Endoluminal transfemoral abdominal aortic aneurysm repair with aorto-uni-iliac graft and femorofemoral bypass

The UK EndoVascular Aneurysm Repair (EVAR) randomised controlled trials: long-term follow-up and cost-effectiveness analysis

BACKGROUND

Short-term survival benefits of endovascular aneurysm repair (EVAR) compared with open repair (OR) of intact abdominal aortic aneurysms have been shown in randomised trials, but this early survival benefit is soon lost. Survival benefit of EVAR was unclear at follow-up to 10 years.

OBJECTIVE

To assess the long-term efficacy of EVAR against OR in patients deemed fit and suitable for both procedures (EVAR trial 1; EVAR-1); and against no intervention in patients unfit for OR (EVAR trial 2; EVAR-2). To appraise the long-term significance of type II endoleak and define criteria for intervention.

DESIGN

Two national, multicentre randomised controlled trials: EVAR-1 and EVAR-2.

SETTING

Patients were recruited from 37 hospitals in the UK between 1 September 1999 and 31 August 2004.

PARTICIPANTS

Men and women aged ≥ 60 years with an aneurysm of ≥ 5.5 cm (as identified by computed tomography scanning), anatomically suitable and fit for OR were randomly assigned 1 : 1 to either EVAR (n = 626) or OR (n = 626) in EVAR-1 using computer-generated sequences at the trial hub. Patients considered unfit were randomly assigned to EVAR (n = 197) or no intervention (n = 207) in EVAR-2. There was no blinding.

INTERVENTIONS

EVAR, OR or no intervention.

MAIN OUTCOME MEASURES

The primary end points were total and aneurysm-related mortality until mid-2015 for both trials. Secondary outcomes for EVAR-1 were reinterventions, costs and cost-effectiveness.

RESULTS

In EVAR-1, over a mean of 12.7 years (standard deviation 1.5 years; maximum 15.8 years), we recorded 9.3 deaths per 100 person-years in the EVAR group and 8.9 deaths per 100 person-years in the OR group [adjusted hazard ratio (HR) 1.11, 95% confidence interval (CI) 0.97 to 1.27; p = 0.14]. At 0-6 months after randomisation, patients in the EVAR group had a lower mortality (adjusted HR 0.61, 95% CI 0.37 to 1.02 for total mortality; HR 0.47, 95% CI 0.23 to 0.93 for aneurysm-related mortality; p = 0.031), but beyond 8 years of follow-up patients in the OR group had a significantly lower mortality (adjusted HR 1.25, 95% CI 1.00 to 1.56, p = 0.048 for total mortality; HR 5.82, 95% CI 1.64 to 20.65, p = 0.0064 for aneurysm-related mortality). The increased aneurysm-related mortality in the EVAR group after 8 years was mainly attributable to secondary aneurysm sac rupture, with increased cancer mortality also observed in the EVAR group. Overall, aneurysm reintervention rates were higher in the EVAR group than in the OR group, 4.1 and 1.7 per 100 person-years, respectively (p < 0.001), with reinterventions occurring throughout follow-up. The mean difference in costs over 14 years was £3798 (95% CI £2338 to £5258). Economic modelling based on the outcomes of the EVAR-1 trial showed that the cost per quality-adjusted life-year gained over the patient's lifetime exceeds conventional thresholds used in the UK. In EVAR-2, patients died at the same rate in both groups, but there was suggestion of lower aneurysm mortality in those who actually underwent EVAR. Type II endoleak itself is not associated with a higher rate of mortality.

LIMITATIONS

Devices used were implanted between 1999 and 2004. Newer devices might have better results. Later follow-up imaging declined, particularly for OR patients. Methodology to capture reinterventions changed mainly to record linkage through the Hospital Episode Statistics administrative data set from 2009.

CONCLUSIONS

EVAR has an early survival benefit but an inferior late survival benefit compared with OR, which needs to be addressed by lifelong surveillance of EVAR and reintervention if necessary. EVAR does not prolong life in patients unfit for OR. Type II endoleak alone is relatively benign.

FUTURE WORK

To find easier ways to monitor sac expansion to trigger timely reintervention.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN55703451.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and the results will be published in full in Health Technology Assessment; Vol. 22, No. 5. See the NIHR Journals Library website for further project information.

Management of Abdominal Aortic Aneurysm: A Decade of Progress

Since the world was first introduced to the concept of endovascular aneurysm repair by Parodi's landmark procedures in 1990, stent-grafts have assumed a prominent role in the management of abdominal aortic aneurysm. Most modern systems are trackable, accurate, and secure. The resulting endovascular procedure is safe, durable, effective, and versatile. Perhaps the most significant increment in the applicability of the endovascular technique was achieved by the development of bifurcated stent-grafts, which dispensed with inadequate distal aortic implantation sites. Additional branches and fenestrations now permit endovascular repair in cases of thoracoabdominal, pararenal, juxtarenal, and bilateral iliac aneurysms. These advances in device performance have been accompanied by a rapid dissemination of necessary skills, leading to the development of a new superspecialty of vascular therapy, with elements of vascular surgery, interventional radiology, and interventional cardiology.

Abdominal Aortic Aneurysms: Experience with the Ivancev-Malmö Endovascular System for Aortomonoiliac Stent-Grafts

Purpose:

To describe a component-based aortomonoiliac stent-graft system and the first clinical results achieved with this device in endovascular abdominal aortic aneurysm (AAA) repair.

Methods:

From November 1993 to October 1996, 45 patients aged 60 to 86 years underwent endoluminal exclusion of true AAAs (median diameter 60 mm) involving the common iliac arteries (median diameter 16 mm right and 15 mm left) using unilimb stent-grafts deployed with the Ivancev-Malmö system.

Results:

Six immediate conversions occurred in the beginning of the series due to endografts that were too short. Complications, including 2 inadvertent renal artery occlusions, 7 kinked grafts, 6 iliac artery dissections, and 3 perioccluder leaks, were prominent features in the first 15 patients. Five patients died in the postoperative period, four of whom were nonsurgical candidates. There were five significant stent-graft migrations: one 3 weeks after surgery due to mechanical injury of the proximal stent and four after 1 year owing to continuous dilation of a wide proximal neck, stent-graft placement in a conical, thrombus-lined proximal neck, and two instances of proximal extension separation from the main graft. Translumbar aneurysm perfusion required embolization in 3 patients.

Conclusions:

Despite early complications associated with a learning curve, exclusion of large AAAs using unilimb stent-grafts is feasible. Strict inclusion criteria are necessary in order to improve mortality among nonsurgical candidates and minimize the risk for late migration.

Changing Aneurysmal Morphology after Endovascular Grafting: Relation to Leakage or Persistent Perfusion

Purpose:

To relate changing abdominal aortic aneurysm (AAA) morphology after endovascular grafting to the presence of leakage, collateral perfusion, and other factors.

