Aneurysm rupture after endovascular repair using the AneuRx stent graft

Risk factors for elective and urgent open conversion after EVAR-a retrospective observational study

BACKGROUND

Endovascular aortic aneurysm repair (EVAR) has become the standard procedure for treating infrarenal abdominal aortic aneurysms (AAA). Various associated complications can lead to open conversion (OC). Thorough follow-up after the procedure is mandatory for the early detection of complications. Persisting perfusion of the aneurysm, a so-called endoleak (EL), paired with structural instability because of aortic wall atrophy and impaired cell functionality induced by EVAR, results in a high risk for aortic rupture.

PURPOSE

The goal of this study was to detect the risk factors for elective and urgent OC as a result of EVAR-induced pathophysiological changes inside the aortic wall.

RESEARCH DESIGN

Retrospective data analysis was performed on all open aortic repairs from January 2016 to December 2020.

DATA COLLECTION AND ANALYSIS

Fifty patients were identified as treated by OC for failure of an infrarenal EVAR. The patients were divided into two subgroups, here depending on the urgency of surgery. Statistical analysis of patient characteristics and outcomes was performed.

RESULTS

The most common indications for OC were various types of EL (74%), resulting in an aortic rupture in 15 patients. Patients with insufficient or absent follow-up were treated more frequently in an emergency setting (16% vs. 63%). The mortality rate was higher in cases of emergency OC (3% vs. 26%).

CONCLUSIONS

Particularly in cases of insufficient or absent follow-up, complications such as EL pose an enormous risk for fatal aortic rupture.

Endovascular Aortic Aneurysm Repair with the Zenith AAA Endovascular Graft: Does Gender Affect Procedural Success, Postoperative Morbidity, or Early Survival?

The purpose of this study was to analyze the effect of gender on deployment, early morbidity, and survival after endovascular aortic aneurysm repair (EVAR) using the Zenith Endovascular Graft. Data were obtained from the U.S. Multicenter Zenith Endograft trial and complemented with results from the Zenith female registry, including 40 women (10.9%) and 326 men (89.1%). Data analysis included preoperative medical risk factors, aneurysm morphology, deployment, and postoperative morbidity data, and 30-day and 1-year results. Preoperatively, women more often had experienced thromboembolic events (13% vs 4.3%; P = 0.04), but less angina pectoris (24% vs 49%; P = 0.002) or myocardial infarction (18% vs 38%; P = 0.01) compared with men. Women had more angulated aneurysm necks and narrower iliac arteries compared with men. Procedural success, cardiovascular, pulmonary, renal, bowel-related, neurologic, or other adverse events were comparable, as were 30-day and 1-year survival. Females experienced more wound dehiscences (5.0% vs 0.0%; P = 0.01) and open surgical conversions in the first year (5%) compared with men (0.31%) ( P = 0.03). With more challenging aneurysm morphologies, women were found to be at a higher risk for conversion in the first year after EVAR using the Zenith endograft. This however does not translate into inferior survival or higher overall morbidity compared with men.

Prognostic Value of Initial Aneurysmal Sac Regression after EVAR

BACKGROUND

The objective of the study was to evaluate the impact of initial aneurysmal sac reduction after endovascular aneurysm repair on the evolution of aneurysmal sac over follow-up.

METHODS

A retrospective cohort study was made of patients subjected to elective treatment between January 2005 and December 2014, with a minimum follow-up of 18 months. An analysis was made of the evolution of the aneurysmal sac according to its condition one year after surgery, defining of two groups: A (sac reduction) and B (stable sac). Follow-up by computed tomography (CT) angiography was made after one month and then every 6 months or annually, depending on the presence of endoleak.

RESULTS

A total of 128 patients were included. Fifty-one patients (39.8%) showed a significant decrease in diameter during the first year (group A), whereas 77 patients (60.2%) showed no initial decrease (group B). Preoperative CT angiography showed the patients in group A to have larger aneurysms (63.5 mm vs. 59.25; P = 0.048), a greater presence of posterior thrombus (68.6% vs. 30.7%; P < 0.001), and fewer patent lumbar vessels (56.9% vs. 83.1%; P = 0.001). The prevalence of endoleak at some point during follow-up was lower in group A (31.4% vs. 74% in group B; P < 0.001), and 100% of all aneurysmal growths were associated to the presence of endoleak. After 5 years, significant differences were observed in the growth-free rate (96.9% in group A vs. 85.2% in group B; hazard ratio [HR] 4.8 [1.1-21.4; P = 0.036]) and in the reintervention-free rate (95,7% vs. 84.6%; HR 6.6 [0.8-52.4; P = 0.07]). No reoperation in group A was due to type II endoleak.

CONCLUSIONS

The aneurysmal sac can be expected to take a favorable course in those cases characterized by initial aneurysmal sac reduction. These findings may imply a change in the follow-up protocol, even in cases with type II endoleak.

Endograft Technology: Highlights of the past 10 Years

The past decade has seen the evolution of an exciting technology that has changed forever the treatment of aortic aneurysmal disease. From rather crude homemade stent-grafts constructed in the surgical suite to elegant commercially manufactured devices in a variety of configurations and sizes, the aortic endograft has experienced a meteoric rise in popularity to become a beneficial, minimally invasive therapy that can obviate the risk of rupture and death. There are now 3 approved endovascular devices on the market for infrarenal abdominal aortic aneurysm repair, and it is likely that additional and improved devices will become available in the future. This review revisits the developmental history of the aortic endograft, noting the ongoing refinements that have arisen from our experiences with the growing population of stent-graft patients. Although research continues to search for solutions to the problems of endoleak and migration, long-term results even with the earlier second and third-generation devices are better than has been achieved with open surgical repair.

