What is the significance of endoleaks and endotension

Occult endoleaks revealed during open conversions after endovascular aortic aneurysm repair in a multicenter experience

BACKGROUND

An occult endoleak (OE) may be the underlying cause of aneurysm sac expansion after endovascular aneurysm repair (EVAR). The aim of this study is to describe intraoperative findings of OE during surgical endograft explantations.

METHODS

This is a retrospective, multicenter analysis of all open conversions (OC) after EVAR from 1997 to 2020 in 12 vascular centers. We excluded patients with a preoperative diagnosis of endograft infection, endograft thrombosis, and thoracic-EVAR. An OE was defined as an endoleak revealed during OC not shown on preoperative imaging, which was likely the real cause for sac enlargement. We reported the number of OE, and we described the type of OE in relation to the initial alleged or associated endoleak. A separate analysis of patients with an initial diagnosis of endotension was also performed.

RESULTS

An OE was found in 32/255 patients (12.5%). In the 78.1% of the cases (25/32) a type II endoleak hid a type I or III endoleak. Endotension was the initial diagnosis of 26/255 patients (10.2%). In 4/26 cases (15.4%), a type I or II OE was revealed. In 5/26 cases (19.2%) an endograft infection was found intraoperatively. In 2/26 cases we found an angiosarcoma. Fifteen cases of endotension (57.7%) remained unexplained.

CONCLUSIONS

OE represent a not negligible cause of EVAR failure. A type II endoleak associated with sac enlargement may actually conceal a higher-flow endoleak. In most of the cases, the initial diagnosis of endotension remains unexplained. However, endotension sometimes conceals severe underlying pathologies such as infections.

Surgical Findings and Outcomes of Endotension following Endovascular Aneurysm Repair

BACKGROUND

Endotension is one of the detrimental complications after endovascular aneurysm repair (EVAR) and surgical management has been considered as standard of care. However, there is a paucity of data regarding the findings and outcomes of such surgical intervention. The aim of this study was to investigate intraoperative findings and outcomes of surgical treatment for endotension after EVAR.

METHODS

Between January 2005 and October 2018, of the 708 patients who underwent EVAR for aneurysm aortic aneurysm; 12 patients (mean age of 76.1; range 66-88) who underwent open repair for endotension were retrospectively analyzed. The anatomical characteristics of the aorta and surgical findings were reviewed. The rates of early and late procedural complications, and overall mortality were evaluated.

RESULTS

The median interval between the EVAR and surgical conversion was 45.9 months (range 17.1-46.9). Three of the twelve patients underwent emergency surgery due to aneurysm rupture. The median aneurysm sac size, the proximal neck diameter, and the proximal neck length before EVAR were 64 mm, 23.5 mm, and 30.5 mm, respectively, that changed before open repair to 93.5 mm (p = .02), 25 mm (p = .011), and 23 mm (p = .003), respectively. In four of the twelve patients, radiographically undetected endoleak was identified during surgery to be Type Ia, Ib, II, and III, respectively. The rates of early and late procedural complications, and overall mortality were 8.3%, 8.3% and 8.3%, respectively.

CONCLUSIONS

Patients with endotension have a risk of delayed endoleak and aneurysm rupture; secondary intervention should be performed in such cases to prevent fatal complications. Surgical treatment appears to be a curative treatment for endotension with favorable outcomes. In addition, the possibility of an undetected endoleak should be considered as a potential cause of endotension.

A Shorter Aortic Arch Sealing Ring (< 10 mm) Distal to the Most Distal Chimney Seems to Be an Additional Important Factor Contributing to a Gutter Endoleak in Aortic Arch TEVAR

BACKGROUND

The aim of the present study was to define the possible anatomical and technical parameter that might predict the occurrence of gutter endoleak or type Ia endoleak (EL Ia) in patients treated with the chimney graft (CG) technique for the brachiocephalic trunk (BCT) and left common carotid artery (LCCA) due to aortic arch pathologies.

METHODS

We reviewed our institutional endovascular aortic database of patients, who between 2010 and 2018 had undergone thoracic endovascular aortic repair (TEVAR) with chimney graft technique (ChTEVAR) as a debranching method of the supraaortic arteries.

RESULTS

ChTEVAR was performed in 45 patients of whom a chimney in both the LCCA and the BCT was used in 32 patients, only in the LCCA in twelve patients, and only in the BCT in one patient. Eight patients (17.8%) had an EL Ia (based on postoperative computed tomography angiography). No late EL Ia was detected during the follow-up period. All patients with a postoperative EL Ia received 2 CGs with one each for the BCT, and LCCA had either no or a sealing ring distal to the most distal chimney of less than 10 mm versus patients with a longer sealing zone (P = 0.043). Patients with an endoleak did not differ from those without endoleak with respect to stent-graft oversizing, the diameter of the proximal and distal landing zones, or the aortic diameter directly proximal to the pathology.

