Options for treatment of persistent aneurysm perfusion after endovascular repair

Endoleak as a Complication of Endoluminal Grafting of Abdominal Aortic Aneurysms: Classification, Incidence, Diagnosis, and Management

The inability to obtain or maintain a secure seal between a vessel wall and a transluminally implanted intra-aneurysmal graft is a complication unique to the evolving technique of endovascular aneurysm exclusion. Because the term “leak” has long been associated with aneurysm rupture, the term “endoleak” is proposed as a more definitive description of this phenomenon.

Embracing both persistent blood flow into the aneurysmal sac from within or around the graft (graft related) and from patent collateral arteries (nongraft related), endoleak can be classified as primary or secondary depending on the time of occurrence (within 30 days of implantation or following apparent initial seal, respectively).

Diagnostic techniques to detect endoleak include arteriography, intraprocedural pressure monitoring, contrast-enhanced computed tomography, abdominal X ray, and duplex scanning. Management strategies for endoleak range from observation with periodic imaging surveillance to correction by additional endoluminal or surgical procedures.

Standardization of the terminology describing this important sequela to endovascular aneurysm exclusion should facilitate uniform reporting of clinical trial data vital to the evaluation of this emerging technique.

European Experience with a System for Bifurcated Stent-Graft Insertion

Purpose:

To test an endovascular aneurysm exclusion system in the presence of a wide range of challenging anatomic features.

Methods:

Bifurcated endovascular stent-grafts were inserted in 52 patients and followed with serial computed tomography for up to 3 years. The device underwent several modifications during this time, the most significant of which represent the difference between the homemade (n = 42) and industry-made (n = 10) versions.

Results:

The initial procedural success rate was 92% in the homemade group and 100% in the industry-made group. In the 3 years of follow-up, the long-term success rate was 64% in the homemade group and 90% in the industry-made group. The primary reasons for failure in the homemade group were graft thrombosis due to kinking early in the series and proximal stent migration later in our experience. All cases of migration occurred when the neck was < 15 mm in length, the neck was lined with thrombus, or the stent was implanted > 15 mm from the renal arteries. Kinking was subsequently overcome by implanting Wallstents throughout the graft limbs. The sole failure in the industry-made group was a case in which collateral perfusion reached the aneurysm through patent lumbar arteries.

Conclusions:

The fruits of this experience are a better technique, a better device, and, most importantly, a better understanding of the system's limits, as reflected in the current selection criteria.

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

Purpose:

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

Methods:

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

Results:

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

Conclusions:

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

Successful Embolization of Persistent Endoleak from a Patent Inferior Mesenteric Artery

Purpose:

To report the successful endovascular occlusion of a persistent endoleak owing to collateral perfusion in a 1-year-old bifurcated aortic endograft.

Methods and Results:

An 81-year-old man underwent endovascular repair of a 5.5-cm abdominal aortic aneurysm (AAA) with a bifurcated stent-graft in 1995; collateral perfusion of the excluded aneurysm by retrograde filling of the patent inferior mesenteric artery (IMA) was noted postoperatively. At his 1-year follow-up, the mid-sac endoleak persisted on contrast-enhanced computed tomography. Using the superior mesenteric artery for access, the stump of the IMA was successfully embolized with glue.

Conclusions:

This case, which highlights the importance of documenting a patent IMA prior to AAA endografting, illustrates one option for the management of persistent collateral perfusion of endovascularly excluded aneurysms.

Surgical corrections of endovascular aneurysms: repair complications

The authors describe their experience with the use of 21 open surgical corrections after endovascular abdominal aneurysm repair, reporting the frequency, type and outcome of these procedures in their group of 165 patients treated during a 10-year period.

Preoperative embolization of collateral side branches: a valid means to reduce type II endoleaks after endovascular AAA repair

PURPOSE

To report the results of preprocedural embolization of collateral branches arising from abdominal aortic aneurysms (AAA) scheduled for endovascular repair.

METHODS

Twenty-three consecutive AAA patients (all men; mean age 73 years, range 56-82) had coil embolization of patent lumbar and inferior mesenteric arteries (IMA) in a staged procedure prior to endovascular repair. Embolization with microcoils was attempted in 37 of the 52 identified lumbar arteries and 14 of 15 inferior mesenteric arteries. Follow-up included biplanar abdominal radiography, spiral computed tomography, and duplex ultrasonography at 1, 30, 90, and 180 days after the stent-graft procedure and at 6-month intervals thereafter.

RESULTS

Successful embolization was obtained in 24 (65%) of lumbar arteries, while all 14 (100%) IMAs were occluded with coils. No complication was associated with embolotherapy. Over a mean 17-month follow-up of 22 patients (1 intraoperative death), there was only 1 (4.5%) type II endoleak from a patent lumbar artery, with no sac expansion after 2 years. There were 4 (18%) type I and 1 (4.5%) type III endoleaks.