Aneurysm rupture from blunt abdominal trauma after endovascular repair

We present a case of aneurysm rupture from severe blunt abdominal trauma due to fight in a patient who had endovascular aneurysm repair. The patient presented to the emergency service with computed tomography evidence of an endoleak and a large retroperitoneal hematoma. The contrast abdominal computed tomography demonstrated a type Ib endoleak, increase in the aneurysm diameter and hematoma in the retroperitoneum. The patient has been taken under interventional procedure for endovascular aneurysm repair revision under urgent condition. Type Ib endoleak was treated by placement of a covered iliac extension limb, but a second leakage from graft body was found in control computed tomography images and open surgical conversion was necessary. Operative findings included a type III endoleak from graft body, defect on fabric. It was seen that the aneurysm sac anterior and posterior parts were ruptured. Upon reviewing the literature, we found that it was an interesting case as the first rupture case which had been developed after severe blunt abdominal trauma during the follow-up period of a patient on which endovascular aneurysm repair procedure had been performed and progressed in this manner.

Most Patients with Abdominal Aortic Aneurysm Are Not Suitable for Endovascular Repair Using Currently Approved Bifurcated Stent-Grafts

Strict morphologic criteria must be used for patient selection to achieve durable success with endovascular aortic aneurysm repair (EVAR). The goal of this study was to assess morphologic suitability (MS) of abdominal aortic aneurysms (AAAs) for 2 currently approved bifurcated stent grafts and identify reasons for exclusion from EVAR. The authors reviewed the electronic charts of 1,795 consecutive patients who were diagnosed as having AAA between January 1999 and July 2001 at their institution. Three hundred and twenty patients had an AAA with a diameter of =5.0 cm, measured on computed tomography (CT). The records of 301 patients, 254 men, 47 women, with a mean age of 74 years were available for review, and these patients constituted the study cohort. Criteria used for MS included a proximal neck length =15 mm; neck diameter between 18 and 26 mm; neck angulation =60°; common or external iliac artery (CIA or EIA) diameters of 7–16 mm and 8–13 mm, respectively, for AneuRx (Medtronic Ave, Santa Rosa, CA) and Ancure (Guidant Cardiac and Vascular Division, Menlo Park, CA) bifurcated grafts. AAAs were suitable for AneuRx device in 14% of patients (43 of 301; 95% CI = 11–19%) and for Ancure in 5% (16 of 301; 95% CI = 3.1–9%). The main reason for exclusion was an inadequate proximal aortic neck (73%). The neck was too short in 49.5%, too wide in 64% and badly angulated in 12% of the patients. Iliac artery morphology precluded EVAR with AneuRx and Ancure devices in 52% and 80%. Both CIAs were too wide for EVAR in 43% and 77%, respectively. When iliac artery diameter =20 mm was accepted, iliac suitability for AneuRx increased from 49% to 70% and overall suitability increased from 14% to 20%. When more permissive criteria were used for MS (neck length =10 mm, neck diameter =30 mm, CIA =20), 39% of patients became candidates for EVAR. More than three fourths of the patients with an AAA =5.0 cm in size, seen in a tertiary referral center, are morphologically not suitable for EVAR using 2 currently approved bifurcated endografts. The main reasons for exclusion are a short or wide proximal aortic neck. Considerable changes in size of the devices and in proximal attachment techniques have to occur before most AAAs will be suitable for EVAR.

Endovascular Repair of Early Rupture of Dacron Aortic Graft

Complications after open aortic surgery pose a challenge both to the vascular surgeon and the patient because of aging population, widespread use of cardiac revascularization, and improved survival after aortic surgery. The perioperative mortality rate for redo elective aortic surgery ranges from 5% to 29% and increases to 70–100% in emergency situation. Endovascular treatment of the postaortic open surgery (PAOS) patient has fewer complications and a lower mortality rate in comparison with redo open surgical repair. Two cases of ruptured abdominal aortic aneurysm (AAA) were managed with the conventional open surgical repair. Subsequently, spiral contrast computer tomography scans showed reperfusion of the AAA sac remnant mimicking a type III endoleak. These graft-related complications presented as vascular emergencies, and in both cases endovascular aneurysm repair (EVAR) procedure was performed successfully by aortouniiliac (AUI) stent graft and femorofemoral crossover bypass. These 2 patients add further merit to the cases reported in the English literature. This highlights the crucial importance of endovascular grafts in the management of such complex vascular problems.

Rupture of Abdominal Aortic Aneurysm in Patients with and without Antecedent Endovascular Repair

BACKGROUND

Reported results of ruptured abdominal aortic aneurysm (rAAA) in patients with antecedent endovascular aneurysm repair (EVAR) to those presenting with de novo rupture show a similar or slightly improved outcome. The aim of this study was to compare differences in the presentation and outcomes of rAAA with and without prior EVAR.

METHODS

A retrospective review of 121 patients with rAAA, ruptured identified 2 groups. Group A included 17 patients (rAAA n = 17) with antecedent EVAR and group B consisted of 104 patients (rAAA n = 104) with de novo ruptures, from January 2001 to March 2015 in 3 teaching hospitals. Patient characteristics and perioperative variables were compared; Fisher's exact test was used for categorical variables. For continuous variables, Student's t-test and Mann-Whitney U test were used.

