Endovascular Repair of Juxtarenal and Pararenal Abdominal Aortic Aneurysms Using a Novel Low-Profile Fenestrated Custom-Made Endograft: Technical Details and Short-Term Outcomes

INTRODUCTION

The aim of this study is to share preliminary experiences and outcomes with a novel custom-made fenestrated TREO® Abdominal Stent-Graft System to treat juxtarenal and pararenal abdominal aortic aneurysms (AAAs).

METHODS

Juxtarenal and pararenal AAA patients treated with the custom-made fenestrated TREO® Abdominal Stent-Graft System were included from 4 high-volume European academic medical centers from June 2021 to September 2023. Technical success and 30-day/in-hospital mortality and complications were analyzed. Technical success was defined as successful endovascular implantation of the stent graft with preservation of antegrade flow to the target vessels, and absence of type 1 or 2 endoleak (EL) at the first postoperative computed tomography angiography (CTA).

RESULTS

Forty-two consecutive patients were included. The majority of the devices were constructed with 2 (N=4; 9.5%), 3 (N=9; 21.4%), or 4 (N=27; 64%) fenestrations. In 1 case, the device was constructed with a single fenestration (2.4%) and 1 device contained 5 fenestrations (2.4%); 17% had previous AAA repair. Target vessel cannulation with placement of a bridging stent was successful in all but 1 vessel (99, 3%). One aneurysm-related death occurred in the direct postoperative period and 2 limb occlusions necessitated reintervention during admission. In the median follow-up period of 101 (2-620) days, 3 more patients died due to non-aneurysm-related causes. Technical success was achieved in 90% of the cases. Nineteen ELs were seen on the first postoperative CT scan: 1 type 1b EL (N=1; 2%), 15 type 2 ELs (N=15; 36%), and 3 type 3 ELs (N=3%). Eleven patients received more than 1 CT scan during a median follow-up of 361 days (82-620): 3 type 2 ELs resolved and 1 type 3 EL was treated in this period. In the follow-up, 1 patient had a coagulation disorder that caused occlusions of the branches.

CONCLUSION

The results of the first experiences using the custom-made fenestrated TREO® Abdominal Stent-Graft System in Europe are promising. There was a low short-term mortality and morbidity rate in these patients of which 17% had previous AAA repair. Mid-term and long-term follow-up data are needed to evaluate endograft durability and performance.

CLINICAL IMPACT

This study shows the first experiences and short-term results of a novel low-profile custom-made device: the custom-made fenestrated TREO® Abdominal Stent-Graft System. Showing these results and experiences can help the physicians in clinical decision-making for their patients.

Intragraft Obstructive Thrombus Two Years After Endovascular Repair of Traumatic Aortic Injury: A Case Report and Review of the Literature

Introduction

Thoracic endovascular aortic repair (TEVAR) is the treatment of choice for blunt thoracic aortic injury (BTAI) and has proven to be a good alternative to open surgery. TEVAR requires less operation time, has fewer complications, can be used for relatively unstable patients, and is associated with a significantly lower mortality rate. Moreover, long term follow up data demonstrate low re-intervention rates and stentgraft failure.

Report

The case of a 21 year old man who sustained severe trauma, including a traumatic pseudoaneurysm of the descending thoracic aorta distal to the left subclavian artery in 2016, is presented. The patient was treated by TEVAR. Two years later, he presented with progressive paraplegia due to stentgraft occlusion occurring four days after a new high velocity motor vehicle accident. An axillofemoral bypass was performed to assure blood flow to the lower body. Two days later the stentgraft was removed via left thoracotomy and replaced by a Dacron graft. Gross examination showed severe thrombus formation at the proximal edge, and a thrombotic occlusion in the middle and distal third of the stent. After three months of hospitalisation the patient was discharged to a rehabilitation clinic with partial recovery of his paraplegia. As of June 2020, the patient was able to walk without assistance and his paraplegia improved with only loss of sensation of his lower legs.

Conclusion

A serious thrombotic complication two years after TEVAR is described. Although TEVAR is the currently preferred treatment for BTAI, more research is needed to examine the mechanisms behind this thrombotic complication and to elucidate whether TEVAR is definitive treatment or a “bridge to further surgery”. Smaller diameter stentgrafts, anticoagulation, regular (lifelong) follow up imaging, and prophylactic surgical conversion in (selected) patients might help to prevent this serious complication.

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Although thoracic endovascular aortic repair is the first choice treatment for blunt thoracic aortic injury, the cause of intragraft thrombus is unknown.

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Nine cases have been reported with thrombotic (near) occlusions of thoracic stentgrafts. This is the first reported total occlusion following a second trauma.

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Oversizing and trauma can potentially play a role in the formation and progression of obstructive thrombus in thoracic stentgrafts.

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Follow up is important to detect intragraft thrombus deposition and to prevent major complications by adjusting anticoagulation or performing prophylactic removal of thrombotic stentgrafts.

Editor's Choice - Nationwide Analysis of Patients Undergoing Iliac Artery Aneurysm Repair in the Netherlands

OBJECTIVE

The new 2019 guideline of the European Society for Vascular Surgery (ESVS) recommends consideration for elective iliac artery aneurysm (eIAA) repair when the iliac diameter exceeds 3.5 cm, as opposed to 3.0 cm previously. The current study assessed diameters at time of eIAA repair and ruptured IAA (rIAA) repair and compared clinical outcomes after open surgical repair (OSR) and endovascular aneurysm repair (EVAR).

METHODS

This retrospective observational study used the nationwide Dutch Surgical Aneurysm Audit (DSAA) registry that includes all patients who undergo aorto-iliac aneurysm repair in the Netherlands. All patients who underwent primary IAA repair between 1 January 2014 and 1 January 2018 were included. Diameters at time of eIAA and rIAA repair were compared in a descriptive fashion. The anatomical location of the IAA was not registered in the registry. Patient characteristics and outcomes of OSR and EVAR were compared with appropriate statistical tests.

RESULTS

The DSAA registry comprised 974 patients who underwent IAA repair. A total of 851 patients were included after exclusion of patients undergoing revision surgery and patients with missing essential variables. eIAA repair was carried out in 713 patients, rIAA repair in 102, and symptomatic IAA repair in 36. OSR was performed in 205, EVAR in 618, and hybrid repairs and conversions in 28. The median maximum IAA diameter at the time of eIAA and rIAA repair was 43 (IQR 38-50) mm and 68 (IQR 58-85) mm, respectively. Mortality was 1.3% (95% CI 0.7-2.4) after eIAA repair and 25.5% (95% CI 18.0-34.7) after rIAA repair. Mortality was not significantly different between the OSR and EVAR subgroups. Elective OSR was associated with significantly more complications than EVAR (intra-operative: 9.8% vs. 3.6%, post-operative: 34.0% vs. 13.8%, respectively).

CONCLUSION

In the Netherlands, most eIAA repairs are performed at diameters larger than recommended by the ESVS guideline. These findings appear to support the recent increase in the threshold diameter for eIAA repair.

Meta-analysis of individual-patient data from EVAR-1, DREAM, OVER and ACE trials comparing outcomes of endovascular or open repair for abdominal aortic aneurysm over 5 years

Background

The erosion of the early mortality advantage of elective endovascular aneurysm repair (EVAR) compared with open repair of abdominal aortic aneurysm remains without a satisfactory explanation.

Methods

An individual‐patient data meta‐analysis of four multicentre randomized trials of EVARversus open repair was conducted to a prespecified analysis plan, reporting on mortality, aneurysm‐related mortality and reintervention.

Results

The analysis included 2783 patients, with 14 245 person‐years of follow‐up (median 5·5 years). Early (0–6 months after randomization) mortality was lower in the EVAR groups (46 of 1393 versus 73 of 1390 deaths; pooled hazard ratio 0·61, 95 per cent c.i. 0·42 to 0·89; P = 0·010), primarily because 30‐day operative mortality was lower in the EVAR groups (16 deaths versus 40 for open repair; pooled odds ratio 0·40, 95 per cent c.i. 0·22 to 0·74). Later (within 3 years) the survival curves converged, remaining converged to 8 years. Beyond 3 years, aneurysm‐related mortality was significantly higher in the EVAR groups (19 deaths versus 3 for open repair; pooled hazard ratio 5·16, 1·49 to 17·89; P = 0·010). Patients with moderate renal dysfunction or previous coronary artery disease had no early survival advantage under EVAR. Those with peripheral artery disease had lower mortality under open repair (39 deaths versus 62 for EVAR; P = 0·022) in the period from 6 months to 4 years after randomization.

Conclusion

The early survival advantage in the EVAR group, and its subsequent erosion, were confirmed. Over 5 years, patients of marginal fitness had no early survival advantage from EVAR compared with open repair. Aneurysm‐related mortality and patients with low ankle : brachial pressure index contributed to the erosion of the early survival advantage for the EVAR group. Trial registration numbers: EVAR‐1, ISRCTN55703451; DREAM (Dutch Randomized Endovascular Aneurysm Management), NCT00421330; ACE (Anévrysme de l'aorte abdominale, Chirurgie versus Endoprothèse), NCT00224718; OVER (Open Versus Endovascular Repair Trial for Abdominal Aortic Aneurysms), NCT00094575.

