Effectiveness of coiling in the treatment of endoleaks after endovascular repair

Transcription

1 From the Society for Clinical Vascular Surgery Effectiveness of coiling in the treatment of endoleaks after endovascular repair Maureen K. Sheehan, MD, a Joel Barbato, MD, a Christopher N. Compton, MD, a Albert Zajko, MD, b Robert Rhee, MD, a and Michel S. Makaroun, MD, a Pittsburgh, Pa Background: Persistent endoleaks are a common problem following endovascular repair of abdominal aortic aneurysms, and the best method of treatment has been an issue of debate. Some experimental evidence has suggested that coiling may not be an effective method because it allows transmission of pressure across the coils with continued expansion of the sac. We reviewed our experience with endoleak coiling to assess the degree of clinical success of this treatment. Methods: A retrospective review of patients with type I or type II endoleaks treated solely by coiling over a 7-year period ( ) was performed. All endoleaks had been observed for at least 6 months prior to intervention to detect spontaneous resolution. All coils were delivered by selective catheterization of the endoleaks. For Type II endoleaks, the branches were all coiled at their junction with the sac when feasible and the endoleak cavity was packed. Clinical success was defined as cessation of endoleak on follow-up computed tomography as well as no further aneurysmal growth (>5mm minor axis). Results: Twenty-eight patients had their endoleaks treated only with coils. There were 22 Ancure, 2 Excluder, 2 AneuRx, and 2 Lifepath endografts in this patient cohort. Procedural morbidity was 0%. Mean follow-up after coiling for all patients was 18 months (range, 1-60 months) while mean follow-up for patients with a type I endoleak was 24 months. Clinical success was achieved in 15 of 19 (79%) patients with type II endoleaks and 8 of 9 (89%) patients with type I. Three patients, all with type I endoleak, required more than 1 episode of coiling, while 2 others, both with type II lumbar endoleaks, required repeat angiography due to inability to access the leak during the first attempt. There were 2 proximal and 6 distal type I endoleaks (2 aortic, 6 iliac) successfully treated while the type II successes included 8 inferior mesenteric artery and 7 sole lumbar endoleaks. Five patients continued to show evidence of endoleak over time: 2 endoleaks were associated with aneurysm growth leading to conversion in 1 patient, 2 patients with type II endoleaks are stable, and the sole type I endoleak with continued perigraft flow has shown significant shrinkage of the sac and continues to be observed 18 months later. No ruptures were noted during follow-up. Conclusion: Coiling as the sole method of endoleak management may be a suitable treatment option in selected patients. Clinical success can be expected in over 80% of patients with type II and select type I endoleaks, with minimal morbidity. (J Vasc Surg 2004;40:430-4.) Endovascular repair has been shown to be an effective means of treatment for aortic aneurysm in select patients. Although the procedure has advantages over open repair, one of the ongoing concerns with the technique is the occurrence of endoleak, defined as any persistent flow that is outside of the graft and present in the native aneurysmal sac following repair. Endoleaks continue to be one of the most common complications of endovascular repair (EVAR), occurring in 15% to 23% of patients 1-5, with the majority of cases comprising types I and II. Type I endoleaks have been associated with poor outcomes if left untreated, and there is general agreement that some form of intervention is required. Although some recent evidence suggests that type From the Divisions of Vascular Surgery a and Interventional Radiology, b University of Pittsburgh Medical Center. Competition of interest: Dr Makaroun has received grants and research support from W. L. Gore, Guidant, Boston Scientific, Edwards, and Cordis. He is a consultant to Edwards and Gore. Presented at Thirty-second Annual Meeting of the Society for Clinical Vascular Surgery, Rancho Mirage, Calif, Mar 10-13, Reprint requests: Michel Makaroun, MD, University of Pittsburgh Medical Center, Division of Vascular Surgery, 200 Lothrop St, A1011 PUH, Pittsburgh, PA ( makarounms@upmc.edu) /$30.00 Copyright 2004 by The Society for Vascular Surgery. doi: /j.jvs II endoleaks may have a more benign clinical course, 6 most endovascular units favor obliteration of the source when feasible, as continued sac expansion and occasional ruptures may occur. 