RESULTS

Both groups were similar in age, gender, the incidence of hypertension, coronary artery disease, diabetes mellitus, chronic obstructive pulmonary disease, and nicotine abuse. Mean time of presentation from EVAR to rupture in group A was 42 ± 22 months. Mean preoperative transverse or anteroposterior diameter of AAA was 6.6 cm in group A and 7.1 cm in group B. Three patients of 17 (17.6%) in group A were hemodynamically unstable as compared to 47 of 104 patients (45.1%) in group B (P = 0.03). Mean red blood cells, fresh frozen plasma, and platelet transfusion were similar in both groups. Thirty-day mortality was 8 of 17 (44.7%) in group A and 44 of 104 (42.3%) in group B (P = 1.0). Postoperative complications were also similar in both groups except the incidence of postoperative respiratory failure was higher in group B (38%) as compared with 11.1% in group A (P = 0.001).

CONCLUSIONS

Patients presenting with rAAA with antecedent EVAR are hemodynamically more stable as compared with patients with de novo rupture of AAA. Postoperative respiratory failure is more common in patients with de novo rupture. rAAA carry high mortality with and without prior EVAR.

Endotension is Influenced by Aneurysm Volume: Experimental Findings

Purpose:

To investigate in an in vitro model whether and to what extent pressure is influenced by aneurysm size.

Methods:

Latex aneurysms of 3 different volumes (24, 30, and 81 mL) were inserted into an in vitro circulation model. The systemic mean pressure (SPmean) was varied from 50 to 120 mmHg. The aneurysms were excluded using a woven polyethylene graft. Aneurysm sac mean pressure (ASPmean) was measured.

Results:

In the in vitro model, endovascular aneurysm repair created a closed chamber without endoleak but showed a relevant aneurysm sac pressure. At an SPmean of 80 mmHg, the ASPmean was 42.0 ± 0.6 mmHg in the 24-mL aneurysm, 40.5 ± 0.5 mmHg in the 30-mL model, and 19.3 ± 0.5 mmHg in the 81-mL aneurysm (p < 0.05). The ASPmean rose with increasing SPmean and was inversely dependent on the aneurysm volume.

Conclusions:

This in vitro model demonstrated that the sac mean pressure correlated to the systemic pressure and that a greater aneurysm volume reduced aneurysm sac pressure. These data highlight the need for further studies regarding endotension.

Comparison of the Fixation Strength of Standard and Fenestrated Stent-Grafts for Endovascular Abdominal Aortic Aneurysm Repair

Purpose:

To determine whether fenestrated stent-grafts provide better stability to resist migration than standard non-fenestrated stent-grafts.

Methods:

Truncated fenestrated stent-grafts with a single fenestration were deployed in bovine aortic segments with a side branch. Balloon-expandable stents were then delivered into the branches. Similarly, standard stent-grafts of the same dimensions were deployed for comparison. The aorta was pressurized to achieve stent-graft oversizing of 5%, 10%, or 20%. The force required to cause distal migration was recorded by a digital force gauge attached to the stent-graft.

Results:

Displacement of the stent-grafts occurred in 2 distinct phases: an initial yield during which the barbs embedded in the aortic wall and a final displacement leading to significant migration and dislodgement of the device. The displacement force that initiated each phase was dependent upon the degree of oversizing of the stent-graft relative to the aortic diameter. For 5%, 10%, and 20% oversizing, the mean displacement forces in the initial displacement phase were 3.39±0.37, 4.32±0.63, and 7.69±1.18 N, respectively, in non-fenestrated grafts and 10.48±1.23, 11.45±1.48, 12.12±1.42 N in fenestrated grafts. The displacement forces in the final displacement phase were 8.10±0.92, 10.76±1.74, and 16.82±0.92 N for non-fenestrated and 22.56±1.60, 28.24±1.56, and 33.01±1.75 N for fenestrated stent-grafts. The differences in displacement forces between standard and fenestrated stent-grafts were significant for both phases (p<0.001) at all oversizing levels.

Conclusion:

Improvement in fixation strength was noted with increasing stent-graft oversizing of up to 20%. Fenestrated stent-grafts offer higher ultimate fixation compared to standard devices. However, the ultimate fixation strength was not recruited until an initial phase of short migration occurred as the barbs engaged. While this movement is inconsequential with standard stent-grafts, it has the potential to crush the stents placed into aortic side branches with fenestrated endografts.

Endovascular Repair of AAA Rupture 20 Months after Endoluminal Stent-Grafting

Purpose:

To demonstrate the feasibility of endovascular repair of a ruptured abdominal aortic aneurysm (AAA) previously treated with an endoluminal stent-graft.

Case Report:

An 84-year-old man with a 9.5-cm AAA underwent endoluminal repair with an Endologix stent-graft, but a type I endoleak was detected postprocedurally. The patient was discharged and lost to follow-up. Twenty months later, he suffered an aneurysm rupture, which was repaired using endovascular techniques. Although he had a postoperative course complicated by aspiration pneumonia and renal failure, he recovered fully and was discharged from the hospital with no evidence of endoleak on the postprocedural imaging studies.

Conclusions:

Late ruptures after endoluminal AAA stent-grafting can be successfully treated with endovascular techniques.

