Midterm changes in aortic aneurysm morphology after endovascular repair

A systematic review and meta-analysis of proximal aortic neck dilatation after endovascular abdominal aortic aneurysm repair

OBJECTIVE

To provide an updated systematic literature review summarizing current evidence on aortic neck dilatation (AND) after endovascular aortic aneurysm repair (EVAR) in patients with infrarenal abdominal aortic aneurysm.

METHODS

An extensive electronic search in major electronic databases was conducted between January 2000 and December 2021. Eligible for inclusion were observational studies that followed up with patients (n ≥ 20) undergoing EVAR with self-expanding endografts, for 12 or more months, evaluated AND with computed tomography angiography and provided data on relevant outcomes. The primary end point was the incidence of AND after EVAR, and the secondary end points were the occurrence of type Ia endoleak, stent graft migration, secondary rupture, and reintervention.

RESULTS

We included 34 studies with a total sample of 12,038 patients (10,413 men; median age, 71 years). AND was defined clearly in 18 studies, but significant differences in AND definition were evidenced. The pooled incidence of AND based on quantitative analysis of 16 studies with a total of 9201 patients (7961 men; median age, 72 years) was calculated at 22.9% (95% confidence interval [CI], 14.4-34.4) over a follow-up period ranging from 12 months to 14 years. The risk of a type Ia endoleak was significantly higher in AND patients compared with those without AND (odds ratio, 2.95; 95% CI, 1.10-7.93; P = .030). Similarly, endograft migration was more common in the AND group compared with the non-AND group (odds ratio, 5.95; 95% CI, 1.80-19.69; P = .004). The combined incidence of secondary rupture and reintervention did not differ significantly between the two groups, even though the combined effect was in favor of the non-AND group.

CONCLUSIONS

Proximal AND after EVAR is common and occurs in a large proportion of patients with infrarenal abdominal aortic aneurysm. AND can influence the long-term durability of proximal endograft fixation and is significantly related to adverse outcomes, often leading to reinterventions.

Type III Endoleak Leading to Aortic Rupture After Endovascular Repair

Endovascular treatment of abdominal aortic aneurysm concerns the introduction of aortic endoprosthesis which aims to isolate aneurysm from the circulation. The leading complication of this technique is the endoleak which is defined by the persistence of blood flow within the aneurysm sac. The main risk is the rupture of the aorta which can jeopardize the vital prognosis of patient. White classification defines five types of endoleaks. Type III is secondary either to a disconnection between the components of the endoprosthesis (type IIIA) or to material damage (type IIIB). This type presents a particularly high risk of aortic rupture. Endovascular approach is the treatment of choice for this type of endoleaks through stent-grafts implantation. Type III endoleak may appear at any time after endovascular aortic aneurysm repair (EVAR). Although the frequency of endoleak after EVAR has been reduced after improvement and development of stent-graft systems, there are still many improvements and additions expected to improve the prognoses for patients after EVAR. Our case is an 80-year-old patient, who received an EVAR in 2012 for his abdominal aortic aneurysm, admitted to our vascular surgery department for a type III endoleak, for which he benefited from an endovascular treatment by placement of stent-grafts.

A Systematic Review of Proximal Neck Dilatation After Endovascular Repair for Abdominal Aortic Aneurysm

Purpose: To provide an updated systematic literature review and summarize current evidence on proximal aortic neck dilatation (AND) after endovascular aneurysm repair (EVAR). Methods: A review of the English-language medical literature from 1991 to 2015 was conducted using MEDLINE and EMBASE to identify studies reporting AND after EVAR. Studies considered for inclusion and full-text review fulfilled the following criteria: (1) reported AND after EVAR, (2) included at least 5 patients, and (3) provided data on AND quantification. The search identified 26 articles published between 1998 and 2015 that encompassed 9721 patients (median age 71.8 years; 9439 men). Results: AND occurred in 24.6% of patients (95% CI 18.6% to 31.8%) over a period ranging from 15 months to 9 years after EVAR. No significant dilatation of the suprarenal part of the aorta was reported by most studies. The incidence of combined clinical events (endoleak type I, migration, reintervention during follow-up) was higher in the AND group (26%) when compared with 2% in the group without AND (OR 28.7, 95% CI 5.43 to 151.67, p<0.001). Conclusion: AND affects a considerable proportion of EVAR patients and was related to worse clinical outcome, as indicated by increased rates of type I endoleak, migration, and reinterventions. Future studies should focus on a better understanding of the pathophysiology, predictors, and risk factors of AND, which could identify patients who may warrant a different EVAR strategy and/or a closer post-EVAR surveillance strategy.

Gender Differences in Aortic Neck Morphology in Patients with Abdominal Aortic Aneurysms Undergoing Elective Endovascular Aneurysm Repair

BACKGROUND

Previous studies have demonstrated that women tend to have adverse aortic neck morphology leading to exclusion of some women from undergoing endovascular aneurysm repair (EVAR). The objective of this study is to investigate differences in aortic neck morphology in men versus women, changes in the neck morphology and sac behavior after EVAR, and investigate how these features may influence outcomes.

METHODS

We conducted a retrospective review of elective EVARs (2004-2013). We excluded patients who underwent elective EVAR with no postoperative imaging available and those patients with fenestrated repairs. Using TeraRecon and volumetric analysis, several features were investigated. These included percent thrombus, shape, length, angulation of the neck, and changes in neck and abdominal aortic aneurysm diameter.