7,8 Management of endoleaks is variable and depends upon the location of the leak and its type, as well as individual factors. Since selective coil embolization of arterial vessels is an established procedure that has been effective in managing many sources of bleeding in the abdomen, periphery, and cranium, its application for control of endoleaks appeared quite logical. Coiling of type II endoleaks as well as of select type I endoleaks became a common technique used for many years. Experimental data cast doubt recently, however, as to the effectiveness of such treatment, by suggesting that arterial pressure can still be transmitted through the coils to the aneurysm wall especially with antegrade flow. 9,10 In addition, since type II endoleaks are often associated with many branches that may be difficult to access, failure to obliterate all blood flow into the sac is not uncommon. This raises the concern as to whether or not coiling will be a long-term solution or if aneurysm growth and rupture may still occur following treatment of an endoleak with coils. Most reports have so far focused on immediate results, as well as technical aspects and variations such as translumbar puncture or the addition

2 JOURNAL OF VASCULAR SURGERY Volume 40, Number 3 Sheehan et al 431 of hemostatic agents to improve early outcomes. However, long-term follow-up of treated patients has not yet been reported. METHODS A retrospective review of all EVAR patients with endoleaks treated solely by selective coiling over a 7-year period ( ) was performed. Excluded from analysis were patients with type I endoleaks who had coiling performed in conjunction with placement of an extension, patients who underwent angiography without the appearance of a leak, and patients in whom no coils were used because the endoleak could not be accessed through small tortuous branches. Thrombin was used adjunctively in 11 of 28 instances to promote faster thrombus formation in large endoleaks. A solution of 1000 units/cc was used, with volumes varying from 1 to 3 ml depending on the size of the cavity. No other adjuncts were used and no injections were made if the inferior mesenteric artery (IMA) was part of the endoleak outflow. These patients were included in the analysis. Our standard follow-up after EVAR during the study period involved abdominal radiographs as well as computed tomography (CT) scanning at 1 month. If no endoleak was detected, the follow-up was repeated at 12 months and yearly thereafter. Patients with endoleaks at 1 month returned for follow-up at 6 months and, if the endoleak was persistent, angiography for evaluation of the endoleak source, and treatment was recommended. Patients with spontaneous resolution of the endoleak on CT at 6 months reverted back to their normal yearly follow-up schedule. Patients with endoleaks underwent angiography in a fixed suite in the interventional radiology department (n 27) or operating room (n 1). The majority of patients underwent angiography from the femoral artery unless a proximal endoleak was suspected by CT. In these patients a proximal brachial artery approach (n 3) was employed so the proximal endoleak could be accessed from above and simplify coil placement. Nonselective flush abdominal aortography was performed initially to identify proximal type I endoleaks. If nonselective aortography failed to demonstrate the endoleak, selective angiography of each limb of the graft was performed as well as of the superior mesenteric artery (SMA), when indicated, and bilateral internal iliacs in an attempt to demonstrate the endoleak. If a leak was demonstrated from an attachment site, selective catheterization of the native aneurysm sac was performed using a 5F straight catheter (Cook, Bloomington, Ind) and inch angled Glidewire (Boston Scientific Vascular). Once the sac was accessed, the endoleak and outflow vessels were evaluated by angiography. Options for treatment included extensions or coiling. Prior to the availability of extensions and large balloon-expandable stents, or when the patient s anatomy did not allow for placement of extensions, coils were chosen as the sole method of treatment of type I endoleaks, and the cavity was packed to the attachment system after the outflow vessels were closed. Fig 1. Selective catheterization of IMA through the superior mesenteric artery and arc of Riolan, using a microcatheter. In cases where the endoleak was noted to be purely a type II problem, coaxial microcatheters were employed for selective catheterization of the IMA (Fig 1), or branches of the internal iliac and lumbar arteries when necessary. The IMA was approached through the middle colic branch of the SMA while the lumbar arteries were selectively catheterized through