Survival comparable

Individual Differences in Heparin Sensitivity and Their Effect on Heparin Anticoagulation During Arterial Vascular Surgery

OBJECTIVES

To investigate whether a fixed heparin dose results in adequate heparinisation levels and consequent inhibition of haemostatic activation in all patients.

METHODS

This prospective clinical pilot study included 24 patients undergoing arterial vascular surgery. Individual heparin responsiveness was assessed using the Heparin Dose Response (HDR) test, while the activated clotting time (ACT) and heparin concentration were measured to monitor the peri-procedural degree of anticoagulation. Finally, peri-operative haemostasis was evaluated with rotational thromboelastometry (ROTEM).

RESULTS

Eight patients were identified with reduced heparin sensitivity (RS group) and 16 patients with normal heparin sensitivity (NS group). Compared with the NS group, the RS group showed less prolonged ACTs after heparinisation with heparin concentrations below the calculated target heparin concentration. ROTEM revealed shorter clot formation times in the intrinsically activated coagulation test (INTEM) 3 min (114 ± 48 s vs. 210 ± 128 s) and 30 min after the initial heparin bolus (103 ± 48 s vs. 173 ± 81 s) in the RS group compared with the NS group. In the RS group, one patient developed a major thromboembolic complication.

CONCLUSIONS

This study shows that a third of the study population had reduced heparin sensitivity, which was associated with lower levels of heparinisation, and lower inhibition levels of clot initiation and clot formation. Identifying patients with reduced heparin sensitivity by monitoring the anticoagulant effect of heparin could decrease the risk of thrombotic complications after arterial vascular surgery.

Higher 30 Day Mortality in Patients with Familial Abdominal Aortic Aneurysm after EVAR

OBJECTIVES

To determine the influence of a positive family history for aneurysms on clinical success and mortality after endovascular aneurysm repair (EVAR).

METHODS

From 2009 to 2011, 1262 patients with abdominal aortic aneurysms (AAA) treated by EVAR were enrolled in a prospective, industry sponsored clinical registry ENGAGE. Patients were classified into familial and sporadic AAA patients according to baseline clinical reports. Clinical characteristics, aneurysm morphology, and follow-up were registered. The primary endpoint was clinical success after EVAR, a composite of technical success and freedom from the following complications: AAA increase >5 mm, type I and III endoleak, rupture, conversion, secondary procedures, migration, and occlusion. Secondary endpoints were the individual components of clinical success, 30 day mortality, and aneurysm related and all cause mortality.

RESULTS

Of the 1262 AAA patients (89.5% male and mean age 73.1 years), 86 patients (6.8%) reported a positive family history and were classified as familial AAA. Duration of follow-up was 4.4 ± 1.7 years. Patients with familial AAA were more often female (18.6% vs. 9.9%, p = .012). No difference was observed in aneurysm morphology. There was no significant difference in clinical success between patients with familial and sporadic AAA (72.1% vs. 79.3%, p=.116). Familial AAA patients had a higher 30 day mortality after EVAR (4.7% vs. 1.0%, adjusted HR 5.7, 1.8-17.9, p = .003) as well as aneurysm related mortality (5.8% vs. 1.3%, adjusted HR 5.4, 1.9-14.9, p = .001), while no difference was observed in all cause mortality (19.8% vs. 24.3%, adjusted HR 0.8, 0.5-1.4, p = .501).

CONCLUSIONS

The current study shows a higher 30 day mortality after EVAR in familial AAA patients. Future studies should determine the role of family history in AAA treatment, suitability for endovascular or open repair, and on adaptation of post-operative surveillance. For the time being, patients with familial forms of AAA should be considered at higher risk for EVAR and warrant extra vigilance.

Quality of life from a randomized trial of open and endovascular repair for abdominal aortic aneurysm

Background

Long-term survival is similar after open or endovascular repair of abdominal aortic aneurysm. Few data exist on the effect of either procedure on long-term health-related quality of life (HRQoL) and health status.

Methods

Patients enrolled in a multicentre randomized clinical trial (DREAM trial; 2000–2003) in Europe of open repair versus endovascular repair (EVAR) of abdominal aortic aneurysm were asked to complete questionnaires on health status and HRQoL. HRQoL scores were assessed at baseline and at 13 time points thereafter, using generic tools, the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36®) and EuroQol 5D (EQ-5D™). Physical (PCS) and mental component summary scores were also calculated. Follow-up was 5 years.

Results

Some 332 of 351 patients enrolled in the trial returned questionnaires. More than 70 per cent of questionnaires were returned at each time point. Both surgical interventions had a short-term negative effect on HRQoL and health status. This was less severe in the EVAR group than in the open repair group. In the longer term the physical domains of SF-36® favoured open repair: mean difference in PCS score between open repair and EVAR −1·98 (95 per cent c.i. −3·56 to −0·41). EQ-5D™ descriptive and EQ-5D™ visual analogue scale scores for open repair were also superior to those for EVAR after the initial 6-week interval: mean difference −0·06 (−0·10 to −0·02) and −4·09 (−6·91 to −1·27) respectively.

Conclusion

In this study EVAR appeared to be associated with less severe disruption to HRQoL and health status in the short term. However, during longer-term follow-up to 5 years, patients receiving open repair appeared to have improved quality of life and health status.

Renal function 5 years after open and endovascular aortic aneurysm repair from a randomized trial

Background

Deterioration of renal function after major vascular surgery is an important complication, and may vary between patients undergoing endovascular (EVAR) or open surgical (OR) repair of an abdominal aortic aneurysm (AAA). The objective was to determine the impact of OR and EVAR on renal function after 5 years.

Methods

This was a post hoc analysis of data collected prospectively from the Dutch Randomized Endovascular Aneurysm Management (DREAM) trial. Five years after surgery, creatinine levels were available for 189 patients (94 after OR and 95 after EVAR). The severity of renal disease was staged using the chronic kidney disease classification of the US National Kidney Foundation clinical guidelines.

Results

Using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, the estimated glomerular filtration rate (eGFR) for the entire group declined over time, with a mean(s.d.) preoperative value of 80·0(7·6) ml per min per 1·73 m2 compared with 75·7(9·7) ml per min per 1·73 m2 after 5 years (mean difference 4·2 (95 per cent confidence interval 3·2 to 5·3) ml per min per 1·73 m2; P < 0·001). Five years after surgery, the mean eGFR (CKD-EPI equation) was not significantly different between the OR and EVAR groups: 76·3(9·3) versus 75·1(10·0) ml per min per 1·73 m2 (mean difference 1·2 (−1·6 to 3·9) ml per min per 1·73 m2; P = 0·410).

Conclusion

Renal function 5 years after OR and EVAR for AAA was similar. Neither surgical procedure accelerated the loss of renal function. Registration number: NCT00421330 (http://www.clinicaltrials.gov).

Residual infrarenal aortic neck following endovascular and open aneurysm repair

BACKGROUND

The effectiveness of open and endovascular aneurysm repair of aortic abdominal aneurysms (AAAs) can be jeopardised by deterioration of the residual infrarenal neck of the aneurysm.

OBJECTIVE

The study aims to determine the length of the residual infrarenal aortic segment after endovascular and open aneurysm repair.

METHODS

In a multicentre randomised controlled trial comparing open and endovascular AAA repair, 165 patients were discharged after open AAA repair (OR) and 169 after endovascular repair (EVAR). Immediately after the operation, surgeons were asked to enter in the case record form whether the level of their anastomosis after open repair was within or beyond 10 mm of the caudal renal artery. Postoperative computed tomography (CT) scans that were obtained within 6 months after surgery were used for comparative analysis. The distance between the caudal renal artery and the proximal anastomosis of the (endo-) graft was measured using axial CT slices and a standardised protocol. CT images were available and suitable for analysis in 156 (95%) of 165 OR patients and in 160 (95%) of 169 EVAR patients. Data are presented as median (range). Differences were analysed using the Mann-Whitney test.

RESULTS

The distance from the caudal renal artery to the proximal anastomosis was 24 mm (16-30 mm) in the OR group versus 0 mm (0-6 mm) in the EVAR group (p < 0.0001, Mann-Whitney). In 140 of 156 (90%) patients, at least 1 cm of untreated infrarenal neck persisted after OR and in 17 of 160 (10%) after EVAR. In 84 of the 156 open repair patients (54%), the surgeon had indicated that the proximal anastomosis was within 10 mm of the caudal renal artery. Only five surgeons (6%) were accurate in this respect.

CONCLUSION

After open repair, a longer segment of the infrarenal aortic neck is left untreated compared with endovascular repair and this length is underestimated by most surgeons. Long-term studies are required to determine the consequences of this difference.

Decision making in AAA repair in 2012: open or endo?