RESULTS

A total of 146 patients were found to meet inclusion criteria (115 men and 31 women) with similar baseline characteristics. Neck angulation was greater in women (23.9° vs. 13.5°; P < 0.028). The percent thrombus in women was higher than men (35.4% vs. 31%; P < 0.02). Abdominal aneurysm's were smaller in women at 1 year (4.2 cm vs. 5.1 cm; P < 0.002), and secondary interventions were higher in men (11.3% vs. 0%; P < 0.05). Other features such as neck shape, changes in neck diameter, neck length, and percent oversizing of graft where not statistically different between genders.

CONCLUSIONS

Gender differences in neck characteristics and changes in neck morphology do not appear to adversely affect EVAR outcomes. Longer follow-up is necessary to further assess whether these findings are clinically durable.

Emergency endovascular treatment of acute symptomatic or ruptured abdominal aortic aneurysm: a single-center experience

The purpose of this study is to report our early experience with endovascular treatment of patients with symptomatic non-ruptured (sAAA) or ruptured (rAAA) abdominal aortic aneurysms. Between September 2005 and September 2008, all patients with a diagnosis of sAAA or rAAA were evaluated for endovascular suitability. We did not consider hemodynamic instability to be a contraindication for endovascular aneurysm repair (EVAR). Patients whose aneurysm anatomy was not suitable for EVAR received open repair (OR). A total of 46 patients with sAAA or rAAA underwent emergency EVAR: in particular, 18/46 patients were treated for sAAA and 28/46 for rAAA. Successful stent-graft deployment was achieved in 44 patients (96%); we had two open surgical conversions. The 30-day mortality rate was 19.5%. Nine patients died during the first 30 postoperative days: four patients died within 24 hours because of severe hypovolemic shock, two died of respiratory failure, one died as a result of bowel ischemia and two because of myocardial infarction after hospital discharge. Complete follow-up data were available for 35 patients (median 185 days; range 30–730 days). In conclusion, endovascular treatment is feasible and the early experience is promising. The capability of offering EVAR and OR for sAAA and rAAA according to our experience suggests that EVAR and OR should be regarded as complementary techniques to improve outcome of patients with acute AAA.

Size of the proximal neck in AAAs treated with balloon-expandable stent-grafts: CTA findings in mid- to long-term follow-up

PURPOSE

To determine the evolution of the proximal aortic neck diameter in mid- to long-term follow-up after endovascular aneurysm repair of abdominal aortic aneurysm (AAA) with a balloon-expandable stent-graft.

METHODS

Thirty patients (27 men; average age 71 years, range 56-87) with infrarenal AAAs were treated with the SETA-Latecba balloon-expandable stent-graft (6 aortomonoiliac and 24 bifurcated configurations). Follow-up ranged from 4 to 8 years (mean 73.4 months). Computed tomography was done systematically before the procedure, after implantation (1-3 months), at 1 year, and annually thereafter. The last follow-up scan was utilized to measure the proximal neck for purposes of comparison with baseline and the initial post-implant scans.

RESULTS

Five patients died during follow-up of causes unrelated to the procedure. No endoleaks or graft migrations were observed. The pre-deployment proximal neck diameter (a) averaged 23.4 mm (range 18-32), the diameter after deployment of the stent-graft (b) averaged 24.9 mm (range 18-34), and the most recent follow-up proximal neck measurement (c) averaged 23.8 mm (range 18-31). Comparing the last follow-up to the post-implant measurements (c-b), the neck diameter decreased in 15 (50%) patients [7 with short necks (i.e., <15 mm)] and remained unchanged (no variation) in 15 (50%) patients (4 with short necks). All patients treated with the SETA-Latecba balloon-expandable stent-graft showed stability of the proximal aortic neck diameter in mid- to long-term follow-up.

CONCLUSION

The study showed that the diameter reached at initial deployment did not increase further in the long term, which supports the safety and reliability of this modular balloon-expandable stent-graft and illustrates that this device does not produce dilatation of the proximal neck after deployment. Future dilatation of the aortic neck is unlikely, and consequently, migration or delayed type I endoleak are also unlikely.

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

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

Should Endovascular Repair Be Used for Small Abdominal Aortic Aneurysms?

The outcomes of endovascular repair for small abdominal aortic aneurysm (4.0-4.9 cm) is reported. All patients undergoing endovascular abdominal aortic aneurysm repair between 2000 and 2006 with maximal diameter 4.0 to 4.9 cm form the small aneurysm study cohort. Data were analyzed retrospectively and life-table methods were used. Of 743 endovascular repairs, 132 (17.8%) were performed for small abdominal aortic aneurysm. Perioperative complication rate was 9.1%. Freedom from aneurysm expansion was 96% at 1 year, 86% at 3 years, and 77% at 5 years. Overall survival was 98%, 93%, and 84% at 1, 3, and 5 years, respectively. Perioperative 30-day mortality was 0.8% with an aneurysm-related mortality of 1.5% at 5 years. There were no deaths from delayed aneurysm rupture. Endovascular repair of small abdominal aortic aneurysm is associated with low perioperative morbidity and mortality compared with published results for open repair, and treatment threshold can be reduced to 4 cm in selected patients.

Endovascular Repair of Abdominal Aortic Aneurysms: Analysis of Aneurysm Volumetric Changes at Mid-Term Follow-Up

PURPOSE

To evaluate the volumetric changes in abdominal aortic aneurysms (AAA) after endovascular AAA repair (EVAR) in 24 months of follow-up.

METHODS

We evaluated the volume modifications in 63 consecutive patients after EVAR. All patients underwent strict duplex ultrasound and computed tomography angiography (CTA) follow-up; when complications were suspected, digital subtraction angiography was also performed. CTA datasets at 1, 6, 12, and 24 months were post-processed through semiautomatic segmentation, to isolate the aneurysmal sac and calculate its volume. Maximum transverse diameters (Dmax) were also obtained in the true axial plane, Presence and type of endoleak (EL) were recorded. A statistical analysis was performed to assess the degree of volume change, correlation with diameter modifications, and significance of the volume increase with respect to ELs.

