Time-related alterations in shape, position, and structure of self-expanding, modular aortic stent-grafts: a 4-year single-center follow-up

A Case of Endovascular Treatment of Severe Graft Limb Kinking after Endovascular Abdominal Aortic Aneurysm Repair

Endovascular aneurysm repair (EVAR) has been recommended as an alternative to open aneurysm repair. The risk of severe perioperative complications is lower than that in open surgical repair; however, late complications are more likely. After EVAR, regular yearly surveillance by duplex ultrasonography or computed tomography is recommended. We report the case of a 67-year-old man with a severely kinked left iliac branch of the stent graft 10 years after EVAR. He had not undergone regular follow-up during the last 4 years. We realigned the endograft kink by percutaneous transluminal angioplasty.

Acute Traumatic Thoracic Aortic Injury: Considerations and Reflections on the Endovascular Aneurysm Repair

Traumatic rupture of the thoracic aorta is a life-threatening lesion and it occurs in 10 to 30% of fatalities from blunt thoracic trauma and is the second most common cause of death after head injury. Immediate surgery is often characterized by a high mortality and morbidity rate. Delayed repair of traumatic aortic injuries has significant survival benefits and a much lower mortality rate compared with early open repair. Despite developments in operative techniques, there still remains considerable operative mortality and morbidity associated with a surgical approach even if delayed. Endovascular stent grafts for the thoracic aorta represents an alternative to the conventional approach for traumatic aortic rupture. Because of the lower invasivity avoiding thoracotomy and use of heparin, endovascular repair can be applied in acute patients without the risk of destabilizing pulmonary, head or abdominal traumatic lesions. However, despite the good deal of convincing evidence for endovascular treatment for thoracic aortic diseases and for traumatic aortic injuries as a valid and efficacious alternative to surgery, several reports show a variety of late complications of thoracic endografts especially for first-generation stent-grafts. In light of this, is the endovascular treatment really safe, efficacious and free from complications in the long term? This manuscript aims to offer a moment of reflection on this important chapter of aortic pathology.

The effect of vacuum freeze-drying and radiation on allogeneic aorta grafts

Vacuum freeze-dried aorta is a satisfactory material for blood vessel grafting. Previous studies have focused on immunity, however, vacuum freeze-drying is a complicated process of heat and mass transfer, and adopting a programmed cooling process may more completely preserve the mechanical properties of the blood vessels. Irradiation, as a method of removing pathogens, lowers the antigenic activity of the blood vessels. In our study, vacuum freeze-drying combined with radiation was used as a treatment for porcine aorta prior to grafting, aimed at deactivating endogenous retrovirus, shielding masses of endothelial cells and lowering the immunogenicity of the blood vessels. As for the mechanical properties, compared with normal aorta, the maximum axial tensile stress (ATS) decreased by 20%, the maximum circumferential tensile stress (CTS) increased by 30% and the maximum puncture stress (PT) decreased by 20%. Our results revealed that 2 months after of grafting, the host cells had migrated into the graft tissue and propagated to initiate endothelialization, the inflammatory reaction was abated and the PT had returned to normal levels.

Challenging endovascular repair of a critical aortic endograft migration and massive type III endoleak

Type III endoleaks, which may be caused by endograft disconnection, pose the risk of aneurysm enlargement and rupture because the pressure in the aneurysmatic sac tends to equal the systolic aortic pressure. We report the endovascular treatment of a critical dislocation of two thoracic aorta endografts with subsequent massive aneurysmatic pressurization of the aneurysmatic sac, which led to its impending rupture. The aberrant migration of both endografts required a combined, right humeral and left femoral, approach to capture the guide wire with an endovascular snare in the aneurismal sac. Several maneuvers were necessary to avoid trapping the guide wire in one of the bare stents. A final 'push-pull' technique was used to loop the wire and advance the new endografts into the ascending aorta to achieve a correct exclusion of the endoleaks. The patient suffered a perioperative stroke which could have been a complication of wire manipulation in the highly atheromatous aortic arch. A review of several maneuvers which may be taken to prevent these complications has been performed.