CONCLUSIONS

The embolization of side branches arising from an infrarenal aortic aneurysm before endovascular repair is feasible, with a high success rate; this maneuver may play a relevant role in reducing the rate of type II endoleak, improving long-term outcome.

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 morphology as a predictor of endoleak following endovascular aortic aneurysm repair: do smaller aneurysm have better outcomes?

Since the Food and Drug Administrations' approval of endovascular devices for abdominal aortic aneurysm (AAA) repair, clinicians have been relaxing the strict inclusion criteria present during the clinical trials. Although the long-term natural history of endoleaks remains unclear, attachment site leaks (type I) are believed to represent an ongoing risk for future rupture. We reviewed our experience with endovascular AAA repair to elucidate factors that predispose toward the development of endoleaks and found that larger AAAs are significantly more likely to have a short proximal neck and severe proximal angulation. These factors likely contribute to the significantly increased rate of type I endoleaks that occurred after endovascular repair of large AAAs. Small AAAs (<5) had the lowest rate of endoleaks overall (8.3%) and of type I endoleaks in particular (0%). We conclude that AAA size and morphology can be used to predict which aneurysms will experience attachment site endoleaks in their course; AAAs from 4.5 to 5 cm in diameter may be particularly well suited for endovascular repair in this regard.

Embolization of type II endoleaks after aortic stent-graft implantation: technique and immediate results

PURPOSE

We report the procedural details and immediate results of treatment of type II endoleaks after aortic stent-graft implantation.

METHODS

In a consecutive series of patients who had either Vangard (n = 53) or Talent (n = 7) aortic stent-grafts implanted, type II endoleaks were confirmed by means of angiography in 18 patients, with a mean (+/- SD) age of 69 +/- 11 years; 16 patients had Vangard stent-grafts, and two patients had Talent stent-grafts. After superselective catheterization of the feeding vessel, with 3F microcatheters, and liberal injections of vasodilators, embolization was performed with either a mixture of biologic glue and Lipiodol (n = 16) or Microcoils (n = 2).

RESULTS

The procedure was performed through the femoral artery in 16 patients and through the brachial artery in the remaining two patients. Overall, superselective catheterization and embolization were successfully undertaken in 17 (94.4%) of 18 patients. In the remaining patient, superselective catheterization proved impossible. This patient was treated with an injection of microparticles completed by means of embolization of biologic glue more proximally in an iliolumbar branch. During follow-up (mean, 13.3 months) after embolization, the aneurysm sac shrank in 13 (72.2%) of 18 patients. A new type II endoleak was diagnosed on helical computed tomography or magnetic resonance imaging in two (11.1%) of 18 patients.

CONCLUSION

Percutaneous embolization is a safe and effective technique for treatment of type II endoleaks. However, despite these initially promising results, large long-term follow-up studies will be required to confirm its efficiency.

Endoleak after endovascular repair of abdominal aortic aneurysm

PURPOSE

We sought to assess the role of endovascular techniques in the management of perigraft flow (endoleak) after endovascular repair of an abdominal aortic aneurysm.

METHOD

We performed endovascular repair of abdominal aortic aneurysm in 114 patients, using a variety of Gianturco Z-stent-based prostheses. Results were evaluated with contrast-enhanced computed tomography (CT) at 3 days, 3 months, 6 months, 12 months, and every year after the operation. An endoleak that occurred 3 days after operation led to repeat CT scanning at 2 weeks, followed by angiography and attempted endovascular treatment.

RESULTS

Endoleak was seen on the first postoperative CT scan in 21 (18%) patients and was still present at 2 weeks in 14 (12%). On the basis of angiographic localization of the inflow, the endoleak was pure type I in 3 cases, pure type II in 9, and mixed-pattern in 2. Of the 5 type I endoleaks, 3 were proximal and 2 were distal. All five resolved after endovascular implantation of additional stent-grafts, stents, and embolization coils. Although inferior mesenteric artery embolization was successful in 6 of 7 cases and lumbar embolization was successful in 4 of 7, only 1 of 11 primary type II endoleaks was shown to be resolved on CT scanning. There were no type III or type IV endoleaks (through the stent-graft). Endoleak was associated with aneurysm dilation two cases. In both cases, the aneurysm diameter stabilized after coil embolization of the inferior mesenteric artery. There were two secondary (delayed) endoleaks; one type I and one type II. The secondary type I endoleak and the associated aneurysm rupture were treated by use of an additional stent-graft. The secondary type II endoleak was not treated.

CONCLUSIONS

Type I endoleaks represent a persistent risk of aneurysm rupture and should be treated promptly by endovascular means. Type II leaks are less dangerous and more difficult to treat, but coil embolization of feeding arteries may be warranted when leakage is associated with aneurysm enlargement.

