Morphometry and classification in abdominal aortic aneurysms: patient selection for endovascular and open surgery

Degradation Phenomena on "Homemade" Explanted Aortic Textile Endografts

Objective

In the 1990s, the concept of “homemade” endografts (EGs) using commercially available materials was proposed in clinical practice for endovascular abdominal aortic repair (EVAR). The aim of this study was to analyse the ageing phenomena of these EGs in light of explant analyses.

Methods

The study focused on five explanted homemade EGs collected from 2012 to 2014. The explants were assessed in accordance with the ISO 9001/13485 certified standard protocol, which included naked eye evaluation, organic remnant cleaning, and microscopic and endoscopic examinations and analysis (magnification range from 20% to 200%). The observations report followed a classification based on 12 features assessing the fabric cover, the stitch filament, and the stents.

Results

The reasons for explantation were type 1 endoleak in three cases and aneurysm sac growth in two. The implantation duration ranged from 56 to 202 months. Sixty three per cent of the fabric surface lesions (holes and tears) were related to abrasion between the fabric and the stents. Up to 33% of the knots used to connect adjacent stents were broken on one EG. Other defects including running suture rupture and stent corrosion were also observed. The overall hole cumulated surface ranged from 0.377 mm² (56 month of implantation) up to 3.21 mm² (78 month of implantation).

Conclusion

In this study, various ageing phenomena on homemade textile EGs were identified and classified. The main damaging mechanisms were related to abrasion stress leading to tears and holes in the fabric, stitch ruptures, and detachment of stent segments responsible for serious EG deformations and further degradation.

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Main homemade endografts damaging mechanisms are related to abrasion stress (friction wear).

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Abrasion stent–metal, knot ruptures, and kinking phenomena were associated.

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Some damaging mechanisms were related to the creation technique (one piece stent skeleton).

[Endovascular treatment of common iliac artery aneurisms]

OBJECTIVE

To demonstrate endovascular management of common iliac artery aneurysms with iliac branch devices and to discuss some technical aspects of these interventions including bilateral procedures.

MATERIAL AND METHODS

Endovascular abdominal aortic aneurysm repair with concomitant implantation of iliac branch devices was performed in 9 patients at the Petrovsky National Research Center of Surgery for the period from January 2019 to December 2020. Mean age of patients was 64.8± years (min 52; max 72 years). Preoperative planning and morphometric analysis were based on CT data with a slice thickness of 1 mm. Angiographic reconstruction was made using Osirix 3D software (OsiriX Foundation, Geneva, Switzerland). Abdominal aortic aneurysm was combined with common iliac artery aneurysm in 7 patients (77.7%). Three (33.3%) patients had isolated common iliac artery aneurysm without significant abdominal aorta enlargement (Reber type I). Bilateral common iliac artery aneurysms were detected in 1 (11.1%) patient. All patients had iliac artery aneurysms over 4 cm. Iliac branch device implantation was accompanied by endovascular abdominal aneurysm repair in all patients.

RESULTS

Technical success rate was 100%. Six-month results were followed-up in 5 patients (55.5%), annual outcomes - in 2 patients (22.2%). Control examination consisted of a telephone interview, ultrasound of abdominal aorta, pelvic and lower limb arteries and computed tomography. All patients had no endoleaks, stent-graft thrombosis, as well as signs of ischemia of pelvic organs and lower extremities. Incidence of iliac artery aneurysm combined with abdominal aortic aneurysms is about 20%. Until recently, treatment of these patients was performed exclusively with covering of internal iliac artery. Improvement of technologies and development of iliac branch devices made it possible to preserve blood flow in internal iliac artery after endovascular management. This approach allowed avoiding of ischemic complications associated with embolization of internal iliac arteries.

Proximal Aortic Neck Progression: Before and After Abdominal Aortic Aneurysm Treatment

Several risk factors including short or highly angulated proximal aortic neck have been associated with long-term outcomes after endovascular or open abdominal aortic aneurysm (AAA) repair. However, research data have emerged recently concerning the behavior of proximal aortic neck, and several authors have tried to evaluate this behavior after endovascular or open repair. Additionally, computed tomography angiography (CTA) remains the golden standard for detecting and observing the morphology of an AAA, both before and after treatment. Moreover, the question of whether the proximal neck’s progression independently affects postoperative morbidity and reintervention risks still remains. Therefore, this focused review aims to present all relevant data on the behavior of an AAAs neck, based on CTA imaging before and after repair, in order to produce useful conclusions for future clinical practice.

Endovascular vs Open AAA Repair: Does Size Matter?