With data from four randomized trials on elective endovascular abdominal aortic aneurysm repair and many more additional post-hoc publications, the evidence can be somewhat overwhelming for the surgeon, let alone the patient. This chapter aims to present the most recent and relevant data for decision making in abdominal aortic aneurysm (AAA) repair in a comparative and concise format. After a comparison of the short- and long-term survival data of the randomized trials, the following post-hoc analyses of the four randomized trials will be presented: causes of death, reinterventions, renal function, prediction of complications, and quality of life. When both open and endovascular repair are a reasonable option for an individual patient, we need to objectively inform our patient about the available evidence from the trials. The three-fold reduction of operative mortality with endovascular repair as compared to open repair should be presented. Next, the convergence of the overall survival curves should be discussed as a key factor in the decision process. The counterintuitive observation may be considered that if endovascular repair is better for any specific subgroup it is for younger patients with low surgical risks. Finally, the patient needs to understand that the risks of reintervention and complications are higher after endovascular than after open repair and that this is even more relevant in older patients with larger aneurysms. The information that the quality of life advantage of endovascular repair is only short lived and for several domains surpassed by open repair is most likely not suitable for direct discussion with the individual patient, but it may put the procedures in the right perspective for the physician and health care managers.

Validation of the Simulator for Testing and Rating Endovascular SkillS (STRESS)-machine in a setting of competence testing

AIM

Endovascular skills are an integral part of modern-day vascular surgery. The STRESS machine has been developed to test these skills in vascular surgeons. This study aims to define an optimal pass/fail cutoff value for the STRESS test score.

METHODS

The STRESS machine consists of a dry glass model of the abdominal aorta and its tributaries with various stenotic lesions, elongations, and tortuosities. A camera and computer software are used to simulate plain fluoroscopy-mode. The test subjects are given two assignments after which two reviewers use a combination of the ICEPS and MRS to produce the final total score; 43 subjects were tested. According to previous endovascular experience, subjects were classified into four groups: novice-low (no experience, less than 11 performed procedures, less than 50 assisted procedures), novice-high (11-25 performed procedures, more than 50 assisted procedures), intermediate (1-10 performed and >11-25 assisted procedures, 11-25 performed and >1-10 assisted procedures or 25-50 performed procedures) and advanced (more than 50 performed procedures).

RESULTS

Test-score and noted experience showed a correlation of 0.794. All intermediate and advanced test subjects scored more than 50 points compared to 4 out of 15 novices.

CONCLUSION

We demonstrated that it is possible to determine an optimal cut-off value for competence testing with the STRESS machine.

Association of the TGF-beta receptor genes with abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a multifactorial condition. The transforming growth factor beta (TGF-beta) pathway regulates vascular remodeling and mutations in its receptor genes, TGFBR1 and TGFBR2, cause syndromes with thoracic aortic aneurysm (TAA). The TGF-beta pathway may be involved in aneurysm development in general. We performed an association study by analyzing all the common genetic variants in TGFBR1 and TGFBR2 using tag single nucleotide polymorphisms (SNPs) in a Dutch AAA case-control population in a two-stage genotyping approach. In stage 1, analyzing 376 cases and 648 controls, three of the four TGFBR1 SNPs and nine of the 28 TGFBR2 SNPs had a P<0.07. Genotyping of these SNPs in an independent cohort of 360 cases and 376 controls in stage 2 confirmed association (P<0.05) for the same allele of one SNP in TGFBR1 and two SNPs in TGFBR2. Joint analysis of the 736 cases and 1024 controls showed statistically significant associations of these SNPs, which sustained after proper correction for multiple testing (TGFBR1 rs1626340 OR 1.32 95% CI 1.11-1.56 P=0.001 and TGFBR2 rs1036095 OR 1.32 95% CI 1.12-1.54 P=0.001 and rs4522809 OR 1.28 95% CI 1.12-1.46 P=0.0004). We conclude that genetic variations in TGFBR1 and TGFBR2 associate with AAA in the Dutch population. This suggests that AAA may develop partly by similar defects as TAA, which in the future may provide novel therapeutic options.

Endovascular aneurysm repair: state-of-art imaging techniques for preoperative planning and surveillance

Endovascular aneurysm repair (EVAR) represents one of the greatest advances in vascular surgery over the past 50 years. In contrast to conventional aneurysm repair, EVAR requires accurate preoperative imaging and stringent postoperative surveillance. Duplex ultrasound (DUS), transesophageal echocardiography, intravascular ultrasound, computed tomography (CT) and magnetic resonance (MR), each provide useful information for patient selection, choice of endograft type and surveillance. Today most interventionists and surgeons will rely on CT or MR to assess aortic morphology, evaluate access artery patency and locate side branch orifices. However, recent developments in cross-sectional imaging, including advanced image postprocessing, multi-modality image fusion and new contrast agents have resulted in improved spatial resolution for preoperative planning. Advanced reconstruction algorithms, like dynamic CTA and MRA, provide valuable information on dynamic changes in aneurysm morphology that might have an important impact on endograft selection. During follow-up, imaging of the graft and aneurysm is of utmost importance to identify patients in need of secondary intervention. This has led to rigorous follow-up protocols including duplex ultrasound and regular CT examinations. The use of these intense follow-up protocols has recently been questioned because of high radiation dose and the frequent use of nephrotoxic contrast agents. New imaging modalities like contrast enhanced DUS, dynamic MR and dual-source CT could reduce radiation dose and obviate the need for nephrotoxic contrast. Up-to-date knowledge of non-invasive vascular imaging and image processing is crucial for EVAR planning and is essential for the development of follow-up programs involving reduced risk of harmful side effects.

Observations on the Failure of Stent-grafts in the Aortic Arch

INTRODUCTION

The results of endovascular stent-grafts in the abdominal aorta and descending thoracic aorta have been encouraging. Expanding the use of thoracic stent-grafts in to the aortic arch has been associated with increasing numbers of complications. Recently isolated cases of stent-graft collapse have been reported.

METHODS

This was a multi-centre European case series. Data was collected retrospectively on seven patients from five experienced endovascular centres with thoracic stent-graft collapse.

RESULTS

Of the seven patients four were treated for traumatic aortic rupture. Six were male, median age 33 (range 17-54) years. During the ensuing 2 months all patients suffered stent-graft collapse. This was symptomatic in 3 patients and the rest were identified on CT. Endovascular management was possible in 6/7 patients using either a balloon expandable stent (n=6) or further stent-graft (n=1). Two patients had persistent type I endoleak despite treatment. Two of the 7 patients died, both of which presented with symptomatic thoracic stent-graft occlusion. Both deaths were a direct result of stent-graft collapse.

CONCLUSIONS

Thoracic stent-graft collapse may be asymptomatic underscoring the importance of stent-graft surveillance. Endovascular management of collapse is possible in most cases using a large balloon expandable stent. Symptomatic collapse is associated with high morbidity and mortality.

Wall Stress Analysis in Small Asymptomatic, Symptomatic and Ruptured Abdominal Aortic Aneurysms

OBJECTIVES

To evaluate the potential of wall stress analysis for the identification of abdominal aortic aneurysm (AAA) at elevated risk of rupture in spite of small diameter.

MATERIALS AND METHODS

Thirty patients with small AAA, 10 asymptomatic, 10 symptomatic and 10 ruptured, were included. Demographic data and results from physical examinations were recorded in a retrospective fashion. After CT-evaluation and the creation of a patient specific 3D model, wall stress was calculated using the finite element method.

RESULTS

No differences were observed in diameter between asymptomatic, symptomatic or ruptured aneurysms (5.1+/-0.2 cm vs. 5.1+/-0.2 cm vs. 5.3+/-0.2 cm respectively; p=0.57). Peak aortic wall stress at maximal systolic blood pressure is significantly higher in ruptured than asymptomatic aneurysms (51.7+/-2.4 N/cm(2) vs. 39.7+/-3.3 N/cm(2) respectively; p=0.04). Wall stress analysis at uniform blood pressure, performed to correct for higher blood pressure in the symptomatic and rupture group did not result in significant differences in peak wall stress (asymptomatic 31.7+/-2.3 N/cm(2); symptomatic 30.5+/-1.3 N/cm(2); rupture 36.7+/-4.0 N/cm(2); p=0.26).

CONCLUSIONS

Wall stress analysis at maximal systolic blood pressure is a promising technique to detect aneurysms at elevated aneurysm rupture risk. Since no significant differences were found at uniform blood pressure, the need for adequate blood pressure control in aneurysm patients is reiterated.

Impact of Study Design on Outcome after Endovascular Abdominal Aortic Aneurysm Repair. A Comparison between the Randomized Controlled DREAM-trial and the Observational EUROSTAR-registry

BACKGROUND

Patients with abdominal aortic aneurysm (AAA) can be treated by transfemoral endovascular intervention and by conventional open surgery. Level-one evidence of the safety and efficacy of one treatment mode over the other is only provided by a randomised controlled trial (RCT). Results reported by voluntary registries are considered less valid than data from RCTs. On the other hand the outcome of a RCT may not be generalisable to the common practice because of vigorous selection of patients and institutions.

PURPOSE

The outcomes reported by the Dutch Randomized Endovascular Aneurysm Management (DREAM) trial were compared with the results of the EURopean collaborators on Stent-graft techniques for AAA Repair (EUROSTAR) registry.