Methods:

Thirty-five patients who underwent successful AAA endovascular grafting were evaluated. Self-expanding Z-stents and Dacron grafts were applied in bifurcated and aortomonoiliac systems. Postoperative diameter changes were calculated from repeated spiral computed tomographic scans, angiograms, and ultrasonic phase-locked echo-tracking scans during a median 6-month follow-up (interquartile range [IQR] 3 to 12).

Results:

At 12 months, the diameters of completely excluded aneurysms had decreased 6 mm (IQR 2 to 11; p = 0.006). The proximal graft-anchoring stents had dilated 2 mm (IQR 0.5 to 3.3; p = 0.01). The aortic diameters immediately below the renal arteries but above the stents had not changed. Endoleakage and collateral perfusion (n = 13) were each associated with preserved aneurysm size and a 12 times higher risk of aneurysm dilation. After the leakage or the collateral perfusion had been treated, the aneurysm size decreased. Aneurysms with extensive intraluminal thrombi presented a reduced risk of leakage or perfusion.

Conclusions:

The diameters of endovascularly excluded AAAs decrease, except in cases of leakage or perfusion. Careful follow-up of patients with aortic endografts is necessary.

Dilatation of the Infrarenal Aneurysm Neck after Endovascular Exclusion of Abdominal Aortic Aneurysm

Purpose:

To determine the fate of the infrarenal aneurysm neck and suprarenal aorta after endovascular exclusion of abdominal aortic aneurysms (AAAs).

Methods:

Thirty-four patients underwent endovascular AAA repair between January 1994 and December 1995 using custom-made stent-grafts constructed from polyester graft material and modified self-expanding Gianturco Z-stents sutured to the graft orifices. Thirty-one patients were available for follow-up. Pre- and postimplantation diameters were measured using spiral computed tomography in the infrarenal aneurysm neck and the suprarenal aorta at the level of the superior mesenteric artery (SMA).

Results:

The mean follow-up time was 25 months. There was a significant increase of the diameter of the infrarenal aneurysm neck (+ 1.65 mm, p = 0.002), but not in the aorta at the level of the SMA (+ 0.52 mm, p = 0.100). There was no difference in the change in diameter in the infrarenal neck in the group with a stent adjacent to the level of measurement (n = 20) compared with the group without an adjacent stent (n = 11, p = 0.790). There was no correlation between preimplantation size of the infrarenal neck and its diameter change (r = 0.14, p = 0.488). There was no correlation (r = 0.10, p = 0.603) or association (chi-square test, p = 0.211) between aortic diameter change at the level of the SMA and the infrarenal neck.

Conclusions:

This investigation shows a significant dilatation of the infrarenal aneurysm neck, but not in the suprarenal aorta, after endovascular AAA repair with this device. The clinical significance of these findings is unclear. Whether such a dilatation in the infrarenal aneurysm neck may affect the long-term attachment of stent-grafts remains to be shown in the future.

Outcomes Following Limb Crossing in Endovascular Aneurysm Repairs

Background:

Crossing the limbs of the stent during endovascular aneurysm repair (EVAR) is often used to aid cannulation of the contralateral limb. This study assessed outcomes following the use of this technique.

Methods:

Retrospective review of crossed (n = 43) and uncrossed (n = 269) EVARs was performed at a tertiary vascular center over 5 years. Primary end points were graft limb occlusion (GLO), endoleak, and sac expansion rates. Indications for limb crossing were also assessed.

Results:

Two-year GLO ( P = .34) and type 1 endoleak ( P = .413) rates were similar between groups. Patients undergoing crossed EVAR experienced more type 2 endoleaks ( P = .002) at 24 months but no increase in sac expansion rates was observed ( P = .275). Thirty-day ( P = .57) and late ( P = .268) mortalities were similar between groups. The main indication for limb crossing was distal aortic angulation (48.8%).

Conclusions:

Crossed EVAR does not increase the risk of GLOs or clinically significant endoleaks. Further studies are needed to determine the effect on type 2 endoleak rates.

Clinical practice change requires more than comparative effectiveness evidence: abdominal aortic aneurysm management in the USA

Adoption of healthcare innovations frequently outpaces the evidence of effectiveness. Endovascular repair (EVAR) for abdominal aortic aneurysms in the USA demonstrates how comparative effectiveness research without evidence-based reimbursement changes may fail to influence clinical practice. Randomized controlled trials for small abdominal aortic aneurysms demonstrate no lasting benefits of EVAR or open surgical repair (OSR) compared with surveillance, and for large abdominal aortic aneurysms demonstrate no lasting survival benefit of EVAR over OSR, and do show poorer durability and higher costs for EVAR. Nonetheless, >50% of elective abdominal aortic aneurysm repairs in the USA use EVAR. Factors that may be driving the high use of EVAR include patient preference, surgeons’ desire to appear ‘up-to-date’ in the procedures they offer, higher hourly surgeon reimbursement for EVAR than OSR, and the expansion of physician specialties able to perform abdominal aortic aneurysm repair from only vascular surgeons with OSR, to vascular surgeons and interventional radiologists/cardiologists with EVAR. By comparison, in Canada, where government health insurance restricts EVAR coverage to high surgical risk patients, only approximately 25% of abdominal aortic aneurysm repairs are performed using EVAR. Country-specific cost studies and a prospective population-based study collecting detailed clinical data to identify patient subgroups that truly benefit from a particular management strategy are needed to inform policy regarding EVAR availability and reimbursement.

Use of baseline factors to predict complications and reinterventions after endovascular repair of abdominal aortic aneurysm

BACKGROUND

It is uncertain which baseline factors are associated with graft-related complications and reinterventions after endovascular aneurysm repair (EVAR) in patients with a large abdominal aortic aneurysm.

METHODS

Patients randomized to elective EVAR in EVAR Trial 1 or 2 were followed for serious graft-related complications (type 2 endoleaks excluded) and reinterventions. Cox regression analysis was used to investigate whether any prespecified baseline factors were associated with time to first serious complication or reintervention.

RESULTS

A total of 756 patients who had elective EVAR were followed for a mean of 3.7 years, by which time there were 179 serious graft complications (rate 6.5 per 100 person years) and 114 reinterventions (rate 3.8 per 100 person years). The highest rate was during the first 6 months, with an apparent increase again after 2 years. Multivariable analysis indicated that graft-related complications increased significantly with larger initial aneurysm diameter (P < 0.001) and older age (P = 0.040). There was also evidence that patients with larger common iliac diameters experienced higher complication rates (P = 0.011).

CONCLUSION

Graft-related complication and reintervention rates were common after EVAR in patients with a large aneurysm. Younger patients and those with aneurysms closer to the 5.5-cm threshold for intervention experienced lower rates.

The UK Endovascular Aneurysm Repair (EVAR) Trials: Design, Methodology and Progress

OBJECTIVES

The endovascular aneurysm repair (EVAR) trials aim to assess the efficacy of EVAR in the treatment of AAA in terms of mortality, quality of life, durability and cost-effectiveness.