Since the natural tendency of the aorta is to increase in diameter and tortuosity with age and since abdominal aortic aneurysms (AAAs) increase in diameter and length over time, encroaching on the renal and hypogastric orifices, early repair of AAAs (when =4.0 cm) may allow greater applicability of the endovascular option because of more favorable aortoiliac morphology. Patients who present at an older age with larger AAAs should be more likely to be anatomically excluded from endovascular AAA repair. Over a 42-month period, 317 consecutive patients referred with aortoiliac aneurysms (infrarenal AAA =4.0 cm) were evaluated by one of the authors (SGL) for endovascular vs open repair based on computed tomography (CT) and angiographic imaging. The 10 anatomic exclusion criteria were those applicable to the Zenith ® endograft (Cook, Inc), which currently is the most anatomically inclusive of the aortic endografts in commercial use in the United States. Based on their aortoiliac morphology, 212 patients were excluded from endovascular repair and 105 were included as acceptable anatomic candidates. Age, AAA size, and the reason(s) for exclusion were recorded for each patient. By use of Student's t test and logistic and linear regression analyses, the groups were compared by age, AAA size, and age + size. There was no significant difference in patient age or AAA size distribution between the group of patients excluded from endovascular repair based on aortoiliac morphology compared to those who met the inclusion criteria. Patients with small AAAs (4.0–5.4 cm) had similar age distribution as those with large (=5.5 cm) AAAs. The majority of patients (87%) were excluded based on proximal aortic neck morphology. The presence of aortoiliac morphology that precludes endovascular repair is independent of patient age or AAA size at presentation. A patient presenting with a small (4.0–5.4 cm) AAA is not more likely to be a candidate for endovascular repair than a patient with a large AAA.

Endovascular aneurysm repair with the Ovation TriVascular Stent Graft System utilizing a predominantly percutaneous approach under local anaesthesia

OBJECTIVE

To present our experience with the Ovation Abdominal Stent Graft System (TriVascular Inc., Santa Rosa, CA) during endovascular aneurysm repair (EVAR) and compare results according to the type of anaesthesia.

METHODS

We conducted a single-centre retrospective study including patients who underwent EVAR using the Ovation endograft between May 2011 and July 2014. Outcome was evaluated regarding pre-, peri- and immediate postoperative and follow-up measures. Overall results are reported, while additional analysis was performed to compare the outcome between groups of patients undertaking either local or regional/general anaesthesia (LA vs RGA).

RESULTS

66 patients were included. Median follow-up was 13 months (range, 1-39 months). Median age was 72 years and median abdominal aortic aneurysm diameter was 58 mm (range, 54-100 mm). Technical success was 63 (95%), while there were 2 (3%) conversions to open surgery. A total percutaneous approach was used in 50/66 (76%) cases. Overall, 9/66 (14%) subjects suffered from any kind of morbidity. Median hospitalization was 3 days (range, 1-16 days). Immediate and midterm mortality rate was 0%. No endoleak Type I, III, IV or stent migration was observed. There were 8 (13%) Type II endoleaks. Overall, additional endovascular procedures were required in 6 (9%), while surgery was performed in 4 (6%) patients. 44 (67%) patients underwent LA and 22 (23%) RGA. Differences between groups were significant for procedural time (85 vs 107 min; p < 0.001), percutaneous access (91% vs 45%; p < 0.001) and systematic complications (2.3% vs 14%; p = 0.05).

CONCLUSION

EVAR with the use of the Ovation endograft shows promising short-term and midterm results regarding safety and effectiveness. Completion of the procedures under LA using a total percutaneous approach seems advantageous and may be used in routine practice.

ADVANCES IN KNOWLEDGE

The Ovation Abdominal Stent Graft System is an ultra-low profile stent graft system that allows percutaneous deployment for EVAR and offers excellent overall efficacy and safety. Totally percutaneous EVAR under LA seems advantageous and may be used as a routine with this specific endograft.

Differential gene expression in the proximal neck of human abdominal aortic aneurysm

OBJECTIVE

Abdominal aortic aneurysm (AAA) represents a common cause of morbidity and mortality in elderly populations but the mechanisms involved in AAA formation remain incompletely understood. Previous human studies have focused on biopsies obtained from the center of the AAA however it is likely that pathological changes also occur in relatively normal appearing aorta away from the site of main dilatation. The aim of this study was to assess the gene expression profile of biopsies obtained from the neck of human AAAs.

METHODS

We performed a microarray study of aortic neck specimens obtained from 14 patients with AAA and 8 control aortic specimens obtained from organ donors. Two-fold differentially expressed genes were identified with correction for multiple testing. Mechanisms represented by differentially expressed genes were identified using Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Some of the differentially expressed genes were validated by quantitative real-time PCR (qPCR) and immunohistochemistry.

RESULTS

We identified 1047 differentially expressed genes in AAA necks. The KEGG analysis revealed marked upregulation of genes related to immunity. These pathways included cytokine-cytokine receptor interaction (P = 8.67*10(-12)), chemokine signaling pathway (P = 5.76*10(-07)), and antigen processing and presentation (P = 4.00*10(-04)). Examples of differentially expressed genes validated by qPCR included the T-cells marker CD44 (2.16-fold upregulated, P = 0.008) and the B-cells marker CD19 (3.14-fold upregulated, P = 0.029). The presence of B-cells in AAA necks was confirmed by immunohistochemistry.

