Transcaval embolization as an alternative technique for the treatment of type II endoleak after endovascular aortic aneurysm repair

Abstract

The purpose of this report is to highlight our experience with transcaval embolization (TCE) for the management of type II endoleaks (T2Es) as well as to provide a technical description of how to improve procedural safety and success. All patients underwent transfemoral venous access with transcaval puncture into the excluded aneurysm sac with coil placement and selective thrombin injection. Six patients (100% male; mean age [standard deviation] 72.7 [10.8] years) underwent TCE. Technical success was 100% with no postoperative complications. At median follow-up of 8.1 months (range, 2-22 months), two patients had persistent T2Es, with one requiring repeat TCE and the other having cessation of aneurysm growth. The TCE provides a practical alternative to transarterial or translumbar access for the management of T2E, with high degrees of technical and clinical success in this small case series. Larger patient numbers and longer-term follow-up are needed to define procedural efficacy and durability.

Although debate exists about when to intervene upon type II endoleak (T2E) after endovascular aortic repair (EVAR), several techniques have been described for the management of this problem. Frequently, superior mesenteric or internal iliac artery collaterals to the inferior mesenteric artery or lumbar arteries are accessed to deliver the embolant; however, limitations of these approaches include technical failure, difficulty in performance, and/or recurrence in 20% to 80% of cases.^1-3 Alternatively, translumbar puncture has been shown to have more durable success rates in >70% to 90% of patients beyond 8 months.^4,5 Despite enthusiasm for a translumbar approach, this technique often necessitates administration of conscious sedation or general anesthesia, and success depends on traversing multiple tissue planes with potential risk of inadvertent injury to neighboring periaortic structures.

As a more direct alternative approach, transcaval embolization (TCE) for the treatment of T2E has been reported.⁶ The focus of this report is to describe our experience with TCE and to highlight the technical conduct of the procedure.

Methods

Clinical database and patient cohort

All patients who underwent attempted TCE were identified. During the study interval (2009-2012), 28 type II embolization procedures were performed. Seven TCE procedures (in six patients) were completed and constitute the study cohort. The study was approved by the University of Florida Institutional Review Board.

A variety of commercially available endografts are used in our practice, and device selection and implantation were based upon the operating surgeon's discretion and according to the manufacturer's instructions for use. Indications for postoperative imaging were based on a predefined computed tomographic angiography (CTA) imaging protocol (1- to 2-mm cuts) that included delayed venous phased imaging at 1, 6, and 12 months and annually thereafter unless radiographic abnormalities, endoleak, or graft integrity dictated otherwise.

Reintervention for T2E was undertaken if endoleak persisted beyond 6 months and there was documented increase (≥5 mm) of aneurysm diameter on centerline reconstruction (TeraRecon Inc, San Mateo, Calif). Technical success was defined as the ability to gain catheter access to the endoleak cavity and deliver embolant without evidence of T2E at case completion. Clinical success was defined as absence of endoleak on follow-up CTA and no requirement for reintervention or further aneurysm growth.

Technical description

The TCE is performed in our hybrid operating room using a percutaneous right transfemoral vein approach, with concomitant ipsilateral or contralateral transfemoral arterial access for aortography. All patients underwent TCE using local anesthesia with light sedation. Aortography was performed to confirm the etiology/type of endoleak and to provide localization relative to the existing endograft and inferior vena cava (IVC). All procedures were performed using either a pediatric ring or a Rösch-Uchida transjugular liver access set (Cook Medical, Bloomington, Ind) through a 9F or 10F (5F inner diameter) venous sheath (Fig 1, A, and inset). Intravascular ultrasound within the IVC (9F; Volcano Corp, San Diego, Calif) was selectively performed to demonstrate proximity of the aortic aneurysm sac relative to the IVC and to facilitate puncture.

Fig 1.

A, Lateral aortic projection with the ring pediatric transjugular intrahepatic portosystemic shunt (TIPS) catheter in place while a retrievable coil is delivered. The black arrow denotes the end of a Spectranetics Quick-Cross catheter (Spectranetics Corporation, Colorado Springs, Colo) within the aneurysm sac with a 0.035-inch coil arising from the catheter. The white arrows indicate coils placed at a previous intervention through a superior mesenteric artery to inferior mesenteric artery approach that failed to obliterate the endoleak. The inset is an ex vivo picture of the pediatric TIPS catheter with the guiding catheter and TIPS needle within the guiding sheath. B, Close approximation of the inferior vena cava to the abdominal aortic aneurysm sac and a pediatric TIPS catheter in place delivering coils to the abdominal aortic aneurysm sac.