METHODS

To obtain comparable study groups with regard to risk factors equal proportions of ASA I, II and III patients as observed in the endovascular arm of the DREAMtrial were selected at random from the EUROSTAR-registry. All patients had an aneurysm of at least 50mm. Only patients, who had been enrolled into the registry from 1999, were selected to avoid the influence of first generation endografts which are not longer in use. Patient characteristics and outcomes of endovascular AAA repair (EVAR) of EUROSTAR and DREAM-trial participants were compared. Differences in early findings between study groups were assessed by Chi-Square tests for discrete variables and by Wilcoxon rank sum tests for continuous variables. Follow-up variables were analysed by Kaplan-Meier and Cox proportional hazard models.

RESULTS

Data of 177 patients of the DREAM trial with randomization to EVAR and 856 patients selected in the EUROSTAR-registry were compared. Baseline characteristics were comparable between the EUROSTAR-cohort and EVAR-arm of the DREAM-trial. The 36-month survival-rate was 87.6% for EVAR-arm in the DREAM-trial similar to the 86.8% found in this EUROSTAR-study population. The freedom of secondary procedures reached after 3 years 85.7%, and 86.9% in the DREAM and EUROSTAR-cohort, respectively.

CONCLUSION

We found comparable characteristics and outcomes between patients of comparable risk class of the EUROSTAR-registry and the EVAR-cohort of the DREAM-trial. This demonstrates the following: first, the EUROSTAR-data provide reliable information, and further comparisons of registry data with patients treated by conventional AAA surgery may be justified. Secondly, the various outcomes of the randomised DREAM trial appear generalisable, as it agrees with observations in a broad common practice derived database.

Subintimal Angioplasty of Supra- and Infrageniculate Arteries

We retrospectively reviewed our experience with subintimal angioplasty for chronic limb ischemia. Hospital records and films of all subintimal angioplasty procedures performed between October 2002 and December 2004 were reviewed and analyzed for demographic data, clinical data, and comorbid condition status. Thirty-nine subintimal angioplasties were performed in 37 patients (65% male, 35% female), with a median age of 73 years. Median follow-up was 9 months. The 30-day mortality rate was 8%. All-cause mortality was 33% after 24 months. In 23 cases (59%), a subintimal angioplasty of the superficial femoral artery (SFA) alone was performed. Both the SFA and popliteal/crural vessels were used in nine limbs (23%), the popliteal artery alone in three limbs (8%), and the crural arteries alone in four limbs (10%). Initial technical and clinical success rates were 67% and 49%, respectively. The complication rate was 28%. Twenty-four additional surgical interventions were performed after the initial angioplasty procedure, of which 12 were major amputations. Amputation-free survival (limb-salvage rate) was 69% at 12 months [95% confidence interval (CI) 52-85%], and overall survival was 69% (95% CI 52-85%) at 12 months. In patients with critical limb ischemia, subintimal angioplasty is feasible and in most cases technically successful. In these high-risk patients, often with combined cardiac, pulmonary, and diabetic risk and considered unfit for bypass surgery, subintimal angioplasty offers a safe and effective alternative.

Computed tomography versus magnetic resonance imaging of endoleaks after EVAR

AIM

The aim of study was to compare the sensitivity of MRI and CTA for endoleak detection and classification after EVAR.

PATIENTS & METHODS

Twenty-eight patients, between 2 days and 65 months after EVAR, were evaluated with both CT and MRI. Twenty-five patients had an Ancure graft and the other three had an Excluder. The MRI protocol for endoleak evaluation included: a T1-weighted spin echo, a high-resolution 3D CE-MRA, and a post-contrast T1-weighted spin echo. In total 40 ml Gadolinium was administered. The CT protocol consisted of a blank survey followed by a spiral CT angiography (CTA) using 140 ml of Ultravist. An experienced, blinded observer evaluated all CTs and MRIs.

RESULTS

Using MRI and MRA techniques significantly more endoleaks (23/35) were detected than with CTA (11/35) (p=0.01, Chi-Square). CT could not determine the type of endoleak in 3 of the 11 endoleaks detected and was uncertain in one. MRI was uncertain about the type in 14 of the 23 endoleaks detected. All endoleaks visible on CT were visible by MRI as well.

CONCLUSIONS

MRI techniques are more sensitive for the detection of endoleak after endovascular AAA repair than CT.

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.

In-hospital Operative Mortality of Ruptured Abdominal Aortic Aneurysm: A Population-based Analysis of 5593 Patients in The Netherlands Over a 10-year Period

OBJECTIVE

To determine the operative mortality of ruptured abdominal aortic aneurysm (RAAA) in The Netherlands.

DESIGN

Retrospective population-based study of nation-wide in-hospital mortality of RAAA repair.

METHODS

Data were obtained from a national registry for medical diagnosis and procedures. In-hospital mortality of RAAA repair, defined as death during hospital admission irrespective of the cause of death, was determined in the period 1991-2000. Variables of potential influence on in-hospital mortality, including age, gender, date of surgery and hospital type (0-399 beds, > or =400 beds or university hospitals) were studied in a multivariate analysis.

RESULTS

The overall in-hospital mortality of RAAA repair in 5593 patients in the 10-year period was 41% (95% confidence interval: 40-42%). In the multivariate analysis, age and hospital type were the most important independent predictors for in-hospital mortality. Gender, year and season of surgery could not be identified as significant risk factors.

CONCLUSIONS

Over a recent decade, in-hospital mortality of RAAA repair remained unchanged at 41%. Age and hospital class were the most important independent risk factors.

Endovascular Aneurysm Repair versus Open Aneurysm Repair: Comparison of Treatment Outcome and Procedure-Related Reintervention Rate

We conducted a retrospective study to compare treatment outcome and procedure-related reintervention rates of endovascular aneurysm repair (EVAR) with those of open repair. Clinical and radiological data of patients treated at the Rijnstate Hospital (Arnhem, The Netherlands) for nonsymptomatic aortic abdominal aneurysm during October 1998-January 2004 were reviewed and analyzed for demographic data, aneurysm specifics, comorbid condition status, and perioperative outcome. There were 99 patients treated with EVAR and 116 patients treated with open repair. Significant differences in age were seen between treatment groups, patients under the age of 80 being more likely to have open repair (p < 0.004). The EVAR group consisted of significantly fewer women (p < 0.029). Of seven comorbid conditions, four reached significant differences between treatment groups; patients with ischemic heart disease (p < 0.044), heart failure (p < 0.006), renal failure (p < 0.033), or peripheral arterial disease (p < 0.006) were more likely to have EVAR. Comparison of aneurysm anatomy showed no difference in size between EVAR (mean 57.7 mm, 95% CI 55.9-59.5 mm) and open repair (mean 60.1 mm, 95% CI 57.9-62.3 mm). Significant differences were seen in aneurysm neck length and diameter. Operative outcome showed differences in length of hospital stay (median, EVAR 7 vs. open repair 11 days), 30-day mortality (p < 0.048), postoperative hematoma (p < 0.001), and postoperative pulmonary infections (p < 0.001), all in favor of EVAR. Follow-up of the EVAR group showed a decrease (mean 10 mm, 95% CI 7-14 mm) of aneurysm diameter in 15% of cases during follow-up (mean 18 months, range 1-66). Despite higher age and more comorbidity of patients undergoing EVAR, 30-day mortality, postoperative pulmonary infection rate, and length of hospital stay were lower than for those undergoing open repair. Both EVAR and open repair can be performed on a subset of patients with low mortality, complication, and reintervention rates.

Application of a clinical grade CD34-mediated method for the enrichment of microvascular endothelial cells from fat tissue

BACKGROUND

Microvascular endothelial cells (MVEC) derived from s.c. fat are seeded on vascular grafts to prevent early occlusion. We have demonstrated the presence of contaminating cells contributing to MVEC seeding-related intimal hyperplasia in MVEC isolates from fat tissue. We found that cell isolates additionally purified after the isolation process, were associated with a reduced thrombogenicity and development of intimal hyperplasia in vitro. A combination of 11Fibrau (F11)- and CD14-coated Dynabeads was used to deplete the contaminating cells, fibroblasts, and monocytes/macrophages. Unfortunately, clinical-grade F11 is not available, and thus cannot be used for clinical practice. CD34 selection with clinical-grade products is widely used for the isolation of hematopoietic progenitors, and endothelial cells (EC) express CD34 on their surfaces. The aims of this study were to test the effectiveness of two different CD34-selection techniques for purification of MVEC, and to compare the results with those of the F11/CD14-method.

METHODS

Liposuction fat was enzymatically digested and centrifuged twice to remove adipocytes and collagenase. CD34 selection was performed using the commercially available methods from Nexell or Miltenyi. Both techniques were modified for our use. The purity after isolation and culture, and recovery were determined by flow-cytometry (CD31-expression) and compared with that of cells purified with the F11/CD14-method.

RESULTS

Besides MVEC, the contaminating fibroblasts and macrophages/monocytes weakly expressed the CD34 Ag. Enrichment of MVEC was not successful with the Miltenyi method. Variations in neither the dose of Ab nor the use of direct selection and different separation programs improved the results. With the Nexell method, MVEC were enriched to 86%, a comparable purity to that obtained with the F11/CD14-method. However, a lower recovery was achieved with the Nexell method.

CONCLUSION

Enrichment of MVEC could be achieved with a modified protocol of the clinical grade CD34(+) selection method from Nexell, but not with the CD34 method from Miltenyi.