RESULTS

Mean reconstruction time was 7 min. Mean volume reduction rates were 6.5%, 8%, and 9.6% at 6, 12, and 24 months follow-up, respectively. Mean Dmax reduction rates were 4.2%, 6.7%, and 12%; correlation with volumes was poor (r = 0.73-0.81). ELs were found in 19 patients and were more frequent (p = 0.04) in patients with higher preprocedural Dmax, The accuracies of volume changes in predicting ELs ranged between 74.6% and 84.1% and were higher than those of Dmax modifications. The strongest independent predictor of EL was a volume change at 6 months < or = 0.3% (p = 0.005), although 6 of 19 (32%) patients with EL showed no significant AAA enlargement, whereas in 6 of 44 (14%) patients without EL the aneurysm enlarged.

CONCLUSION

The lack of volume decrease in the aneurysm of at least 0.3% at 6 months follow-up indicates the need for closer surveillance, and has a higher predictive accuracy for an endoleak than Dmax.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

DISCUSSION

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

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.

Volume regression of abdominal aortic aneurysms and its relation to successful endoluminal exclusion

OBJECTIVES

Evaluating the success of endoluminal repair of abdominal aortic aneurysms (AAAs) is frequently based on diameter measurements and determining the presence of endoleaks. The use of three-dimensional volumetric data and observation of morphologic changes in the aneurysm and device have been proposed to be more appropriate for postdeployment surveillance. The purpose of this study was to analyze the long-term volumetric and morphologic data of 161 patients who underwent endovascular AAA exclusion and to assess the utility of volume measurements for determining successful AAA repair.

METHODS

Patients with spiral computed tomography scans obtained preoperatively, within the first postoperative month, at 6 months, and annually thereafter, were included in this analysis. Computerized interactive three-dimensional reconstruction of each AAA scan was performed. Total aneurysm sac volume was measured at each time interval (mean preoperative volume 169.0 +/- 78.5 mL), and the significance of volume changes was determined by mixed linear modeling, a form of repeated measures analysis, to account for longitudinal data clustered at the individual level. Sixty-two patients (38%) developed endoleaks at some time during follow-up-15 type I leaks, 45 type II leaks, and 2 type III leaks. The patients with type I and type III leaks were treated with cuffs, and the type II leaks were treated either with observation, side-branch embolization, or required open conversion.

RESULTS

Aneurysm sac volume increased slightly at 1-month follow-up (+3.3%), and then decreased steadily to -12.9% at 5 years (P <.0001). This effect remained unchanged after controlling for the three device types used in our study population. Patients who did not exhibit an endoleak (n = 99) showed a significant decrease in aneurysm volume across the entire follow-up duration when compared with those who did exhibit an endoleak (n = 62) (P <.0001). The presence of a 10% or greater decrease in volume at 6 months demonstrated a sensitivity of 64%, a specificity of 95%, a positive predictive value of 95%, a negative predictive value of 62%, and an accuracy of 75% for predicting primary clinical success defined by successful deployment of the device; freedom from aneurysm- or procedure-related death; freedom from endoleak, rupture, migration, or device malfunction; or conversion to open repair.

CONCLUSIONS

Volumetric analysis may be used to predict successful endoluminal exclusion of AAAs. Volume regression appears to be device-independent and should be expected in most clinically successful cases. The presence of volume increases in the first 6 months is suspicious for an endoleak that is pressurizing the aneurysm sac and heralds the need for closer evaluation and possible intervention. A volume decrease of 10% or greater at 6 months and continuing regression over time is associated with successful endovascular repair.

Does transrenal fixation of aortic endografts impair renal function?

OBJECTIVES

Transrenal fixation (TFX) of aortic endografts is thought to increase the risk for renal infarction and impaired renal function. We studied the late effects of TFX on renal function and perfusion.

METHODS

Of 189 patients with commercial aortic endografts, which we inserted between 1995 and 2002, we reviewed data for 130 patients (112 men, 18 women) with available creatinine (Cr) concentration and contrast enhanced computed tomography (CT) scans preoperatively and 1 to 97 months after the procedure. Of the 130 patients, 69 patients had TFX and 61 patients had infrarenal fixation (IFX). Both groups were physiologically comparable. Average age was 76 +/- 8 years for patients with TFX and 75 +/- 8 years for patients with IFX. Presence of renal infarct or renal artery occlusion was determined by nephrograms on serial contrast-enhanced CT scans.

RESULTS

Mean follow-up was 17 +/- 16 months (range, 1-54 months) for TFX and 21 +/- 21 months (range, 1-97 months) for IFX. Mean serum Cr concentration increased significantly during long-term follow-up in both groups (TFX, 1.3 +/- 0.5 mg/dL to 1.5 +/- 0.8 mg/dL, P <.01; IFX, 1.3 +/- 0.7 mg/dL to 1.4 +/- 0.8 mg/dL, P <.03). Creatinine clearance (CrCl) similarly decreased over long-term follow-up in both groups (TFX, 53.3 +/- 17.7 mL/min/1.73 m(2) to 47.9 +/- 16.2 mL/min/1.73 m(2), P <.01; IFX, 58.1 +/- 22.7 mL/min/1.73 m(2) to 53.1 +/- 23.4 mL/min/1.73 m(2), P <.02). There were no significant differences in the increase in Cr concentration (P =.19) or decrease in CrCl (P =.68) between TFX and IFX groups. Small renal infarcts were noted in four patients (5.8%) in the TFX group and one patient (1.6%) in the IFX group. No increase in Cr concentration or decrease in CrCl was noted in any patient with a renal infarct. Postoperative renal dysfunction developed in 7 of 69 patients (10.1%) in the TFX group and 7 of 61 patients (11.5%) in the IFX group. There were no statistically significant differences between groups with respect to number of patients with new renal infarcts (P =.37) or postoperative renal dysfunction (P =.81).

