the propagating wave was measured to assess changes in velocity with different pressures. RESULTS: Increasing hydrostatic pressure in the rubber model correlated well with the cumulative phase shift (R(2) = 0.96-0.99; P < .0001). By using a pump to generate dynamic pressure (between 110 and 200 mm Hg), the cumulative phase shift correlated well with the square of the mean pressure (R(2) = 0.92; P < .0001); however, the correlation with pulse pressure was poor (24-36 mm Hg; r = 0.38; P < .02). In the porcine in vitro aortic sac model, the cumulative phase shift detected with both laser (r = 0.94-0.99; P < .0001) and Doppler (r = 0.96-0.99; P < .0001) correlated well with the aneurysm pressure. CONCLUSIONS: Application of vibrometry for noninvasive measurement of aortic aneurysm sac tension is feasible in an in vitro setting. The concept of vibrometry may be used to detect endotension noninvasively after EVAR. Vibrometry may also be used to estimate wall stress in native aneurysms, and it may predict the risk of aneurysm rupture. CLINICAL RELEVANCE: Vibrometry may offer a technique for completely noninvasive monitoring of aneurysm sac pressure after EVAR. Vibrometry is based on the following principles: radiation pressure, such as that generated by modulated US, can induce surface vibration at a distance; by measuring the change in wave velocity of vibration, it is possible to detect changes in tensile stress and calculate the pressure through the vibrated surface. We tested this concept in an in vitro model and found that application of vibrometry for noninvasive measurement of aortic aneurysm sac tension is feasible. Vibrometry may also be used to estimate wall stress in native aneurysms.     

Aortic neck dilation is not associated with adverse outcomes after fenestrated endovascular aneurysm repair

Objective

Long-term outcomes after endovascular aneurysm repair (EVAR) are threatened by aortic neck dilation (AND), graft migration, and subsequent endoleak development. The aim of this study was to determine the rate of AND and the occurrence of endoleaks after fenestrated EVAR of juxtarenal aneurysms with physician-modified endovascular grafts (PMEGs).

Treatment of Complex Aneurysmal Disease with Fenestrated and Branched Stent Grafts

ObjectivesTo describe our experience of treating juxtarenal (JRAAA's <4 mm neck) and thoracoabdominal aortic aneurysms (TAAA's) using fenestrated and branched stent graft technology.DesignProspective single centre experience.MethodsSince 2005, 29 fenestrated/branched procedures have been performed. 15 patients are studied with JRAAAs (n = 7; median neck length 0 mm (IQR 0–3.8)) or TAAAs (type I (n = 2), III (n = 2), IV (n = 4)). ASA grade III in 12/15. Maximum diameter of aneurysm 64 mm (56–74 mm). Aneurysms were excluded using covered stents or branches from the main body to patent visceral vessels (40 target vessels total). Pre-operative and follow-up CT scans (1, 3, and 12 months) were analysed by a single Vascular Interventional Radiologist.ResultsTechnical success for cannulation and stenting of target vessels was 98%. In-hospital mortality was 0%. One patient underwent conversion to open repair. Five had major complications including one paraplegia (type III TAAA) with subsequent recovery. Median length of stay was 9 days (IQR 7–18.75).At a median follow-up of 12 months (9–14), CT confirmed 36/37 (97%) target vessels remain patent. Sac size increased >5 mm in one patient only. There were no type I endoleaks, three type II endoleaks (one embolised, two under surveillance) and three type III endoleaks (two successfully treated percutaneously, one aneurysm ruptured 18 months after endografting and died).ConclusionIn selected patients, fenestrated and branched stents appear to be a safe and effective alternative to surgery for juxtarenal and thoracoabdominal aneurysms. The complication and mortality rates are low. The long-term durability of this procedure, however, needs to be proven.