The Impact of Endovascular Treatment on In-hospital Mortality Following Non-ruptured AAA Repair over a Decade: A Population Based Study of 16,446 Patients

OBJECTIVES

We hypothesised that over the past decade, the nation-wide outcome of infrarenal abdominal aortic aneurysm (AAA) repair has improved with the introduction of endovascular treatment. The aim of the study was to identify endovascularly-treated patients in a national registry and to assess the impact on in-hospital mortality of non-ruptured AAA repair, if any, after the introduction of endovascular repair.

MATERIALS AND METHODS

We retrospectively studied the nation-wide outcome of non-ruptured AAA repair over the past decade. Variables studied were age and gender of the patients, hospital size and type and the year in which treatment was performed and the outcome on in-hospital mortality. The in-hospital mortality of non-ruptured AAA repair in 16,446 patients in the 10-year period from 1991 to 2000 was 7.3% (6.2-8.2%). In the 15,589 (95%) patients that underwent conventional treatment, in-hospital mortality was 7.6% (7.0-8.1%), whereas in the endovascular group it was 1.9% (0.6-3.5%). In the multivariate analysis, age and endovascular repair were the most important independent predictors of in-hospital mortality.

CONCLUSION

With the limitations of a national registry aside, the introduction of endovascular aneurysm repair seems to have had a small but significant impact on in-hospital mortality following infrarenal AAA repair.

In vivo transluminal microvascular endothelial cell seeding on balloon injured rabbit arteries

AIM

Seeding venous endothelial cells (EC) onto damaged vascular surfaces attenuates the development of intimal hyperplasia. Unlike venous EC, fat derived microvascular endothelial cells (MVEC) do not require a culture step to increase the yield. The authors investigated whether fat derived MVEC are suitable to reduce intimal hyperplasia after PTA.

METHODS

Five rabbits were subjected to percutaneous transluminal angioplasty (PTA) of both iliac arteries. One side was seeded transluminally with autologous perirenal fat derived MVEC, using a double balloon catheter. The contralateral side was sham seeded, and served as a control. Follow-up was 4 weeks. Another rabbit was used for a feasibility experiment. This rabbit was subjected to a 1-sided seeding procedure and was sacrificed after 1 week. In a 7th rabbit, a 1-sided PTA was transformed, and autologous labelled cells were injected in the distal aorta instead of seeded, follow-up was 1 week. Histological investigation was per-formed.

RESULTS

The MVEC seeded artery of the pilot experiment was patent. All sham seeded arteries (5) except for 1 were patent. The patent ones showed moderate intimal hyperplasia. MVEC seeding (5) resulted in occlusion twice. In the patent MVEC seeded arteries intimal hyperplasia was present in more extended form than in the sham seeded arteries. Both the patent MVEC- and sham-seeded arteries were covered with an EC layer. Injected labelled MVEC were not found again on the de-endothelialized artery.

CONCLUSION

In this study seeding of fat derived MVEC on damaged native arteries results in an increased development of intimal hyperplasia and a decreased patency. One of the reasons may be the presence of non-EC in the seeded cell population.

Quality of Life after Endovascular and Open AAA Repair. Results of a Randomised Triala

AIM

To compare the quality of life (QoL) in the first postoperative year after elective endovascular abdominal aortic aneurysm repair (EVAR) and open repair (OR) in a randomised study.

METHODS

In the Dutch Randomised Endovascular Aneurysm Management (DREAM) trial, patients are randomly allocated to EVAR or OR. QoL questionnaires (SF-36 and EuroQoL-5D) were sent to all patients preoperatively (PREOP) and at five time points in the first postoperative year (3W, 6W, 3M, 6M and 12M). Between November 1999 and August 2002, 153 patients (141 male; 12 female) were randomised (78 EVAR and 75 OR; one crossover from OR to EVAR). The EuroQoL-5D scores and the eight domains of the SF-36 for the two groups were compared using the Mann-Whitney test. Changes over time were analysed using the Wilcoxon sign test.

RESULTS

There were no statistically significant differences in baseline characteristics (age, gender and SVS risk factors). The preoperative QoL scores of the study group were similar to the QoL scores of the general population of the same age. After 3W the OR group showed a significant decrease on the EuroQol-5D (p=0.022) and in six of the eight SF-36 domains. The EVAR group also showed a significant decrease on the EuroQol-5D (p=0.004) and in 5 of the 8 domains of the SF-36. At 6W the EuroQol-5D had recovered to baseline in the OR group and the decreased domains of the SF-36 had partially recovered. In the EVAR group the EuroQol-5D and three of the five decreased SF-36 domains, had returned to baseline. From 6M on, the OR group reported a significantly higher score on the EuroQoL-5D than the EVAR group (p=0.045 (6M) and p=0.001 (12M)).

CONCLUSION

In the early postoperative period there is a small, yet significant QoL advantage for EVAR compared to OR. At 6 months and beyond, patients reported better QoL after OR than after EVAR.

[Endovascular treatment of 4 patients with a traumatic rupture of the thoracic aorta]

OBJECTIVE

To present our initial results with the endovascular treatment of traumatic rupture of the thoracic aorta.

DESIGN

Retrospective.

METHOD

Between April and October, 2002, 4 men between the ages of 22 and 46 were treated endovascularly for a traumatic rupture of the thoracic aorta. The diagnosis 'rupture of the thoracic aorta' was made on the basis of CT-angiography in all cases. In the first case, a thoracic Gore TAG-endoprosthesis (Gore & Associates; Den Bosch) was used, and in 3 cases a Talent-endoprosthesis (Medtronic AVG; Heerlen).

RESULTS

There was an average of 2.5 days (limits: 0-5 days) between admission and the placement of the endoprosthesis. There was one intra-operative complication in the form of a dissection of the right femoral artery when the endoprosthesis was inserted. In 3 cases, the left subclavian artery was occluded by the prosthesis. This had no negative consequences for the patients during the follow-up period (limits: 4-12 months). The CT-angiogram taken 3 months after the operation consistently showed a good position of the endoprosthesis with no signs of leakage.

CONCLUSION

For a limited follow-up period, the endovascular treatment of a traumatic rupture of the thoracic aorta has been shown to be safe and effective. The long term results must be awaited.

Decision-making in follow-up after endovascular aneurysm repair based on diameter and volume measurements: a blinded comparison

OBJECTIVE

to assess whether volume, in addition to diameter, measurements facilitate decision-making after endovascular aneurysm repair (EVAR).

MATERIAL/METHODS

patients (n = 82) with an immediately post-EVAR, and at least one follow-up (3-60 months), computed tomographic angiogram (CTA) were studied. The actual and all preceding proportional sac size changes were recorded. The resulting 347 diameter and 347 volume data were placed in random order and reviewed by three blinded observers who then recommended one of three treatment policies: "good/wait", "uncertain/intensify follow-up" or "not good/further diagnostics (Dx) or intervention (Rx)". The observers were instructed to consider changes of 10% relevant. One observer reviewed the graphs twice.

RESULTS

the interobserver agreements (kappa) for the diameter were 0.92, 0.81 and 0.76 and for volumes 0.91, 0.88 and 0.86. The intra-observer agreement was 0.93 for both diameter and volume. Volume data resulted in significantly more "good/wait" decisions out to 36 months. Diameter data resulted in more "not good/Dx or Rx"-decisions out to 36 months (all p < 50.005).

CONCLUSION

post-EVAR aneurysm sac volume data appears to provide earlier reassurance, reduce unnecessary interventions and to be more sensitive to secondary problems than diameter data alone.

Rapid, arteriovenous graft failure due to intimal hyperplasia: a porcine, bilateral, carotid arteriovenous graft model

BACKGROUND

The loss of patency constitutes the major complication of arteriovenous (AV) polytetrafluoroethylene hemodialysis grafts. In most cases, this graft failure is due to intimal hyperplasia at the venous outflow tract, including proliferation of vascular, smooth muscle cells and fibroblasts with deposition of extracellular matrix proteins. Thus far, procedures developed for improving patency have proven unsuccessful, which can be partly explained by the lack of relevant animal models. For this purpose, we developed a porcine model for AV graft failure that will allow the assessment of promising therapeutic strategies in the near future.

MATERIALS AND METHODS

In 14 pigs, AV grafts were created bilaterally between the carotid artery and the jugular vein using expanded polytetrafluoroethylene. Two, 4 or 8 weeks after AV shunting, the grafts and adjacent vessels were excised and underwent histologic analysis.

RESULTS

From 2 weeks onwards, a thick neo-intima developed at the venous anastomosis, predominantly consisting of alpha-actin-positive vascular smooth muscle cells (VSMC). Intimal area increased over time, coinciding with a decreased graft flow. Grafts remained patent for at least 4 weeks. At 8 weeks, patency rates declined to less than 50% due to thrombus formation superimposed on progressive neo-intima formation.

CONCLUSIONS

Implantation of an AV graft between the carotid artery and jugular vein in pigs causes a rapid neo-intimal response, accompanied by a loss of patency of 50% at 8 weeks after surgery. This model offers a suitable tool to study local interventions aimed at the improvement of AV graft patency rates.