Clinical Outcome and Technical Considerations of Late Removal of Abdominal Aortic Endografts: 8-Year Single-Center Experience

During an 8-year period, 355 patients underwent endovascular repair of mainly true (97%) infrarenal aneurysms. After a mean follow-up of 48 months, 11 (3.1%) patients required conversion to open repair and 10 were eligible for open surgical intervention. Via a midline incision, explantation of the endograft was performed by using an infrarenal aortotomy. Explantation was done for rupture in four patients (40%), with a marked difference in mortality rates between acute (50%) and elective (0%) explantations.

The main reason for explantation was proximal type I endoleak caused by (1) malposition of the device, (2) proximal migration of the endograft, and (3) dislodgment of a tube endograft that followed former central reconstruction. Proximal migration is most worrisome and demands preventive endovascular reintervention.

The mortality and morbidity rates of elective explantation are acceptable. When delayed conversion is indicated, priority has to be given to operate on these patients.

Late Rupture of Abdominal Aortic Aneurysm After Previous Endovascular Repair

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.

Advancements in identifying biomechanical determinants for abdominal aortic aneurysm rupture

Abdominal aortic aneurysms are a common health problem and currently the need for surgical intervention is determined based on maximum diameter and growth rate criteria. Since these universal variables often fail to predict accurately every abdominal aortic aneurysms evolution, there is a considerable effort in the literature for other markers to be identified towards individualized rupture risk estimations and growth rate predictions. To this effort, biomechanical tools have been extensively used since abdominal aortic aneurysm rupture is in fact a material failure of the diseased arterial wall to compensate the stress acting on it. The peak wall stress, the role of the unique geometry of every individual abdominal aortic aneurysm as well as the mechanical properties and the local strength of the degenerated aneurysmal wall, all confer to rupture risk. In this review article, the assessment of these variables through mechanical testing, advanced imaging and computational modeling is reviewed and the clinical perspective is discussed.

Ruptured Abdominal Aortic Aneurysm with Antecedent Endovascular Repair of Abdominal Aortic Aneurysm

Late aortic rupture following successful endovascular repair of abdominal aortic aneurysm still does occur. It represents the ultimate failure of endovascular aortic repair of abdominal aortic aneurysm (EVAR) and subjects patients to equivalent risk of death as de novo rupture. Unfortunately, it is difficult to identify patients at risk for post-EVAR rupture as many present with aortic rupture in the absence of any endograft-related complications. Continued surveillance and timely intervention are of paramount importance to assure rupture-free survival, the ultimate goal of any aneurysm treatment modality. The vascular surgeon needs to be prepared to provide the optimal therapy, whether open or endovascular, for this challenging cohort of patients.

Endo-exuberance and abdominal aortic aneurysm management: have we gone too far?

HYPOTHESIS

new technology, such as endovascular abdominal aortic aneurysm repair (EVAR) may promote an 'irrational exuberance' for its application.

METHODS

nonsuprarenal AAA repairs performed at a single institution over a 7 year period were retrospectively studied. Method of repair, 30-day mortality and EVAR aortic neck anatomy were assessed.

RESULTS

431 AAA repairs were performed between January 1996 and June 2002, 238 (55%) open and 193 (45%) EVAR. The percentage of EVAR increased steadily from approximately 20% in 1996 and 1997 to a peak of 69.5% in 2000. However, in 2001-2002 the percentage of EVAR fell to approximately 40% of total repairs. In this time period our selection criteria for EVAR became more conservative, with treatment of fewer patients with short aortic necks (12.8 vs. 28.9% with neck length < or = 20 mm, p = 0.05; 3.8 vs. 10.8% with neck length < or = 15 mm, p = 0.1) or highly angulated necks (3.8 vs. 28.9% with neck angulation > or = 40 degrees, p = 0.04) in 2001-2002 versus 1999-2000, respectively. Institutional volume of AAA repairs doubled over the study period (p = 0.001). 30-day mortality over the study period for nonruptured EVAR and open AAA repair was 2.6 and 3.3%, respectively (p = NS). The complexity of open repairs increased significantly during the final 3 years of the review.

CONCLUSIONS

the application of EVAR has fallen from a high of 69.5% of our AAA repairs in 2000 to approximately 40% in 2001-2002. More prudent patient selection in recent years regarding unfavorable aortic neck anatomy was felt to be a primary etiology of changes in overall EVAR utilization. The anticipated improvement in long-term results from EVAR await multi-year follow-up.

Non-contrast MR imaging for detecting endoleak after abdominal endovascular aortic repair

Our aim was to investigate the possibility of ruling out endoleak after endovascular aortic repair (EVAR) of abdominal aortic aneurysm (AAA) using non-contrast MRI. Twenty-three patients (20 males, aged 73 ± 8 years) with an EVAR-treated AAA underwent 1.5-T MRI using axial, coronal and sagittal oblique true-FISP sequences. Two blinded and independent readers with 4 (R1) and 2 (R2) years of experience evaluated these images considering an area of even less than 5 mm in diameter with a signal intensity higher than that of normal muscles visible in the excluded aneurysmal sac as a sign of potential endoleak. The final assessment, mainly based on MR angiography and previous examinations, served as reference standard. Out of 23 patients, 13 (57%) were negative for endoleak at final assessment, while the remaining 10 (43%) were positive, with the following type distribution: Ia (n = 4), Ib (n = 2), II (n = 3), and III (n = 1). Sensitivity was 10/10 (100%; CI 95% 69-100%), specificity 7/13 (54%; 25-81%), accuracy 17/23 (74%; 52-90%), PPV 10/16 (63%; 35-85%) and NPV 7/7 (100%; 59-100%) for R1; 9/10 (90%; 56-100%), 8/13 (62%; 32-86%), 17/23 (74%; 52-90%), 9/14 (64%; 35-8%), and 8/9 (89%; 52-100%) for R2, respectively. Inter-reader Cohen κ was 0.810. A negative non-contrast true-FISP MR study can be used to rule out endoleak after EVAR of AAA. This hypothesis may contribute to the reduction of ionizing radiation exposure and contrast material administration for monitoring patients with an EVAR-treated AAA.