CONCLUSIONS

The role of immunity in AAA is controversial. This study suggests that immune pathways are also upregulated within the undilated aorta proximal to an AAA.

Placement of endovascular stent across the branching arteries: long-term serial evaluation of stent-tissue responses overlying the arterial orifices in an experimental study

PURPOSE

This study was designed to investigate the effects of stenting across the branching arteries on the patency and stent-tissue responses over the branching arterial orifices.

METHODS

Thirteen dogs were observed after placing aortic stents across the celiac arteries (CA), superior mesenteric arteries (SMA), and renal arteries (RA). The animals were grouped according to stent types: large-cell group (n = 6) and small-cell group (n = 7). Angiography was performed to evaluate the branching artery patency at 2, 6, and 12 months after stent insertion, and the stent-tissue responses covering the orifices were evaluated on histopathologic examination.

RESULTS

All branching arteries were patent on follow-up angiography; however, three patterns of stent-tissue responses over the orifices were observed: neointimal layering, bridging septa, and papillary hyperplasia. Although neointimal layering and bridging septa were evenly observed, severe papillary hyperplasia was more frequent at SMA and CA than RA. Four RA showed less than 50% ostial patency, and localized infarct was observed in six kidneys (24%). The ostial patency tended to decrease with small-cell stent during the follow-up period.

CONCLUSIONS

Various stent-tissue responses over the branching artery orifices are induced by the aortic stent covering the branching arteries and may not be easily detected by conventional angiography. Subclinical renal infarct also may occur despite patent renal angiography.

Endovascular repair of abdominal aortic aneurysms: only a mechanical solution for a biological problem?

Endovascular aneurysm repair has matured significantly over the last 20 years and is becoming increasingly popular as a minimally invasive treatment option for patients with abdominal aortic aneurysms (AAA). Long-term durability of this fascinating treatment, however, is in doubt as continuing aneurysmal degeneration of the aortoiliac graft attachment zones is clearly associated with late adverse sequelae. In recent years, our growing understanding of the physiopathology of AAA formation has facilitated scrutiny of various potential drug treatment concepts. In this article we review the mechanical and biological challenges associated with endovascular treatment of infrarenal AAAs and discuss potential approaches to ongoing aneurysmal degeneration, which hampers long-term outcomes of this minimally invasive therapy.

Long-term results of balloon-expandable LifePath endografts in abdominal aortic aneurysm: a single-center experience

OBJECTIVE

This retrospective single-center study analyzed long-term results after LifePath (Edwards Lifesciences LLC, Irvine, Calif) endoprosthesis implantation for abdominal aortic aneurysm (AAA), primarily focusing on the wire form fracture issue and consecutive endoleak rate.

METHODS

Between 1999 and 2004, all consecutive patients with LifePath AAA devices in our institution were included in the retrospective analysis. All patients had computed tomography angiography (CTA) imaging preoperatively and image postprocessing. The follow-up using CTA imaging specifically addressed material fatigue (wire form fractures) resulting in migrations and type I endoleaks.

RESULTS

During the 6-year study period, which included the 1-year withdrawal and redesign of the device, 51 patients were treated with LifePath AAA endografts. The 30-day mortality was 0%. The perioperative 30-day morbidity was 9.8%. One patient required a primary conversion due to misdeployment of the iliac limbs within the graft main body. The primary endoleak rate was 20.56% (type I, 2%; type II, 19.6%). During the mean follow-up of 40.7 months, 12 patients died, six were lost to follow-up, and 32 underwent subsequent CTA imaging. Eight patients (25%) demonstrated a proximal type I endoleak, seven (22%) had a type II endoleak, and three had a type III endoleak (9%). In nine patients (28.1%), wire form fractures could be detected at image postprocessing. Four patients required a secondary conversion due to endoleak and aneurysm growth (2 type I endoleaks and 2 type III endoleaks).

CONCLUSION

Wire form fracture is the major structural problem in the LifePath balloon-expandable endograft device, resulting in a significant endoleak rate. We must caution those patients with a LifePath device in-situ that careful follow-up must be performed due to material fatigue and they should consider secondary conversion.