Screening for asymptomatic internal carotid artery stenosis and aneurysm of the abdominal aorta: comparing the yield between patients with manifest atherosclerosis and patients with risk factors for atherosclerosis only

OBJECTIVE

The purpose of this study was to investigate whether screening for internal carotid artery stenosis (ICAS) and aneurysm of the abdominal aorta (AAA) is indicated in patients with either manifest atherosclerotic disease or with only risk factors for atherosclerosis.

STUDY DESIGN

Data were obtained for 2274 patients enrolled in the SMART study, an ongoing single-center, prospective cohort study of patients referred to our vascular center with manifest atherosclerotic disease (peripheral atherosclerotic disease [PAD]; transient ischemic attack [TIA], stroke, or ICAS; AAA; angina pectoris; or myocardial infarction [MI]) or with only risk factors for atherosclerosis (diabetes mellitus, hypertension, hyperlipidemia). The presence of ICAS or AAA was determined with duplex scanning and ultrasonography.

RESULTS

The prevalence of ICAS 70% or greater is low in patients with risk factors for atherosclerosis only (1.8%-2.3%), intermediate in patients with angina pectoris or MI (3.1%), and highest in patients with PAD (12.5%) or AAA (8.8%). The prevalence of AAA 3 cm or larger is low in patients with risk factors for atherosclerosis only (0.4-1.6%), intermediate in patients with angina pectoris or MI (2.6%), and highest in patients with PAD (6.5%) or TIA, stroke, or ICAS (6.5%). The prevalence of AAA larger than 5 cm is low in all of the considered patient groups. The yield of screening can be optimized through selection on the basis of simple patient characteristics. In patients with PAD, selecting those with advanced age (>54 years) increased the prevalence of ICAS to 21.8%. Selecting patients with lower diastolic blood pressure (<83 mm Hg) increased the prevalence of ICAS to 17.9%. In patients with both advanced age and lower diastolic blood pressure, the prevalence of ICAS increased to 34.7%. Selecting patients with advanced age increased the prevalence of AAA 3 cm or larger to 9.6%. In patients with TIA, stroke, or ICAS, selecting those with advanced age increased the prevalence of AAA 3 cm or larger to 8.2%. Selecting patients with taller stature (>169 cm) increased the prevalence of AAA 3 cm or larger to 9.3%. In patients with advanced age and taller stature, the prevalence of AAA 3 cm or larger increased to 13.1%.

CONCLUSIONS

Screening for ICAS should be limited to patients referred with PAD or AAA, especially those with advanced age or with low diastolic blood pressure. Screening for AAA should be limited to patients referred with PAD or with TIA, stroke, or ICAS, particularly those with advanced age or tall stature. In patients referred with angina pectoris or MI and those referred with only risk factors for atherosclerosis, screening cannot be endorsed.

[Treatment of abdominal aortic aneurysms]

Three treatment options are available for an asymptomatic abdominal aortic aneurysm (AAA): an expectant approach with ultrasonographic check-ups, reconstruction of the abdominal aorta via the conventional ('open') approach and endovascular repair. For aneurysms less than 5.5 cm in diameter the annual rupture risk is less than 1%. For these patients a better alternative to the expectant approach does not seem to exist. The risk of rupture needs to be weighed up against the risks of a conventional operation. The operation mortality of patients with a non-ruptured AAA is about 7% while other serious complications occur in about 10%. The short to medium-term results of endovascular aneurysm repair are characterized by high reintervention rates, material fatigue and device failure. The three treatment options described are currently being investigated in several large-scale randomised studies for AAAs greater than 5.5 cm in diameter.

The Dutch Randomised Endovascular Aneurysm Management (DREAM) trial. Background, design and methods

After the introduction of endovascular repair of abdominal aortic aneurysms (AAA), both benefits and drawbacks of this new technique have been reported. To assess whether the new technique is an adequate substitute of conventional AAA repair, a randomised study is due. The Dutch Randomised Endovascular Aneurysm Management (DREAM) trial is a randomised multicenter trial enrolling patients eligible for elective treatment of infrarenal AAAs. In this study, the cost-effectiveness of endovascular aneurysm repair (EAR) is compared with that of conventional transabdominal surgery, in patients that are considered suitable for both types of treatment. The primary endpoint is combined operative mortality and morbidity. Secondary endpoints and additional assessments include event free survival, quality of life, length of hospital stay and costs. It is expected that the DREAM-trial will lead to a safe and controlled introduction of a new technology. Also, the medical community will obtain valid scientific evidence of the merits of endovascular AAA repair. Finally, policy makers will be provided with accurate cost-effectiveness data for the Dutch healthcare system. The aim of the present paper is to describe the background, methods and design of the DREAM-trial.

Reduction of non-endothelial cell contamination of microvascular endothelial cell seeded grafts decreases thrombogenicity and intimal hyperplasia

INTRODUCTION

fat derived microvascular endothelial cells (MVEC) seeded on prosthetic vascular grafts, improve patency in animals. Results in humans were disappointing, due to thrombogenicity and progressive intimal hyperplasia. Also in animals intimal hyperplasia was found. We postulate that contaminating cells present in the transplant are involved in the intimal hyperplasia. We developed a method to further purify human MVEC from 40-90%. Here we tested the effects of enrichment upon thrombogenicity and seeding-related intimal hyperplasia.

METHODS

liposuction fat was enzymatically digested and centrifuged. To enrich MVEC, contaminating macrophages and fibroblasts were removed with dynabeads coated with macrophage- and fibroblast-specific antibodies. Thrombogenicity was assessed by measuring tissue factor and thrombomodulin activity, presence of endothelial nitric oxide synthase and via perfusion of the cells with whole blood. To investigate seeding-related intimal hyperplasia, PTFE grafts were seeded with the cells and cultured for 3 weeks.

RESULTS

tissue factor activity of purified cells was reduced compared to nonpurified cells. Purified cells showed thrombomodulin activity and eNOS expression. Fragment 1+2 and Fibrinopeptide A generation after perfusion of purified cells were significantly lower than after perfusion of nonpurified cells, and only nonpurified cells were covered with platelets and fibrin. Prostheses seeded with nonpurified cells showed an EC monolayer above a multilayer of myofibroblasts, prostheses seeded with purified cells only showed a single EC monolayer. Mixing experiments with human umbilical cord EC (HUVEC) and fibroblasts showed that when more than 25% HUVEC were present a confluent EC layer was formed. When the amount of fibroblasts was 25% or less, no development of a subendothelial multilayer of myofibroblasts was found within 3 weeks.

CONCLUSION

reduction of non-endothelial cell contamination of microvascular endothelial cell seeded grafts decreases thrombogenicity and might prevent seeding-related intimal hyperplasia.

The sac shrinking process after EAR does not start immediately in most patients

OBJECTIVE

the aim of this study was to determine the pattern of shrinkage after endovascular aneurysm repair (EAR) using logarithmic, exponential and linear models and to calculate a lag time is present.

PATIENTS AND METHODS

patients with a complete CTA follow-up of 2 years and a primary shrinking aneurysm were included, resulting in a study group of 29 patients. Six functions, logarithmic, exponential and linear, all with and without lag time, were fitted to the thrombus volume obtained from measurements postoperative and after 6, 12 and 24 months. The correlation coefficient was used to determine the association between the calculated and measured values. A correlation coefficient >0.95 was considered a good fit.

RESULTS

a logarithmic model produced the best fits. From the 29 patients, two patients could not be described by any model. The remaining 27 patients could be fitted using a logarithmic function with a correlation coefficient of >0.95 (median 0.99, range 0.95-1.00). Twenty-two of these patients had a lag time (median 63.4 days, range 5.8-252.3). Only five of the initial 44 patients (11%) showed immediate sac shrinkage.

CONCLUSION

almost all shrinkage processes could be described by a logarithmic function. In over 75% of patients a lag time to shrinkage could be calculated. In only a small proportion did the shrinking process start immediately after EAR.

Contaminants from the transplant contribute to intimal hyperplasia associated with microvascular endothelial cell seeding

OBJECTIVES

seeding prosthetic grafts with fat-derived microvascular endothelial cells (MVEC) results not only in a non-thrombogenic EC layer, but also in intimal hyperplasia. Here we investigated incidence, composition, progression, and cause of this intimal hyperplasia.

DESIGN

EPTFE grafts with MVEC were implanted as carotid interpositions in six dogs with 1 month, and in three dogs with 4, 8 and 12 months follow-up. Grafts seeded without cells, implanted in the contralateral carotid, served as a control. In another three dogs labelled cells were seeded to investigate the contribution of the seeded cells (2-3 weeks).

MATERIALS AND METHODS

MVEC were isolated from the falciform ligament. Cells were pressure seeded on ePTFE grafts. Labelling was performed using retroviral gene transduction. The grafts were analysed with immunohistochemical techniques.

RESULTS

after 1 month, all patent non-seeded grafts (5/6) showed fibrin and platelet deposition, and all patent seeded grafts (5/6) were covered with a confluent endothelial monolayer on top of a multilayer of myofibroblasts, elastin and collagen. After long term follow-up, all non-seeded grafts were occluded, all patent seeded grafts (4 and 12 months) were covered with an EC-layer with intimal hyperplasia underneath. The thickness of the intima did not progress after 1 month. Transduced cells were found in the endothelial monolayer, hyperplastic intima and luminal part of the prosthesis.