CONCLUSION

There is a slight increase in serum Cr concentration and decrease in CrCl after aortic endografting. However, there was no significant difference in these changes between patients with TFX and IFX. Although TFX may produce a higher incidence of small renal infarcts, these do not impair renal function. Thus our midterm results suggest that TFX can be performed safely, with no greater change in renal function than observed after IFX.

Long-term renal function following endovascular aneurysm repair with infrarenal and suprarenal aortic stent-grafts

PURPOSE

To determine in a retrospective analysis the incidence of renal impairment (RI) following endovascular repair (EVR) of abdominal aortic aneurysm (AAA), to assess the morbidity and mortality in endograft patients with preoperative RI, and to examine the impact of suprarenal stent-grafts on renal function.

METHODS

From March 1994 to October 2001, 315 AAA patients (289 men; mean age 72.4+/-7.0 years) undergoing EVR were entered prospectively into a vascular registry. The patients received either an in-house custom-made stent-graft or one of several commercially made devices implanted with infrarenal or suprarenal fixation. Renal function was monitored by serum creatinine measurements prior to discharge and at 3, 6, and 12 months and annually thereafter. Preoperative RI was defined as a serum creatinine >130 micro mol/L and/or long-term dialysis. Postoperative RI referred to a >20% increase in the serum creatinine over baseline. Additional deterioration of renal function in patients with preoperative RI was referred to as postoperatively worsened RI.

RESULTS

Of the 315 patients treated, 220 (69.8%) were considered high risk (ruptured AAA or ASA grade III or IV). Sixty-nine (21.9%) patients had preoperative RI (6 [1.9%] on preoperative dialysis). A suprarenal stent-graft was used in 169 (53.7%) patients and infrarenal stent-graft in the remaining 146 (46.3%). The mean follow-up was 30.1+/-22.7 months. Postoperative RI occurred in 53 (16.8%) patients (24 [7.6%] transient, 29 [9.2%] persistent). Patients with preoperative RI had a significantly higher incidence of postoperatively worsened RI (37.7% versus 11.0%, p<0.0001) and a higher mortality related to RI (7.2% versus 1.6%, p=0.02). Suprarenal fixation had no influence on the incidence of RI, on perioperative mortality, or on mortality related to RI. The only significant predictive factor of postoperative RI was preoperative RI (risk ratio 5.09, 95% CI 2.38 to 10.87, p=0.0001).

CONCLUSIONS

Endovascular AAA repair may lead to persistent postoperative RI in nearly 10% of cases, especially in patients with preoperative RI. Suprarenal stent-graft fixation does not seem to have any deleterious effect on renal function. Further long-term studies are required to confirm the innocuous nature of transrenal stent placement.

Does the type of endograft affect AAA volume change after endovascular aneurysm repair?

PURPOSE

To compare thrombus volume changes in a longitudinal study over 2 years after endovascular aneurysm repair using the Ancure and Excluder endografts.

METHODS

In 2 institutions, all consecutive patients treated with a bifurcated Ancure or Excluder endograft were included in this retrospective comparison of computed tomographic angiography (CTA) data recorded and stored to disk postoperatively and at the 12 (12M) and 24-month (24M) follow-up examinations. In one institution, among 45 Ancure endograft patients, 35 (group A) had the 3 requisite scans available. In the second institution, 23 (group B) of 36 patients with the Excluder endograft were eligible for analysis. The proportional volume change was calculated at 12M and 24M and compared to the postoperative CT data. More than 10% shrinkage was considered significant.

RESULTS

In both groups, the median absolute volume changed significantly. In group A, significant shrinkage was found in 66% (23/35) at 12M and 74% (26/35) at 24M; in group B, 46% (10/23) had significant shrinkage at 12M as well as at 24M (p=0.027 for the difference between groups A and B at 24M). Statistical analysis of the proportional volume change showed a significant difference between the Ancure and the Excluder devices at 12M (p=0.009) and 24M (p=0.001). Multivariate analysis found aneurysm size (p<0.012) and endograft type (p=0.026) to be independently predictive of the absolute volume change.

CONCLUSIONS

Sac volume shrinkage after endovascular aneurysm repair is less pronounced and less frequent with the Excluder endoprosthesis than with the Ancure endograft.

Controversies in the management of type II "branch" endoleaks following endovascular abdominal aortic aneurysm repair

Successful endovascular aortic aneurysm repair (EVAR) is often defined as complete exclusion of blood flow within the aneurysm sac. Perigraft flow, also known as endoleak, is the most common complication following EVAR. Attachment site related endoleaks (type I) are generally considered to warrant some form of intervention due to the belief that they represent a risk for future rupture. Management of type II endoleaks, also known as branch or collateral endoleaks, is more controversial. Some advocate a policy of watchful-waiting whereas others treat all type II endoleaks as soon as they are discovered. The following review explores the controversies pertaining to the management, diagnosis and surveillance imaging, and treatment of type II endoleaks.

The Zenith aortic stent-graft: a 5-year single-center experience

PURPOSE

To evaluate the efficacy and midterm results of the Zenith stent-graft in the treatment of abdominal aortic aneurysms (AAA).