small connections from the internal iliac arteries. Sos and Rim catheters were used for main vessel catheterization and Turbotracker and Renegade microcatheters for the small branches. A variety of coils (Tornado or Hilal microcoils) were delivered by selective catheterization of the endoleaks, and branch vessels were coiled at their junction with the sac when feasible. To avoid the need to place multiple coils in patients with large endoleaks, thrombin ( units in divided doses) was injected in the cavity after initial coiling and demonstrating no outflow into the IMA on sac injection. Patients underwent follow-up CT 1 or 2 months later to evaluate the results of treatment. Clinical success was defined as cessation of the endoleak on follow-up CT as well as no further aneurysmal growth ( 5 mm minor axis). Likewise, aneurysm shrinkage was defined as decrease in sac size 5mm along the minor axis. Patients with residual endoleaks were returned to the angio-suite for additional episodes of coiling when appropriate. Patients with complete sealing reverted to the yearly follow-up schedule. RESULTS Twenty-eight patients had their endoleaks treated with coils without adjunctive stent or stent-graft placement. During the same time period, but excluded from analysis, 19 patients with type I endoleak were treated with ballooning or extension graft, 8 of whom had concomitant coiling.

3 432 Sheehan et al JOURNAL OF VASCULAR SURGERY September 2004 Fig 3. Computed tomography of same patient, demonstrating complete shrinkage of aneurysm sac around endografts and coils. Fig 2. Computed tomography following coiling of type I endoleak. Coils were placed in the aneurysm sac in perigraft space which communicated with the Type I endoleak. Also excluded were 25 patients who had spontaneous resolution of the endoleak, while another 8 patients underwent angiography for an endoleak and either the source of the endoleak was not demonstrated (n 6) or access to the endoleak could not be obtained (n 2). There were 22 Ancure, 2 Excluder, 2 AneuRx, and 2 Lifepath endografts in the patient cohort who underwent analysis. Procedural morbidity was 0%. All procedures were performed in an outpatient setting. Mean follow-up for all patients after coiling was 18 months (range, 1-60 months), with a mean follow-up of 24 months for patients with a type I endoleak. Clinical success was achieved in 15 of 19 (79%) patients with type II endoleak and 8 of 9(89%) patients with type I endoleak, with an overall success rate of 82%. There were 2 proximal and 6 distal type I endoleaks (2 aortic, 4 iliac) successfully treated while the type II successes included 1 pure IMA, seven pure lumbar, and 7 combined endoleaks. Type I. Nine patients with type I endoleaks underwent an attempt at a coiling procedure. Three patients required more than 1 episode of coiling. Eight patients had successful treatment requiring 12 interventions. One patient with a distal endoleak treated successfully required 3 attempts. After coiling the lumbars, IMA, and part of the sac the first time, flow was still noted on subsequent CTs. The patient required 2 more interventions consisting of deposition of coils in the sac for cessation of flow in the native sac. The patient did well for the next 3 years with documented reduction in aneurysm size, but then developed an aortoduodenal fistula secondary to coil erosion, 4.5 years after the initial repair. 11 The other 2 patients each required 1 additional intervention. One required additional coil placement in the aneurysm sac while the other had a repeat angiogram that failed to reveal the endoleak. Both of these patients have subsequently died from non-aortic causes. Type II. Fifteen of 19 patients with type II endoleaks were treated successfully with coiling. Two patients, both with lumbar endoleaks, required repeat angiography due to inability to access the leak during the first attempt. They were successfully accessed and treated during the second attempt. Failures. Five of 28 patients were considered clinical failures. Three were known to have incomplete exclusion at the end of the initial coiling procedure due to inaccessible lumbar arteries. In 1, coils were placed in the IMA, but filling continued from the lumbars that could not be accessed. The aneurysm has remained stable in size with no further intervention for a follow-up period of 12 months. The second patient had an endoleak from 2 sets of lumbars with only 1 set coiled. The other lumbars giving rise to an endoleak were located in the distal part of the aneurysm neck and could not be reached transarterially. Due to continued growth of the sac the patient underwent an