CONCLUSIONS

MVEC seeding in dogs results in intimal hyperplasia in all patent grafts, which contains myofibroblasts. Contaminants from the transplant contribute to this intimal hyperplasia.

[Spiral computed tomographic angiography as a substitute for intra-arterial angiography of aorta and its branches]

Until recently, intra-arterial angiography was the diagnostic method of first choice when pathology of the aorta or its branches was suspected. A disadvantage of this technique is that only the lumen of spaces with blood flow can be visualised and that the soft tissue surroundings remain (partly) invisible. Spiral computer tomographic angiography (CTA) has some major advantages compared with conventional angiography. The technique is less invasive and faster. Also, the soft tissue is imaged by CTA. In addition, computer reconstructions allow viewing from all directions without the limitations of overprojection. Spiral CTA is a suitable technique for imaging the thoracic part of the aorta: in case of dissection if transoesophageal echography is not available, in case of an aneurysm to determine the diameter and in case of rupture as a highly sensitive but not very specific examination technique. For imaging of the abdominal part of the aorta, spiral CTA may be considered. In case of an aneurysm or a possible rupture of this part of the aorta it is then possible to visualize the operation area and to choose the optimal approach. For the exclusion of stenoses in mesenteric arteries or in renal arteries, spiral CTA offers the advantage of non-invasivity. The technique is less suitable for demonstration of these stenoses and does not allow immediate intervention.

Cerebral Blood Flow in Relation to Contralateral Carotid Disease an MRA and TCD Study

OBJECTIVE

to describe redistribution of cerebral blood flow in patients with severe internal carotid artery (ICA) stenoses in relation to contralateral ICA disease.

METHODS

sixty-six patients scheduled for carotid endarterectomy (CEA) were grouped according to severity of contralateral stenosis (<30% [group I]; 30-69% [group II]; 70-99% [group III]; occlusion [group IV]. Transcranial Doppler (TCD) and magnetic resonance angiography (MRA) investigations were performed preoperatively.

RESULTS

TCD demonstrated a reversed flow in the contralateral anterior cerebral artery (A(1)segment) and ophthalmic artery in three-quarters of group IV patients (p <0.0001). Group IV patients also exhibited decreased blood flow velocity in the contralateral middle cerebral artery (p =0.001). MRA showed increased ipsilateral ICA and basilar artery (BA) blood flow volumes (Q-flows) in group IV patients when compared to the other groups (p <0.001). No changes in total Q-flow (ICAs+BA) were found.

CONCLUSIONS

in patients considered for CEA, the severity of the contralateral ICA disease is an important determinant of the pattern of blood flow redistribution through the anterior communicating pathway and ophthalmic artery. Significant flow redistribution through the posterior communicating pathway occurs especially in patients with contralateral ICA occlusion.

Concerns for the durability of the proximal abdominal aortic aneurysm endograft fixation from a 2-year and 3-year longitudinal computed tomography angiography study

OBJECTIVE

To provide a long-term perspective on the durability of the proximal abdominal aortic aneurysm endograft fixation from a single device series with perpendicular neck measurements in two groups of patients with complete 2- and 3-year follow-up.

DESIGN

This was a prospective study of postoperative, radiologic images.

SETTING

The study used a referral center, institutional practice, and ambulatory patients.

SUBJECTS

From January 1994 until May 1998, 37 endografts were implanted for abdominal aortic aneurysm. In the first postoperative year, there were four unrelated deaths and six conversions, leaving 27 patients with complete 24-month data and 13 with complete 36-month data.

MAIN OUTCOME MEASURE

Computed tomography angiograms were processed on a work station to measure the neck perpendicular to the central lumen line of the aorta. The surface area at the proximal endovascular anastomosis was recorded at each follow-up interval and related to the postoperative size at the same level.

RESULTS

Significant dilatation of the surface area was found: 20% (16% to 27%) at 24 months (c2 = 30; P < .001, Friedman) and 23% (18% to 28%) at 36 months (c2 = 27; P < .001, Friedman). This increase in neck size was continuous and linear, with a yearly rate of approximately 10% surface area; translated into diameter, this approximates 1 mm/y.

CONCLUSION

A continuous aortic enlargement of approximately 1 mm/y at the level of the proximal endovascular anastomosis was found. Because of the practice of oversizing the endograft relative to the infrarenal aortic neck, a loss of the endovascular seal may not become apparent until several years after endovascular abdominal aortic aneurysm repair is performed.

Early experience with intravascular ultrasound in evaluating the effect of statins on femoropopliteal arterial disease: hypothesis-generating observations in humans

The purpose of this study was to compare the vascular response seen with intravascular ultrasound (IVUS) at 1-year follow-up between statin-treated and non-statin-treated patients. Patients (n = 10) undergoing percutaneous transluminal angioplasty (PTA) of the femoropopliteal artery were studied with IVUS immediately after PTA and at 1-year follow-up. In nondilated matched vascular segments, the change in lumen, vessel, and plaque volume was assessed. In balloon-dilated matched vascular segments, the change in lumen, vessel, and plaque area was assessed. A comparison was made between statintreated (n = 5) and non-statin-treated patients (n = 5) in lumen, vessel, and plaque changes. At follow-up, both statin-treated and non-statin-treated patients showed a similar increase in plaque volume at the nondilated segment (+4% and +2%, respectively). In statin-treated patients the plaque volume increase was compensated by an increase in vessel volume (+2%), resulting in an increase in lumen volume (+1%). In non-statin-treated patients, on the other hand, the increase in plaque volume was associated with a decrease in vessel volume (-2%), resulting in a decrease in lumen volume (-4%). At the balloon-dilated segment a similar trend in changes of lumen, vessel, and plaque was encountered. Differences between both groups of patients were not statistically significant. Despite the nonsignificant nature of the observation, this small retrospective IVUS study may generate the hypothesis that statin therapy may contribute to superior long-term lumen dimensions by inducing positive vascular remodeling both in nondilated and balloon-dilated vascular segments.

Preoperative MRA flow quantification in CEA patients: flow differences between patients who develop cerebral ischemia and patients who do not develop cerebral ischemia during cross-clamping of the carotid artery

BACKGROUND AND PURPOSE

We sought to investigate whether preoperative volume flow in the internal carotid arteries (ICAs), the basilar artery (BA), and the middle cerebral arteries (MCAs) and collateral flow via the circle of Willis differ between patients who do and patients who do not develop cerebral ischemia during clamping of the carotid artery in carotid endarterectomy (CEA).

METHODS

Quantitative volume flow in the ICAs, BA, and MCAs and directional flow in the circle of Willis were measured preoperatively with 2-dimensional phase-contrast MR angiography in 86 CEA patients. During the operation, electroencephalographic (EEG) recordings were obtained that were monitored by a clinical neurophysiologist. Reference volume flow values were assessed in 24 control subjects.

RESULTS

In patients with an ICA stenosis without contralateral ICA occlusion (n=62), of whom 16% developed ischemic EEG changes during clamping, preoperative flow in the clamped ICA was significantly higher in patients with cerebral ischemia than in patients without (mean, 278 versus 160 mL/min; P:<0.05). Flow in the contralateral ICA (156 versus 273 mL/min; P:<0.01), flow in the BA (116 versus 165 mL/min; P:<0.05), and presence of collateral flow via the circle of Willis to the clamped ICA (0% versus 37%; P:<0.05) were significantly lower. MCA flow did not differ significantly between groups. Additionally, in patients with an ICA stenosis and a contralateral ICA occlusion (n=24), of whom 42% developed cerebral ischemia, preoperative flow in the clamped ICA was significantly higher in patients with cerebral ischemia than in patients without (309 versus 239 mL/min; P:<0.05). BA flow, MCA flow, and presence of willisian collateral flow (0% versus 14%) did not differ significantly between groups.

CONCLUSIONS

Preoperative volume flow in the clamped ICA is significantly higher in CEA patients with ischemic EEG changes during clamping than in CEA patients without such changes. The latter patients probably have better developed collateral pathways preoperatively.

Inter- and intraobserver variability of CT measurements obtained after endovascular repair of abdominal aortic aneurysms

OBJECTIVE

Important decisions are made on the basis of CT angiographic measurements of aneurysm size obtained after endovascular abdominal aortic aneurysm repair; however, little is known about the variability of these measurements. We evaluated the variability of CT angiographic measurements of aneurysm size obtained after endovascular abdominal aortic aneurysm repair.

MATERIALS AND METHODS

Thirty CT angiographic data sets were randomly chosen from 91 sets, including preoperative, postoperative, and follow-up CT images. All images were obtained according to a standardized acquisition protocol. On a workstation, three parameters were measured: maximum aneurysm diameter, maximum aneurysm cross-sectional area, and aneurysm volume. All data sets were measured twice by two investigators in a random order. The difference of each pair of measurements was plotted against the mean value. The mean difference and its standard deviation were calculated with a repeatability coefficient.

RESULTS

The intraobserver repeatability coefficient for observer 1 was 3.8 mm for diameter, 201.7 mm(2) for cross-sectional area, and 5.6 mL for volume. For observer 2, these figures were 3.0 mm, 219.0 mm(2), and 8.1 mL, respectively. The interobserver repeatability coefficients were 3.9 mm, 236.2 mm(2), and 10.3 mL.