Total laparoscopic repair of abdominal aortic aneurysm with short proximal necks

With the development of endovascular aneurysm repair, abdominal aortic aneurysms with short infrarenal necks (< or =10 mm, AAASN) are considered juxtarenal aneurysms. Minimally invasive treatment consists of hybrid procedures or fenestrated endografts. We present our experience with direct aortic repair for AAASN performed via a total laparoscopic approach. Data are expressed as median values with extremes. From February 2002 to December 2007, 32 patients had total laparoscopic AAASN repair. Length of the infrarenal aortic neck was 5 mm (0-10). Median age of the 29 men and three women was 70 years (range 50-84). Nine patients presented with preoperative grade 1 renal insufficiency (28.1%). The procedure was totally laparoscopic in 30 patients (93.7%). Aortic approaches included left retrorenal (n = 24) and transperitoneal left retrocolic (n = 8) exposures. Median operative and clamping times were 270 (range 215-410) and 83 (range 36-147) min, respectively. Aortic clamping was suprarenal in 14 cases (43.7%), with suprarenal clamping time of 24 min (range 9-37). Median blood loss was 850 mL (range 215-2,400). Thirty-day mortality was 3.1% (one patient died from myocardial infarction). Two patients presented with severe systemic complications (6.4%, postoperative coagulopathy with hemorrhagic syndrome, pneumopathy). Seventeen patients developed mild or moderate systemic nonlethal complications (53.1%): transient renal insufficiencies (n = 12), grade 1 ischemic colitis (n = 1), surrenal insufficiency (n = 1), myocardial ischemia (n = 1), and cardiac arythmia (n = 2). One patient was reoperated for an intestinal obstruction. Liquid diet was reintroduced after 1 day (range 1-13). Most patients were ambulatory by day 3 (range 2-17). Median lengths of stay were 48 hr (range 12-552) in the intensive care unit and 10 days (range 4-37) in the hospital. With a median follow-up of 27 months (range 1-50), 28 patients are alive, with complete recovery without graft anomalies. Three patients died, from pneumopathy (n = 1) and carcinoma (n = 2), respectively, at 29, 19, and 44 months' follow-up. Two patients presented stable juxta-renal aortic dilation <35 mm. Total laparoscopic juxtarenal AAA repair is feasible and worthwhile for patients with AAASN. Short- and midterm results match well with those of open surgery. Total laparoscopic repair in AAASN reduces the trauma of extensive surgical approaches. Based on these encouraging early results, we elected to perform laparoscopy whenever possible in good surgical risk patients with AASN.

[Infrarenal aortic aneurysm]

An abdominal aortic aneurysm is defined as the increase of infrarenal aortic diameter of 3.0 cm and more. Infrarenal aortic aneurysm is frequent in the elderly and causes 1-3% of all deaths among men aged between 65 and 85 years. These aneurysms are typically asymptomatic until the life threatening event of rupture. Therefore screening of risk populations like elderly persons and persons with cardiovascular risk factors for aortic aneurysm seems to be most important. An aortic aneurysm is usually detected by sonography. An infrarenal aortic aneurysm with a diameter of 5.0-5.5 cm should be treated either with open surgical or endovascular therapy. If surgical or endovascular therapy is indicated, additional computer tomography (CT) or magnet resonance imaging (MRI) are necessary. The mode of treatment mainly depends on patient co-morbidity and on morphology of the aneurysm according to the CT/MRI-findings and should be determined individually.

EVAR of aortoiliac aneurysms with branched stent-grafts

INTRODUCTION

Branched iliac stent-grafts (bSG) have recently been developed in order to preserve internal iliac artery (IIA) flow in patients with aneurysmal or short common iliac arteries. The aim of this study is to evaluate a single-center experience with bSG for the IIA.

METHODS

Twenty-two male patients (70 (IQR 65-79) years old) underwent EVAR with 23 bSG (1 bilateral repair) between September 2002 and August 2007. Median AAA diameter was 52 (37-60) mm while common iliac diameter on the side of the bSG was 34 (27-41) mm. Two in-house modified Zenith SG and subsequently 21 commercially available bSG (18 Zenith Iliac Side and 3 Helical Branches) were used. Follow-up (FU) included CT at one month and yearly thereafter. Data was prospectively entered in a database.

RESULTS

Primary technical success was 91% (21 bSG). Median FU duration was 20 (8-31) months. One patient (5 %) died after discharge from acute myocardial infarction on day 13. Another patient died 30 months after EVAR of an unrelated cause. The overall bSG patency was 74% due to 6 branch occlusions (2 intraoperative and 4 late). All patients with patent bSG were asymptomatic. Three occlusions were asymptomatic findings on CT, while the other three developed claudication (two patients with contralateral IIA occlusion and one with simultaneous occlusion of the external iliac). One patient (5%) developed an asymptomatic type III endoleak at 1 month and was successfully treated with a bridging SG. Overall, four patients (18%) required reinterventions (1 bilateral stenting of the external iliac arteries, 1 external and 1 internal SG extensions and 1 femoro-femoral cross-over bypass). Nine out of 16 patients (56%) with CT-FU>/=1 year had shrinking aneurysms. There were no postoperative aneurysm expansions.

CONCLUSIONS

EVAR of aortoiliac aneurysms with IIA bSG is a good alternative to occlusion of the IIA in patients with challenging distal anatomy.