open conversion at 4.5 years and has done well since. The third patient had a small persistent proximal type I endoleak that was expected to resolve spontaneously since the outflow and the majority of the inflow had been treated. Subsequent CTs revealed a persistence of the endoleak, but no further interventions were conducted because the aneurysm size has remained stable over a period of 18 months. Two failures that were thought to have been completely sealed at the time of coiling have shown a residual endoleak on follow-up CT. Both have remained stable in size and have had no further interventions. Long-term follow-up. Mean follow-up was 18 months after coiling (range, 1-60 months). Thirty percent of the successfully coiled patients have had a follow-up of at least 3 years. Among the 28 patients, 7 (25%) have had a significant decrease in aneurysm size (Figs 2 and 3) (average

4 JOURNAL OF VASCULAR SURGERY Volume 40, Number 3 Sheehan et al 433 decrease, 11 mm) while 20 patients have aneurysm sacs that remained stable in size. Only 1 patient with an Excluder device had a late sac expansion treated by explantation and conversion to open repair. No late-appearing or recurrent endoleaks were noted during late follow-up after successful exclusion. There were no ruptures during follow-up. DISCUSSION The goal of EVAR is to prevent aneurysm rupture by complete exclusion of the aneurysm sac from native flow and, ideally, from systemic pressure as well to prevent further aneurysm growth. Failure to completely exclude the sac is referred to as endoleak and can occur in 15% to 23% of patients treated with EVAR. Various methods for treatment of endoleaks exist depending on the type of endoleak, anatomical factors, and physician preference and experience. Treatment methods include embolization using either liquid embolic agents such as glue 12 or coils, employment of cuffs or extension limbs, and endoscopic or open ligation of branches. Open conversion to a standard repair is the last resort for refractory endoleaks associated with expansion of the sac. How long endoleaks should be observed prior to treatment has been the subject of hot debate. Opinions vary from immediate attention to the endoleak either in the operating theater or after the first post-operative assessment, to a chronic follow-up until the aneurysm enlarges. Obviously, the source of the endoleak is a critical element in that decision. We have elected to wait 6 months prior to intervention since many early endoleaks subside spontaneously without untoward long term effects. 13 Since noninvasive diagnostic tests are rarely conclusive in determining the exact etiology, we continue to believe that a detailed angiogram is indicated after this initial observation period to ascertain the source of the endoleak, and if the leak is easily accessible, to perform the treatment. 13 Type I endoleaks occurring at the proximal or distal attachment sites are probably best treated with extension cuffs when feasible. However, when important arterial branches prevent such extensions, another method of treatment of the endoleak is necessary, such as placing balloonexpandable stents to increase apposition to the aortic wall or filling the gap with a thrombogenic material. Coiling has been examined as a possible option in these patients. Our 89% success rate is similar to the reported experience of others. Faries et al 1 had 8 patients with type I endoleaks who had inadequate length of normal artery required to deploy an extension graft and were poor candidates for conversion to open repair. All 8 patients had coil embolization of the aneurysm sac until no flow was noted in the sac, and all were successful. Kato et al 14 likewise used coiling in 8 patients with type I endoleaks (7 thoracic stents, 1 abdominal stent) and was successful in obliterating the endoleak in all. None of the studies has a large number of patients, since the optimal treatment of these endoleaks usually involves other options. Our long-term results as well as other reported studies demonstrate coiling to be a viable option for treatment of type I endoleaks when cuffs or extensions are not feasible. Treatment of type II endoleaks is more controversial. When noted after the early experience with EVAR, they were considered a failure of the procedure, and aggressive attempts were made at sealing them. The need for such attempts was highlighted by reports of significantly increased pressures in the sac associated with these leaks. However, increasing clinical experience with inaccessible branches has suggested that type II endoleaks may be more benign than initially anticipated. Lack of size increase or rupture in a majority of these cases as well as spontaneous sealing has been frequently documented, validating a less aggressive stance in their treatment. Enlargement and even rupture, however, have been documented in this setting, so not all type II endoleaks may be ignored. 