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.

Endoleaks following endovascular repair of abdominal aortic aneurysm: the predictive value of preoperative anatomic factors--a review of 100 cases

OBJECTIVE

The failure to maintain a secure exclusion of aortic aneurysms with intraluminally placed grafts has been termed endoleak. We performed a retrospective review of our first 100 transluminally repaired abdominal aortic aneurysms (AAAs) in an effort to identify preoperative factors that could predict which patients would have endoleaks.

METHODS

Between February 1993 and September 1998, 100 infrarenal aneurysms were treated with tube (39), bifurcated (45), and aortoiliac grafts (16). Endoleaks (early and late) developed in 34 patients. Preoperative computed tomography scans and angiograms for all patients were individually inspected by a single reviewer. Aortic characteristics analyzed included number of patent lumbar arteries, presence of a patent inferior mesenteric artery (IMA), calcification and thrombus at proximal and distal attachment sites, proximal aortic angulation, and graft-vessel size discrepancy at proximal and distal attachment sites. The prevalence of the preoperative factors was compared among patients with and without endoleaks.

RESULTS

Endoleaks developed in 44% of tube, 33% of bifurcated, and 47% of aortoiliac grafts (P =.51). Correlation between total number of patent lumbar arteries, presence of a patent IMA, and endoleaks was not significant (P =.44,.95). Calcification at either proximal or distal attachment site did not increase the risk of endoleaks (P =.50,.62). The presence of thrombus at the attachment site (proximally or distally) also failed to increase endoleak rates (P =.12,.78). Degree of proximal aortic angulation did not differ between groups (P =.39). Size discrepancies between graft and aorta or iliac vessels at proximal or distal sites did not significantly differ (P >.54, >.13). Subgroup analysis of endoleaks with different tube types also failed to demonstrate significant differences among the three graft types (P >.05).

CONCLUSION

Endoleaks develop in a significant number of endovascularly repaired AAAs. We were unable to demonstrate a statistically significant association with anatomic characteristics thought to predispose to the development of endoleaks. We find no predictive value associated with these anatomic factors.

Endoleaks after endovascular repair of aortic aneurysm: are they predictable?-initial results

PURPOSE

To evaluate the predictability of endoleak.

MATERIALS AND METHODS

Thirteen women and 60 men (mean age, 69.8 years) underwent transfemoral insertion of endoluminal stent-grafts for treatment of aortic aneurysms. Follow-up included helical computed tomography (CT) at 3-month intervals. In the cases of endoleak, angiography also was performed to document the number of leak sites, their size and position, the feeding artery, the size of the aneurysm, the amount of thrombus, and the visualization of the lumbar arteries and inferior mesenteric artery. These data were correlated (Student t test) with the probability of endoleak.

RESULTS

A total of seven (10%) endoleaks were identified at CT in 68 patients. The feeding vessels were lumbar arteries in three cases, the inferior mesenteric artery in three cases, and the median sacral artery in one case. Of all factors, only the number of lumbar arteries visualized preoperatively (P <.005) had a significant correlation with probability of endoleak. In 71% (five of seven patients) of the cases of lumbar endoleak, four lumbar arteries were patent, whereas among the 61 patients with successfully repaired aneurysm, only eight (13%) had four patent lumbar arteries. Endoleaks were never found in the primarily thrombosed sections of an aneurysm.

CONCLUSION

Prediction of endoleaks with absolute certainty remains elusive. The single correlating risk factor identified from the data was patency of four or more lumbar arteries visualized preoperatively at CT.

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Relationship between preoperative patency of the inferior mesenteric artery and subsequent occurrence of type II endoleak in patients undergoing endovascular repair of abdominal aortic aneurysms

OBJECTIVES

The purpose of this study was (1) to find out whether preoperative inferior mesenteric artery (IMA) patency (on radiographic imaging) predicts IMA-related endoleaks after endovascular repair of infrarenal abdominal aortic aneurysms, (2) to determine feasibility of measuring aneurysm sac pressures in patients with endoleaks, and (3) to report early evidence of effective endovascular obliteration of IMA endoleaks.

METHODS

We studied 76 consecutive cases of infrarenal aortic aneurysms that were repaired with an endovascular approach (March 1998-April 1999).

RESULTS

There were 13 (17%) endoleaks persistent 30 days after the procedure. Eleven (85%) of these 13 were IMA-related endoleaks, which were documented with selective superior mesenteric artery angiography. The preoperative finding (on computed tomographic scan) of a patent IMA does not always predict an IMA-related endoleak, but results in a statistically and clinically significant higher ratio of patients with IMA-related endoleaks in the immediate postoperative period (24% versus 3%, P <.035). In eight of the 11 patients with persistent IMA-related endoleaks, measurement of intra-aneurysm sac pressures was possible, and six of these patients had systemic pressures within the excluded aneurysm sac. Nine (82%) of 11 IMA-related endoleaks were successfully obliterated by means of selective IMA embolization.