Use of dynamic computed tomography to evaluate pre- and postoperative aortic changes in AAA patients undergoing endovascular aneurysm repair

PURPOSE

To utilize dynamic computed tomographic angiography (CTA) on pre- and postoperative endovascular aneurysm repair (EVAR) patients to characterize cardiac-induced aortic motion within the aneurysm neck, an essential EVAR sealing zone.

METHODS

Electrocardiographically-gated CTA datasets were acquired utilizing a 64-slice Philips Brilliance CT scanner on 15 consecutive pre- and postoperative AAA patients. Axial pulsatility measurements were taken at 2 clinically relevant levels within the aneurysm neck: 2 cm above the highest renal artery and 1 cm below the lowest renal artery. Changes in aortic area and diameter were determined.

RESULTS

Significant aortic pulsatility exists within the aneurysm neck during the cardiac cycle. Preoperative aortic area increased significantly, with a maximum increase of up to 12.5%. The presence of an endograft did not affect aortic pulsatility (p=NS). Postoperative area also changed significantly during a heart cycle, with a maximum increase of up to 14.5%. Diameter measurements demonstrated an identical pattern, with significant pre- and postoperative intracardiac pulsatility within and above the aneurysm neck (p<0.05). An increase in maximum diameter change up to 15% was evident.

CONCLUSION

Patients undergoing EVAR experience aortic diameter changes within and above the aneurysm neck. The presence of an endograft does not abrogate this response to intracardiac pressure changes. Static CT imaging may not adequately identify patients with large aortic pulsatility, potentially resulting in endograft undersizing, stent-graft migration, intermittent type I endoleaks, and poor patient outcomes. The current standard regime of 10% to 15% oversizing based on static CT may be inadequate for some patients.

Pathology, natural history and treatment of abdominal aortic aneurysms

With increasing age of the population and improvement of diagnostic tools, the incidence of abdominal aortic aneurysms (AAA) has been rising steadily. Despite an improvement in operative and interventional treatment options, AAA is the cause of death in 1-3% of men over 65 years of age in industrial countries, mostly due to rupture [1]. Therefore, routine screening for AAA by ultrasonography has been postulated in the past: a 60 year old man with an abdominal aortic diameter of less than 3 cm has a life-time risk of developing AAA close to zero. However, routine screening has not been found to be cost effective. Despite of the results of two well-designed studies, the limits of AAA qualifying the patient for surgery or intervention in contrast to conservative treatment is still a matter of debate. The present review article summarizes the current knowledge of the pathology, incidence, risks, natural course as well as symptoms and current treatment strategies of AAA on the basis of the recent literature.

Mid-term results of endovascular aneurysm repair with branched and fenestrated endografts

PURPOSE

The technique of fenestrated and branched endovascular aneurysm repair (EVAR) has been used for the treatment a variety of aortic aneurysms. Although technically successful, longer-term results have been lacking. This article reports on the mid-term results of aneurysm repair with fenestrated and branched endografts from a European center with a large endovascular experience.

METHODS

Between 2001 and 2005, 38 patients were prospectively enrolled in a single institution, investigational device protocol database. Indications for fenestrated or branched EVAR included unfavorable anatomy for traditional EVAR and an abdominal aortic aneurysm >5.5 cm in maximum diameter. Customized stent-grafts were either fenestrated or branched and based on the Zenith system. Data were analyzed on an intention-to-treat basis. Differences between groups were determined using analysis of variance with P < .05 considered significant.

RESULTS

The mean (SD) follow-up was 25.8 +/- 12.7 months (median, 25.0 months; range, 9 to 46 months), and no patients were lost to follow-up. All cause mortality was 13% (5/38), with all deaths occurring within the first postoperative year; 30-day mortality was 2.6%. No patient died during the operation. Completion angiography demonstrated successful sealing in 37 of 38 patients and an overall operative visceral vessel perfusion rate of 94% (82/87). Cumulative visceral branch patency was 92% at 46 months. Stent occlusions, when they did occur, all happened within the first postoperative year. All postoperative occlusions occurred in unstented fenestrations or scallops. No occlusions occurred in stented vessels. The difference in serum creatinine preoperatively and postoperatively at 6 months, 1, 2, and 3 years was not significant (P = NS). No patient required dialysis. The aneurysm sac size decreased significantly during the first year and then remained stable (P < .05). Limb perfusion as assessed by the ankle/brachial index was not affected by the presence of a fenestrated or branched endograft.

CONCLUSIONS

The intermediate-term results of fenestrated and branched endografts support their continued use in patients with anatomic contraindications for standard EVAR. Close surveillance is mandatory for early identification of visceral or branched vessel stenosis and preocclusion. All cases of failure appear to occur during the first year and then level off in subsequent longer-term follow-up. This includes death, secondary interventions, branch vessel patency, and complications. As the procedure matures, long-term results and randomized clinical trials will ultimately be required to determine the safety, efficacy, and stability of this system.