DESIGN

Male and female patients aged at least 60 years with an AAA diameter measuring at least 5.5 cm on a computed tomography (CT) scan are assessed for anatomical suitability for EVAR. Suitable patients are offered entry either into EVAR Trial 1 if they are considered fit for conventional open repair or EVAR Trial 2 if they are considered unfit. EVAR 1 randomly allocates patients to EVAR or open repair and EVAR 2 randomly allocates patients to EVAR with best medical treatment or best medical treatment alone. Target recruitment for EVAR Trials 1 and 2 is 900 and 280 patients, respectively.

PROGRESS

Recruitment began in September 1999 and there are currently 40 UK centres participating in the trials. Monthly targets are being exceeded in EVAR Trial 1 with 1037 patients randomised by October 2003. EVAR Trial 2 is also meeting monthly targets with a total of 319 patients randomised. When recruitment closes in December 2003 patients will need to be followed for at least 1 year from their operation. Publication of full results for both trials is expected in mid 2005.

The Vanguard Endovascular Stent-graft: Mid-term Results from a Single Centre

PURPOSE

Despite initial enthusiasm for endovascular aortic repair, few descriptions of longer-term follow-up of any endovascular device have been published. This paper represents the experience of a single centre with the Vanguard device over a 5-year period.

METHODS

Fifty-five patients with a median age of 71 years (range 45-87 years) and aneurysm diameter of 59 mm (45-84 mm) received a bifurcated Vanguard stent-graft between December 1995 and July 1999. Follow-up was according to the Eurostar criteria (clinical assessment, plain film radiography and computed tomography) at 1, 3, 6, 12, 18 and 24 months and then annually thereafter.

RESULTS

All primary stent deployments were successful. Median duration of surgery was 120 min (70-360 min). Median post-operative stay was 3 days (1-19 days) with a peri-operative mortality of 5.5%. In the follow-up period (median 40 months, range 6-64 months) there was one aneurysm associated death, and 14 deaths due to other causes. There have been three device migrations, 12 occluded graft limbs, four type II endoleaks and nine type III endoleaks. At 48 months, this has resulted in a survival rate of 67%, an endoleak free survival of 81% and intervention free survival of 59% (Kaplan-Meier).

CONCLUSION

Medium term results with the Vanguard device appear to be at least equivalent to open repair with regard to morbidity and mortality. Nevertheless, several delayed complications appear to be related to endograft limb distortion. Important lessons have been learnt in relation to the deployment of bifurcated endografts to reduce the incidence of secondary limb related problems.

Durability of femorofemoral bypass grafting after aortouniiliac endovascular aneurysm repair

INTRODUCTION

Endovascular aneurysm repair (EVAR) with aortouniiliac prostheses extends the morphologic range of aneurysms that can be treated and is potentially a more rapid and simple operation than bifurcated endovascular repair. It may, however, be limited by durability of the femorofemoral extra-anatomic bypass graft required to revascularize the contralateral lower limb. Previous studies of femorofemoral bypass grafts were performed almost exclusively in patients with occlusive disease. An 8-year single center experience with use of the femorofemoral bypass graft in aneurysmal disease is reported.

METHODS

All patients undergoing EVAR with an aortouniiliac endovascular stent graft over eight years (1994-2002) at a single institution were included in a retrospective study. Patient data were collected from a prospectively maintained local endovascular database. All patients gave informed consent and were part of an endovascular program approved by the local ethics committee.

RESULTS

Over the 8 years, 231 patients underwent EVAR with an aortouniiliac endovascular stent-graft. Median follow-up was 22 months. Localized wound complications were observed in 25 patients (11%). Cumulative 3-year patency rate for the femorofemoral bypass graft was 91%. At the end of 5 years 83% of grafts remained patent.

CONCLUSIONS

The femorofemoral bypass graft used during EVAR with aortouniliac stent grafts offers encouraging medium and long-term patency. When graft occlusion occurs, it is usually directly attributable to inadequate inflow from the endovascular stent graft itself or to endoluminal damage of the external iliac artery. Awareness and early detection of stent-graft distortion or complications in the external iliac artery may result in improved patency rates.

Endovascular repair of ruptured abdominal aortic aneurysm--a challenge to open repair? Results of a single centre experience in 20 patients

INTRODUCTION

The mortality from ruptured abdominal aortic aneurysm (AAA) remains in the region of 50% despite advances in critical care. Endovascular repair of AAA has been shown to be associated with reduced physiological stress in the elective setting. It is hypothesised that the reduced physiological stress associated with EVAR may improve the outcome in patients with ruptured AAA.

METHODS

A feasibility study of endovascular repair of ruptured AAA was undertaken at the University Hospital, Nottingham, U.K. between 1994 and 2000. Patients admitted with ruptured AAA were assessed by a team familiar with endovascular techniques for elective repair of AAA. After giving informed consent patients underwent spiral computed tomographic angiography (CTA) in the majority of cases. Patients were then transferred to the operating theatre for EVAR.

RESULTS

Twenty patients underwent repair of ruptured AAA. Of these 20 patients, seven were referred from another hospital. Eight patients were considered unfit for open repair. The median duration of procedure was 180 min (range 120-480) and median blood loss was 1200 ml (range 750-2000 ml). The overall peri-operative mortality was 45%. A number of intra-operative and peri-operative procedures (both open and endovascular) were required to ensure aneurysm exclusion and to deal with the complications of endovascular surgery.

CONCLUSIONS

Ruptured AAA remains a particularly hazardous condition to treat. There are a number of advantages of EVAR in this condition. A number of the problems early in the experience of EVAR have been addressed, but further experience is required to demonstrate its efficacy when compared with open repair.

Neurologic injury after endovascular stent-graft and bilateral internal iliac artery embolization for infrarenal abdominal aortic aneurysm

The authors report a rare neurologic complication after the implantation of a bifurcated stent-graft for abdominal aortic aneurysm. The stent-graft was extended to both external iliac arteries after embolization of both internal iliac arteries. The patient subsequently had weakness and numbness of both lower limbs with bowel and bladder incontinence. He probably had ischemic injury to the nerve roots or the lumbosacral plexus, which was related to extensive occlusion of their supplying arteries. The mechanism of spinal cord and neurologic ischemia after aortic stent-graft implantation is discussed.

Endoluminal aortic grafting with renal and superior mesenteric artery incorporation by graft fenestration

PURPOSE

To explore the use of juxta- and suprarenal aortic segments for endograft fixation in abdominal aortic aneurysm (AAA) patients and to develop methods of graft implantation that use endograft fenestrations to preserve renal and visceral vessel perfusion.