CONCLUSIONS

A sealing ring distal to the most distal chimney of more than 10 mm seems to be associated with a reduced risk of an EL Ia. The relatively few patients and the single-center nature require larger studies to verify the present results.

EVAR and OPEN treatment of abdominal aortic aneurysm: What is the role of MMP-9 in the follow-up?

INTRODUCTION

The aim of our study is to verify the role of metalloproteinases in endovascular repair (EVAR) and OPEN surgery treatment for abdominal aortic aneurysm (AAA). Postoperatively, these enzymes could represent an important biomarker to adapt diagnostic tests and further investigations during follow-up.

MATERIAL AND METHOD

From 2004 to 2008, 55 patients were considered with AAA. Of these, 33 patients (mean age: 70.1 years), (mean AAA diameter: 5.4cm) were treated with OPEN surgery (group A) and 22 (mean age: 74.1 years) (mean AAA diameter: 5.1cm) were treated with EVAR. In 17 of them, there were no signs of endoleak (group B1), while in 5 patients, a presence of endoleak (group B2) was detected. Plasma samples were collected in order to determine MMP-9 activity. Enzyme immunoassay was performed preoperatively at 1, 3, 6 and 12 months. Patients treated conventionally were clinically examined after 1 and 12 months by ultrasound. Patients undergoing EVAR treatment were clinically examined by CT scan after 1, 3, 6 and 12 months. The analysis was done by assessing the interaction over time of the MMP-9 value in B1 and B2 groups.

RESULTS

The average values observed for MMP-9 were preoperatively and at 1, 3, 6 and 12 months, respectively: in group A 150.8ng/mL (SD=30.5), 252.5ng/mL (SD=25.2), 315.4ng/mL (SD=22.7), 295.3ng/mL (SD=26.8), 210.7ng/mL (SD=30.2); in group B1 105ng/mL (SD=10.8), 125.6ng/mL (SD=18), 85.8ng/mL (SD=19.9), 95ng/mL (SD=20.2), 80.4ng/mL (SD=15.6); in group B2 149ng/mL (29.2), 375.4ng/mL (SD=40.2), 215ng/mL (SD=35.9), 180ng/mL (SD=20.2), 175ng/mL (SD=33.4). The MMP-9 level was higher in group B2 compared to group B1 (P=0.01), suggesting a correlation with the presence of the endoleak.

CONCLUSIONS

This preliminary study shows that MMP-9 may be a biomarker of the presence of endoleak. Other further investigations and larger series are needed to show that metalloproteases could play a role in the follow-up of EVAR treated patients.

Endoleak Assessment Using Computational Fluid Dynamics and Image Processing Methods in Stented Abdominal Aortic Aneurysm Models

Endovascular aortic aneurysm repair (EVAR) is a predominant surgical procedure to reduce the risk of aneurysm rupture in abdominal aortic aneurysm (AAA) patients. Endoleak formation, which eventually requires additional surgical reoperation, is a major EVAR complication. Understanding the etiology and evolution of endoleak from the hemodynamic perspective is crucial to advancing the current posttreatments for AAA patients who underwent EVAR. Therefore, a comprehensive flow assessment was performed to investigate the relationship between endoleak and its surrounding pathological flow fields through computational fluid dynamics and image processing. Six patient-specific models were reconstructed, and the associated hemodynamics in these models was quantified three-dimensionally to calculate wall stress. To provide a high degree of clinical relevance, the mechanical stress distribution calculated from the models was compared with the endoleak positions identified from the computed tomography images of patients through a series of imaging processing methods. An endoleak possibly forms in a location with high local wall stress. An improved stent graft (SG) structure is conceived accordingly by increasing the mechanical strength of the SG at peak wall stress locations. The presented analytical paradigm, as well as numerical analysis using patient-specific models, may be extended to other common human cardiovascular surgeries.

Aneurysm Sac Pressure Measurement with a Pressure Sensor in Endovascular Aortic Aneurysm Repair

Aortic endograft surveillance is a necessity for the lifetime of a patient owing to the risk of endoleaks and device complications. The current standard of care for surveillance is radiologic imaging. The most commonly used modality is computed tomographic angiography. Magnetic resonance angiography and ultrasonography have also been used as surveillance tools. These imaging techniques have risks and limitations, and alternative surveillance tools are being investigated. Remote pressure sensing is a promising technology that can provide adjunctive support to the current imaging modalities. The technology is applicable to both abdominal and thoracic endograft implantation and surveillance. It has recently gained clearance from the US Food and Drug Administration for acute aneurysm exclusion during an abdominal endograft insertion. As more data are accumulated, it may be possible for remote pressure sensing to replace current imaging techniques as the sole modality for endograft surveillance.

Ten-Year Outcomes after Endovascular Aneurysm Repair (Evar) and Magnitude of Additional Procedures

Background and Aims:

With any new technology complications are possible, and problems with first-generation aortic stentgrafts have been extensively reported. The long-term outcome of this patient population and the magnitude of additional secondary procedures are, however, less well covered.