Conversion to open repair after endografting for abdominal aortic aneurysm: a review of causes, incidence, results, and surgical techniques of reconstruction

PURPOSE

To review the incidence, causes, and mortality rates of early and late conversion to open surgery after endovascular aneurysm repair (EVAR) of abdominal aortic aneurysm (AAA).

METHODS

A systematic search of the English-language literature from 2002 to 2009 was performed by interrogation of the PubMed, MEDLINE, and EMBASE databases. Studies were included if they: (1) had >100 patients treated with EVAR and (2) provided adequate data to calculate incidence and associated mortality rates. The search yielded 13 articles with sufficient data to analyze early conversion (12,236 patients, 178 conversions) and 15 articles with available data for late conversion (14,298 patients, 279 conversions).

RESULTS

The rate of early conversion among the 13 articles reviewed ranged from 0.8% to 5.9%; more recent studies carried lower rates of early conversion. Mortality rates of early conversion varied between 0% and 28.5%. Overall, there were 178 (1.5%) early conversions among the 12,236 AAAs treated with EVAR, with an average mortality of 12.4%. The rates of late conversion ranged from 0.4% to 22%. Of the 14,289 AAA patients undergoing endovascular repair, 279 (1.9%) required late conversion; the mortality rate was 10%.

CONCLUSION

Though the incidence is gradually declining, secondary interventions persist as the Achilles' heel of EVAR. A lifelong follow-up strategy for AAA patients treated with EVAR is essential for early detection and treatment of complications of the procedure. Vascular surgeons should be familiar with the complex open conversion procedures.

Early type III endoleak with an Endurant endograft

We report the case of an 81-year-old man who presented with an intraoperative type III endoleak after treatment with an Endurant endograft for a 60-mm abdominal aortic aneurysm. To our knowledge, this is the first case of a type III endoleak reported with this new device. It was most likely due to a tear in the polyester graft, the cause of which remains speculative. The tear was demonstrated by postoperative angiography, which was more informative than computed tomography. The endoleak was successfully treated by relining with an aorto-uni-iliac device.

Aortic aneurysm surgery: problems and innovations

A long way was traveled since the first surgery was performed for the treatment of abdominal aortic aneurysm. Throughout this time, several innovations have been created in order to reduce the invasiveness of the surgical procedures and to improve their safety and durability. This review discusses the major and recent advances on aortic aneurysm interventions, including, the endovascular aortic repair, the laparoscopic aortic surgery, the conventional hybrid and endovascular techniques, combined laparoscopic and endovascular techniques, as well as future prospects for both thoracic and abdominal aorta. Faced with so many changes and developments, modern vascular surgeons must keep their minds open to innovations and should develop comprehensive training with different techniques, to provide the best therapeutic option for their patients.

The proximal fixation strength of modern EVAR grafts in a short aneurysm neck. An in vitro study

OBJECTIVES

The study aims to measure the strength of the proximal fixation of endografts in short and long necks.

DESIGN

Three types of endografts were compared: Gore Excluder, Vascutek Anaconda and Medtronic Endurant.

MATERIALS AND METHODS

The proximal part of the stent grafts was inserted in bovine arteries and the graft was then attached to a tensile testing machine. The force to obtain dislodgement (DF) from the aorta was recorded for each graft at proximal seal lengths of 10 and 15 mm.

RESULTS

The median DF (interquartile range, IQR) for the Excluder, the Anaconda and the Endurant with a seal length of 15 mm was: 11.8 (10.5-12.0) N, 20.8 (18.0-30.1) N and 10.7 (10.4-11.3) N. With the shorter proximal seal of 10mm, DF was, respectively: 6.0 (4.5-6.6) N, 17.0 (11.2-36.6) N and 6.4 (6.1-12.0) N.

CONCLUSIONS

The proximal fixation of the Anaconda is superior to the Excluder and the Endurant at short necks of 10 and 15 mm in an experimental set-up. There is a statistically significant decrease of proximal fixation for the Excluder stent graft, when decreasing the length of the proximal neck from 15 to 10 mm.