2,7,8 Surveillance is paramount and those individuals with documented growth of the aneurysm should undergo treatment. The abundance of treatment suggestions highlights the difficulty of completely addressing all type II endoleaks with the same approach. Clearly, any minimally invasive procedure is preferred to an open ligation, as many of the patients undergoing EVAR are not considered good open operative candidates. Coil embolization has been most popular in this setting as demonstrated by a consensus statement in which 85% of respondents named coiling as their preferred method for treatment for type II endoleaks. 15 However, coiling of type II endoleaks has had varied success rates. The difficulty of selectively catheterizing such vessels as well as recurrence of endoleaks from other untreated branches has frustrated many attempts and resulted in the description of many alternative techniques to abolish these branches. Direct translumbar puncture as well use of chemical agents to induce thrombosis are variations on the same theme. The variability in success is likely related to numerous factors, including technique as well as complexity of the endoleak. Solis et al 2 found that coiling was significantly less effective in treating complex endoleaks (those with multiple communicating vessels; 17%) than simple endoleaks (1 vessel in communication with the sac; 83%). Likewise, other studies have found that coiling was less effective when only the feeding vessels were addressed rather than including the endoleak cavity in the coiling process. 16,17 We routinely place coils in the aneurysm sac when possible. This technique may account for our success rate. One of the nagging concerns regarding the use of coiling as the sole treatment for endoleaks is that systemic pressure may be transmitted through the coils and thus the patient may still be at risk for aneurysm growth and rupture. Marty et al 8 found that the pressure in synthetic aneurysms in dogs remain elevated after successful coiling of a created endoleak. The experimental model, however, was an acute intervention for a graft defect that is quite dissimilar from the clinical situation. Baum et al 7 confirmed a decrease in sac pressures from systemic to 20 to 30 mm Hg following translumbar coiling in 5 patients with type II endoleaks. Our long-term assessment failed to identify a pattern of persistent pressurization of the sac even in the case of type

5 434 Sheehan et al JOURNAL OF VASCULAR SURGERY September 2004 I endoleaks. One in 4 patients showed a significant reduction in aneurysm sac size over time, confirming the effectiveness of this treatment in isolating the sac from the arterial pressure. Our only patient with sac enlargement from a pair of inaccessible lumbars was associated with an Excluder device more than 4 years after implantation. Since the Excluder device has been known to have late sac enlargement, 18 it is unclear which factor was more important in this late-developing sac growth. There are some disadvantages to coiling. One is that the artifact caused by the coils on follow-up CTs can make subsequent detection of endoleak difficult. Additionally, the long-term effect of coils on the aneurysm sac is unknown. One of our patients presented years later with an aortoenteric fistula suspected to be due to erosion of the coils through the native sac. Since another patient without coils had a similar late complication of an Ancure graft, the exact role of the coils in causing this complication is unclear. Whether this only occurs with overzealous coil placement, or can occur over time with only a few coils is subject to speculation. CONCLUSIONS Endoleaks continue to be one of the most common complications following EVAR. Although some endoleaks are benign, treatment with coils when leaks are easily accessible simplifies their follow-up. We believe that coiling is an effective and durable therapy for patients with most type II endoleaks and is a viable alternative to open repair for treatment of type I endoleaks not amenable to cuffs or extensions. REFERENCES 1. Faries PL, Cadot H, Agarwal G, Kent KC, Hollier LH, Marin ML. Management of endoleak after endovascular aneursym repair: cuffs, coils, and conversion. J Vasc Surg 2003;37: Solis MM, Ayerdi J, Babcock GA, Parra JR, McLafferty RB, Gruneiro LA, et al. 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