Materials and Methods:

Between February 1997 and November 1999, 48 patients (44 men and 4 women; mean age 70 years; range 54–85) with AAA (average 57mm, range 40–90mm) were treated with a Vanguard® endoprosthesis. Stentgrafts were sized by CT and angiography-based measurements. Results were continuously assessed using contrast-enhanced CT before discharge, 1, 3, 6 and 12 months after the procedure and thereafter annually. Since 2001 plain abdominal X-rays have been performed annually.

Results:

The technical implant success rate was 100%. Median follow-up was 91 months (range 7.6–120 months). None of the patients was lost during this period. Hospital mortality was 0%. There were 25 subsequent deaths (52%), the most common cause being coronary artery disease. There were ten late conversions to open surgical repair, including three emergency operations: two due to rupture and one to thrombosis. EVAR-related complications were encountered in 43 patients (90%): 12 primary endoleaks (all type II), 36 late endoleaks (16 type I, 2 type II and 18 type III), 22 migrations, 25 row separations, 20 thromboses, one endotension and 3 ruptures of the AAA. Secondary procedures were required in 39 patients (81%): 1 re-endografting by aortoiliac bifurcated graft and 3 with a uni-iliac graft; 33 limb graft repairs were performed and 19 infrarenal cuffs were placed. There were 4 late embolizations and 4 attempts, and 6 thrombolyses, four of which were successful. Further, 9 femoro-femoral crossover by-pass and 2 axillo-femoral by-pass operations and 2 amputations were carried out during the follow-up. Only one patient was alive without complications.

Conclusions:

The impact of long-term follow-up of patients treated with the new technology was emphasized in this patient population. A careful surveillance protocol and active endovascular treatment of complications can yield acceptable results and low AAA rupture and aneurysm mortality rates, also with the first-generation endovascular graft. A new technology, however, may involve unpredictable problems which can magnify the workload and incur high costs over several years after the initial procedure.

Predictors and outcomes of endoleaks in the Veterans Affairs Open Versus Endovascular Repair (OVER) Trial of Abdominal Aortic Aneurysms

OBJECTIVE

The Veterans Affairs Open Versus Endovascular Repair (OVER) Trial of Abdominal Aortic Aneurysms study was a randomized controlled trial comparing open vs endovascular repair (EVAR) in standard-risk patients with infrarenal aortic aneurysms. The analysis reported here identifies characteristics, risk factors, and long-term outcome of endoleaks in patients treated with EVAR in the OVER cohort.

METHODS

The OVER trial enrolled 881 patients, of whom 439 received successful EVAR. Logistic regression analysis was used to identify predictors for endoleaks and secondary interventions. Kaplan-Meier survival analysis, longitudinal plots, and generalized linear mixed models methods were used to describe time to endoleak detection, resolution, or death.

RESULTS

During a mean follow-up of 6.2 ± 2.4 years, 135 patients (30.5%) developed 187 endoleaks. Four patients with EVAR went on to rupture; these four patients did not all have an endoleak. Mortality between patients who did and did not develop endoleaks was not significantly different. The 187 endoleaks included 12% type I, 76% type II, 3% type III, 3% type IV, and 6% indeterminate. Patient demographics and vascular risk factors were not associated with endoleak development. The presence of endoleaks resulted in an increase in aneurysm diameter over time (P < .0001). Fifty-three percent of endoleaks resolved spontaneously, and 31.9% received secondary interventions. The initial aneurysm size independently predicted a need for secondary interventions (P < .0003). Delayed type II endoleaks (detected >1 year after EVAR) were associated with aneurysm enlargement compared with the early counterpart. There was no difference in aneurysm size or length of survival between type II and other types of endoleak.

CONCLUSIONS

We present one of the most comprehensive and longest follow-up analyses of patients treated with aortic endografts. Endoleaks were common and negatively affected aneurysm diameter reduction. Delayed type II endoleaks were associated with late aneurysm diameter enlargement. Endoleaks and aneurysm diameter enlargement were not associated with excess mortality compared with those without these features.

An in Vitro Twist Fatigue Test of Fabric Stent-Grafts Supported by Z-Stents vs. Ringed Stents

Whereas buckling can cause type III endoleaks, long-term twisting of a stent-graft was investigated here as a mechanism leading to type V endoleak or endotension. Two experimental device designs supported with Z-stents having strut angles of 35° or 45° were compared to a ringed control under accelerated twisting. Damage to each device was assessed and compared after different durations of twisting, with focus on damage that may allow leakage. Stent-grafts with 35° Z-stents had the most severe distortion and damage to the graft fabric. The 45° Z-stents caused less fabric damage. However, consistent stretching was still seen around the holes for sutures, which attach the stents to the graft fabric. Larger holes may become channels for fluid percolation through the wall. The ringed stent-graft had the least damage observed. Stent apexes with sharp angles appear to be responsible for major damage to the fabrics. Device manufacturers should consider stent apex angle when designing stent-grafts, and ensure their devices are resistant to twisting.