The Endowedge and Kilt Techniques to Achieve Additional Juxtarenal Seal during Deployment of the Gore Excluder Endoprosthesis

The proximal 4 mm of the Gore Excluder endoprosthesis are scalloped. Our purpose is to describe our initial experience of a novel technique, referred to as the "endowedge," that takes advantage of this scalloped configuration in aneurysms with short proximal necks. The technique utilizes a balloon in the renal artery to aid alignment of a scallop and allow additional juxtarenal seal. A retrospective review of aneurysms treated with the endowedge technique at our institution was initiated. Renal balloons were placed via the brachial approach. Excluder endografts were deployed by flowering the first one or two rings, then advancing upward against the inflated balloon during completion of deployment. In patients with dumbbell-shaped morphology, an aortic cuff was deployed in the distal seal zone prior to the main body (kilt technique). Eight patients were identified, three of whom underwent an adjuvant kilt procedure. Average preoperative proximal neck length was 8.5 mm (range 6-12). Average additional juxtarenal seal was 2.3 mm. Mean follow-up was 5 months (range 2.5 weeks to 9 months). There were no type I endoleaks. There were two type II endoleaks. Average aneurysm size decreased from 6.0 to 5.5 cm. No aneurysm has enlarged or ruptured. We conclude that the endowedge technique allows additional juxtarenal seal during endograft placement. Our early results suggest that this technique may allow for safe treatment of aneurysms with short necks.

Dynamic magnetic resonance angiography of the aneurysm neck: Conformational changes during the cardiac cycle with possible consequences for endograft sizing and future design

OBJECTIVE

Proper proximal fixation and stent-graft sealing within the aneurysm neck are critical for endovascular aneurysm repair (EVAR) durability. Computed tomography angiography (CTA) is the gold standard for preoperative sizing of endograft diameters, but the accuracy of these measurements is uncertain because they rely on static images of a dynamic process. The aortic configuration and diameter may change during the cardiac cycle. We studied these phenomena using dynamic electrocardiograph-triggered magnetic resonance angiography (MRA).

METHODS

Eleven consecutive EVAR patients were included. Dynamic MRA was used to perform preoperative and postoperative measurements. Changes were measured in transverse aortic sections 10 mm below the lowest renal artery (level A), at the level of the renal arteries (level B), and 3 cm above the lowest renal artery (level C). Data were analyzed using image segmentation software. Aortic area and diameter changes along 256 axes were determined.

RESULTS

Dynamic MRA demonstrated significant aortic area changes during the cardiac cycle before and after EVAR at all three measured levels. Pre-EVAR aortic area significantly increased per cardiac cycle: 8.4% at level A; 9.3% at level B; and 13.3% at level C (P < .001 for all levels). Post-EVAR aortic area increased 9.7% at level A, 9.6% at level B, and 15.8% at level C per cardiac cycle (P < .001 for all levels). Significant diameter changes during cardiac cycles were also observed at all three levels. Pre-EVAR mean diameter changed up to 8.9% (P < .001) compared with post-EVAR aortic changes of up to 11.5% (P < .001). EVAR had no effect on change in aortic area and diameter. Dynamic MRA also demonstrated that pulsatile aortic distension was not equal in all axes, but rather occurred as an asymmetrical expansion and contraction.

CONCLUSION

In patients with (atherosclerotic) aneurysm disease, the aortic dimensions at the level of and proximal to the aneurysm neck change during the cardiac cycle. This phenomenon is preserved after EVAR. Therefore, maximum diameter using dynamic MRA may not be similar to the maximum diameter with static CTA in all patients, and a standard regimen of 10% to 15% oversizing of an endograft based on static CTA images may be inadequate for some patients. Further studies using dynamic MRA to evaluate effects of different endografts are anticipated, with possible consequences for endograft designs.

Dynamic CE-MRA for Endoleak Classification after Endovascular Aneurysm Repair

AIM

To evaluate the value of dynamic contrast enhanced magnetic resonance angiography (CE-MRA) for classification of endoleaks after endovascular aneurysm repair (EVAR).

MATERIALS AND METHODS

Twenty-eight patients, between 2 days and 54 months after EVAR, were evaluated with CTA, MRI and dynamic CE-MRA. The additional diagnostic value of the dynamic 3D CE-MRA was evaluated by determining the ability of the dynamic series in pinpointing the site of inflow of an endoleak.

RESULTS

An endoleak was detected in 23 patients. Seventeen of the 23 dynamic series were technically successful (no disturbing artifacts limiting the diagnostic value). Using MRI our findings were: 2 type I, 6 type II, 1 type III, no type IV endoleaks and in 14 cases classification could not be made. The classification results for MRI plus the dynamic CE-MRA were: 2 type I, 12 type II, 1 type III, no type IV endoleaks and in eight cases classification could not be made. In six cases the dynamic MRA allowed classification of the endoleak, which was not possible with the non-dynamic images alone (p=0.091, Fisher exact).

