Symposium on distortion and structural deterioration of endovascular grafts used to repair abdominal aortic aneurysms. Introduction

Evaluation the Aortic Aneurysm Remodeling After a Successful Stentgraft Implantation

Background

Routine imaging follow-up after endovascular treatment of abdominal aortic aneurysms (EVAR) is mainly aimed at detection of endoleaks. The aim of the study was to assess changes in the size of the abdominal aortic aneurysm sack using CT angiography (CTA) after successful treatment using endovascular stent graft implantation.

Material/Methods

A retrospective analysis of CTA results included 102 patients aged 54–88, who had no postoperative complications. Patients underwent CTA before EVAR and after the treatment (mean time between studies, 7.6 months). The largest cross-sectional area of the aneurysm sac was measured using a curved multiplanar reconstruction. A change of the aneurysm cross-sectional over 10% was considered significant.

Results

The average cross-sectional area decreased after EVAR by 3% and this change was not statistically significant. Regression of the cross-sectional area was observed in 18.6% of patients, progression was in 23.5%, and no change was seen in 57.8%. Cross-sectional areas before and after EVAR were significantly correlated (r=0.75, p<0.0001). There was no correlation between the cross-sectional area change after EVAR and patients’ age or the time between the treatment and the follow-up CTA. Cross-sectional area before the treatment predicted changes in the aneurysm size after EVAR (p=0.0045).

Conclusions

Remodeling of abdominal aortic aneurysms after EVAR is not uniform. The change of aneurysm size depends on the initial aneurysm size but not on the time from EVAR. The size of the aneurysm after EVAR should not be considered as a measure of the treatment efficacy.

Long-term outcome after aortic endovascular repair: the Buenos Aires experience

Long-term (5 years) outcome of 30 patients whose aneurysm was excluded using the Parodi endograft (PE) was assessed. Thirty patients with a mean follow-up of 59 months were the basis of the analysis. Additionally, 100 consecutive patients treated with the Vanguard Endograft (VE) were followed up for 28 months (range, 7 to 56 months). Results were analyzed and both groups compared. There were no late failures related to the loss of the integrity of the device in the PE group. Aorto aortic systems showed distal neck dilatation in high proportion of patients (80%). Aorto-uni-iliac endograft was successful in 80% of the patients. Only one late type I endoleak developed in a patient in whom the proximal stent was placed far from the renal arteries and in contact with thrombus. Also, persistent type II endoleaks were the cause of failure. No neck dilatation was noted. In the VE group, most of the failures were device related.

Risk factors of early and late complications in patients undergoing endovascular aneurysm repair

OBJECTIVES

to identify pre-operative factors that could predict complications following from transluminal repair of abdominal aortic aneurysms (AAA).

METHODS

during a 5-year period, 96 consecutive patients underwent elective endovascular treatment of a AAA. In all patients, helical CT and/or Magnetic Resonance Imaging (MRI), and plain abdominal roentgenogram were performed at 1, 3, 6, 12, 18, and 24 months and yearly thereafter. Angiography was performed systematically 1 year after the stent-graft implantation, or earlier if helical CT or MRI diagnosed an increase in the maximal transverse diameter or a high flow endoleak.

RESULTS

early (<30 days) morbidity (12%) was significantly increased by pre-operative renal insufficiency (p < 0.01). Early mortality (2%) correlated with ASA score (p = 0.01). Median follow-up was 27 months (range 3-66). Mortality (12%) during follow-up was correlated to the pre-operative coronary status (p = 0.01). A type I endoleak was diagnosed in 18 patients (19%). Common iliac artery diameter was correlated with the presence of type I endoleak (p < 0.001). A type II endoleak was diagnosed in 47 (49%) patients. The diagnostic of type II endoleak was significantly increased (p = 0.001) in patients with pre-operative patent IMA associated with more than four patent lumbar arteries. The anatomic characteristics of the aneurysm were correlated to the additional endovascular procedures during stentgraft implantation (p = 0.01), and to the implantation of a complementary iliac limb extension during follow-up (p = 0.01).

CONCLUSIONS

the risk factors determined by this statistical analysis could help surgeons to select more accurately patients suitable for endovascular treatment.