Prospective, intraindividual comparison of MRI versus MDCT for endoleak detection after endovascular repair of abdominal aortic aneurysms

This study compares MRI and MDCT for endoleak detection after endovascular repair of abdominal aortic aneurysms (EVAR). Forty-three patients with previous EVAR underwent both MRI (2D T1-FFE unenhanced and contrast-enhanced; 3D triphasic contrast-enhanced) and 16-slice MDCT (unenhanced and biphasic contrast-enhanced) within 1 week of each other for endoleak detection. MRI was performed by using a high-relaxivity contrast medium (gadobenate dimeglumine, MultiHance). Two blinded, independent observers evaluated MRI and MDCT separately. Consensus reading of MRI and MDCT studies was defined as reference standard. Sensitivity, specificity, and accuracy were calculated and Cohen's k statistics were used to estimate agreement between readers. Twenty endoleaks were detected in 18 patients at consensus reading (12 type II and 8 indeterminate endoleaks). Sensitivity, specificity, and accuracy for endoleak detection were 100%, 92%, and 96%, respectively, for reader 1 (95%, 81%, 87% for reader 2) for MRI and 55%, 100%, and 80% for reader 1 (60%, 100%, 82% for reader 2) for MDCT. Interobserver agreement was excellent for MDCT (k = 0.96) and good for MRI (k = 0.81). MRI with the use of a high-relaxivity contrast agent is significantly superior in the detection of endoleaks after EVAR compared with MDCT. MRI may therefore become the preferred technique for patient follow-up after EVAR.

Effect of Systemic Blood Pressure on Aneurysm Size in the Presence of a Type II Endoleak

The objective of this study was to determine whether hypertension is a risk factor for aneurysm enlargement in patients with an untreated type II endoleak after endovascular abdominal aortic aneurysm repair (EVAR). Between January 2000 and December 2005, 296 patients underwent elective EVAR using a bifurcated Zenith stent graft. Forty-nine (17%) patients had a type II endoleak triaged to observation. Patient clinical data and data on endoleak status, aneurysm size, and endoleak intervention were collected prospectively. Aneurysm size remained the same or decreased in 39 of 49 (80%) patients. In the remaining 10 (20%) patients with aneurysm enlargement, 7 required intervention. There was no difference in initial aneurysm size, patient age, gender, or comorbidities between patients with enlarging aneurysms and those with stable or regressing aneurysms. However, patients with enlarging aneurysms had a mean systolic blood pressure (SBP) of 144 ± 14 mm Hg compared with 136 ± 13 mm Hg for patients with stable or regressing aneurysms ( p = .08). Multivariate regression analysis demonstrated increased SBP to be an independent predictor of aneurysm enlargement ( p = .05). Patients with systolic hypertension and an untreated type II endoleak are more likely to demonstrate aneurysm enlargement after EVAR. Aggressive blood pressure control may be an important adjunct in the management of patients with type II endoleak after EVAR.

A review of the in vivo and in vitro biomechanical behavior and performance of postoperative abdominal aortic aneurysms and implanted stent-grafts

Endovascular repair of abdominal aortic aneurysms has generated widespread interest since the procedure was first introduced two decades ago. It is frequently performed in patients who suffer from substantial comorbidities that may render them unsuitable for traditional open surgical repair. Although this minimally invasive technique substantially reduces operative risk, recovery time, and anesthesia usage in these patients, the endovascular method has been prone to a number of failure mechanisms not encountered with the open surgical method. Based on long-term results of second- and third-generation devices that are currently becoming available, this study sought to identify the most serious failure mechanisms, which may have a starting point in the morphological changes in the aneurysm and stent-graft. To investigate the "behavior" of the aneurysm after stent-graft repair, i.e., how its length, angulation, and diameter change, we utilized state-of-the-art ex vivo methods, which researchers worldwide are now using to recreate these failure modes.

Imaging Techniques for Detection and Management of Endoleaks after Endovascular Aortic Aneurysm Repair1

Endovascular aortic aneurysm repair (EVAR) is evolving into a viable alternative to open surgical repair for many patients with abdominal and thoracic aortic aneurysms. Endoleak development is a complication of EVAR and represents one of the limitations of this procedure. Endoleaks represent blood flow outside the stent-graft lumen but within the aneurysm sac. Lifelong imaging surveillance of patients after EVAR is critical to detect endoleaks for the patient's benefit and to determine the long-term performance of the stent-graft. Although computed tomographic angiography is the most commonly used examination for imaging surveillance, magnetic resonance angiography, ultrasonography, and digital subtraction angiography all have a role in endoleak detection and management. This review will focus on imaging techniques used for endoleak detection and the role imaging surveillance plays in the overall care of the post-EVAR patient.

Long-Term Single-Center Results with Aneurx Endografts for Endovascular Abdominal Aortic Aneurysm Repair

PURPOSE

To evaluate the long-term single-center results with the AneuRx stent-graft in endovascular abdominal aortic aneurysm (AAA) repair (EVAR).

METHODS

Between December 1996 and August 2003, 212 patients (197 men; mean age 71.3+/-7.0 years) were treated with the AneuRx stent-graft for an infrarenal AAA. Postoperatively, patients were enrolled in a fixed surveillance protocol, and data were prospectively captured into a database.

RESULTS

Graft deployment was successful in 98.6% (209/212). Thirty-day mortality was 2.4%. Median hospital stay was 4.3+/-5.5 days. Median follow-up was 52.0 months (range 1-109); only 1 patient was lost to follow-up. At 9 years, patient survival was 56% and freedom from secondary interventions was 48%. In 68% of cases, these reinterventions were needed for a fixation-related complication, and most of these complications (75%) encompassed the area of the proximal aneurysm neck. Primary clinical success was 37% at 9 years. After secondary interventions, the assisted primary clinical success improved to 73% at 9 years. Freedom from aneurysm-related death was 97% at 1 year and 90% at 9 years.