METHODS

From August 1998 to May 2000, 13 AAA patients with unsuitable infrarenal aortic necks were treated with custom-designed endovascular grafts employing the juxta- and suprarenal aortic segments for proximal sealing. Flow to 33 renal and superior mesenteric arteries was maintained via graft fenestrations that were aligned by use of radiopaque graft markers. The fenestration-orifice interface for renal arteries was secured with modified balloon-expandable stents.

RESULTS

All fenestrated grafts were deployed as planned, and all target vessels (33/33) were preserved. Two patients did not receive any stents, one being the first in the series and another who had incorporation of a renal accessory artery only. Without the use of transgraft stenting, 5 renal arteries would have been occluded by the endograft or poorly perfused. Procedural success was 100%. No conversion to open operation or graft-related complications occurred. There was no primary endoleak in any patient by angiographic criteria. Two patients required additional surgical procedures related to access vessels. Periprocedural mortality at 30 days was nil. Follow-up ranging from 3 to 24 months on all patients has not demonstrated any proximal or distal endoleaks. One stented renal vessel has occluded; all other arteries remain patent at last examination.

CONCLUSIONS

This study has demonstrated the ability to successfully place a multifenestrated endoluminal graft in an aortic aneurysm using juxta- and suprarenal aortic segments to obtain a satisfactory seal. Stenting of the fenestration-renal ostium junction has helped to maintain renal patency.

Fixation of infrarenal aortic stent-grafts using laparoscopic banding -- an experimental study in pigs

PURPOSE

to test whether a laparoscopically-placed external band around the infrarenal aorta could stop vessel dilatation and prevent stent-graft detachment from the aortic wall.

METHODS

in 13 growing pigs Gianturco-based stent-grafts were placed in the infrarenal aorta. In eight pigs, an external PTFE band (1 cm width) was placed laparoscopically around the infrarenal aorta. The remaining five pigs served as controls. Angiographic aortic diameters were measured: (1) at the most distal renal artery; (2) 1.5 cm further distally; (3) at the middle of the stent-graft; and (4) below the stent-graft, 1 cm above the aortic bifurcation.

RESULTS

at a median follow-up of 16 weeks the pigs in the control group (n =5) and in the banded group ( n =7) increased their weight from 24 kg to 107 kg and 23 to 83 kg, respectively. In the control group, aortic dimensions increased by approximately 40% at all levels. In the banded group, aortic dimensions were unchanged at levels 2 and 3, but increased significantly at levels 1 and 4 (i.e. above and below the stent-graft). In the control group all stent-grafts detached causing a proximal perigraft leakage. No detachment or proximal perigraft leak was observed in the banded group.

CONCLUSION

a laparoscopically placed external band around the infrarenal aorta of growing pigs seems to counteract the vessel dilatation and thereby provides a stable fixation of self-expandable stent-grafts.

Incidence and treatment of intraoperative technical problems during endovascular repair of complex abdominal aortic aneurysms

PURPOSE

The purpose of this study was to assess the incidence and management of intraoperative technical problems during endovascular repair (EVR) of complex abdominal aortic aneurysms (AAA).

METHODS

From February 1995 to March 1999, 204 EVRs of nonruptured AAA were performed at our institution. One hundred seventy-six patients had an in-house custom-made graft; 172 were aorto-uni-iliac grafts, and four were aortoaortic grafts. Twenty- eight patients had a bifurcated graft. One hundred fourteen patients (56%) were high risk for conventional open repair. One hundred nine patients (53%) were not suitable for most commercially available devices.

RESULTS

Intraoperative technical problems occurred in 81 patients (40%). There were 37 endoleaks (27 proximal, 10 distal), 15 graft stenoses, one failure of graft deployment, two graft thromboses, three aortoiliac ruptures, five renal artery occlusions (one bilateral, four unilateral), and 18 internal iliac occlusions (five bilateral, 13 unilateral). Endovascular management of these problems was successful in 37 of the 81 patients (46%) and included 15 balloon dilatations, 21 additional stent placements, and one graft thrombectomy. Fifteen of the 81 patients (19%) had open procedures (four periaortic ligature placements, six open aneurysm repairs, three common iliac ligations, and two extra-anatomic bypass grafts). In the remaining 29 patients, the on-table problem was managed expectantly. During follow-up, two of 37 patients (5%) who were treated successfully with endovascular procedures experienced recurrence. There were five deaths (33%) among the 15 patients who underwent open procedures.

CONCLUSION

Intraoperative problems occur frequently during the endovascular management of complex aneurysms. Many of these problems can be managed with additional endovascular techniques without an increased risk of recurrence or procedure-related complications. Open procedures in high-risk patients carry a high mortality rate. The team performing EVR of AAA should be skillful in advanced endovascular and open surgical procedures.

Anatomical risk factors for proximal perigraft endoleak and graft migration following endovascular repair of abdominal aortic aneurysms

INTRODUCTION

proximal perigraft endoleak (PPE) and graft migration are associated with significant morbidity and mortality. Objective data establishing correlation between neck anatomy and these complications are lacking. The aim of this study was to analyse the anatomy of the neck in order to find which variables were significantly associated with PPE and graft migration.

METHODS

one hundred and eighty-four patients underwent endovascular repair (EVR) of infrarenal AAA using an in-house custom-made stent graft (Gianturco stents plus Dacron). Thirty-one patients had PPE and fifteen had graft migration. Neck diameter was measured at the level of renal arteries and lower limit of the neck. Necks were classified according to shape. Neck angulation was measured from spiral computed tomography (CT) or magnetic resonance imaging (MRI) reconstructions, or angiograms. Thrombus or atheroma lining and presence of calcifications were recorded.

RESULTS

neck angulation was significantly greater in patients who had PPE (50+/-16, p=0. 0005) or graft migration (54+/-20, p=0.003), compared to patients who had none of these two complications (37+/-18). Neck diameter was significantly greater in patients with PPE (p=0.05). Incidence of PPE or graft migration was not significantly higher in the presence of a conical shape, thrombus or atheroma lining and calcifications.

CONCLUSION

neck angulation was the risk factor most significantly related to PPE and graft migration.

Distal migration of stent-grafts after endovascular repair of abdominal aortic aneurysms

PURPOSE

To analyze patients after endovascular repair of abdominal aortic aneurysm (AAA) with respect to distal migration of stent-grafts and its underlying causes.

MATERIALS AND METHODS

Sixty-five patients underwent endovascular repair between January 1994 and February 1997. There were seven women and 58 men, with a mean age of 71 years (range, 51-84 years). Three patients died in the perioperative period (one of myocardial infarction and two of multiorgan failure) and two patients died within 4 months of the procedure of non-procedure-related causes. In addition, two patients were followed at another hospital. The remaining 58 patients were followed up with spiral computed tomography scans at 1, 3, and 6 months, and biannually thereafter. Angiography was performed at 1 month and 1 year after the procedure and additionally when deemed clinically necessary. Mean follow-up was 29 months (range, 1-49). Migration more than 5 mm was considered significant.