Effect of curvature on displacement forces acting on aortic endografts: a 3-dimensional computational analysis

PURPOSE

To determine the effect of curvature on the magnitude and direction of displacement forces acting on aortic endografts in 3-dimensional (3D) computational models.

METHOD

A 3D computer model was constructed based on magnetic resonance angiography data from a patient with an infrarenal aortic aneurysm. Computational fluid dynamics tools were used to simulate realistic flow and pressure conditions of the patient. An aortic endograft was deployed in the model, and the displacement forces acting on the endograft were calculated and expressed in Newtons (N). Additional models were created to determine the effects of reducing endograft curvature, neck angulation, and iliac angulation on displacement forces.

RESULTS

The aortic endograft had a curved configuration as a result of the patient's anatomy, with curvature in the anterolateral direction. Total displacement force acting on the endograft was 5.0 N, with 28% of the force in a downward (caudal) direction and 72% of the force in a sideways (anterolateral) direction. Elimination of endograft curvature (planar graft configuration) reduced total displacement force to 0.8 N, with the largest component of force (70%) acting in the sideways direction. Straightening the aortic neck in the curved endograft configuration reduced the total force acting on the endograft to 4.2 N, with a reduction of the sideways component to 55% of the total force. Straightening the iliac limbs of the endograft reduced the total force acting on the endograft to 2.1 N but increased the sideways component to 91% of the total force.

CONCLUSION

The largest component of the force acting on the aortic endograft is in the sideways direction, with respect to the blood flow, rather than in the downward (caudal) direction as is commonly assumed. Increased curvature of the aortic endograft increases the magnitude of the sideways displacement force. The degree of angulation of the proximal and distal ends of the endograft influence the magnitude and direction of displacement force. These factors may have a significant influence on the propensity of endografts to migrate in vivo.

Emergency endovascular treatment of sac rupture for type IIIa endoleak in thoracic aortic aneurysm previously excluded with endovascular repair

Elective endovascular treatment of thoracic aortic pathology has been applied in a variety of conditions. The complications of thoracic aortic stenting are also well recognized. Endoleak after endovascular repair of thoracic aortic aneurysms is the most frequent complication; among them, type III is the least frequent. Endovascular treatment of type III endoleak is generally performed under elective conditions; less frequently, in emergency. We report a successful emergency endovascular management of post-thoracic endovascular repair for thoracic aortic aneurysm rupture due to type IIIa endoleak.

Endovascular device design in the future: transformation from trial and error to computational design

Endovascular devices have been designed by trial and error, with bench and animal testing followed by human clinical trials to determine whether the devices are safe and effective. Despite remarkable advances over the past 15 years, there are persistent concerns regarding the long-term durability of endovascular devices. This may be due to deficiencies in device design, which has lagged behind other industries in adopting computational methods that are now routinely used to design, develop, and test new aircraft and automobiles. Similar computational design and failure mode simulations that evaluate performance under stress conditions have not been widely applied in the development of endovascular devices. Advances in medical imaging and computational modeling now allow simulation of physiological conditions in patient-specific 3-dimensional vascular models, which can provide a framework to design and test the next generation of endovascular devices. This modeling will allow the prospective design of devices that can withstand the force variations in the cardiovascular system that occur during bending, coughing, and varying degrees of exercise, as well as the extremes encountered during sudden impact in contact sports. Utilization of computational design methodology that takes into consideration the physiology of the cardiovascular system will improve future endovascular devices so that they are safer and more effective and durable.

Late Type III endoleak and graft failure of an Ancure stent-graft

The authors report a case of a delayed type IIIb endoleak with sac expansion 6 years after an endovascular repair of an abdominal aortic aneurysm with an Ancure bifurcated stent-graft. The presumed etiology of the leak was secondary to erosion of the main body graft material by metal stents placed within the graft to correct kinking of the iliac limbs at the index operation. The endoleak was successfully treated by endovascular means with an aortouni-iliac device, contralateral iliac plug followed by a femoral-to-femoral bypass graft.