CONCLUSION

As an alternative to open repair, EVAR with the AneuRx device has low perioperative mortality. Reinterventions are mostly due to fixation-related complications. While the overall mortality risk in this population was 5% per year, annual aneurysm-related death was only 1%. The focus should be on surveillance and reducing the rate of long-term complications, which might be possible with improved proximal stent-graft fixation.

Should usual criteria for intervention in abdominal aortic aneurysms be "downsized," considering reported risk reduction with endovascular repair?

Two randomized trials have demonstrated the safety of waiting until abdominal aortic aneurysm (AAA) diameter reaches 5.5 cm for repair in most patients. Other recent randomized trials have demonstrated lower perioperative mortality and morbidity with endovascular aneurysm repair (EVAR) compared to open surgery. Therefore, it is logical to assume that endovascular repair may change the appropriate threshold for intervention. However, endovascular repair is not as durable as open surgery and is associated with ongoing risks of rupture and reintervention. Decision analysis based on data available in 1998 showed that endovascular repair should not change the threshold for intervention. Since that time retrospective data have emerged to suggest that outcomes with endovascular repair are improved in smaller AAAs, although this may simply represent selection bias and the natural history of small AAAs. Randomized trials are appropriate to determine whether improved endovascular outcomes in small AAAs reduce late rupture and reintervention enough to justify early intervention in patients with appropriate anatomy. In the absence of data from these trials, the threshold for intervention should not be changed.

Systematic Review and Meta-analysis of 12 Years of Endovascular Abdominal Aortic Aneurysm Repair

BACKGROUND

Endovascular repair (ER) of abdominal aortic aneurysm (AAA) is a new technique, and reported rates of endoleak, conversion to open repair, rupture and mortality vary widely. The aim of this study was to estimate these rates from the published data, and examine how this has changed as more patients have undergone ER.

METHODS

A systematic review and meta-analysis of publications identified through searches of the electronic databases EMBASE and Medline. All publications quoting endoleak, conversion to open repair, rupture and mortality rates for a series of patients undergoing ER were included.

RESULTS

163 studies pertaining to 28,862 patients undergoing ER were identified as relevant for the review and meta-analysis. The pooled estimate for operative mortality was 3.3% (95% confidence interval 2.9 to 3.6%). The pooled estimate for type 1 endoleaks was 10.5% (95% confidence interval 9.0 to 12.1%), with an annual rate of 8.4% (95% confidence interval 5.7% to 12.2%). The pooled estimate of type 2,3 and 4 endoleaks was 13.7% (95% confidence interval 12.3 to 15.3%), with an annual rate of 10.2% (95% confidence interval 7.4% to 14.1%). The pooled estimate for primary conversion to open repair was 3.8% (95% confidence interval 3.2 to 4.4%), and for secondary conversion to open repair 3.4% (95% confidence interval 2.8 to 4.2%). The pooled estimate for post-operative rupture was 1.3% (95% confidence interval 1.1 to 1.7%), with an annual rupture rate of 0.6% (95% confidence interval 0.5% to 0.8%). Multivariate meta-regression analysis showed that rates of operative mortality, post-operative rupture and total number of endoleaks all fell significantly (p<0.05) over time.

CONCLUSIONS

This study demonstrates a low mortality and a gradual reduction in vascular morbidity and mortality associated with endovascular repair since it was first introduced.

Biomechanics of abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a condition whereby the terminal aorta permanently dilates to dangerous proportions, risking rupture. The biomechanics of AAA has been studied with great interest since aneurysm rupture is a mechanical failure of the degenerated aortic wall and is a significant cause of death in developed countries. In this review article, the importance of considering the biomechanics of AAA is discussed, and then the history and the state-of-the-art of this field is reviewed--including investigations into the biomechanical behavior of AAA tissues, modeling AAA wall stress and factors which influence it, and the potential clinical utility of these estimates in predicting AAA rupture.

Salvage of failed prior endovascular abdominal aortic aneurysm repair with fenestrated endovascular stent grafts

Three patients with type I proximal endoleak after previous endovascular abdominal aortic aneurysm (AAA) repair were treated with fenestrated endovascular stent grafts. Six renal arteries, three superior mesenteric arteries, and one coeliac axis were targeted for incorporation by graft fenestration. The fenestration-renal ostium interface was secured with balloon-expandable stents and completion angiography demonstrated no endoleaks and antegrade perfusion in all target vessels. All patients made an uncomplicated recovery. Fenestrated endovascular stent grafts can be used to salvage failed prior endovascular AAA repair in patients who are considered unsuitable for other endovascular or open surgical interventions.

Aortic Aneurysm, Thoracoabdominal Aneurysm, Juxtarenal Aneurysm, Fenestrated Endografts, Branched Endografts, and Endovascular Aneurysm Repair

The development of endovascular devices to treat aneurysms that abut or involve the visceral vessels has occurred in an effort to reduce the significant procedural morbidity and mortality associated with conventional repair. To accomplish this, three systems have been trialed. The first technique was developed to treat juxtarenal aneurysms and involves the placement of customized fenestrations strategically placed within the fabric of the graft. These are aligned with the ostia of the visceral vessels incorporated by the repair and supplemented by the placement of a balloon expandable stent. In a similar fashion, aneurysms that involve the visceral vessels can be treated with a fenestrated graft where the fenestration is reinforced with a nitinol ring. This is then mated with a balloon-expandable stentgraft, allowing the devices to seal at the level of the nitinol ring. An alternative means of incorporating the visceral vessels is to use directional branches where one or more additional limbs (typically 8 mm) are anastomosed to the aortic graft, through which access into the visceral vessel is attained. Mating stentgrafts for the later design can be of a self-expanding or balloon expandable nature. The experience with fenestrated devices is mature and associated with a low perioperative mortality (<2%) without many long-term complications. The treatment of thoracoabdominal aneurysms with branches has provided us with optimism regarding the technique, but results are only short term in nature. Further device development is ongoing and dissemination of this technology is now occurring in Europe, Australia and Canada.