RESULTS

Twenty-six patients (45%) showed distal migration of stent-grafts during follow-up. Mean follow-up time at detection of migration was 13 months (range, 1-36 months). Thirteen cases of migration were ascribed to dilatation of the proximal aneurysmal neck during follow-up. Ten cases of migration were ascribed to causes other than neck dilatation or poor patient selection. In three cases, no obvious cause for the migration was found. The migration was complete in eight cases, leading to late conversion to open surgical repair. On two of these occasions, complete migration lead to aneurysm rupture. In addition, four patients received additional stent-grafts as proximal extensions.

CONCLUSIONS

Distal migration of stent-grafts after endovascular AAA repair occurred frequently in this series. Dilatation of the proximal aneurysmal neck is a major cause of distal migration of stent-grafts. Improved proximal fixation is needed to secure long-term durability.

Is endoluminal abdominal aortic aneurysm repair using an aortoaortic (tube) device a durable procedure?

Endoluminal repair of abdominal aortic aneurysm (AAA) is being adopted as a less invasive alternative to conventional open repair in many centers worldwide. Although the initial results are encouraging, the long-term durability of this procedure remains unknown. Endoluminal AAA repair in 29 patients using three different devices (EVT tube Endograft(R), aortouniiliac device, and Stentortrade mark bifurcated system) is described. Overall, 24 procedures (83%) were completed successfully. Complications included two deaths due to microembolization, five early conversions, two chest infections, three patients with buttock claudication, and three patients with trashed foot. Perigraft leaks were detected in four patients (three proximal, one distal) treated with the EVT tube Endograft. Continued aneurysm expansion was observed in three of the patients. One of the leaks was discovered at the 1-year follow-up. In this patient the aneurysmal process was not retarded by endoluminal repair. The findings in this patient may have implications for the durability of this technique. Therefore, careful long-term evaluation of this procedure is recommended prior to its widespread use.

Blood product requirements in patients undergoing elective endovascular abdominal aortic aneurysm repair

OBJECTIVE

Endovascular repair (EVR) of abdominal aortic aneurysm (AAA) has many potential advantages, one of which may be reduced blood product requirements. The aim of this study was to compare the current blood product usage in our unit for three types of elective operation: EVR of AAA, open AAA repair and femorofemoral crossover grafts.

DESIGN

Prospective data analysis with historical controls.

MATERIALS

One-hundred and thirty-two patients undergoing elective EVR of AAA, 35 patients undergoing elective open repair of AAA and 37 patients having femorofemoral crossover grafts.

METHODS

Data was collected on the blood product requirements of patients having EVR of AAA, with open AAA repair and femorofemoral crossover graft providing historical controls.

RESULTS

There was no difference in the haematological parameters preoperatively between the three groups but postoperatively patients having EVR had a slightly lower haemoglobin than the open group (10.6 g/dl vs. 10.85 g/dl, p = 0.015). The number of patients who received blood transfusion in the EVR group was 82/132 (62%) and the open group 27/35 (77%), p = 0.4.

CONCLUSION

Patients undergoing EVR of AAA require blood transfusion in the same numbers when compared to those undergoing open repair.

Early complications of femorofemoral crossover bypass grafts after aorta uni-iliac endovascular repair of abdominal aortic aneurysms

OBJECTIVE

The following procedures are the 3 main methods of endovascular repair (EVR) of abdominal aortic aneurysms (AAA): aorto-aortic bypass grafting, bifurcated bypass grafting, and aorta uni-iliac grafts. The latter method has the potential disadvantage of requiring an extra anatomic graft (ie, a femorofemoral crossover bypass graft) to maintain contralateral pelvic and limb perfusion. The aim of this study was to assess the complications associated with the femorofemoral crossover bypass graft after aorta uni-iliac EVR of AAA.

METHOD

A prospective review was conducted of the complications attributable to the femorofemoral crossover bypass graft in 136 patients who underwent EVR of AAA with an aorta uni-iliac device.

RESULTS

During a median follow-up of 7 months (range, 0 to 36 months), 4 patients had superficial wound infections that required antibiotic treatment and 2 patients had bypass graft infections. Nine hematomas developed: 7 (5%) groin hematomas (6 in patients with Dacron bypass grafts), 1 scrotal hematoma, and 1 perigraft hematoma. One bypass graft thrombus developed.

CONCLUSION

The femorofemoral crossover bypass graft is a safe and a durable component of EVR of AAA with an aorta uni-iliac device. The results are similar to those with bifurcated devices.

A study on the patency of the inferior mesenteric and lumbar arteries in the incidence of endoleak following endovascular repair of infra-renal aortic aneurysms

OBJECTIVE

An endoleak is defined as the presence of contrast medium within the aneurysm sac on post-operative contrast-enhanced computed tomography scans (CT) in patients following endovascular repair (EVR) of abdominal aortic aneurysms (AAA). The aim of this study was to correlate the incidence of endoleaks with the presence of patent lumbar (LA) and inferior mesenteric arteries (IMA) as seen on pre-operative angiography.

DESIGN, MATERIALS AND METHODS

Forty-seven patients were assessed pre-operatively by both CT and angiography by a blinded radiologist prior to EVR of AAA. The number and size of patent vessels was recorded and correlated with the incidence of LA or IMA endoleaks on follow-up CT. Patent lumbar vessels were scored: 1 = small, 2 = medium, 3 = large.

RESULTS

Five patients were noted to have patent IMA on pre-operative angiography but none developed an endoleak. In this series, five patients had an endoleak due to a patent LA. The median score for patients with no endoleak was 1 (0-9) and for those with a lumbar endoleak 2 (0-5) (P = 0.26, Mann-Whitney U-test). The number of patent lumbar arteries was not predictive of a subsequent endoleak. Two out of nine (22 %) patients with large patent LA subsequently developed an endoleak. If a policy of pre-operative embolization on the basis of large patent LA had been adopted, seven patients would have had an unnecessary invasive procedure.

CONCLUSION

Pre-operative angiography to look for patent LA and IMAs is not required in patients undergoing EVR or AAA.

Dilatation of the infrarenal aneurysm neck after endovascular exclusion of abdominal aortic aneurysm

PURPOSE

To determine the fate of the infrarenal aneurysm neck and suprarenal aorta after endovascular exclusion of abdominal aortic aneurysms (AAAs).

METHODS

Thirty-four patients underwent endovascular AAA repair between January 1994 and December 1995 using custom-made stent-grafts constructed from polyester graft material and modified self-expanding Gianturco Z-stents sutured to the graft orifices. Thirty-one patients were available for follow-up. Pre- and postimplantation diameters were measured using spiral computed tomography in the infrarenal aneurysm neck and the suprarenal aorta at the level of the superior mesenteric artery (SMA).