Renewed endovascular repair for recurrent acute abdominal aortic aneurysm

The aim of the study was to describe the successful endovascular management of a patient who was admitted urgently with a second episode of acute abdominal aortic aneurysm (AAA) 30 months after emergency endovascular abdominal aortic aneurysm repair (eEVAR) for a ruptured AAA. The patient, an 84 year-old male physician, presented with severe acute abdominal and back pain. Contrast-enhanced computer tomography scanning showed type III endoleak owing to complete disconnection of both graft limbs and the prosthetic main body. Treatment consisted of acute stent-grafting with two bridging stent-grafts to seal the endoleak and reline the graft. The patient is alive and well 6 months postoperatively. This case indicates the need for follow-up after eEVAR, but also that complications can be managed endovascularly.

Mid-Term Comparison of Bifurcated Modular Endograft Versus Aorto-Uni-Iliac Endograft in Patients with Abdominal Aortic Aneurysm

The aim of this prospective study was to compare the outcome of the Talent bifurcated endograft versus the Endofit aorto-uni-iliac endograft in the short-term and mid-term. Between March 2000 and December 2003, 86 patients were treated with the Talent bifurcated endograft (group A) and 21 with the Endofit aorto-uni-iliac endograft (group B) in the same institute by the same surgical team. All patients followed a prospective protocol of preoperative evaluation and postoperative follow-up. We compared groups A and B in terms of perioperative mortality and morbidity, mid-term endoleak rate, mid-term success rate, and mid-term survival. The perioperative mortality for group A was 1.63%, while that for group B was 0% (P = 0.62). The endoleak rate for group A was 4.65%, and that for group B was 14.29% (P = 0.135). The mid-term success rate was 96.5% for group A and 100% for group B (P = 0.386). There was no significant difference in outcome between the patients treated with the Talent and those treated with the Endofit endoprosthesis. Treating abdominal aortic aneurysms with aorto-uni-iliac endoprosthesis is as safe and effective as treating them with bifurcated endografts.

Methods for Three-Dimensional Geometric Characterization of the Arterial Vasculature

Complex vascular anatomy often affects endovascular procedural outcome. Accurate quantitative assessment of three-dimensional (3D) in-vivo arterial morphology is therefore vital for endovascular device design, and preoperative planning of percutaneous interventions. The aim of this work was to establish geometric parameters describing arterial branch origin, trajectory, and vessel curvature in 3D space that eliminate the errors implicit in planar measurements. 3D branching parameters at visceral and aortic bifurcation sites, as well as arterial tortuosity were determined from vessel centerlines derived from magnetic resonance angiography data for three subjects. Errors in coronal measurements of 3D branching angles for the right and left renal arteries were 3.1 +/- 3.4 degrees and 7.5 +/- 3.7 degrees , respectively. Distortion of the anterior visceral branching angles from sagittal measurements was less pronounced. Asymmetry in branching and planarity of the common iliac arteries was observed at aortic bifurcations. The renal arteries possessed considerably greater 3D curvature than the abdominal aorta and common iliac vessels with mean average values of 0.114 +/- 0.015 and 0.070 +/- 0.019 mm(-1) for the left and right, respectively. In conclusion, planar projections misrepresented branch trajectory, vessel length, and tortuosity proving the importance of 3D geometric characterization for possible applications in planning of endovascular interventional procedures and providing parameters for endovascular device design.

Beyond the aortic bifurcation: Branched endovascular grafts for thoracoabdominal and aortoiliac aneurysms

OBJECTIVES

To evaluate the use of novel technology to treat complex aortic aneurysms involving branches that provide critical end-organ blood supply.

METHODS

A prospective study was conducted in patients with thoracoabdominal, suprarenal, or common iliac aneurysms (TAA, SRA, or CIA) at high risk for open surgical repair. An endovascular graft using the Zenith platform was customized to fit patient anatomy (TAA or SRA) and combined with Jomed balloon-expandable stent-grafts. Prefabricated hypogastric branches were used with a Zenith abdominal aortic aneurysm (AAA) or Fluency self-expanding fenestrated device in conjunction with a self-expanding stent-graft. Analyses were conducted in accordance with the endovascular aneurysm reporting standards document. Follow-up studies occurred at discharge, 1, 6, and 12 months, and included computed tomography and duplex ultrasound scans, and flat plate radiography.