CONCLUSIONS

Many endoleaks are caused by a patent IMA, and this can result in persistence of systemic pressure within the aneurysm sac. The preoperative finding (on computed tomographic scan) of a patent IMA is a predictor of increased rates of IMA endoleaks, and IMA endoleaks can be successfully obliterated through endovascular procedures, after endovascular abdominal aortic aneurysm repair.

Endovascular stent-graft deployment: temporary vena caval occlusion with balloons to control aortic blood flow-experimental canine study and initial clinical experience

Vena caval occlusion was evaluated in animal experiments. In five patients with thoracic aortic aneurysms, two balloon catheters were introduced via the femoral vein to the inferior vena cava and superior vena cava and inflated before stent-graft deployment. Aortic pressure and flow were immediately decreased, which minimized the downstream shift of the stent-grafts. Temporary vena caval occlusion is safe and effective for precise aortic stent-graft deployment.

Diagnosis and treatment of inferior mesenteric arterial endoleaks after endovascular repair of abdominal aortic aneurysms

PURPOSE

To review the incidence and repair of inferior mesenteric arterial (IMA) type II endoleaks after endovascular repair of abdominal aortic aneurysms.

MATERIALS AND METHODS

Fifty patients who underwent endovascular repair of abdominal aortic aneurysms were examined. If an endoleak was identified at 30-day postoperative computed tomography, conventional arteriography was performed to identify and eliminate its source. After the exclusion of attachment site leaks, a catheter was placed selectively in the superior mesenteric artery (SMA). If retrograde filling of the IMA and aneurysm was identified, coil embolization was attempted through the SMA and middle colic artery. Intrasac pressures were measured at embolization.

RESULTS

Eight of 50 patients (16%) had type II endoleaks that were attributed to retrograde flow in the IMA. Intrasac measurements demonstrated systemic pressure in six patients and one-half systemic pressure in two patients. The IMA was embolized through the SMA and left colic artery in seven patients and through the translumbar aorta in one patient.

CONCLUSION

Retrograde flow in the IMA is responsible for many type II endoleaks. Systemic pressures are transmitted into the aneurysm sac from the IMA. The IMA can be embolized successfully with an SMA approach in most patients.

Endovascular aneurysm repair in high-risk patients

PURPOSE

The purpose of this study was to evaluate the role of endovascular aneurysm repair in high-risk patients.

METHODS

The elective endovascular repair of infrarenal aortic aneurysm was performed in 116 high-risk patients with either custom-made or commercial stent grafts. The routine follow-up examination included contrast-enhanced computed tomography (CT) before discharge, at 3, 6, and 12 months, and annually thereafter. Patients with endoleak on the initial CT underwent re-evaluation at 2 weeks. Those patients with positive CT results at 2 weeks underwent endovascular treatment.

RESULTS

Endovascular repair was considered feasible in 67% of the patients. The mean age was 75 years, and the mean aneurysm diameter was 6.3 cm. The American Society of Anesthesiologists grade was II in 3.4%, III in 65.5%, IV in 30.1%, and V in 0.9%. There were no conversions to open repair. Custom-made aortomonoiliac stent grafts were implanted in 77.6% of the cases, custom-made aortoaotic stent grafts in 11.2%, and commercial bifurcated stent grafts in 11.2%. The 30-day rates of mortality, major morbidity, and minor morbidity were 3.4%, 20.7%, and 12%, respectively, in the first 58 patients and 0%, 3.4%, and 3.4%, respectively, in the last 58. The late complications included five cases of stent graft kinking, two cases of femorofemoral graft occlusion, and three cases of proximal stent migration, one of which led to aneurysm rupture. At 2 weeks after repair, endoleak was present in 10.3% of the cases. All the type I (direct perigraft) endoleaks underwent successful endovascular treatment, whereas only one type II (collateral) endoleak responded to treatment. The technical success rate at 2 weeks was 86.2%, and the clinical success rate was 96.6%. The continuing success rate was 87.9%. Seventeen patients died late, unrelated deaths.

CONCLUSION

Endovascular aneurysm repair is safe and effective in patients at high risk, for whom it may be the preferred method of treatment.

Endovascular repair of abdominal aortic aneurysms: where do we stand?