Complications of Endovascular Repair of Abdominal Aortic Aneurysms: A Review

The endovascular procedure for repair of abdominal aortic aneurysms has had an enormous impact on the treatment of this challenging disease. Complications, however, do occur and it is important to have a thorough understanding of the array of complications and appropriate management strategies. In this review of endovascular complications, we describe early and late complications paying particular attention to preventive, treatment and surveillance strategies.

Three-dimensional visualization of suprarenal aortic stent-grafts: evaluation of migration in midterm follow-up

PURPOSE

To investigate the midterm results of transrenal fixation of abdominal aortic stent-grafts with regard to device migration and encroachment of stent wires on the renal and visceral branches.

METHODS

Imaging data from 18 patients (15 men; mean age 75 years, range 63-84) undergoing transrenal stent-graft fixation for abdominal aortic aneurysm (AAA) were included in the study. Computed tomographic angiographic data acquired within 1 week of stent-graft implantation were compared to the latest follow-up images. Postprocessing methods generated 3-dimensional (3D) maximum intensity projections (MIP) and virtual intravascular endoscopy (VIE) for evaluation of the relationship between suprarenal stents and aortic branches. Aortic neck angulation was measured in each patient for correlation with the incidence of stent migration.

RESULTS

The mean follow-up period was 40 months. 3D image visualizations showed that the stent-graft moved caudally in all patients (range 2.6-14.2 mm), with migration (>10 mm) observed in 4 (22%) patients. Corresponding VIE images documented changes in stent wire encroachment on the aortic branch ostia in 11 patients, including the number and position of crossing stent wires. There was no close relationship between aortic neck angulation and stent migration.

CONCLUSION

The current study demonstrated that migration occurs at midterm follow-up in transrenally deployed stent-grafts. 3D images were valuable for the assessment of stent migration, as well as its relationship with aortic branch ostia. Long-term follow-up of transrenal fixation deserves to be investigated, especially after observing stent migration relative to aortic ostial encroachment.

The importance of iliac fixation in prevention of stent graft migration

OBJECTIVE

Secure proximal fixation of endografts to the infrarenal aortic neck is known to be important in the short- and long-term success of endovascular aneurysm repair. We sought to determine the relative importance of distal iliac fixation in preventing endograft migration and adverse clinical events after endovascular aneurysm repair.

METHODS

We reviewed the outcome of 173 patients treated from 1996 to 2003 at Stanford University Medical Center with an externally supported stent graft. Quantitative image analysis of the postimplantation computed tomography scan was performed to determine the proximal aortic and distal iliac fixation lengths and the proximity the distal end of the stent graft to the iliac bifurcation. Subsequent follow-up computed tomography scans were reviewed for evidence of stent graft migration. Patients were grouped according to good (>15 mm), intermediate, or bad (<10 mm) aortic fixation and good (iliac fixation length > or =25 mm and iliac limbs <10 mm from iliac bifurcation), intermediate, or bad (<25-mm fixation length) iliac fixation.

RESULTS

Stent graft migration of 10 mm or more was seen in 17 patients (10%) during the 23 +/- 19-month follow-up period. Patients with no migration had a greater iliac fixation length (30 +/- 12 mm) than those with migration (22 +/- 8 mm; P = .01), and the distal ends of the iliac limbs were closer to the iliac bifurcation (15 +/- 12 mm) than in patients with migration (25 +/- 10 mm; P < .001). Patients with no migration also had a greater proximal aortic fixation length (23 +/- 12 mm) than migration patients (13 +/- 7 mm; P = .001). There were no migrations among patients with good iliac fixation whether aortic fixation was good, intermediate, or bad (0/63; 0%). Among patients with bad/intermediate iliac and good aortic fixation, there were 5 (9%) of 58 patients had migrations. Patients with both bad/intermediate iliac and bad/intermediate aortic fixation had the highest migration rate (12/52; 23%). Cox proportional hazards regression modeling revealed that the significant factors predicting migration were poor proximity of the distal end of the iliac limbs to the iliac bifurcation (odds ratio 17.2; P = .01) and aortic fixation length (odds ratio 2.0; p = 0.007 for each centimeter). Iliac extender modules were placed in 9 patients with bad iliac fixation and migration, with no further migration during a mean follow-up of 12 months. Patients with good iliac and aortic fixation and no endoleak on the initial postprocedure computed tomography scan (n = 43) had no migrations, secondary procedures, or adverse clinical events over a 2-year follow-up period.

CONCLUSIONS

Iliac fixation, along with proximal aortic fixation, is an important factor in preventing the migration of stent grafts that have longitudinal columnar support. Patients with good iliac fixation did not experience migration even in the presence of suboptimal proximal aortic fixation. Close proximity of the distal end of the stent graft to the iliac bifurcation seems to provide stability against migration.