METHODS

Since March 1994, 364 patients have undergone endovascular repair of infrarenal AAA. Of the 94 who were treated with the Zenith stent-graft from 1996 to 2002, 88 patients (82 men; mean age 72.6 +/- 6.5 years, range 47-88) with at least 6-month follow-up were analyzed. Sixty-one (69.3%) patients were considered at high risk for intervention; 7 ruptured AAAs were treated emergently. In all, 68 (77.3%) bifurcated stent-grafts (including 18 TriFab systems) and 20 aortomonoiliac configurations were used. Cumulative data on endoleak, migration, secondary procedures, and survival were evaluated with Kaplan-Meier analyses.

RESULTS

Implantation success was 97.7%; 2 (2.3%) access-related failures were converted to open repair (1 immediate, 1 at 3 months). There were 3 (3.4%) graft limb thromboses (2 immediate, 1 late), 3 (3.4%) cases of colon ischemia due to embolization in 1 and hypogastric artery occlusion in 2, and 1 (1.1%) renal infarction due to embolism. Three (3.4%) patients died within 30 days. Eleven (12.5%) endoleaks and 1 (1.1%) late endograft migration were recorded. The 5-year cumulative endoleak and migration rates were 15% and 7%, respectively. Sixty-three (71.6%) patients did not present any complication related to the repair during a mean follow-up of 20.6 +/- 14.9 months (range 6-68); notably, no complications were associated with the 18 TriFab systems. Six (6.8%) secondary procedures were performed (31% 5-year cumulative secondary procedural rate). All 6 (6.8%) aneurysm-related deaths (the 3 perioperative, 2 from late AAA rupture, and 1 during a secondary procedure) and 14 of 18 (20.4%) non-aneurysm-related deaths occurred in high-risk patients; the 5-year cumulative survival rates were 57% for any death and 92% for aneurysm-related deaths.

CONCLUSIONS

The Zenith stent-graft appears both safe and effective in terms of midterm outcome of endovascular aortic aneurysm repair.

Stent-graft migration after endovascular repair of abdominal aortic aneurysm

PURPOSE

To report the incidence of graft migration in patients after endovascular repair of abdominal aortic aneurysms (AAA) and assess the significance of neck diameter changes in patients with and without suprarenal stent implantation.

METHODS

The medical records and imaging studies of 176 consecutive patients (175 men; median age 71 years, range 48-88) who had endovascular AAA repair with the Nottingham aortomonoiliac system were reviewed. The following parameters were recorded: preoperative neck diameter and length, presence of intraoperative and late graft migrations, time to onset of late migration, length of late migration, and neck diameter changes in patients with documented late graft migration. The patients were divided into 2 groups based on the placement of an endograft with or without suprarenal bare stent fixation. Median follow-up was 15 months (range 1-48).

RESULTS

There were 15 (8.5%) graft migrations (6 intraoperative and 9 late). Of those, 14 (10.9%) were in the 128-patient infrarenal fixation group and 1 (2.1%) in the 48-patient suprarenal stent group. Median neck diameters on preoperative and postoperative computed tomography scans in patients with late migration were 22.2 mm and 23.0 mm, respectively (p>0.05). The median time to graft migration was 14 months after the original operation (range 6-36).

CONCLUSIONS

Distal device migration occurred frequently with the Nottingham system. Late graft migration was not associated with neck enlargement. Endografts with a suprarenal stent may have a decreased incidence of graft migration.

Stent-graft migration following endovascular repair of aneurysms with large proximal necks: anatomical risk factors and long-term sequelae

PURPOSE

To evaluate the outcome of aortic endografts deployed in large infrarenal necks and to identify any association of preoperative aneurysm characteristics and postoperative morphological changes with the incidence of neck dilatation and device migration in this patient subset.

METHODS

The records of 47 patients (41 men; mean age 74, range 55-84) with large aortic neck diameters treated with Talent stent-grafts from 1998 to 2001 were reviewed. Patients with anatomical criteria that precluded aneurysm exclusion with currently available devices were preferentially selected. Mean baseline aneurysm morphology included 27.6-mm (range 18-33.4) suprarenal and 28.1-mm (range 24-34) infrarenal neck diameters; the infrarenal neck length was 26 +/- 16 mm with angulation of 37 degrees +/- 18 degrees. Computed tomographic (CT) angiograms up to 3 years were analyzed using specialized interactive software; migration was defined as >1-cm change in the distance from the lower renal artery to the top of the device. Pre- and postoperative morphological characteristics of the aneurysm were compared between patients with and without migration.

RESULTS

Of the 45 patients successfully treated, 40 had complete CT data for analysis. During a mean 17-month follow-up, 7 (17.5%) of the 40 devices exhibited distal migration. Six patients required secondary procedures; 5 were in the migration cohort. No preoperative anatomical characteristic or degree of neck dilatation over time was predictive of stent-graft migration. Aneurysm sac regression was significant at 1 (-0.09 +/- 4.90 mm) and 2 (-1.48 +/- 2.56 mm) years in endografts without migration (p<0.001). Distal endograft migration >1 cm predicted the need for secondary interventions (p<0.001), with 83% sensitivity and 94% specificity.

CONCLUSIONS

Endovascular repair is successful in patients with large infrarenal necks and complex neck morphology. Changes in aneurysm remodeling over time were similar to reported observations in patients with more favorable neck criteria. Although no anatomical factor associated with migration could be identified from this analysis, distal displacement >1 cm correlated with the need for a secondary intervention.

Aneurysm neck diameter after endovascular repair of abdominal aortic aneurysms

PURPOSE

To determine aneurysm neck diameter change after endovascular repair (EVR) of abdominal aortic aneurysm (AAA) and its relationship to stent-graft diameter.