Endovascular repair of abdominal aortic aneurysms has evolved dramatically within the past few years. In light of the potential to reduce morbidity and mortality associated with open surgical repair, endoluminal grafting offers therapeutic options to patients who are not surgical candidates because of comorbidities. With the development of bifurcated devices, more complex aneurysms may be treated by endovascular grafting. Although successful placement of endovascular grafts requires a pronounced learning curve, including appropriate patient selection, midterm results seem consistent with those of traditional open repair of aneurysms. This review describes the current indications, minimal requirements, different devices and associated techniques, and potential complications of endoluminal repair of abdominal aortic aneurysms. Future aspects of endoluminal grafting are also discussed.

Algorithm for the diagnosis and treatment of endoleaks

BACKGROUND

Endoluminal grafting of abdominal aortic aneurysms (AAA) has shown promising early results. However, endoleaks present a new and challenging obstacle to successful aneurysm exclusion. We report our experience with primary, persistent endoleaks and provide an algorithm for their diagnosis and management.

METHODS

Over a 19-month period, 73 patients underwent endoluminal repair of their AAAs using a modular bifurcated endograft as part of a US FDA Investigational Device Exemption trial. Spiral computed tomography (CT) scanning was performed prior to discharge after repair to evaluate for complete aneurysm exclusion. If no endoleak was present on that initial CT scan, color-flow duplex scanning was performed at 1 month, with repeat CT scanning at 6 months and 1 year. If the initial CT scan revealed the presence of an endoleak, repeat CT scanning was performed at 2 weeks, 1 month, and 3 months, or until the endoleak resolved. Any patient with an endoleak that persisted beyond 3 months underwent angiographic evaluation to localize the source of the leak.

RESULTS

At 1 month, 62 patients (85%) had successful aneurysm exclusion. The remaining 11 patients (15%) had primary endoleaks, 8 (11%) of which persisted beyond 3 months, prompting angiographic evaluation. In 2 patients the endoleak was related to a graft-graft or graft-arterial junction. One was from the endograft terminus in the common iliac artery and was successfully embolized, along with its outflow lumbar artery. The other required placement of an additional endograft component across a leaking graft-graft junction to successfully exclude the aneurysm. The remaining six endoleaks were due to collateral flow through the aneurysm sac. In 4 cases this was lumbar to lumbar flow fed by hypogastric artery collaterals to the inflow lumbar artery. In the remaining 2 patients the endoleak was found to be due to flow between a lumbar and inferior mesenteric artery. Resolution of the endoleak by coil embolization of the feeding hypogastric artery branch in 1 patient was unsuccessful due to rapid recruitment of another hypogastric branch. Two of the six collateral flow endoleaks have resolved spontaneously without treatment, while the remaining cases have been followed up without evidence of aneurysm expansion.

CONCLUSION

Systematic postoperative surveillance facilitates proper diagnosis and treatment of endoleaks. This involves serial CT scans to detect the presence of endoleaks, followed by angiography to determine their etiology and guide treatment, if clinically indicated.

Endoleak after stent-graft treatment of abdominal aortic aneurysm: a meta-analysis of clinical studies

BACKGROUND

Endoleak is the major complication after endovascular treatment of abdominal aortic aneurysm (AAA) and its incidence seems to remain significant. Little is known about the association of device type and configuration with respect to the incidence, location, time of onset and fate of endoleakage.

METHODS

A meta-analysis was performed via a Medline search of clinical studies after 1995 dealing with the endovascular treatment of AAA. Details of number of patients treated, configuration and type of endovascular device were collected. Data concerning site of origin, time of occurrence and fate of the endoleak were retrieved, along with information on change in diameter of the aneurysm with time.

RESULTS

The 23 publications included reported on 1189 patients. The 1118 patients with successfully inserted transfemoral endovascular grafts experienced 270 endoleaks (24 per cent). The majority arose from the distal stent attachment site (36 per cent), were present immediately after stent-graft placement (66 per cent) and were persistent in time (37 per cent). Tube grafts were more frequently affected by endoleakage (35 per cent; P < 0.0001), especially at the distal stent attachment site (51 per cent), than bifurcated grafts (18 per cent; P = 0.004) and aortounilateral devices (20 per cent; P = 0.70). Self- expandable stent-grafts were more frequently associated with endoleaks (25 per cent) than balloon-expandable stent-grafts (17 per cent) (P = 0.037).

CONCLUSION

Endovascular treatment of AAA is an evolving field. Even after the initial learning curve and attention to device-related problems, it is still accompanied by a significant number of endoleaks. Uniform presentation of results of treatment is necessary for analysing the effect of differences between patients, aneurysm morphology and device type.

Endovascular abdominal aortic aneurysm repair with percutaneous transfemoral prostheses deployment under local anaesthesia. Initial experience with a new, simple-to-use tubular and bifurcated device in the first 27 cases

BACKGROUND

Modification of endografts are required to simplify and improve the safety of the endovascular management of abdominal aortic aneurysms (AAA).

OBJECTIVES

The aim of this study is to evaluate the efficacy of a new custom-made, tubular and bifurcated device.