CONCLUSION

Determination of the repeatability coefficient of aneurysm size measurements obtained after endovascular abdominal aortic aneurysm repair provides a good description of precision.

Three-dimensional intravascular ultrasound assessment of abdominal aortic aneurysm necks

PURPOSE

To document the accuracy of an automated analysis system for measuring lumen diameter and neck lengths of abdominal aortic aneurysms (AAAs) from intravascular ultrasound (IVUS) images and to describe additional features associated with 3-dimensional (3D) IVUS imaging.

METHODS

Twenty-two aortic aneurysms were studied with IVUS. Lumen diameters obtained using the automated analysis system were compared with manual measurements from axial IVUS scans, as were neck lengths obtained using automated analysis versus those measured with the aid of a displacement sensing device. Automated analyses were repeated by a second observer. Agreement was expressed as the coefficient of variation (CV).

RESULTS

Twenty proximal aortic, 6 distal aortic, and 3 iliac necks were available for analysis. Comparison between automated analysis and manual measurements for lumen diameter revealed a difference of 0.45 +/- 0.42 mm (mean +/- SD, Pearson's r = 0.99, p < 0.001, CV = 2.1%) and a difference of 0.05 +/- 0.12 cm (r = 0.99, p = 0.04, CV = 4.1%) for neck length. Interobserver difference for lumen diameter was 0.13 +/- 0.66 mm (r = 0.99, p < 0.001, CV = 3.4%) and 0.05 +/- 0.11 cm for length measurements (r = 0.99, p = 0.02, CV = 3.5%). The 3D IVUS imaging facilitated the identification of neck configuration.

CONCLUSIONS

Automated analysis of IVUS images allows accurate measurement of the lumen diameter of proximal and distal AAA necks and gives length measurements comparable to those of manual analysis. Longitudinal display of IVUS images aids in the elucidation of neck anatomy.

A simple technique to improve the accuracy of proximal AAA endograft deployment

PURPOSE

To report a technique for overcoming the positioning errors caused by angulation and rotation of the proximal aortic neck when anteroposterior fluoroscopic imaging is used during endograft deployment.

TECHNIQUE

Aortic neck angulation and rotation were measured preoperatively using spiral computed tomographic angiography in sagittal and axial projections. Before proximal graft deployment, the proximal end of the endograft was centered in the field of view, and the position of the C-arm was adjusted to the aortic neck angulation. Using this technique, optimal positioning of the endograft relative to the true position of the renal arteries can be achieved.

CONCLUSIONS

C-arm angulation and rotation is helpful in facilitating perfect positioning for an optimal seal between the endograft and the infrarenal aortic neck.

Maximal aneurysm diameter follow-up is inadequate after endovascular abdominal aortic aneurysm repair

BACKGROUND

follow-up after endovascular abdominal aortic aneurysm repair (EAR) generally consists of serial diameter measurements. A size change after EAR, however, is the consequence of alterations of the excluded aneurysm sac volume.

OBJECTIVE

to assess the agreement between diameter measurements and volume measurements after endovascular aneurysm repair.

PATIENTS AND METHODS

from 53 consecutive patients scheduled for EAR, follow-up of at least 6 months was available in 35 patients. CTA was performed on all patients at discharge, at 6 months and yearly thereafter. The resulting 113 datasets were processed on a workstation in a blinded and random order. Maximal aneurysm diameter (DMAX) was measured along the central lumen line. Total aneurysm volume was measured by manual segmentation. All measurements of an individual patient were compared with each other, resulting in 149 comparisons. The significance of individual size changes was classified based on the 95% confidence limits of the intra-observer variability, using difference-of-means analysis. DMAX changes were compared to volume changes.

RESULTS

in 37% of the comparisons, discordance was found between DMAX and volume measurements. A decrease in aneurysm size was missed using DMAX in 14% of cases and an increase in 19% of cases.

CONCLUSION

aneurysm size changes after EAR are not noticed using maximal diameter measurements in over one-third of cases.

Mortality and morbidity rates after conventional abdominal aortic aneurysm repair

AIM

To grade and analyse by levels of evidence the mortality and morbidity rates of elective abdominal aortic aneurysm (AAA) surgery as reported over the past 12 years.

METHODS

Articles on elective AAA surgery published between 1985 and 1996 were retrieved and classified into 5 levels of evidence. Level 1 contains prospective studies and is subdivided into population-based (Level 1a) and hospital-based (Level 1b) studies. Level 2 includes retrospective studies, subdivided into population-based (Level 2a), hospital-based (Level 2b), and hospital-based studies concerning a specified group of selected patients (Level 2c). Operative mortality and systemic and local/vascular complication rates and 95% confidence intervals were calculated per level of evidence.

RESULTS

Seventy-two articles describing a total of 37,654 patients could be included: 2 level 1a studies (patient total: 692), 9 Level 1b studies (patient total: 1,677), 13 Level 2a studies (patient total 21,409), 32 Level 2b studies (patient total: 12,019), and 16 Level 2c studies (patient total: 1,857). The mean 30-day mortality rates of the two population-based levels were similar: 8.2% (6.4%-10.6%) for the prospective (1a) and 7.4% (7.0%-7.7%) for the retrospective series (2a). These figures were significantly higher than the remarkably similar hospital-based mortality rates: 3.8% (3.0%-4.8%) for the prospective (1b), 3.8% (3.5%-4.2%) for the retrospective (2b), and 3.5% (2.8%-4.4%) for selected patient group studies (2c). The most frequent complication was of cardiac origin. In the population-based series the cardiac complication rate was 10.6% (8.5%-13.2%) and 11.1% (9.1%-13.6%) for Levels 1a and 2a respectively. This compared well with the 12.0% (10.5%-13.9%) for the prospective, hospital-based series (Level 1b). The cardiac complication rates in the retrospective, hospital-based studies was significantly lower: 8.9% (8.4%-9.5%) and 6.1% (4.9%-7.6%) for Levels 2b and 2c respectively.

CONCLUSION

There is a clear and consistent disagreement in reported mortality rates between hospital-based and population-based studies of elective AAA-surgery. Prospective studies give the best documentation of postoperative morbidity.

Dilatation of the proximal neck of infrarenal aortic aneurysms after endovascular AAA repair

OBJECTIVES

to assess size changes of the proximal aortic neck after endograft placement.

METHODS

since 1994, 54 consecutive patients have undergone abdominal aortic aneurysm (AAA) repair with the Endovascular Technologies (EVT) endograft. The study group comprised the 33 patients who had completed at least six months of the prospective follow-up protocol. The pre-, postoperative and follow-up helical computed tomography (CT) angiograms (CTAs) were processed on a workstation. The proximal neck dimensions were measured perpendicular to the central lumen line of the aortic neck. The cross-sectional area was measured at the proximal attachment system and at 1 cm proximal to the renal arteries.

RESULTS

while the dimensions of suprarenal aorta did not change, a significant dilatation of the proximal neck was found. The median increase was 10.3% at 6 months and 15.5% at 12 months. No correlation could be found between the amount of dilatation and pre- or postoperative neck-size, graft diameter and amount of graft-oversizing.

CONCLUSION

the infrarenal aortic neck demonstrates continued dilatation during follow-up after endograft placement.

The effect of bisoprolol on perioperative mortality and myocardial infarction in high-risk patients undergoing vascular surgery. Dutch Echocardiographic Cardiac Risk Evaluation Applying Stress Echocardiography Study Group

BACKGROUND

Cardiovascular complications are the most important causes of perioperative morbidity and mortality among patients undergoing major vascular surgery.

METHODS

We performed a randomized, multicenter trial to assess the effect of perioperative blockade of beta-adrenergic receptors on the incidence of death from cardiac causes and nonfatal myocardial infarction within 30 days after major vascular surgery in patients at high risk for these events. High-risk patients were identified by the presence of both clinical risk factors and positive results on dobutamine echocardiography. Eligible patients were randomly assigned to receive standard perioperative care or standard care plus perioperative beta-blockade with bisoprolol.

RESULTS

A total of 1351 patients were screened, and 846 were found to have one or more cardiac risk factors. Of these 846 patients, 173 had positive results on dobutamine echocardiography. Fifty-nine patients were randomly assigned to receive bisoprolol, and 53 to receive standard care. Fifty-three patients were excluded from randomization because they were already taking a beta-blocker, and eight were excluded because they had extensive wall-motion abnormalities either at rest or during stress testing. Two patients in the bisoprolol group died of cardiac causes (3.4 percent), as compared with nine patients in the standard-care group (17 percent, P=0.02). Nonfatal myocardial infarction occurred in nine patients given standard care only (17 percent) and in none of those given standard care plus bisoprolol (P<0.001). Thus, the primary study end point of death from cardiac causes or nonfatal myocardial infarction occurred in 2 patients in the bisoprolol group (3.4 percent) and 18 patients in the standard-care group (34 percent, P<0.001).

CONCLUSIONS

Bisoprolol reduces the perioperative incidence of death from cardiac causes and nonfatal myocardial infarction in high-risk patients who are undergoing major vascular surgery.