MATERIALS AND METHODS

The cases of 73 patients with AAAs who underwent EVR were reviewed retrospectively: 68 had preoperative imaging available. Neck diameter was reviewed by a single observer (M.F.B.) on preoperative, immediate postoperative, annual, and most recent contrast-enhanced computed tomographic scans. Baseline and follow-up neck diameters were compared with the manufacturers' values for unconstrained stent-graft diameters.

RESULTS

Intraobserver error was 2 mm. Aneurysm neck diameter increased from 21.8 mm (range, 17-28 mm) at baseline to 22.8 mm (range, 19-30 mm) postoperatively and 25.8 mm (range, 19-31 mm; P <.001) at a mean follow-up of 25.5 months (range, 6.2-60.8 mo). Neck diameter increase was more than 2 mm in 24 patients (33%). Mean change in the first, second, third, and fourth years was +1.63 mm, +0.52 mm, +0.25 mm, and +0.33 mm, respectively. Baseline mean stent-graft oversizing was 2.9 mm (13.7%; range, -1 to +8 mm), which decreased to 0.7 mm (range, -4 to +6 mm) at latest follow-up. Neck diameter exceeded stent-graft diameter (mean, 1.8 mm; range, 1-4 mm) in 21 cases (28%) and by more than 2 mm in five cases (6.8%). When neck diameter change was correlated with change in sac diameter, it was found to be insignificant (P =.24); however, it was significantly correlated with baseline oversizing (P =.01).

CONCLUSIONS

After EVR, the aneurysm neck dilates, mostly in the first 2 years, by greater than 2 mm in one third of patients. This is possibly related to the presence of the endograft. The associated reduction of stent-graft oversizing warrants continued vigilance for proximal endoleak.

Intra-aneurysm sac pressure--the holy grail of endoluminal grafting of AAA

OBJECTIVES

To relate intra-aneurysm sac pressure during endoluminal AAA repair to early and late endoleak, as well as to the aneurysm size upon follow-up.

DESIGN

Prospective clinical investigation.

METHODS AND PATIENTS

In 46 patients who had their AAAs treated by a stent graft (group I), intra-operative pressure measurement was performed (aorta uni-iliac stent grafts: 25 cases, bifurcated stent grafts: 21 cases). In 18 patients with open repair (group II) flow in the inferior mesenteric artery, and the pressure in the aneurysm sac was measured, before and after aortic and iliac cross clamping. Values are given in median with range.

RESULTS

In group I, complete exclusion of AAA (no endoleak on intra-operative control angiogram) resulted in a statistically significant decrease in mean sac pressure from 74 (55-101) to 47 (4-104) mmHg. Pulse pressure reduced from 67 (34-103) to 8 (0-74) mmHg. In 11 patients a proximal type I endoleak was sealed by balloon modeling, after which the mean sac pressure reduced from 63 (14-91) to 52 (4-74) mmHg (n.s. versus patients with primary seal). Intra-operative pressure did not correlate with change in AAA diameter during twelve months follow-up. In group II, cross clamping of the proximal aorta significantly reduced mean sac pressure to 32 (21-55) mmHg, and the pulse pressure to 0 (0-13) mmHg (p < 0.05). Subsequent cross clamping of the iliac arteries did not significantly change the pressures.

CONCLUSIONS

Measurement of intra-aneurysm sac pressure can help to detect and treat endoleaks during endoluminal grafting. However, the intra-operative sac pressure did not predict the fate of aneurysm during follow up. Compared to open repair of AAA, the sac pressure after endoluminal grafting remains significantly higher, in relation to pulse pressure.

Potential impact of therapeutic warfarin treatment on type II endoleaks and sac shrinkage rates on midterm follow-up examination

OBJECTIVE

Successful endovascular aortic aneurysm repair depends on exclusion and spontaneous thrombosis of the aneurysm sac. The need for chronic postoperative anticoagulation therapy could limit the applicability of this technology with delay or prevention of sac thrombosis resulting in endoleak formation and altered remodeling of the aneurysm sac. The purpose of this study was the determination of whether chronic therapeutic anticoagulation therapy with warfarin was associated with an increased incidence rate of early or delayed postoperative endoleaks or altered rates of reduction in aneurysm sac maximum diameter.

METHODS

Two hundred thirty-two consecutive patients underwent abdominal aortic endografting during a 32-month period. The data were recorded prospectively with a current mean follow-up period of 18 months. The patients with endoleaks identified with 30-day postoperative computed tomographic scan angiograms subsequently underwent selective arteriography to characterize the source. The patients who underwent chronic warfarin therapy that resulted in a therapeutic internationalized normalized ratio comprised the study group. The control group was defined as all the patients with healthy coagulation profiles.

RESULTS

Thirty-six patients (15%) were undergoing warfarin therapy after surgery, and their conditions were chronically maintained with a therapeutic international normalized ratio. Forty-three patients (18%) had endoleaks on 30-day computed tomographic scan angiographic results. There were 39 patients with type II endoleaks and four patients with type I endoleaks. None of the type I endoleaks occurred in patients who were undergoing warfarin therapy, and all endoleaks were repaired with either proximal or distal covered extensions. At 30 days, seven patients (19.4%) undergoing chronic warfarin therapy had type II endoleaks as compared with 36 controls (18.4%; P =.798). Four patients had delayed type II endoleaks develop, two in the control group and two in the warfarin group (P =.3). Ten control individuals (31%) had spontaneous resolution of type II endoleaks develop, whereas spontaneous endoleak thrombosis was not observed in the warfarin group (P =.33). Aneurysm sac remodeling assessed with mean percent reduction in maximum sac diameter at 12 months revealed a statistical difference between the control group (17.5%) and the warfarin group (7.6%; P =.04).