Endovascular Aortic Aneurysm and Dissection Repair (EVAR) in Iran: Descriptive Midterm Follow-up Results

Background:

Endovascular repair of aorta in comparison to open surgery has a low early operative mortality rate, but its long-term results are uncertain.

Objectives:

The current study describes for the first time our initial four-year experience of elective endovascular aortic repair (EVAR) at Tehran heart center, the first and a major referral heart center in Iran, as a pioneer of EVAR in Iran.

Patients and Methods:

A total of 51 patients (46 men) who had the diagnosis of either an abdominal aortic aneurysm (AAA) (n = 36), thoracic aortic aneurysm (TAA) (n = 7), or thoracic aortic dissection (TAD) (n = 8) who had undergone EVAR by Medtronic stent grafts by our team between December 2006 and June 2009 were reviewed.

Results:

The rate of in-hospital aneurysm-related deaths in the group with AAA stood at 2.8% (one case), while there was no in-hospital mortality in the other groups. All patients were followed up for 13-18 months. The cumulative death rate in follow-up was nine cases from the total 51 cases (18%), out of which six cases were in the AAA group (four patients due to non-cardiac causes and two patients due to aneurysm-related causes), one case in the TAA group (following a severe hemoptysis), and two cases in the TAD group (following an expansion of dissection from re-entrance). The major event-free survival rate was 80.7% for endovascular repair of AAA, 85.7% for endovascular repair of TAA, and 65.6% for endovascular repair of TAD.

Conclusion:

The endovascular stent-graft repair of the abdominal and thoracic aortic aneurysm and aortic dissection had high technical success rates in tandem with low-rate early mortality and morbidity, short hospital stay, and acceptable mid-term free symptom survival among Iranian patients.

Magnetic Resonance Imaging with a Weak Albumin Binding Contrast Agent can Reveal Additional Endoleaks in Patients with an Enlarging Aneurysm after EVAR

OBJECTIVES/BACKGROUND

To examine the additional diagnostic value of magnetic resonance imaging (MRI) after administration of a weak albumin binding contrast agent in post-endovascular aneurysm repair (EVAR) patients with aneurysm growth with no or uncertain endoleak after computed tomography angiography (CTA).

METHODS

This was a prospective diagnostic cross sectional study carried out between April 2011 and August 2013. MRI was performed in all patients with aneurysm growth≥5 mm after EVAR implantation and no or uncertain endoleak on CTA, or the inability, on CTA, to identify the source of a visible endoleak. All MRI scans were performed on a 1.5 T clinical MRI scanner after administration of a weak albumin binding contrast agent. The presence of endoleaks was assessed by visually comparing pre- and post-contrast T1-weighted images with fat suppression. Post-contrast images were acquired 5 and 15 minutes after contrast administration.

RESULTS

Twenty-nine patients (26 men; 90%) with a median age of 74 years (interquartile range [IQR] 67-76) were included. The median interval between EVAR and MRI was 39 months (IQR 20-50). The median increase in maximum aneurysm diameter during total follow up after EVAR was 11 mm (IQR 6-17). At CTA, 16 patients (55%) had no detectable endoleak, five patients (17%) had suspected but uncertain endoleak, and eight patients had a definite endoleak (28%). On the post-contrast MRI images, endoleak was observed in 24 patients (83%). In all patients with uncertain endoleak on CTA, endoleak was detected with MRI. For type II endoleaks, feeding vessels were detected in 22/23 patients (96%) and these were all, except one, lumbar arteries.

CONCLUSION

In patients with enlarging aneurysms of unknown origin after EVAR, MRI with a weak albumin binding contrast agent has additional value for both the detection and determination of the origin of the endoleak.

Aneurysmal degeneration and type Ib endoleak with proximal aneurysm rupture: A case report, review of literature and technical suggestions

INTRODUCTION

Despite the reduction in mortality incidences of AAA in proportion to increased use of EVAR, the natural history of aneurysms with the presence of an endoleak post EVAR remains unclear. With a cumulative AAA rupture incidence of 2% at six years post EVAR, the lack of an immediate endoleak is not an indicator of success.

CASE REPORT

We present a case of an 80-year-old man who presented to the emergency department with generalised abdominal pain and hypotension. Four years earlier he had underwent an EVAR for a 6 cm infra-renal AAA. The computed tomography angiogram (CTA) illustrated aneurysmal dilatation of the left common iliac artery with extensive retroperitoneal haemorrhage. The patient was transferred to the operating room for an endovascular repair but due to significant episodes of haemodynamic instability, an emergency exploratory laparotomy was performed. To our surprise, there was a left-sided infra-renal anterolateral rupture of the aneurysm sac. The stent was explanted with difficulty from its fixed proximal aortic section down to left-sided common iliac artery. The fixed bare portion of the stent in the proximal aorta and in the right common iliac artery was left in-situ and the rest was integrated to a trouser graft with an end-to-end technique.