MATERIALS AND METHODS

The graft consisted of a continuous, self-expanding, stainless steel, Z-stent structure, covered with a thin wall PTFE tube. Bifurcated grafts were constructed in vivo from three PTFE tubes with a continuous Z-stent structure. Twenty-seven high risk patients with a mean age of 74 (62-86) years and AAA, mean diameter 5.9 cm, were treated in the last 26 months. Tube grafts were deployed in 13 aortic and one iliac cases, bifurcated grafts in nine cases and aorto-uni-iliac grafts with femorofemoral bypass in four cases. Grafts were deployed percutaneously under local anaesthesia. Patients were followed with contrast CT periodically.

RESULTS

All grafts were deployed. There were no open conversions or other major complications. There were nine proximal and one distal postoperative endoleak. Four sealed spontaneously, three were treated successfully with endovascular techniques and three are under surveillance. In the 7 (2-23) months follow-up, one patient died due to heart failure 3 months post-procedure.

CONCLUSIONS

Local anaesthesia and percutaneous graft introduction simplify and improve the efficacy of the procedure. Continuous aortic graft support provides stability and reduces the risk of migration. PTFE is a flexible, low-profile material for use in endovascular stent-grafts. The bifurcation concept used offers a simple technique for bifurcated grafts.

Abdominal aortic aneurysm in high-risk patients: short- to intermediate-term results of endovascular repair

PURPOSE

To assess the safety and efficacy of endovascular repair of abdominal aortic aneurysm in high-risk patients during the short to intermediate term.

MATERIALS AND METHODS

Endovascular aneurysm repair was performed in 50 patients considered too high risk for conventional repair. Stent-grafts were inserted through surgically exposed femoral arteries with fluoroscopic guidance. The anesthetic technique was epidural in 36 patients, general in 12, and local in two. Aortouniiliac stent-grafts were inserted in 42 patients and aortoaortic in eight.

RESULTS

There were no deaths and no conversions to open surgical repair. The primary success rate (complete aneurysm exclusion according to CT criteria) was 88% (44 of 50). The secondary, clinical, and continuing success rates were all 98% (49 of 50). Surgical time was 196 minutes +/- 67 (mean +/- SD), blood loss was 284 mL +/- 386, and volume of contrast material administered was 153 mL +/- 64. The time from the end of the surgery to resumption of a normal diet was 0.58 days +/- 0.56, to ambulation was 1.22 days +/- 0.77, and to discharge from the hospital was 3.63 days +/- 1.60. Wound problems accounted for the majority of complications. There were no instances of pulmonary failure, renal failure, stent-graft migration, or late leakage.

CONCLUSION

Endovascular repair of abdominal aortic aneurysm is feasible in two-thirds of high-risk patients, with a low mortality and high success rate during the short to intermediate term.

Immediate and late explantation of endovascular aortic grafts: the endovascular technologies experience

PURPOSE

The morbidity and clinical outcome of the failure to successfully repair an abdominal aortic aneurysm with Endovascular Technologies (EVT) grafts, resulting in explantation of the device, was assessed.

METHODS

The records of all patients worldwide undergoing attempted endovascular repair with EVT devices from February 1993 to October 1997 were retrospectively reviewed. Of 669 patients, 19 (3%) were converted to open procedure with immediate explantation during the initial attempt at endovascular repair, and 27 patients (4%) required explantation at a later date, ranging from 1 day to 40 months. The incidence, morbidity, mortality, and effect on clinical outcome were evaluated.

RESULTS

Causes of immediate conversion with explantation were: inaccurate deployment of the proximal or distal attachment systems (11 of 19; 58%); twists in the system (3 of 19; 16%); mechanism malfunction during deployment (4 of 19; 21%); and an aortic tear (1 of 19; 5%). Among the 27 patients undergoing late explantation, 20 (74%) did so because of persistent endoleaks. Three cases (11%) were performed because of aneurysm rupture, three (11%) because of graft occlusion, one because of aortic dissection (4%), and one (4%) because of graft migration into the aneurysm sac. The overall perioperative mortality rate was 11% (2 of 19) for immediate explantation and 7% (2 of 27) for late explantation. The average length-of-stay was 11 days for immediate explantation and 14 days for late explantation (NS). Complications included myocardial infarction (4%), pulmonary insufficiency (13%), wound infection (4%), and permanent renal failure (2%). There were no significant differences in the incidence rates of these complications between immediate and late explants. No cases of limb loss occurred. Median American Society of Anesthetists (ASA) classification was 3, and there was no correlation between ASA classification and mortality rate. Average operating time was 374 minutes for immediate explantation (including the time for the failed endovascular procedure) and 185 minutes for late explantation.