CONCLUSION

Warfarin treatment is not associated with an increase in the incidence rate of early or delayed postoperative endoleaks. However, the rate of reduction in maximum aneurysm sac diameter after aortic endografting is slower in patients who undergo therapeutic warfarin therapy at 1-year follow-up examination, a statistically significant difference from the control group. In addition, type II endoleaks may be less likely to undergo spontaneous thrombosis in patients who undergo warfarin therapy.

Significance of endoleaks after endovascular repair of abdominal aortic aneurysms: The EUROSTAR experience

OBJECTIVE

The purpose of this study was to assess the incidence, risk factors, and consequences of endoleaks after endovascular repair of abdominal aortic aneurysm.

METHODS

Data on 2463 patients were collected from 87 European centers and recorded in a central database. Preoperative data were compared for patients with collateral retrograde perfusion (type II) endoleak (group A), patients with device-related (type I and III) endoleaks (group B), and patients in whom no endoleak was detected (group C). Only endoleaks observed after the first postoperative month of follow-up were taken into consideration. Regression analysis was performed to investigate statistical relationships between the occurrence and type of endoleak and preoperative patient and morphologic characteristics, operative details, type of device, and experience of the operating team. In addition, postoperative changes in aneurysmal morphology, the need for secondary interventions, conversions to open repair, aneurysmal rupture, and mortality during follow-up were compared between these study groups.

RESULTS

Patients in group A had a higher prevalence of a patent inferior mesenteric artery compared with patients without endoleak. Patients in group B were treated more frequently than patients in group C by an operating team with experience of less than 30 procedures. The mean follow-up period was 15.4 months. Secondary interventions were needed in 13% of the patients. Rupture of the aneurysm during follow-up occurred in 0.52% (1/191) in group A, 3.37% (10/297) in group B, and 0.25% (5/1975) in group C. Life table analysis comparing the three study groups demonstrated a significantly higher rate of rupture in group B than in group C (P =.002). The incidence of conversion to open repair during follow-up was higher in group B than in the other two study groups (P <.01). Death was related to the aneurysm or to endovascular repair of the aneurysm in 7% of patients. Secondary outcome success, defined as absence of rupture and conversion, was significantly higher in group A and C compared with that in group B (P =.006 and P =.0001, respectively).

CONCLUSIONS

The presence of device-related endoleaks correlated with a higher risk of aneurysmal rupture and conversion compared with patients without type I or III endoleaks. Type II endoleak was not associated more often with these events. Consequently, intervention in type II endoleak should only be performed in case of increase of aneurysm size.

Intra-aneurysmal pressure after incomplete endovascular exclusion

PURPOSE

An endoleak results from the incomplete endovascular exclusion of an aneurysm. We developed an experimental model to analyze hemodynamic changes within the aneurysm sac in the presence of an endoleak, with and without a simulated open collateral branch.

METHODS

With a latex aneurysm model connected to a pulsatile pump, pressures were measured simultaneously within the system (systemic pressure) and the aneurysm sac (intrasac pressure). The experiments were performed without endoleak (control group) and after creating a 3.5-mm (group 1), 4.5-mm (group 2), and 6-mm (group 3) diameter orifice in the endograft, simulating an endoleak. Pressures were also registered with and without a patent aneurysm side branch.

RESULTS

In each endoleak group, the intrasac diastolic pressure (DP) and mean pressure (MP) were significantly higher than the systemic DP and MP (P =.01, P =.006, and P =.001, respectively), although the pressure curve was damped. The presence of an open side branch significantly reduced the intrasac DP and MP.

CONCLUSION

In this model, intrasac pressures were significantly higher than systemic pressures in the presence of all endoleaks, even the smallest ones. Intrasac pressures higher than systemic pressure may pose a high risk for aneurysm rupture. Although patent side branches significantly reduce these pressures, the aggressive management of an endoleak should be pursued.

Aneurysm sac hygroma: a cause of endotension

PURPOSE

To describe a new pathophysiological mechanism for endotension.

CASE REPORTS

Four patients developed aneurysm sac expansion after repair of abdominal aortic aneurysms, one with a conventional polytetrafluoroethylene (PTFE) graft and the others with a variety of commercially made endografts (2 PTFE, 1 Dacron). Pressures within the sacs were nonpulsatile and approximately half the systemic blood pressure. Attenuation on computed tomography (CT) was significantly less in the sac than in the graft in 3 of the patients. A clear, highly viscous fluid was aspirated from all 4 sacs, supporting the diagnosis of aneurysm sac hygroma. Prominent local hyperfibrinolysis in the sac was combined with signs of local coagulation activation.

CONCLUSIONS

A new mechanism for continued sac expansion based on aneurysm sac hygroma is proposed. Measurement of attenuation may be of diagnostic value. It is further proposed that local hyperfibrinolysis/coagulation may promote rebleeding, liquefaction, and continued expansion analogous to the chronic subdural hematoma.

The impact of stent-graft development on outcome of AAA repair--a 7-year experience

OBJECTIVE

to analyse the impact of stent-graft (SG) design and operator skill on the outcome of endovascular AAA repair.

DESIGN

prospective non-randomised open.

MATERIAL

a total of 158 patients (mean age 71) underwent SG repair. Patients were treated with five different types of SG: first (n =58) and second ( n =17) generation Ivancev-Malmö monoiliac SG (IM I and IM II respectively) combined with femoral-femoral crossover, Chuter bifurcated SG (n =15), Vanguard SG ( n =15) and the Zenith SG ( n =53).

METHODS

patients underwent DSA and contrast CT preoperatively and were then followed with CT and digital scans. Recently, one change in AAA diameter and endoleaks (EL) were recorded. Mortality, complications and secondary interventions were recorded and life-table analysis for intervention-free SG survival calculated.