RESULTS

Fifty patients were treated (9 TAA, 20 SRA, 21 CIA). The mean aneurysm size was 7.6 cm (TAA), 7.2 cm (SRA), and 6.1 cm AAA size associated with a mean CIA size of 3.8 cm. Bilateral CIA aneurysms were present in 86% (18/21) of patients with CIA aneurysms. Perioperative mortality was 2% (1/50) and resulted from a myocardial infarction after a planned conduit and iliac endarterectomy required for device access. Five late deaths occurred (2 TAA, 2 SRA, 1 CIA), three of which (2 TAA, 1 SRA) were aneurysm related. Failure to access internal iliac arteries occurred in three cases, and two late hypogastric branch thromboses occurred. No visceral branches were lost acutely or occluded during follow-up. Sac shrinkage (>5 mm) was noted in 65% of patients at 6 months and in all patients (10/10) by 12 months. There were no ruptures or conversions, but nine patients required secondary interventions.

CONCLUSIONS

Branch vessel technology has made it technically feasible to preserve critical end-organ perfusion in the setting of CIA, SRA, and TAA aneurysms. The relatively low acute mortality rate and lack of short-term branch vessel loss are encouraging and merit further investigation. These advances have the potential to markedly diminish the complications associated with conventional management of complex aneurysms.

In Vitro Analysis of Modular Aortic Stent-Graft Failure

PURPOSE

To investigate the theoretical forces involved in and the nature of fixation between the modular components of a variety of aortic stent-grafts.

METHODS

An in vitro study of 6 aortic stent-grafts was performed using a tensometer. The modular stent-graft components were distracted until the iliac limb was completely separated from the main body. Tests were repeated at least 6 times for each stent-graft.

RESULTS

The maximum pullout force was 36.0 N using the Fortron stent-graft, which resulted in stent-graft disintegration. The maximum median forces of the other stent-grafts were 23.7 N (19.9-31.2) for the Aorfix, 7.3 N (6.9-7.6) for the AneuRx, 7.0 N (6.8-7.1) for the Zenith BiFab, 5.4 N (5.0-6.5) for the Talent, and 2.4 N (2.2-2.4) for the Vanguard II CONCLUSION: The results of this in vitro study suggest that current forms of iliac limb fixation in modular aortic stent-grafts are adequate provided the components are deployed with sufficient overlap. However, for many of the stent-grafts tested, the safety margin was small.

Long-term outcome after Talent endograft implantation for aneurysms of the abdominal aorta: A multicenter retrospective study

BACKGROUND

The development of newer-generation endografts for the endovascular treatment of abdominal aortic aneurysms has resulted in considerable improvements in clinical performance. However, long-term outcome data are still scarce. To assess long-term clinical and radiographic outcomes after use of the Talent stent graft, a retrospective analysis was performed that was based on 165 patients treated with this endograft in Germany between October 1996 and December 1998.

METHODS

Data were collected according to the recommendation of the ad hoc committee for standardized reporting practices in vascular surgery and were evaluated statistically by using univariate and multivariate analyses.