CONCLUSION

Immediate and late explantation are infrequent events, occurring in 3% and 4%, respectively, of attempted EVT endovascular aortic stent placements. The mortality rate was higher for both immediate (11%; P <.05) and late (7%; NS) explantation when compared with the mortality rate of all patients undergoing EVT aortic endograft placement (1.5%). There does not appear to be increased long-term morbidity among patients undergoing successful explantation. Early recognition of the need to convert to open procedure, device improvement, and increased operator experience should continue to minimize the incidence of immediate and late explantation and their associated complications.

The role of infrarenal aortic side branches in the pathogenesis of endoleaks after endovascular aneurysm repair

AIM

To investigate the relation between the number of preoperative patent side branches and the presence or absence of postoperative endoleaks, and to study the fate of patent branches after operation.

PATIENTS AND METHODS

Thirty consecutive patients were included. Cine mode viewing of axial CT angiography images was applied to detect infrarenal aortic side branches. The position of side branches relative to the renal arteries, branch patency and run-off pathways were studied.

RESULTS

A total of 160 patent side branches were found. All patients had two or more patent side branches. A patent inferior mesenteric artery was found in 22/30 patients (73%). Postoperative CT scans revealed major endoleaks in five patients (16%) and minor endoleaks in eight (27%). There was no significant difference in the number of preoperative patent side branches in patients with a completely thrombosed aneurysm sac (five; range 2-8) compared to patients with postoperative endoleaks (six; range 3-9; p = 0.12). Backbleeding from patent side branches as the sole cause of endoleak was seen in one patient only (3.3%).

CONCLUSION

Postoperative endoleaks are not related to the number of preoperative patent side branches. In patients without endoleaks, contrast enhancement of side branches was repeatedly seen in the vicinity of the aneurysm wall. Although close follow-up of these branches is warranted, they did not affect the outcome of endovascular aneurysm repair.

Endovascular management of "endoleaks" after transluminal infrarenal abdominal aneurysm repair

PURPOSE

To investigate the reasons for endoleaks after transluminal infrarenal abdominal aneurysm management and the potential for transluminal interventions in subsequent management.

METHODS

Prospective analysis of 50 consecutive patients undergoing endovascular aneurysm repair at a single institution with Stentor and Vanguard grafts from March 1995 to March 1997.

SETTING

Academic teaching hospital.

RESULTS

Two procedures were converted for other reasons than leak. In the remaining 48 successful procedures endoleaks were detected in 11 (22.9%): proximal aortic leak (2.1%), distal aortic leak (8.3%), iliac leak (12.5%). Leaks were treated at the initial procedure in five patients, resulting in 87.5% excluded aneurysms. Twelve and a half per cent were discharged with a primary leak. Redo was performed on all iliac leaks within 7 weeks. All aortic leaks showed spontaneous thrombosis within 3 months, but reappeared with local aneurysm expansion. Aortic redo-procedures were performed by proximal tubular extension or converting a tube graft into a bifurcation graft. All rescue procedures were successful. Secondary leaks have been observed twice in this series, both treated by endovascular means.

CONCLUSIONS

Endovascular treatment of primary and secondary endoleaks is possible, and may be a safe alternative to a difficult open procedure.

Helical CT of aorta after endoluminal stent-graft therapy: value of biphasic acquisition

OBJECTIVE

We report our prospective study evaluating biphasic helical CT of the aorta after endoluminal stent-graft placement.

SUBJECTS AND METHODS

Biphasic helical CT scans in 95 patients with abdominal and thoracic aortic aneurysms who had undergone endoluminal stent-graft placement were reviewed. After a test bolus injection of 15 ml of contrast media at a rate of 3.5 ml/sec for the measurement of the optimal start delay, the aorta was scanned using the following parameters: collimation of 5 mm, table speed of 7 mm per rotation, tube rotation time of 0.75 sec, 120 kV, and 295 mA. A delayed helical CT scan was obtained 15 sec after the initial acquisition using the same parameters.

RESULTS

Biphasic helical CT scans showed perigraft leakage in 45 (47%) of 95 patients. Leakage was shown only on arterial phase CT in eight patients and only on the delayed scans in three patients. In two patients, leakage shown on the delayed acquisition was retrospectively seen on the first scan. Leakage and outflow vessels were most visible on the arterial phase acquisition in 17 patients and on the second acquisition in six patients. Overall, biphasic acquisition was superior to arterial phase acquisition alone in 15 (16%) of 95 patients.

CONCLUSION

The diagnostic value of biphasic helical CT is superior to arterial phase acquisition alone for the evaluation of the aorta after endoluminal stent-graft therapy.

Persistent collateral perfusion of abdominal aortic aneurysm after endovascular repair does not lead to progressive change in aneurysm diameter

PURPOSE

To differentiate between the phenomenon of collateral perfusion from a side branch versus graft-related endoleaks after endovascular repair of abdominal aortic aneurysms (AAA), with respect to aneurysm size and prognosis.