RESULTS

The mean follow-up time was 25 months. There was a significant increase of the diameter of the infrarenal aneurysm neck (+ 1.65 mm, p = 0.002), but not in the aorta at the level of the SMA (+0.52 mm, p = 0.100). There was no difference in the change in diameter in the infrarenal neck in the group with a stent adjacent to the level of measurement (n = 20) compared with the group without an adjacent stent (n = 11, p = 0.790). There was no correlation between preimplantation size of the infrarenal neck and its diameter change (r = 0.14, p = 0.488). There was no correlation (r = 0.10, p = 0.603) or association (chi-square test, p = 0.211) between aortic diameter change at the level of the SMA and the infrarenal neck.

CONCLUSIONS

This investigation shows a significant dilatation of the infrarenal aneurysm neck, but not in the suprarenal aorta, after endovascular AAA repair with this device. The clinical significance of these findings is unclear. Whether such a dilatation in the infrarenal aneurysm neck may affect the long-term attachment of stent-grafts remains to be shown in the future.

The Quality of Surgical Care Project: benchmark standards of open resection for abdominal aortic aneurysm in Western Australia

BACKGROUND

The Quality of Surgical Care Project (QSCP) was established in May 1996, to evaluate surgical outcomes and where indicated, recommend changes to improve the quality of surgical care in Western Australia (WA). The purpose of this study is to establish benchmark standards in WA for operative mortality, 5-year survival and length of stay in all patients who were surgically treated for aneurysm of the abdominal aorta (AAA) in WA.

METHODS

The WA Linked Database was used to link the morbidity and mortality records of all patients admitted and surgically treated for AAA in WA from 1985 to 1994. The linked chains of de-identified hospital morbidity and death records were selected using diagnostic and procedure codes pertaining to AAA. Three groups were separated for analysis: those admitted for rupture, those admitted for elective repair, and those who were admitted to hospital as an emergency without mention of rupture but who underwent repair for AAA. Independent analysis for gender and patients 80 years or more were included in the study. Patients were excluded from the study if they were less than 55 years of age.

RESULTS

A total of 1475 cases (1257 males, 218 females) were identified. The mean age in elective cases was 70.4 years in males and 72.4 years in females, and for rupture the mean ages were 71.9 and 74.8 years, respectively. Median length of stay for males was 12 days for elective cases. Admission type or age did not significantly influence length of stay. Thirty-day mortality in males was 4.4% for elective repair and 36.7% for ruptured AAA and 5-year survival was 71.7 and 47.7%, respectively. The overall case fatality rate for ruptured AAA was 79.3% which included those cases who died from rupture without being admitted to hospital.

CONCLUSIONS

These community-wide data provide a realistic measure of surgical performance for open repair of AAA. The outcomes for elective and rupture repair for AAA compare favourably with standards reported by international centres of excellence. They also support the use of this procedure in patients over 80 years of age with rupture. This information can be used for ongoing audit purposes and as a benchmark for the introduction of new treatment modalities.

Reduced pulsatile wall motion of abdominal aortic aneurysms after endovascular repair

PURPOSE

The reduced size of abdominal aortic aneurysms (AAAs) after endovascular repair suggests lowered intraaneurysmal pressure. In the presence of endoleaks, the size is not decreased. Although postoperative intraaneurysmal pressure is difficult to record, the pulsatile wall motion (PWM) of aneurysms can be measured noninvasively. The aim of this study was to assess the PWM of AAAs before and after endovascular repair and to relate the change in the PWM to aneurysmal size and presence of endoleaks.

METHODS

Forty-seven patients underwent endovascular repair of an AAA. The aneurysm diameter and PWM were measured with the use of ultrasonic echo-tracking scans preoperatively; at 1, 3, and 6 months; and thereafter biannually. Fifteen aneurysms developed endoleaks, whereas 32 were completely excluded. The leaks were characterized with the use of computed tomographic scanning and angiography. Median follow-up was 12 months (interquartile range, 5 to 24 months).

RESULTS

The preoperative PWM of the aneurysms was 1.0 mm (range, 0.8 to 1.3 mm). After complete endovascular exclusion, the PWM was 25% (range, 16% to 37%) of the preoperative value (p < 0.001), and aneurysm diameter decreased by 8 mm (range, 6 to 14 mm) (p < 0.001). After 18 months, no further diameter reduction occurred. In three patients without endoleaks but with enlarging aneurysms, the postoperative PWM showed less reduction (p < 0.05). Aneurysms with endoleaks showed no diameter decrease, and the postoperative PWM was 50% higher than that in the totally excluded cases (p < 0.01). In five patients with transient endoleaks, the PWM was reduced after leakage ceased (p < 0.05). Leaks of various sources displayed similar PWM.

CONCLUSION

The size and PWM of aneurysms are reduced after endovascular repair. The diameter reduction may cease after 1.5 years. Endoleaks are associated with higher PWM than expected. Pressure may be transmitted without evidence of leaks.

Endoleaks after endovascular graft treatment of aortic aneurysms: classification, risk factors, and outcome

PURPOSE

Incomplete endovascular graft exclusion of an abdominal aortic aneurysm results in an endoleak. To better understand the pathogenesis, significance, and fate of endoleaks, we analyzed our experience with endovascular aneurysm repair.

METHODS

Between November 1992 and May 1997, 47 aneurysms were treated. In a phase I study, patients received either an endovascular aortoaortic graft (11) or an aortoiliac, femorofemoral graft (8). In phase II, procedures and grafts were modified to include aortofemoral, femorofemoral grafts (28) that were inserted with juxtarenal proximal stents, sutured endovascular distal anastomoses within the femoral artery, and hypogastric artery coil embolization. Endoleaks were detected by arteriogram, computed tomographic scan, or duplex ultrasound. Classification systems to describe anatomic, chronologic, and physiologic endoleak features were developed, and aortic characteristics were correlated with endoleak incidence.

RESULTS

Endoleaks were discovered in 11 phase I patients (58%) and only six phase II patients (21%; p < 0.05). Aneurysm neck lengths 2 cm or less increased the incidence of endoleaks (p < 0.05). Although not significant, aneurysms with patent side branches or severe neck calcification had a higher rate of endoleaks than those without these features (47% vs 29% and 57% vs 33%, respectively), and patients with iliac artery occlusive disease had a lower rate of endoleaks than those without occlusive disease (18% vs 42%). Endoleak classifications revealed that most endoleaks were immediate, without outflow, and persistent (71% each), proximal (59%), and had aortic inflow (88%). One patient with a persistent endoleak had aneurysm rupture and died.

CONCLUSIONS

Endoleaks complicate a significant number of endovascular abdominal aortic aneurysm repairs and may permit aneurysm growth and rupture. The type of graft used, the technique of graft insertion, and aortic anatomic features all affect the rate of endoleaks. Anatomic, chronologic, and physiologic classifications can facilitate endoleak reporting and improve understanding of their pathogenesis, significance, and fate.