RESULTS

A total of 165 patients were treated with a Talent endograft in 9 German centers before December 31, 1998. Most were asymptomatic (94.5%), male (97.6%), and treated with a bifurcated graft (86.7%). Two patients (1.2%) died within 30 days, and 28 (17%) died during the follow-up period. The cause of death was aneurysm rupture in one case. Survival was 95.4% +/- 1.7% at 1 year, 89% +/- 2.6% at 2 years, 78.1% +/- 3.6% at 5 years, and 76.2% +/- 4.1% at 7 years. Patients classified as American Society of Anesthesiologists grade IV had a significantly lower survival rate (24.9%) than those classified as American Society of Anesthesiologists grade II and III (91.9% and 77.3%). During a mean follow-up period of 53.2 +/- 20.1 months (range, 1-84 months), 47 secondary procedures were performed in 31 patients (18.8%). Kaplan-Meier estimates showed a freedom from secondary intervention of 94.7% +/- 1.8%, 81.7% +/- 3.3%, and 77.4% +/- 3.6% at 1, 3, and 7 years, respectively. The reason for secondary treatment was endograft thrombosis in 10 patients (6.1%), persisting primary endoleak in 9 (5.5%), late secondary endoleak in 6 (3.6%), graft migration in 3 (1.8%), aneurysm rupture in 2 (1.2%), and graft infection in 1 (0.6%). Device migration (> or =10 mm) occurred in seven patients (4.2%). Other graft changes, such as graft kinking (n = 4; 2.4%), fracture of metallic stents (n = 2; 1.2%), erosion of the longitudinal bar (n = 2; 1.2%), or modular component separation (n = 1; 0.6%), were rare. Follow-up computed tomographic imaging revealed a decrease of the maximum aneurysm sac diameter (>5 mm) in 106 (64.2%) patients and an increase in 14 (8.5%) patients. The mean aneurysm diameter significantly decreased (P < .001). Of the factors recorded at baseline, only endoleaks showed a significant correlation with the risk of aneurysm increase during follow-up (P < .001). Adverse anatomy (neck diameter >28 mm, neck length <15 mm, and '5 patent aortic branches) did not adversely influence the aneurysm shrinkage rate, the risk for a secondary procedure, or the clinical success rate. A significantly higher rate of clinical success (P < .05) was observed in patients older than 65 years of age.

CONCLUSIONS

Implantation of the Talent endograft device is a safe and effective alternative to open surgery for exclusion of abdominal aortic aneurysm. In comparison with first-generation grafts, the device showed superior durability for as long as 5 to 7 years after implantation. Even if prototypes of the Talent device were implanted in this study, the graft was also successfully used in most patients, even in those with adverse anatomy. Because improvements of the endograft have been made to address connecting bar breaks, a lower incidence of graft limb occlusion can be expected in the future.

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.

Risk-Adjusted Outcome Analysis of Endovascular Abdominal Aortic Aneurysm Repair in a Large Population:How Do Stent-Grafts Compare?

PURPOSE

To compare differences in the applicability and incidence of postoperative adverse events among stent-grafts used for repair of infrarenal aortic aneurysms.

METHODS

An analysis of 6787 patients from the EUROSTAR Registry database was conducted to compare aneurysm morphological features, patient characteristics, and postoperative events for the AneuRx, EVT/Ancure, Excluder, Stentor, Talent, and Zenith devices versus the Vanguard device (control) and each other. Annual incidence rates of complications were determined, and risks were compared using the Cox proportional hazards analysis.

RESULTS

The annual incidence rates were: device-related endoleak (types I and III) 6% (range 4%-10%), type II endoleak 5% (range 0.3%-11%), migration 3% (range 0.5%-5%), kinking 2% (range 1%-5%), occlusion 3% (range 1%-5%), rupture 0.5% (range 0%-1%), and all-cause mortality 7% (range 5%-8%). After adjustment for factors influencing outcome, AneuRx, Excluder, Talent, and Zenith devices were associated with a lower risk of migration, kinking, occlusion, and secondary intervention compared to the Vanguard device. Significant increased risk for conversion (EVT/Ancure) and reduced risk of aneurysm rupture (AneuRx and Zenith) and all-cause mortality (Excluder) were found compared to the Vanguard device.

CONCLUSIONS

Significant differences exist between stent-grafts of different labels in terms of applicability and complications during intermediate to long-term follow-up. Since each stent-graft has its drawbacks, no single label can be identified as the best. It is reassuring that developments in stent-grafts indeed result in better performance than the early stent-grafts. However, a single device incorporating all the perceived improvements should still be pursued.

Flow Visualization in a Model of a Bifurcated Stent-Graft

PURPOSE

To use an in vitro flow model to investigate the flow patterns in a bifurcated stent-graft for abdominal aortic aneurysm (AAA) repair.