DISCUSSION

On detection of an endoleak, the aim should focus on their endovascular management, as open conversions are associated with high mortality and morbidity.

CONCLUSION

If open conversion is indicated, all technical aspects of the repair including partial stent extraction should be considered for best outcome.

Stent fabric fatigue of grafts supported by Z-stents versus ringed stents: An in vitro buckling test

Stent-grafts externally fitted with a Z-shaped stents were compared to devices fitted with ringed stents in an in vitro oscillating fatigue machine at 200 cycles per minute and a pressure of 360 mmHg for scheduled durations of up to 1 week. The devices fitted with Z-stents showed a considerably lower endurance limit to buckling compared to the controls. The contact between the apexes of adjacent Z-stents resulted in significant damage to the textile scaffolds and polyester fibers due to the sharp angle of the Z-stents. The ringed stents did not cause any fraying in the textile scaffolds.

Vascular Endostapling Systems for Vascular Endografts (T)EVAR—Systematic Review—Current State

Purpose:

Recently, vascular endostapling systems were developed to achieve better sealing at the proximal neck of the aneurysm and to prevent endograft migration. The purpose of this study was to provide a systematic review about the current state and possible options of vascular endostapling systems.

Results:

No randomized controlled trials were published. The results showed that the use of an endostaple system considerably reduced the rates of endoleaks type 1a and endograft migration. Regarding the use of endostaples in different types of endografts, only a few results were available.

Conclusion:

The results are not conclusive. With endostaple systems, patients with difficult anatomic features and high risk can potentially be treated. These systems might reduce the high reintervention rates after endovascular aneurysm repair. Controlled randomized trials with larger number of patients are warranted with endostapling use in primary endograft implantation and for use in reintervention for late endoleaks or endograft migrations.

Quality improvement guidelines for imaging detection and treatment of endoleaks following endovascular aneurysm repair (EVAR)

Major concerns after aortic aneurysm repair are caused by the presence of endoleaks, which are defined as persistent perigraft flow within the aortic aneurysm sac. Diagnosis of endoleaks can be performed with various imaging modalities, and indications for treatment are based on further subclassifications. Early detection and correct classification of endoleaks are crucial for planning patient management. The vast majority of endoleaks can be treated successfully by interventional means. Guidelines for Imaging Detection and Treatment of endoleaks are described in this article.

Endoscopic type 2 endoleak repair following endovascular aortic aneurysm repair: acute results and follow-up experience

The purpose of this study was to evaluate immediate and long-term results of endoscopic type 2 endoleak repair (EER) following endovascular abdominal aortic aneurysm repair. The basic methods include a retrospective review of electronic and paper medical records of patients admitted or referred to our institution for EER. Between July 1999 and October 2007, eight consecutive patients underwent EER. Mean operative time was 190 (104–355) min. One patient died preoperatively, due to profuse venous bleeding . One procedure was redone due to a missed pair of lumbar arteries. Mean hospital stay was five days (2–10). During mean follow-up, 50 months (29–91), one patient required additional coil embolization for a persistent type 2 endoleak. Four patients were diagnosed with a type 1 and one with a type 3 endoleak; three of these patients required an additional procedure. In conclusion, in this small series EER proved not to be beneficial.

Endovascular abdominal aortic aneurysm repair: nonenhanced volumetric CT for follow-up

PURPOSE

To evaluate the clinical usefulness of volumetric analysis at nonenhanced computed tomography (CT) as the sole method with which to follow up endovascular abdominal aortic aneurysm repair (EVAR) and to identify endoleaks causing more than 2% volumetric increase from the previous volume determination.

MATERIALS AND METHODS

The study had institutional review board approval. Images were reviewed retrospectively in a HIPAA-compliant manner for 230 CT studies in 70 patients (11 women, 59 men; mean age, 74 years) who underwent EVAR. The scannning protocol consisted of three steps: (a) contrast material-enhanced CT angiography before endovascular stent placement, (b) contrast-enhanced CT angiography 0-3 months after repair to depict immediate complications, and (c) nonenhanced CT at 3, 6, and 12 months after repair. At each follow-up visit, immediate aortic volume analysis was performed. If the interval volumetric change was 2% or less, no further imaging was performed. If the volume increased by more than 2% on the nonenhanced CT image, contrast-enhanced CT angiography was performed immediately to identify the suspected endoleak. Confidence intervals (CIs) were obtained by using bootstrapping to account for repeated measurements in the same patients.

RESULTS

Mean volume decrease was -3.2% (95% CI: -4.7%, -1.9%) in intervals without occurrence of a clinically relevant endoleak (n = 183). Types I and III high-pressure endoleaks (n = 10) showed a 10.0% (95% CI: 5.0%, 18.2%) interval volumetric increase. Type II low-pressure endoleaks (n = 37) showed a 5.4% (95% CI: 4.6%, 6.2%) interval volumetric increase. Endoleaks associated with minimal aortic volume increase of less than 2% did not require any intervention. This protocol reduced radiation exposure by approximately 57%-82% in an average-sized patient.