Late endoleak after endovascular repair of an abdominal aortic aneurysm with multiple proximal extender cuffs

Late onset graft or attachment site-related endoleaks may be hazardous, and early identification of patients at risk is important. We describe a patient who underwent implantation of a bifurcated stent graft 5.5 cm below the renal arteries because of a technical error with three extender cuffs implanted proximally to bridge the gap. During the 1st year, aneurysm diameter decreased from 68 to 52 mm. After 1 year, the patient had an acute endoleak develop, which originated between two of the extender cuffs and which was accompanied by severe abdominal pain and reexpansion of the aneurysm. This endoleak was treated with insertion of an additional bifurcated stent graft within the extender cuff segment. The patient has been subsequently followed for 6 months and has had no endoleak or symptoms, and aortic diameter has decreased once again to 55 mm.

Endoleak as a predictor of outcome after endovascular aneurysm repair: AneuRx multicenter clinical trial

OBJECTIVE

The purpose of this study was to determine whether evidence of blood flow in the aneurysm sac (endoleak) is a meaningful predictor of clinical outcome after successful endovascular aneurysm repair.

METHODS

We reviewed all patients in Phase II of the AneuRx Multicenter Clinical Trial with successful stent graft implantation and predischarge contrast computed tomographic (CT) imaging. The clinical outcome of patients with evidence of endoleak was compared with the outcome of patients without evidence of endoleak. The CT endoleak status before hospital discharge at 6, 12, and 24 months was determined by each clinical center as well as by an independent core laboratory. Endoleak status at 1 month was assessed with duplex scanning examination or CT at each center without confirmation by the core laboratory.

RESULTS

Centers reported endoleaks in 152 (38%) of 398 patients on predischarge CT, whereas the core laboratory reported endoleaks in 50% of these patients (P <.001). The center-reported endoleak rate decreased to 13% at 1 month. Follow-up extended to 2 years (mean, 10 +/- 4 months). One patient had aneurysm rupture and underwent successful open repair at 14 months. This patient had a Type I endoleak at discharge but no endoleak at 1 month or at subsequent follow-up times. There were no differences between patients with and patients without endoleak at discharge in the following outcome measures: patient survival, aneurysm rupture, surgical conversion, the need for an additional procedure for endoleak or graft patency, aneurysm enlargement more than 5 mm, the appearance of a new endoleak, or stent graft migration. Despite a higher endoleak rate identified by the core laboratory, neither the endoleak rate reported by the core laboratory nor the endoleak rate reported by the center at discharge was significantly related to subsequent outcome measures. Patients with endoleak at 1 month were more likely to undergo an additional procedure for endoleak than patients without endoleaks. Patients with Type I endoleaks at discharge and patients with endoleak at 1 month were more likely to experience aneurysm enlargement at 1 year. However, there was no difference in patient survival, aneurysm rupture rate, or primary or secondary success rate between patients with or without endoleak. Actuarial survival of all patients undergoing endovascular aneurysm repair was 96% at 1 year and was independent of endoleak status. Primary outcome success was 92% at 12 months and 88% at 18 months. Secondary outcome success was 96% at 12 months and 94% at 18 months.

CONCLUSIONS

The presence or absence of endoleak on CT scan before hospital discharge does not appear to predict patient survival or aneurysm rupture rate after endovascular aneurysm repair using the AneuRx stent graft. Although the identification of blood flow in the aneurysm sac after endovascular repair is a meaningful finding and may at times indicate inadequate stent graft fixation, the usefulness of endoleak as a primary indicator of procedural success or failure is unclear. Therefore, all patients who have undergone endovascular aneurysm repair should be carefully followed up regardless of endoleak status.

Endovascular Treatment of Aortic Disease

A review is given of endovascular treatment for AAA, thoracic aortic aneurysms, dissections as well as complications following previous aortic surgery. In several of these conditions endovascular treatment has advantages like a reduced operative trauma, shorter stay in hospital, and the possibility of treating patients who would have been unfit for open surgery. On the other hand, problems like endoleak, deformation of the endoprosthesis, retrograde filling of the aneurysmal sack, and graft limb occlusion need to be solved before the place of endovascular treatment can be defined. It is possible that the steadily improving quality of the implants as well as the introducer systems will widen the indications for endovascular surgery, but randomised clinical trials are warranted and a longer follow-up period is necessary to draw final conclusions.