Abdominal aortic aneurysms: experience with the Ivancev-Malmö endovascular system for aortomonoiliac stent-grafts

PURPOSE

To describe a component-based aortomonoiliac stent-graft system and the first clinical results achieved with this device in endovascular abdominal aortic aneurysm (AAA) repair.

METHODS

From November 1993 to October 1996, 45 patients aged 60 to 86 years underwent endoluminal exclusion of true AAAs (median diameter 60 mm) involving the common iliac arteries (median diameter 16 mm right and 15 mm left) using unilimb stent-grafts deployed with the Iancev-Malmö system.

RESULTS

Six immediate conversions occurred in the beginning of the series due to endografts that were too short. Complications, including 2 inadvertent renal artery occlusions, 7 kinked grafts, 6 iliac artery dissections, and 3 perioccluder leaks, were prominent features in the first 15 patients. Five patients died in the postoperative period, four of whom were nonsurgical candidates. There were five significant stent-graft migrations: one 3 weeks after surgery due to mechanical injury of the proximal stent and four after 1 year owing to continuous dilation of a wide proximal neck, stent-graft placement in a conical, thrombus-lined proximal neck, and two instances of proximal extension separation from the main graft. Translumbar aneurysm perfusion required embolization in 3 patients.

CONCLUSIONS

Despite early complications associated with a learning curve, exclusion of large AAAs using unilimb stent-grafts is feasible. Strict inclusion criteria are necessary in order to improve mortality among nonsurgical candidates and minimize the risk for late migration.

Renal arteries covered by aortic stents: clinical experience from endovascular grafting of aortic aneurysms

OBJECTIVES

During the endovascular repair of abdominal aortic aneurysms (AAAs), effective anchoring of the stent-graft is difficult in the presence of a short infrarenal aneurysm neck. The aim of this study was to investigate renal artery patency and renal function after deployment of graft anchoring stents across the renal arteries.

DESIGN

Retrospective open study.

PATIENTS

Twenty-five renal arteries, in 18 patients treated by endovascular exclusion of an AAA, were intentionally covered with the Gianturco Z-stent to ensure stent graft attachment.

METHODS

Renal artery patency was assessed by repeated spiral computed tomography (CT) scans and angiography. Creatinine levels, blood pressure and antihypertensive medication were recorded. Follow-up was a median 6 months (2-9).

RESULTS

All 25 stent-covered renal arteries remained patent. CT showed a small infarct in one kidney. Creatinine was 108 mumol/l (89-133) before intervention and 98 mumol/l (87-127) at follow-up. Blood pressure was 150/80 mmHg on both occasions. Antihypertensive therapy was intensified in one patient whose creatinine level remained stable and whose separate renin sampling was normal.

CONCLUSIONS

Covering the renal arteries with the Gianturco Z-stent does not seem to affect renal function within 6 months. Further follow-up is needed before suprarenal stent deployment can be advocated.

The anatomy of abdominal aortic aneurysms: implications for sizing of endovascular grafts

OBJECTIVE

To determine the full range of aorto-iliac anatomy of patients with abdominal aortic aneurysms (AAAs) and thence the range of endovascular graft sizes required to deal with the majority of AAAs.

DESIGN

Analysis of preoperative spiral CT measurements.

MATERIALS

One hundred and sixty-eight patients with AAAs.

METHODS

Multiplanar reconstruction measurements were taken of proximal aortic neck diameter and length, lowermost renal artery to the aortic bifurcation distance and length and diameter of common iliac arteries. Based on these measurements a range of graft sizes that would fit the majority of AAAs was determined.

RESULTS

Ranges of anatomical variables were as follows: proximal aortic neck diameter 18-30 mm, renal artery to aortic bifurcation distance 93-210 mm, common iliac artery length 13-108 mm, common iliac artery diameter 6-67 mm. Over 750 graft sizes would be required to cover all anatomical combinations using a one-piece aorto-uni-iliac graft.

CONCLUSION

A wide variety of aorto-iliac anatomy exists in patients with AAAs. The large number of graft sizes required to deal with the majority of AAAs makes the production of one-piece endovascular grafts commercially impractical. A proposed two-piece modular graft would allow the majority of AAAs to be treated using only 16 graft sizes.

Changing aneurysmal morphology after endovascular grafting: relation to leakage or persistent perfusion

PURPOSE

To relate changing abdominal aortic aneurysm (AAA) morphology after endovascular grafting to the presence of leakage, collateral perfusion, and other factors.

METHODS

Thirty-five patients who underwent successful AAA endovascular grafting were evaluated. Self-expanding Z-stents and Dacron grafts were applied in bifurcated and aortomonoiliac systems. Postoperative diameter changes were calculated from repeated spiral computed tomographic scans, angiograms, and ultrasonic phase-locked echo-tracking scans during a median 6-month follow-up (interquartile range [IQR] 3 to 12).

RESULTS

At 12 months, the diameters of completely excluded aneurysms had decreased 6 mm (IQR 2 to 11; p = 0.006). The proximal graft-anchoring stents had dilated 2 mm (IQR 0.5 to 3.3; p = 0.01). The aortic diameters immediately below the renal arteries but above the stents had not changed. Endoleakage and collateral perfusion (n = 13) were each associated with preserved aneurysm size and a 12 times higher risk of aneurysm dilation. After the leakage or the collateral perfusion had been treated, the aneurysm size decreased. Aneurysms with extensive intraluminal thrombi presented a reduced risk of leakage or perfusion.

CONCLUSIONS

The diameters of endovascularly excluded AAAs decrease, except in cases of leakage or perfusion. Careful follow-up of patients with aortic endografts is necessary.

Aneurysm pressure following endovascular exclusion

OBJECTIVES

To assess the effect of stent-graft implantation on the pressure within an abdominal aortic aneurysm.

METHODS

Aneurysm exclusion was performed using an aorto-uniiliac stent-graft in eight patients. Following stent-graft implantation, pressure measurements were performed through a catheter adjacent to the graft in the aneurysm. This "aneurysm pressure" was compared with radial arterial pressure.

RESULTS

The pressure was lower in the aneurysm than in the radial artery, in all cases. Mean aneurysm pressure was 36.5/33.8 mmHg, while mean radial arterial pressure was 118.5/50.5 mmHg (p < 0.05, for both systolic and diastolic pressures). These findings corresponded with a reduction in the palpable abdominal pulse, and an absence of perigraft perfusion on follow-up computerised tomography.

CONCLUSION

Stent-graft implantation produces a fall in the pressure within an abdominal aortic aneurysm.

Early results of endovascular aortic aneurysm surgery with aortouniiliac graft, contralateral iliac occlusion, and femorofemoral bypass

PURPOSE

The aim of this study was to evaluate the feasibility of endovascular aortic aneurysm repair with use of an aortouniiliac graft secured with self-expanding (Gianturco) stents.