CONCLUSION

This pilot study shows that dynamic CE-MRA can have additional value in the classification of endoleaks. Dynamic CE-MRA might obviate the need for diagnostic digital subtraction angiography and aid planning for intervention.

Endovascular repair of abdominal aortic aneurysms: CTA evaluation of contraindications

Endovascular aortic aneurysm repair (EVAR) is considered an acceptable alternative to open surgery in selected patients. Its feasibility depends mainly on anatomic factors that represent the important predictors of success and the most important exclusion criteria. Poor anatomic patient selection is generally associated with a higher risk for procedural complications and compromised long-term outcomes. Therefore pretreatment imaging is crucial for evaluating patient suitability for EVAR. Multidetector computed tomographic angiography represents the current standard of reference in the evaluation of the abdominal aorta and iliac axis anatomy because it provides all the details needed for selection of patients who are suitable for endograft and the choice of the appropriate device. This report identifies and reviews computed tomographic angiographic anatomic contraindications for EVAR.

Midterm Survival After Endovascular Versus Open Repair of Infrarenal Aortic Aneurysms

PURPOSE

To report the midterm survival after endovascular repair (ER) of infrarenal aortic aneurysms and to compare the outcomes to contemporaneous patients treated with open repair (OR).

METHODS

Between January 1995 and December 2001, 498 patients were treated for abdominal aortic aneurysm: 289 (52%) underwent OR and 209 (48%) underwent ER at a single center. Preoperative risk factors were graded according to the SVS/AAVS risk stratification. A computerized database was used to record demographic, clinical, and follow-up data.

RESULTS

Significant benefits (p<0.0001) were observed in the ER group in terms of mean procedural time (163+/-66 versus 132+/-61 minutes), mean blood loss (1268+/-923 versus 122.5+/-284 mL), and mean hospital length of stay (16.24+/-13.3 versus 9.3+/-11.6 days). The perioperative mortality for OR and ER patients were, respectively, 5.1% and 1.5% (p=0.04). The mean follow-up was 40 months in the OR group (range 0-85) and 19 months in the ER group (range 2-80). Contact was lost with 31 (6%) patients during the study. No overall survival advantage was observed for OR over ER, and comparison of OR and ER according the risk classifications did not yield any significant differences. No patients died of aneurysm rupture, but 7 ER patients had to be converted to open surgery. The cumulative freedoms from reinterventions at 4 years for the OR and ER groups, respectively, were 87% and 63% (p=0.001). Patients treated by OR had better clinical success (p=0.001). Patients in the ER group without iliac artery aneurysm showed a significant improvement (p=0.035) over patients with aneurysmal iliac arteries.

CONCLUSIONS

Over the 7 years of this study, ER realized its goal: prevention of aneurysm rupture. Despite a greater number of reinterventions for ER patients, no overall survival difference was observed.

Multidetector CT Angiography Versus Digital Subtraction Angiography for Aortoiliac Length Measurements Prior to Endovascular AAA Repair

PURPOSE

To assess observer variation between calibrated-catheter digital subtraction angiography (DSA) and software-enhanced multidetector computed tomography angiography (CTA) in measuring vessel length prior to endovascular aortic aneurysm repair (EVAR).

METHODS

Thirty patients (25 men; mean age 65 years, range 61-85) scheduled for EVAR underwent CTA in 4x2-mm collimation using advanced vessel analysis software. CTA measurements were performed twice by 2 blinded readers in random order with at least a 4-week interval between readings. Nine patients were found unsuitable for endovascular repair after the CTA, so DSA was performed in 21 patients for morphometric evaluation of the abdominal aorta and the iliac arteries. The following segments were measured: H1 (aneurysm neck), H2 (lower renal artery to distal aspect of the aneurysm), H3 (lower renal artery to aortic bifurcation), and H4a/H4b (lower renal artery to iliac bifurcations). Length measurements on DSA were made by (1) following the catheter path in the aortic lumen and (2) dividing tortuous vessel anatomy into segments and measuring each segment along an idealized centerline. Addition of the various segments allowed comparison with data obtained from CTA measurements.

RESULTS

CTA was performed with good intraobserver agreement for all length parameters except H3 in reader 2 (p<0.05). While good interobserver agreement was demonstrated for CTA over long aortoiliac distances (H4a, H4b), higher interobserver agreement was obtained with DSA for shorter segments (H1, H2). Considerable differences were observed between CTA and DSA for the lengths H2 and H4b.

CONCLUSIONS

CTA produces better intra and interobserver correlations in measuring vessel length than DSA. It has the potential to replace DSA as an imaging method before EVAR.

Suprarenal fixation of endograft in abdominal aortic aneurysm treatment: focus on renal function

OBJECTIVE

The objective of this work was to evaluate any variation of renal function detected by renal scintigraphy after the suprarenal fixation of endografts for abdominal aortic aneurysm (AAA) repair.