Preoperative planning allows identification of radiographic markers on the stent graft or other landmarks that may facilitate access to the endoleak (eg, graft bifurcation, device overlap points, or aortic wall calcifications) by guiding transcaval puncture after the desired orientation of the transjugular intrahepatic portosystemic shunt (TIPS) assembly is confirmed in two radiographic projections. A transfemoral aortogram can also be performed to visualize the endoleak and further guide alignment. In selected cases, intraoperative flat panel volume CT (Philips XperCT; Philips, Andover, Mass) can be used to supplement the ability to optimize needle orientation relative to the aneurysm sac.

The common wall of the vena cava and aorta are punctured with the TIPS needle, and a wire is advanced through the needle into the aneurysm sac (Fig 1). Brisk bleeding may be encountered upon entry into the endoleak, and injection of dye through the needle (sacogram) can verify access. After the TIPS needle is removed, a wire and catheter can be used to select the endoleak cavity. We preferentially use 0.035- or 0.018-inch detachable coils, with the coil diameter dependent upon endoleak cavity volume (estimated by sacography and CTA). Intrasac thrombin was used selectively if cessation of flow was not demonstrated after the endoleak cavity was filled with coils.

After confirmation of successful embolization by sacography/aortography, the TIPS system is removed, and an aortogram and vena cavogram are performed to determine if there is evidence of aortocaval fistula or contrast extravasation. All patients were admitted overnight and underwent noncontrast CT on the day of discharge to evaluate for retroperitoneal hematoma. Follow-up CTA with delayed venous phase imaging was performed 1 month after the procedure (Fig 2) and then at intervals defined by the protocol after EVAR.

Fig 2.

Axial computed tomographic scan before (top panels) and after (bottom panels) transcaval embolization of a type II endoleak. Note the close approximation of the inferior vena cava to the abdominal aortic aneurysm sac.

Results

Six patients (100% male; mean age [standard deviation] 72.7 [10.8] years) underwent a total of seven TCE procedures. Median follow-up time was 8.1 months (range, 2-22 months). Patient demographics and procedure-specific details of previous EVAR and attempted embolizations are listed in Table I. Median time from EVAR to TCE was 52 months (range, 17-98 months). During that period, patients experienced a mean of 17.8 (11.9) mm of aneurysm diameter enlargement.

Table I. Patient demographics, previous endovascular aneurysm repair, attempted embolizations, and transcaval embolization procedural details.

Patient	Age, years	Comorbidities	EVAR device	Time since EVAR, months	No. prior embolizations	Aneurysm diameter growth, mm	Contrast, mL	Fluoroscopy time, minutes	EBL, mL	Total procedura time, minutes	TCE embolanta	Clinical success
1	83	CAD, tobacco, prior TAA repair	LeMaitre AUI	43	0	20	NA	24	20	79	Framing coil ×9	Y
2	85	CAD, DM, HTN, HLD	AneuRx	93	1	18	125	22	25	61	Framing coil ×4, HydroCoil ×2	N
3	57	HTN, HLD, COPD	TCook, Zenith	20	0	16	NA	21	20	52	Stainless steel coil ×4, framing coil ×2	Y
4	75	DM, HTN, COPD	Cook, Zenith	17	1	7	115	26	20	121	Stainless steel coil ×10, framing coil ×2, HydroCoil ×1, thrombin	N
5	64	CAD, DM, HTN, COPD	Cook, Zenith	61	0	9	45	23	25	84	Framing coil ×7	Y
6	72	CAD, HTN, HLD, COPD	Gore excluder	98	1	37	45	26	15	109	Stainless steel coil ×2, framing coil ×1	Y

CAD, Coronary artery disease; COPD, chronic obstructive pulmonary disease; DM, diabetes mellitus; EVAR, endovascular aneurysm repair; HLD, hyperlipidemia; HTN, hypertension; NA, not applicable; TAA, thoracic aortic aneurysm; TCE, transcaval embolization.

Patient demographics, comorbidities, and procedure-related details regarding prior endovascular repair, aneurysm growth due to endoleak, and previous embolization attempts are given. Transcaval embolization procedure-specific details, including contrast exposure, estimated blood loss, fluoroscopy and procedural times, and procedure-specific outcome data, also are given.

^aCoils used were Cook Medical (Bloomington, Ind) stainless steel or Terumo Medical (Somerset, NJ) retrievable 0.018- or 0.035-inch AZUR framing coils or HydroCoils.

Procedure-specific details of TCE are also listed in Table I. The mean number of coils deployed was 7.3 (3.6). Two patients had selective thrombin injection after multiple coils failed to thrombose the endoleak. Intravascular ultrasound was used in four cases, and two patients underwent intraoperative CT to guide catheter placement. Technical success was 100%, and there were no postoperative complications. Specifically, no evidence of retroperitoneal hematoma, aortocaval fistula, or malpositioned embolant was seen on any early or late postoperative imaging.