CONCLUSION

Serial volumetric analysis of aortic aneurysm with nonenhanced CT serves as an adequate screening test for endoleak, causing volumetric increase of more than 2% from the volume seen at the previous examination.

A comparison between standard and high density Resilient AneuRx in reducing aneurysm sac pressure in a chronic canine model

OBJECTIVES

Low intra-aneurysm sac pressure has been shown to correlate with sac shrinkage following endovascular aneurysm repair (EVAR) whereas high pressure results in sac enlargement. The Resilient AneuRx (RSA) has higher density Dacron compared with the standard AneuRx (STA) and was developed in an attempt to reduce type 4 and 5 endoleaks, thereby more effectively reducing sac pressure. The purpose of this study is to compare the ability of RSA and STA in reducing sac pressure in a chronic canine aneurysm model.

MATERIALS AND METHODS

Artificial polytetrafluoroethylene (PTFE) aneurysm (26 x 50 mm) with an Endosure wireless pressure sensor (CardioMEMS, Atlanta, Ga) attached to the inner surface was implanted in the abdominal aorta of 10 mongrel dogs. Two weeks after creation of the aneurysm, each animal underwent EVAR with either STA (n = 5) or RSA (n = 5). Following EVAR, intra-sac pressure was measured with the implanted wireless pressure sensor up to 3 months postoperatively when the animals were sacrificed.

RESULTS

EVAR was successful with no signs of an endoleak in all 10 dogs. Pressure sensing with the wireless sensor was also successful in each animal until the end of the study. Systolic intra-sac pressure remained at a high level in the STA group, whereas it gradually lowered over time in the RSA group. This difference reached statistical significance at 2 months and lasted to 3 months. No endoleak was detected in either group at the time of sacrifice. Gross analysis confirmed that all the aneurysm sacs were thrombosed without any flow inside the sac.

CONCLUSION

Despite absence of an endoleak, intra-sac pressure remained high in the STA group. RSA effectively reduced sac pressure over time. Graft porosity appears to be an important factor that may determine the outcome of EVAR. These findings may be useful in designing improved endograft.

Remodeling of the aortic neck with a balloon-expandable stent graft in patients with complicated neck morphology

Graft migration and other device-related problems are more frequent in abdominal aortic aneurysm (AAA) patients with a complicated neck. We wanted to evaluate the performance of a balloon-expandable stent graft in these cases. Complicated aortic neck morphology was defined as a combination of short (<15 mm) and angulated (>45 degrees) necks with or without circumferential thrombus. Severe aortic angulation was defined as less than 120 degrees. During a 24-month period, 18 consecutive patients with complicated neck anatomy were treated with the Vascular Innovations (VI)-Datascope balloon-expandable endograft. In two patients, a balloon-expandable cuff was implanted to remodel the neck prior to insertion of a bifurcated endograft (Excluder, W.L. Gore & Associates, Flagstaff, AZ). Demographic, procedural, and outcome data were collected prospectively and retrospectively analyzed. All patients had preoperative computed tomographic (CT) angiography to determine aortic neck angulation and were followed with duplex ultrasonography and CT every 3 and 6 months postoperatively to assess aortic neck and sac dilatation, as well as device migration. The VI-Datascope graft consists of an aortounifemoral polytetrafluoroethylene (PTFE) graft sutured to a proximal balloon-expandable stent. The length of the graft is 40 cm; thus, the distal end of the graft always protrudes through the ipsilateral arteriotomy and can be cut to an appropriate length for each patient. The covered portion of the graft was deployed just below the level of the lowest renal artery. The proximal bare metal stent was deployed in the suprarenal area. An endoluminal hand-sewn anastomosis was performed between the aortounifemoral limb and the distal external iliac or the common femoral arteries. An occluder device was placed in the contralateral common iliac artery to prevent retrograde perfusion of the aneurysm. A femorofemoral 8 mm Dacron graft bypass was then performed to establish flow to the contralateral extremity and pelvis. Using this approach, remodeling and straightening of angulated aortic neck morphology were achieved in all cases, including in 44% of patients with severe aortic neck angulation. The average follow-up period was 11.5 months (4-21 months). There was one early occlusion (<30 days after implantation) of the PTFE limb requiring thrombectomy and one late occlusion (6 months after implantation) requiring thrombectomy and implantation of a Viabahn stent graft (W.L. Gore & Associates). Scheduled CT scans did not show any graft migration or proximal neck dilatation. Neither neck dilatation nor endograft migration was observed with the balloon-expandable stent graft. In patients with complicated aortic neck morphology, balloon-expandable stent grafts such as the VI-Datascope graft provide more secure fixation and better long-term outcomes compared with the more commonly used self-expanding endografts.