METHODS

Thirty patients with a median age of 72 years (age range, 52 to 86 years) and aneurysm diameter of 6.0 cm (range, 4.0 to 9.0 cm) were treated with an aortouniiliac endovascular graft. Of these 30 procedures, 28 were carried out electively and two as emergencies for leaking aneurysm. Of the 30 patients, 21 (70%) were considered to be at high risk for open surgery. A modified Gianturco stent, Dacron graft, and Wallstent were used for these procedures.

RESULTS

Endovascular repair was successfully carried out in 25 of 30 (83.3%) patients. All these patients were mobile and had resumed a normal diet within 48 hours of the procedure. The overall 30-day mortality rate was two in 30 (6.6%), but it was one in 28 (3.5%) for the elective cases; all deaths occurred in the group at high risk for surgery. Other complications encountered within 30 days of procedure included myocardial infarction in one patient, pneumonia in two patients, homonymous quadrantanopia in one patient, and colonic ischemia in one patient, giving an overall morbidity rate of four in 30 (13.3%). At a median follow-up of 4 months (range, 1 to 13 months), 27 of 30 (90%) patients remain alive and well.

CONCLUSION

Endovascular aortouniiliac repair of abdominal aortic aneurysm with Gianturco stent is feasible in both elective and emergency situations. It appears to be minimally traumatic, and the majority of patients deemed to be at high risk for open surgery can safely undergo endovascular repair. However, data on more patients with longer follow-up is required to determine its role in the management of abdominal aortic aneurysm.

Juxtarenal aortic aneurysm: endoluminal transfemoral repair?

Endoluminal transfemoral repair of an abdominal aortic aneurysm by a stent graft placement requires a segment of the nondilated infrarenal aorta of at least 15 mm long for safe stent graft attachment. The possibility of endoluminal treatment of a juxtarenal abdominal aortic aneurysm with partially covered spiral Z stent was assessed in experiment and in three clinical cases. In the experiment, the noncovered spiral Z stent was placed into the abdominal aorta, across the origins of renal arteries and mesenteric arteries, in six dogs. In the clinical cases, a partially covered stent graft was attached in 3 patients with the juxtarenal abdominal aortic aneurysm (of the group of 12 patients with abdominal aortic aneurysm). The stent grafts were attached with proximal uncovered parts across the origins of the renal arteries. In experiment, the renal artery occlusions or stenoses were not observed 36 months after stent placement, and in clinic, 3 patients with the juxtarenal aortic aneurysm were successfully treated by stent graft placement. There were no signs of flow impairment into the renal arteries 14 months after stent graft implantation. This approach can possibly expand the indications for endoluminal grafting in the treatment of juxtarenal aortic aneurysms in patients who are at high risk for surgery.

A telescopic stent-graft for aortoiliac implantation

OBJECTIVES

To test a new delivery system for a telescopic stent-graft.

MATERIALS

Variable overlap between the components of this stent-graft combination allows length adjustment. This device differs from other multi-component stent-grafts in that both components are contained within a single delivery system.

METHODS

The stent-graft was implanted in the distal thoracic to suprarenal aorta of five pigs (35-50 kg), where the arterial diameter falls by almost 50%. The proximal and distal components of the stent-graft were targeted to bony landmarks in the vertebral column.

RESULTS

Inspection of completion angiograms showed both proximal and distal stent-grafts to be within 1 mm of their target locations in all five experiments. Overall combined stent-graft length varied from 13.5 cm to 16.1 cm depending on the location of the bony landmark chosen as the distal target, and on the size of the pig.

CONCLUSIONS

This system may be useful for the repair of abdominal aortic aneurysm whenever preoperative sizing is difficult due to aortic tortuosity, or precluded due to the urgency of the procedure.

The Perth endoluminal bifurcated graft system--development and early experience

The study aim was to develop a reliable endoluminal graft system that would enable the deployment of a bifurcated graft for infrarenal abdominal aortic aneurysms. A life-size plastic model was made of an abdominal aorta and iliac arteries, with a 50-mm infrarenal abdominal aortic aneurysm. This model was used to develop and test self-expanding graft systems, based on a barbed Gianturco stent and series of stainless-steel 'Z' stents within a woven Dacron graft. The bifurcated system developed involves a trouser graft with one long leg and one short. This graft-system is delivered through one femoral artery with deployment of the proximal aortic end infrarenally and the longer trouser leg within the ipsilateral common iliac artery. The short trouser leg is left hanging free within the distal end of the aneurysm cavity, just above the bifurcation. It is held open by a self-expanding stent and is cannulated from the contralateral femoral artery with a guide wire. A simple straight self-expanding stented graft is then deployed to extend this short trouser leg down into the common iliac artery, effectively creating an extension to the short leg. The graft system has been deployed in 21 patients with satisfactory exclusion of the aneurysm in 17 (81%). There has been one mortality and no conversion to open repair. All 17 aneurysms remain excluded at median follow-up of 30 (range 4-60) weeks. None of the four graft stents that leaked (two proximal and two distal) sealed spontaneously. Deployment of the uncovered Gianturco stent across the renal artery origins in 18 cases (85%) has not been associated with renal artery occlusion or deterioration in renal function at a median follow-up of 30 (range 4-60) weeks. The ability to deploy a bifurcated system increases the potential for endoluminal treatment of abdominal aortic aneurysm.

Comparison of magnetic resonance imaging measurements of abdominal aortic aneurysms with measurements obtained by other imaging techniques and intraoperative measurements: possible implications for endovascular grafting

PURPOSE

Abdominal aortic aneurysm morphologic evaluation with conventional imaging techniques is inadequate when endovascular repair is being contemplated. This study has addressed the problem with magnetic resonance imaging (MRI).

METHODS

Twenty patients (14 men, 6 women) with a median age of 73 years were recruited and assessed according to current endovascular graft selection criteria. Thirteen patients subsequently underwent open aneurysmorrhaphy, and the intraoperative parameters have been compared with those of duplex ultrasonography and MRI.

RESULTS

No significant difference was demonstrated in the diameter of the infrarenal neck among ultrasonography, MRI, and intraoperative findings (p > 0.05, Mann Whitney U Test) and also during assessment of infrarenal neck length; however, duplex sonography accurately defined the renal ostia in only five cases. MRI visualized 38 of 40 renal arteries. Distal aortic involvement (cuff diameter and length) and the length and diameter of the common iliac arteries were accurately determined by MRI in all cases, and no significant difference was demonstrated with the intraoperative findings. Comparison of the intraoperative and MRI aneurysm lengths suggested a slight trend of overestimation by MRI resulting from angulation of the aneurysm, but this figure did not reach statistical significance. Only two patients met the current criteria for endoluminal straight grafting.

CONCLUSIONS

Both MRI and duplex sonography accurately predicted aortic morphologic characteristics; however, MRI provided the most comprehensive anatomic picture for patient selection and should be considered the nonionizing imaging modality of choice when an endovascular repair is being contemplated.