METHODS

Experiments were performed in an in vitro test rig incorporating a simplified non-planar model of an AAA. A two-component bifurcated device consisting of a stent structure and transparent polyurethane "graft" was deployed in the AAA model. Using a blood analogue fluid, a pulsatile blood flow waveform simulating resting flow condition was produced by means of a piston pump system. Flow patterns in the lateral and anteroposterior planes of the stent-graft were recorded and analyzed using flow visualization techniques.

RESULTS

The flow patterns within the stent-graft were complex and influenced by the geometry of the stent-graft itself, as well as that of the aortic neck and iliac vessels. Regions of flow separation, low velocity and stagnation, and slow oscillatory flow near the walls were seen in the main body of the stent-graft. Constriction at the stump in the contralateral limb resulted in flow disturbances and flow separation. Kinking at the junctions of stent segments and folding of the graft compounded these complex flow structures.

CONCLUSIONS

The flow structures within stent-grafts are complex, with features that may predispose to thrombus formation. Arterial geometry, including aortic neck angulation and iliac vessel tortuosity, and the design of the stent-graft are factors that influence hemodynamics and may impact the performance of aortic stent-grafts.

Static mechanical properties of custom-made aortic endografts

Several cases of delayed aortic rupture after endovascular aneurysm repair have been attributed to in vivo endograft fatigue. Such complications could involve damage to structural components during introduction. The purpose of this study was to compare forces applied during introduction to forces needed to damage the endograft. Testing was carried out on the custom-made endograft (CMEG) that has been in almost exclusive use at our center since 1996. Findings showed that the force applied during introduction was less than the force necessary to damage the endograft. No alteration in the mechanical properties of the CMEG was observed immediately after implantation.

Endovascular Treatment of Proximal Bilateral Iliac Limb Dislocation and Kinking following Endovascular Abdominal Aortic Aneurysm Repair

We report the case of a 69-year-old man with a late type 1b endoleak due to proximal migration of both iliac limbs 5 years after endovascular repair of an abdominal aortic aneurysm. The endovascular method used to correct bilaterally this condition is described. Final angiographic control shows patency of the stent-graft without signs of endoleak.

An Investigation Into the Cause of Distal Endoleaks: Role of Displacement Force on the Distal End of a Stent-Graft

PURPOSE

To investigate if the forces developed by pulsatile flow on a stent-graft and dimensional changes of the graft material might contribute to distal endoleak and stent-graft kinking.

METHODS

An in vitro experimental model was used to measure the peak displacement force developed by pulsatile flow pressure on the distal end of a stent-graft. Polytetrafluoroethylene (PTFE) graft material (110 mm long, 22 mm in diameter) was evaluated in a flow circuit, with water as the circulating liquid. In addition, the effect of internal pressure on PTFE graft dimensions was measured under nonpulsatile conditions in 3 configurations (1 bifurcated and 2 straight).

RESULTS

Pressure in the PTFE graft did not cause a change in graft diameter but did increase the length of the graft. The mean load required to prevent retrograde displacement was 208.5+/-2.5 g. Peak retrograde displacement force developed on the distal end of the stent-graft by the pressure of pulsatile flow was strongly associated with the systolic phase of the cardiac cycle.

CONCLUSIONS

The distal end of the stent-graft is subject to a retrograde displacement force by the pressure of pulsatile arterial flow. In addition, pressure inside the PTFE graft causes its length to increase. Both of these factors may be important in the development of late complications of stent-grafting.

Initial Results After Combined Repair of Aortic Arch Aneurysms by Sequential Transposition of the Supra-Aortic Branches and Consecutive Endovascular Stent-Graft Placement

BACKGROUND

To evaluate safety and efficacy of a combined repair of aortic arch aneurysms by sequential transposition of the supra-aortic branches and endovascular stent-graft placement.

METHODS

Between October 2002 and September 2003, 5 patients (mean age, 79.5 years) presented with aortic arch aneurysms involving the origin of the left carotid artery. Treatment was made by sequential transposition of the left carotid artery into the brachiocephalic trunk and transposition of the left subclavian artery into the already transposed left common carotid artery with consecutive endovascular stent-graft placement into the aortic arch.