Endovascular conversion with femorofemoral bypass as a treatment of endotension and aneurysm sac enlargement

We report a case of a patient treated with a Gore Excluder endograft for AAA in November 2003 with subsequent aneurysm sac enlargement in the absence of an identified endoleak. The patient had a Type I endoleak treated with a Palmaz stent at the neck and later developed a Type II endoleak treated with translumbar coil embolization. This was successful with absence of pressure in the sac after the procedure and stable aneurysm size over the next nine months. Surveillance of the patient with both CT and ultrasound then revealed an increase in the aortic sac diameter in the absence of endoleak. A Cook Zenith converter was used to reline this PTFE endograft. Subsequently, imaging showed aneurysm sac shrinkage. This is a report of endotension with aneurysm expansion following Gore Excluder placement which was treated successfully with a dacron endograft.

Endovascular aneurysm repair at 5 years: does aneurysm diameter predict outcome?

OBJECTIVE

The appropriate size threshold for endovascular repair of small abdominal aortic aneurysms (AAA) is unclear. We studied the outcome of endovascular aneurysm repair (EVAR) as a function of preoperative aneurysm diameter to determine the relationship between aneurysm size and long-term outcome of endovascular repair.

METHODS

We reviewed the results of 923 patients treated in a prospective, multicenter clinical trial of EVAR. Small aneurysms were defined according to two size thresholds of 5.5 cm and 5.0 cm. Two-way analysis was used to compare patients with small aneurysms (<5.5 cm, n = 441) to patients with large aneurysms (> or =5.5 cm, n = 482). An ordered three-way analysis was used to compare patients with small AAA (<5.0 cm, n = 145), medium AAA (5.0 to 5.9 cm, n = 461), and large AAA (> or =6.0 cm, n = 317). The primary outcome measures of rupture, AAA-related death, surgical conversion, secondary intervention, and survival were compared using Kaplan-Meier estimates at 5 years.

RESULTS

Median aneurysm size was 5.5 cm. The two-way comparison showed that 5 years after EVAR, patients with small aneurysms (<5.5 cm) had a lower AAA-related death rate (1% vs 6%, P = .006), a higher survival rate (69% vs 57%, P = .0002), and a lower secondary intervention rate (25% vs 32%, P = .03) than patients with large aneurysms (> or =5.5 cm). Three-way analysis revealed that patients with small AAAs (<5.0 cm) were younger (P < .0001) and were more likely to have a family history of aneurysm (P < .05), prior coronary intervention (P = .003), and peripheral occlusive disease (P = .008) than patients with larger AAAs. Patients with smaller AAAs also had more favorable aortic neck anatomy (P < .004). Patients with large AAAs were older (P < .0001), had higher operative risk (P = .01), and were more likely to have chronic obstructive pulmonary disease (P = .005), obesity (P = .03), and congestive heart failure (P = .004). At 5 years, patients with small AAAs had better outcomes, with 100% freedom from rupture vs 97% for medium AAAs and 93% for large AAAs (P = .02), 99% freedom from AAA-related death vs 97% for medium AAAs and 92% for large AAAs (P = .02) and 98% freedom from conversion vs 92% for medium AAAs and 89% for large AAAs (P = .01). Survival was significantly improved in small (69%) and medium AAAs (68%) compared to large AAAs (51%, P < .0001). Multivariate Cox proportional hazards modeling revealed that aneurysm size was a significant independent predictor of rupture (P = .04; hazard ratio [HR], 2.195), AAA-related death (P = .03; HR, 2.007), surgical conversion (P = .007; HR, 1.827), and survival (P = .001; HR, 1.351). There were no significant differences in secondary intervention, endoleak, or migration rates between small, medium, and large AAAs.

CONCLUSIONS

Preoperative aneurysm size is an important determinant of long-term outcome following endovascular repair. Patients with small AAAs (<5.0 cm) are more favorable candidates for EVAR and have the best long-term outcomes, with 99% freedom from AAA death at 5 years. Patients with large AAAs (> or =6.0 cm) have shorter life expectancy and have a higher risk of rupture, surgical conversion, and aneurysm-related death following EVAR compared to patients with smaller aneurysms. Nonetheless, 92% of patients with large AAAs are protected from AAA-related death at 5 years. Patients with AAAs of intermediate size (5 to 6 cm) represent most of the patients treated with EVAR and have a 97% freedom from AAA-related death at 5 years.

Acute symptomatic abdominal aortic aneurysm secondary to endovascular stent graft associated type II endoleak

Endovascular abdominal aneurysm repair (EVAR) is popular because of its low invasiveness and feasibility for high-risk patients. Endoleak is common after EVAR and is characterized by blood flow within the aneurysm sac but outside the stent graft. Type II or collateral endoleak commonly results from retrograde filling of the aneurysm from collateral visceral vessels, lumbar, inferior mesenteric, accessory renal or sacral arteries. Collateral leaks are generally thought to be benign and over half of the early leaks will seal spontaneously. Sporadically, collateral endoleak could lead to aneurysm sac pressurization and place the patient at ongoing risk of rupture. Herein, we report an uncommon case of early post-stent graft placement symptomatic abdominal aortic aneurysm associated with type II endoleak.