METHODS

We successfully treated 64 AAA patients with endovascular grafting. We followed all the patients postoperatively with spiral computed tomography at one, three, six and 12 months, and biannually thereafter. We measured aneurysm diameters preoperatively and postoperatively. We calculated preoperatively the relation of maximum aortic diameter (D) to the thrombus-free lumen diameter (L) expressed as an L/D ratio. Median follow-up was 15 months.

RESULTS

Sixteen patients had collateral perfusion during follow-up. We successfully treated two patients with embolization. One patient showed resolution of collateral perfusion after we stopped warfarin treatment. Two patients died of unrelated causes during follow-up. One patient was converted to surgical treatment, and two patients showed spontaneous resolution of their collateral perfusion. The group of patients with perfusion showed no statistically significant change of their aortic diameter on follow-up. The group of patients without perfusion showed a median decrease in aortic diameter of 8mm (p < 0.0001) at 18 months postoperatively. The group of patients with perfusion had significantly less thrombus in their aneurysm sac preoperatively than the group without perfusion, as expressed by the L/D ratio (mean L/D 0,61 versus 0,78, respectively; p=0.0021.)

CONCLUSION

There was no significant increase in aortic diameter on an average 18 months postoperatively despite persistent collateral perfusion. This may indicate a halted disease progression in the short term. Embolization of collateral vessels is associated with risk of paraplegia. We recommend a conservative approach with close observation if aneurysm diameter is stable.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Successful embolization of persistent endoleak from a patent inferior mesenteric artery

PURPOSE

To report the successful endovascular occlusion of a persistent endoleak owing to collateral perfusion in a 1-year-old bifurcated aortic endograft.

METHODS AND RESULTS

An 81-year-old man underwent endovascular repair of a 5.5-cm abdominal aortic aneurysm (AAA) with a bifurcated stent-graft in 1995; collateral perfusion of the excluded aneurysm by retrograde filling of the patent inferior mesenteric artery (IMA) was noted postoperatively. At his 1-year follow-up, the mid-sac endoleak persisted on contrast-enhanced computed tomography. Using the superior mesenteric artery for access, the stump of the IMA was successfully embolized with glue.

CONCLUSIONS

This case, which highlights the importance of documenting a patent IMA prior to AAA endografting, illustrates one option for the management of persistent collateral perfusion of endovascularly excluded aneurysms.

Endoleak as a complication of endoluminal grafting of abdominal aortic aneurysms: classification, incidence, diagnosis, and management

The inability to obtain or maintain a secure seal between a vessel wall and a transluminally implanted intra-aneurysmal graft is a complication unique to the evolving technique of endovascular aneurysm exclusion. Because the term "leak" has long been associated with aneurysm rupture, the term "endoleak" is proposed as a more definitive description of this phenomenon. Embracing both persistent blood flow into the aneurysmal sac from within or around the graft (graft related) and from patent collateral arteries (nongraft related), endoleak can be classified as primary or secondary depending on the time of occurrence (within 30 days of implantation or following apparent initial seal, respectively). Diagnostic techniques to detect endoleak include arteriography, intraprocedural pressure monitoring, contrast-enhanced computed tomography, abdominal X ray, and duplex scanning. Management strategies for endoleak range from observation with periodic imaging surveillance to correction by additional endoluminal or surgical procedures. Standardization of the terminology describing this important sequela to endovascular aneurysm exclusion should facilitate uniform reporting of clinical trial data vital to the evaluation of this emerging technique.

European experience with a system for bifurcated stent-graft insertion

PURPOSE

To test an endovascular aneurysm exclusion system in the presence of a wide range of challenging anatomic features.

METHODS

Bifurcated endovascular stent-grafts were inserted in 52 patients and followed with serial computed tomography for up to 3 years. The device underwent several modifications during this time, the most significant of which represent the difference between the homemade (n = 42) and industry-made (n = 10) versions.

RESULTS

The initial procedural success rate was 92% in the homemade group and 100% in the industry-made group. In the 3 years of follow-up, the long-term success rate was 64% in the homemade group and 90% in the industry-made group. The primary reasons for failure in the homemade group were graft thrombosis due to kinking early in the series and proximal stent migration later in our experience. All cases of migration occurred when the neck was < 15 mm in length, the neck was lined with thrombus, or the stent was implanted > 15 mm from the renal arteries. Kinking was subsequently overcome by implanting Wallstents throughout the graft limbs. The sole failure in the industry-made group was a case in which collateral perfusion reached the aneurysm through patent lumbar arteries.

CONCLUSIONS

The fruits of this experience are a better technique, a better device, and, most importantly, a better understanding of the system's limits, as reflected in the current selection criteria.