RESULTS

immediate and late conversions as well as 30-day mortality were reduced for 2nd (Zenith and Vanguard) compared to 1st generation SG (IM I, Im II and chuter). SG migrations occurred only with the IM I and Chuter SG. Type I EL were significantly more common in 1st generation SG. First generation SG required significantly more secondary interventions than 2nd SG up to 20 months post-operatively. The number of unplanned intraoperative adjunctive manoeuvres was increased with 2nd SG.

CONCLUSIONS

enhanced SG design has improved the probability of SG success after endovascular AAA repair. Better technical skills may also have contributed to improved results.

Changes in aneurysm morphology and stent-graft configuration after endovascular repair of aneurysms of the descending thoracic aorta

OBJECTIVE

We sought to study changes in morphology and stent-graft configuration of descending thoracic aortic aneurysms after endovascular repair.

METHODS

Twenty-three patients treated with custom-made stent-grafts were studied. The stent-graft consisted of continuous, stainless-steel Z stents mounted within a polyester graft. In the last 11 cases the stents were interconnected with 3 longitudinal wires. Contrast-enhanced spiral computed tomography was performed preoperatively and at 1, 3, and every 6 months postoperatively. Angiography was used preoperatively and at 1-year follow-up. Proximal and distal necks were assessed for diameter and length. Aneurysm diameter, endoleaks, stent-graft migration, and changes in stent-graft configuration were evaluated.

RESULTS

During follow-up (median, 18 months; range, 1-48 months), excluded aneurysms decreased in diameter by 4 mm (0.5-10 mm, P =.0018). Endoleaks prevented size decrease. Five patients displayed neck dilatation, 4 at both the proximal and distal fixation sites and 1 only distally. In 7 (30%) patients there was proximal migration of the distal end of the stent-graft. Three (13%) patients displayed both distal migration of the proximal end of the stent-graft and proximal migration of the distal end of the stent-graft. There was a significant correlation between stent-graft kinking and appearance of proximal or distal stent-graft migration (P =.05 and P =.0007, respectively). In no case did the migration lead to appearance of an endoleak before intervention was performed.

CONCLUSION

Excluded descending thoracic aortic aneurysms decrease in size on midterm follow-up. A subgroup of patients prone to neck dilatation might exist. A combination of neck dilatation and vector forces acting on stent-grafts in the tortuous thoracic aorta might lead to stent-graft migration.

Intraoperative proximal endoleaks during AAA stent-graft repair: evaluation of risk factors and treatment with Palmaz stents

PURPOSE

To study factors that might contribute to intraoperative proximal type I endoleak and to evaluate the placement of giant Palmaz stents as a therapeutic option.

METHODS

Thirty-three patients (30 men; median age 72 years, range 50-85) with abdominal aortic aneurysms underwent implantation of fully supported Gianturco Z-stent-based endografts (12 custom-made aortomonoiliac and 21 bifurcated Zenith devices). Ten (30%) patients were treated for intraoperative proximal endoleaks. Stent-graft oversizing and neck angulation, length, and shape were compared between patients with and without leaks.

RESULTS

In 9 cases, the endoleaks were successfully treated with intraoperative placement of Palmaz stents without complications. In 1 patient, a leak that was resolved intraoperatively with balloon dilation reappeared 1 month later; a Palmaz stent was deployed successfully. Stent-graft oversizing did not differ significantly between patients who developed proximal endoleaks and those who did not (median 4.0 mm in both groups, p = 0.47). Median neck length was 21.0 mm in patients with endoleak and 28.0 mm in those without (p > 0.99). Median neck angulation was 30 degrees in both groups (p = 0.33), and the presence of a conical aneurysm neck was not significantly different (2/10 versus 6/23, p > 0.99). All aneurysms remained excluded at a median follow-up of 13 months (range 6-24).

CONCLUSIONS

Stent-graft oversizing and neck morphology (length, angulation, and conical shape) do not seem to correlate with the incidence of proximal type I endoleaks. Palmaz stent placement appears to be a feasible and safe treatment option for this complication.

Does successful embolization of endoleaks lead to aneurysm sac shrinkage?

PURPOSE

To determine whether embolization of endoleaks after endovascular repair of aortic aneurysms is associated with a decrease in the diameter of the aneurysm.

METHODS

Fifteen patients (13 men; median age 76 years) demonstrated primary endoleaks persisting > or =3 months after endovascular abdominal aortic aneurysm repair with a variety of commercial endografts. In 8 patients, coil embolization failed to completely obliterate the leak, whereas embolotherapy proved successful in the remaining 7 patients. Surveillance of endoleaks and the effect of their embolization on aneurysm size were followed with serial computed tomographic (CT) scans. Follow-up after embolization extended for at least 12 months.

RESULTS

Patients with persistent leak exhibited a slight increase in mean aneurysm area from 21.41+/-4.25 to 22.47+/-6.70 cm2. Medians differed from 20.03 (range 16.59-28.73) to 23.03 (range 14.14-33.69) cm2 (p = 0.0078, 95% confidence interval [CI] = 0.0075 to 0.0081). Successfully treated patients, however, showed a mean decrease from 20.58+/-3.63 (median 19.87) to 16.36+/-6.46 cm2 (median 18.10) at 1 year (p = 0.0156, 95% CI = 0.0151 to 0.0160). The medians differed significantly between groups (p < 0.05).

CONCLUSIONS

Persistent endoleaks after endovascular aortic aneurysm treatment led to an increase in the diameter of the aneurysm, whereas complete occlusion was associated with a significant decrease in aneurysm diameter.