Progressive growth of a pelvic collection five years after endovascular aneurysm repair: an atypical presentation of an asymptomatic contained rupture

We report a case of an unusual and late presentation of an asymptomatic contained rupture after modular stent-graft implantation to treat an aortobiiliac aneurysm. Follow-up computed tomography (CT) scans 4 and 5 years after endovascular aneurysm repair showed a homogeneous, nonenhancing, but clearly growing, pelvic collection. CT-guided drainage of the collection was performed, and cultures of the evacuated brown fluid were negative for any infection. Control CT scan after drainage showed a complete collapse of both the collection and the previously excluded iliac aneurysms. A direct communication between the sterile pelvic collection and the excluded iliac aneurysm was suggested on this CT imaging and confirmed afterwards by surgery. From these imaging and surgical findings, this pelvic collection can be considered as an atypical presentation of an asymptomatic contained rupture of the excluded aneurysm.

Secondary conversion of the Gore Excluder to operative abdominal aortic aneurysm repair

OBJECTIVE

Reports continue to document the occurrence of major adverse events after endovascular aortic aneurysm repair. Although many of these problems can be successfully managed through endovascular salvage, operative conversion with explantation of the endoprosthesis remains necessary in some patients. We report herein a review of all patients initially enrolled in multicenter US clinical trials of the Excluder endograft who underwent secondary conversion to open surgical repair.

METHODS

Clinical data and relevant medical records of patients enrolled in phase I and II multicenter US clinical trials of the Excluder endograft were retrospectively reviewed for adverse events and further narrowed to those patients who underwent secondary operative conversion. Hospital records, operative and anesthesia reports, and all imaging studies were analyzed at initial implantation and at the time of subsequent open surgical repair.

RESULTS

Late open conversion was performed in 16 (2.7%) of the 594 patients enrolled in the Excluder clinical trials. Presumed endotension accounted for 8 of 16 of secondary conversions. In two of these patients, however, an endoleak was identified at the time of open surgical repair. Of the remaining eight patients, two underwent conversion for device infection, five for persistent endoleak, and one for aneurysm rupture. The overall 30-day mortality was 6.25% (1/16), with one death occurring in a patient with a ruptured aneurysm. Of patients who underwent conversion because of endotension, the maximal abdominal aortic aneurysm diameter (mean +/- SD) at the time of initial implantation and subsequent graft removal was 61 +/- 11 mm and 70 +/- 10 mm, respectively. The mean time to open conversion for treatment of endotension was 37 +/- 12 months (range, 20-50 months; median, 42 months). Freedom from conversion was 98.6% and 96.7% at 24 and 48 months, respectively.

CONCLUSIONS

Endotension in the absence of a demonstrable endoleak has been a major indication for late surgical conversion in patients treated with the Excluder endograft. Given the potential presence of an undetected endoleak and the possible effects of progressive sac enlargement on long-term device stability, continued close surveillance of patients with assumed endotension is required. Should changes in device design eliminate endotension, a further reduction in the already low incidence of late open conversion of the Excluder endograft can be anticipated.

Nonoperative approach to endotension

OBJECTIVE

The necessity of operative treatment of endotension after endovascular grafting of abdominal aortic aneurysms (endovascular aneurysm repair; EVAR) is under debate. The proposed causes of endotension and related treatment protocols are controversial. We report the outcome of a nonoperative approach to five patients with endotension after EVAR.

METHODS

From February 1997 to August 2004, 160 patients who underwent EVAR of an infrarenal abdominal aortic aneurysm were evaluated for the incidence of endotension. According to the endovascular protocol, plain radiographs, spiral computed tomography, and angiography were performed before and after surgery for follow-up. To detect endotension, spiral computed tomography was performed by using a delayed imaging technique after the infusion of contrast medium. Endotension was defined as an aneurysm sac enlargement after EVAR without evidence of endoleak. Aneurysm sac rupture was defined as discontinuity of the calcific rim of the aneurysmal sac and the presence of intra-aneurysmal fluid outside the sac.

RESULTS

We found five (3.1%) patients with endotension. Three of these experienced aneurysmal sac rupture. Only one of the three was underwent operation on experiencing sudden intestinal occlusion due to intra-abdominal adhesions. This patient had no intra-abdominal or retroperitoneal bleeding or hematoma but died after intensive care as a result of non-aneurysm-related problems. Four patients with endotension are still being closely followed up according to our surveillance protocol, and they are doing clinically well. After rupture, clear shrinking of the aneurysm sac was seen in two patients.

CONCLUSIONS

Endotension after EVAR may cause subsequent aneurysm rupture. Endotension is evidently not associated with endoleak I to III provided that the endovascular graft is maintained in appropriate position and that free endovascular flow is observed. We propose to consider a nonoperative approach in the clinically asymptomatic patient with aneurysm enlargement after EVAR if endoleak is excluded by well-performed imaging techniques.