SUMMARY BACKGROUND DATA

In the few articles that have considered this problem, renal function was evaluated only by biochemical tests, which are inadequate in demonstrating small changes in renal function and in appreciating the worsening of a single kidney's function.

METHODS

Between April 1999 and May 2002, 47 patients with an inappropriate infrarenal proximal neck had a suprarenal fixation for AAA. To assess renal function, a technetium-99m diethylene triamine penta-acetic acid (TC-DTPA) perfusion scintigraphy was performed preoperatively on the third postoperative day and at 6, 12 months, and then yearly thereafter. Worsening of renal function was defined as a decrease of glomerular filtration rate (GFR) > or =20% (detected with Gates method). Serum creatinine level was tested preoperatively and at the first and third postoperative day.

RESULTS

Endograft deployment was technically successful in 44 patients (93.6%); clinical perioperative success was obtained in 46 patients (97.8%). In 12 patients (25.5%), a permanent reduction of the GFR was observed using postoperative TC-DTPA perfusion scintigraphy. By 99m TC-DTPA perfusion scintigraphy, a permanent reduction of GFR was observed postoperatively in 12 patients. A slight GFR reduction (<20%) was present in 7 (14.9%) patients, due to the planned occlusion of accessory renal arteries. A more significant GFR reduction (>20%) was present unexpectedly in 5 (10.6%) patients, in 3 of these a single kidney was involved, in 5 both with an increase of the serum creatinine level >20%.

CONCLUSIONS

Suprarenal fixation of endografts in AAA treatment is a safe procedure with good early and midterm procedural results and a risk of GFR impairment (>20%) of 10.6%.

Treatment of short-necked infrarenal aortic aneurysms with fenestrated stent-grafts: short-term results

INTRODUCTION

A proximal neck of 15 mm length is usually required to allow endovascular repair of abdominal aortic aneurysms (EVAR). Many patients have been refused EVAR due to a short neck. By customising fenestrated grafts to the patients' anatomy, we can offer an endovascular solution, especially for patients who are unsuitable for open repair.

METHODS

Eighteen patients were selected for fenestrated stent-grafting if they presented with an abdominal aneurysm of at least 55 mm in diameter, a short neck (less than 15 mm), plus contra-indications for open repair (cardiopulmonary impairment or a hostile abdomen). The stent-graft used was a customised fenestrated model based on the Cook Zenith composite system. We used additional stents to ensure apposition of the fenestrations with the side branches.

RESULTS

All endovascular procedures were successful. Out of the 46 targeted side branches (10 superior mesenteric arteries, 36 renal arteries), 45 were patent at the end of the procedure. One accessory renal artery became occluded by the stent-graft. There was one possible proximal type I endoleak, which later proved to be a type II endoleak. There was no mortality, but complications occurred in six patients: two cardiac complications, three urinary complications and one occlusion of a renal artery. At follow-up (mean 9.4 months, range 1-18), there were no additional renal complications and all the remaining targeted vessels stayed patent.

DISCUSSION

By customizing fenestrated stent-grafts, it is possible to position the first covered stent completely inside the proximal neck, thus achieving a more stable position. The additional side-stents may also contribute to a better fixation. This technique may become a valuable alternative for patients who are at high risk from open surgery.

Endovascular aneurysm repair with a bifurcated endovascular graft at a primary referral center: Influence of experience, age, gender, and aneurysm size on suitability

OBJECTIVE

The purpose of this study was to assess the suitability for endovascular repair of abdominal aortic aneurysm (EVAR) in an unselected patient population.

PATIENTS AND METHODS

Between February 1999 and May 2002 all consecutive patients with a nonemergent abdominal aortic aneurysm (AAA) were prospectively examined with contrast material-enhanced spiral computed tomography (CT). Those patients probably suitable for EVAR on the basis of CT findings underwent calibrated angiography. A panel of radiologists and vascular surgeons reviewed the clinical data and vascular anatomy, and decided on the appropriateness of EVAR with the bifurcated Zenith AAA endovascular graft.

RESULTS

One hundred seven patients were included. Fifty-six patients (52%) had one or more contraindications for EVAR. Unsuitability was most frequently (88%) related to the proximal neck. Inadequate neck length was the most common specific reason. Inadequate iliac anatomy was the reason for unsuitability in 59% of patients. The rate of unsuitability decreased from 61% during the first half of the study to 40% during the second half (P =.03) Unsuitability was equal between men and women. Age and maximum diameter did not differ between candidates and noncandidates.

CONCLUSION

Almost half (48%) of patients with an infrarenal AAA referred to a primary referral center are suitable for EVAR with the bifurcated Zenith AAA endovascular graft. Neck anatomy was the most frequent reason for rejection. Rate of suitability increased over time, probably as a result of increasing experience. Suitability was not influenced by gender, age, or aneurysm size.