RESULTS

All patients survived both procedures. At completion angiography, a small type 1a endoleak was observed in 1 patient. After 1 week, the patient was readmitted for completion three-dimensional computed tomographic scan. The leak had already occluded spontaneously. Mean follow-up was 10 months (range, 4 to 16 months). At follow-up, all patients had normal computed tomographic scans with regular perfusion of the supra-aortic branches without any signs of endoleaks.

CONCLUSIONS

Combined repair of aortic arch aneurysms by sequential transposition of the supra-aortic branches with consecutive endovascular stent-graft placement is feasible. Extended application of this technique will enable safe and effective treatment of a highly selected subgroup of patients with aortic aneurysms by avoiding conventional arch aneurysm repair in deep hypothermia and circulatory arrest.

Stent-Graft Migration:A Reappraisal of Analysis Methods and Proposed Revised Definition

PURPOSE

To demonstrate the need for a radiographic definition of migration that accurately describes a specific failure mode of an aortic stent-graft.

METHODS

The diagnosis of endograft migration, as defined by the Society for Vascular Surgery/American Association for Vascular Surgery (SVS/AAVS) standards, requires a synthesis of clinical and/or radiographic observations. Radiographic studies and clinical reports of 704 consecutive patients treated over a 6-year period with abdominal aortic endografts were retrospectively reviewed. According to the current SVS/AAVS standards, 25 patients were identified as having endograft migration. Follow-up computed tomographic scans and radiographs available for 24 of these patients were scrutinized from discharge to the time of any observed proximal or distal fixation system movement based upon the discharge or 30-day CT scan. Proximal migration was defined with respect to the origin of the superior mesenteric artery (SMA) as movement in a caudal or cranial direction of >/=10 mm or >2 times the reconstructed resolution of the imaging study (whichever measurement was less). Distal migration was similarly defined using the aortic bifurcation and respective hypogastric artery origin as reference points. In an effort to assess the scan-to-scan variation, the distance between the SMA and lowest renal artery, which was expected to remain consistent, was measured.

RESULTS

Film analysis with application of the revised migration definition confirmed fixation system failure with respect to the native arterial system in 12 (50%) of the 24 patients. Subjects judged to have endograft migration according to the reporting standards but not to have radiographic evidence of migration based on the modified criteria included 2 proximal endoleaks without evidence of device movement treated with proximal extensions, 1 procedure-related migration, 2 type III endoleaks treated with a second prosthesis implanted within the first, 1 distal endoleak treated with a limb extension, 1 rupture with presumed distal limb migration, and 2 cases of component separation. Three limb extensions were placed in the absence of leak or migration. These 12 patients all had radiographic evidence that the proximal and distal aspects of the originally implanted device did not move with respect to the native arterial vasculature, thus confirming stability of the respective fixation system.

CONCLUSIONS

Adherence to this comprehensive definition of device migration, which differs from the published reporting standards, allows differentiation of the specific mechanisms of device failure. Data viewed in this context will aid in the understanding of device strengths and weaknesses, potentially improve patient assessment, and encourage design modifications to address specific aspects relating to fixation failure.

Endovascular treatment of abdominal aortic aneurysm

BACKGROUND

Endovascular repair of abdominal aortic aneurysm has become widely used. Supporters claim high success rates, few complications and a dramatically reduced hospital stay. However, endoleak, endotension and reports of endoprosthesis rupture are causes of concern.

METHODS

A Medline search was undertaken to identify articles on endovascular repair of abdominal aortic aneurysm. Additional papers were identified by manual scanning of the references from key articles.

RESULTS AND CONCLUSION

Endoleak is a potentially serious complication of the endovascular technique and occurs in a significant proportion of patients. It is still not possible to judge whether the presence of an endoleak alone signifies failure of treatment, and the long-term durability of prosthetic covered stents is unknown. However, endovascular repair does appear to confer a degree of protection from rupture although patients must be advised of the need for life-long imaging surveillance and, perhaps, further intervention.