Therapeutic outcomes

Clinical success was achieved in four patients (66%). Two patients had persistent T2E, with one showing no aneurysm growth at 6 months. The other patient had persistent growth requiring repeat TCE at 21 months. In the patient who underwent repeat TCE, CTA performed at 1 and 6 months demonstrated endoleak obliteration and no growth of the aneurysm.

Discussion

Transarterial embolization (TAE) treatment of T2E frequently fails because the endoleak behaves like an arteriovenous malformation whereby embolization of one branch inevitably leads to hypertrophy or recruitment of another with persistence of the endoleak.⁷ This is potentially why failure rates of TAE are as high as 80%.^1-3,8 Several methods of direct aneurysm sac access have been described, including translumbar, percutaneous/laparoscopic transperitoneal, and transcaval methods. Advantages of TCE include utilization of supine positioning, which facilitates patient comfort and concomitant arterial access. This allows confirmation of the type of endoleak, concurrent TAE if necessary, and verification of endoleak obliteration. Furthermore, with TCE, the IVC is punctured through one wall instead of both, as required when the right translumbar/transcaval approach is performed, and lower risk of retroperitoneal hemorrhage or inadvertent bowel injury may be anticipated.⁶

Although it is valuable to compare outcomes of different techniques, it is more useful to appreciate that these remedial strategies are complementary. Our treatment algorithm depends on the source and location of the endoleak and is predicated on the philosophy that the embolant must be delivered directly to the aneurysm sac (Fig 3). If the endoleak emanates from the inferior mesenteric artery and there is direct communication to the superior mesenteric artery, we preferentially attempt initial management using transsuperior mesenteric artery embolization. If the endoleak originates from a lumbar or middle sacral vessel, we directly access the aorta via either a translumbar or a transcaval approach, with the approach dictated by the location of the endoleak and the aorta relative to the IVC and lumbar spine.

Fig 3.

Algorithm demonstrating our current treatment paradigm for type II endoleaks, with an emphasis on delivering coils directly to the excluded abdominal aortic aneurysm sac. CT, Computed tomography; EL, endoleak; IMA, inferior mesenteric artery; IVC, inferior vena cava; SMA, superior mesenteric artery.

The technical and clinical outcomes of the various transcatheter T2E management strategies are listed in Table II. All forms of transcatheter therapies have been reported to achieve high rates of technical success. However, definitions of “clinical success” in the reports are heterogeneous, with many stating that success is absence of measured increase in aneurysm diameter or reintervention. If a more strict definition is used, whereby success is defined as absence of aneurysm growth, reintervention, plus elimination of endoleak, the cumulative combined reported success of transarterial and translumbar procedures is ≤70%. This is comparable to the early results of TCE.

Table II. Technical and clinical outcomes of the various transcatheter therapies for type II endoleak after EVAR.

Approach	Author	No. of patients	Technical success, %	Clinical success, %	Reintervention, %	Follow-up time, monthsb
Transcaval
	Mansueto6	12	92	83	NS	12
	Scali (present study)	6	100	67	17	8
Cumulative			96	75	0-17
Transarterial
	Baum2	8	88	NS	NS	NS
	Görich1	11	100	100	0	25
	Haulon11,a	18	94	89	0	13
	Baum4	20	90	20	45	14
	Solis9	10	90	40	20	NS
	Kasirajan12,a	8	75	75	0	9
	Becquemin10	33	66		NS
	Stavropoulos13,a	23	96	78	13	17
	Nevala14,a	10	40	22	33	NS
	Massis15,a	65	66	59	NS	4
Cumulative			82	60	0-45
Translumbar
	Baum2	7	100	100	0	5
	Baum4	13	100	92	NS	9
	Stavropoulos13,a	9	100	67	33	14
	Stavropoulos13,a	62	100	73	16	20
	Nevala14,a	3	100	67	33	NS
	Massis15,a	36	100	75	NS	4
Cumulative			100	79	0-33

Comparative descriptions of the technical and clinical outcomes of the reported series for transcaval, transarterial (including superior mesenteric artery-inferior mesenteric artery), and translumbar embolization procedures are given.

EVAR, Endovascular aortic repair; NS, not specified.

^aTranslumbar transcaval approach.

^bFollow-up time is set or averaged interval from time of embolization procedure.

Limitations of this report are that it is a small series of highly selected patients with no comparative alternative management strategy. The inherent selection bias and potential for type II error underscore the need for larger patient numbers and/or prospectively randomized validation. Although no complications occurred, multiple potential complications of TCE include inadvertent intracaval embolization of coils, retroperitoneal hemorrhage, unintentional puncture of the existing endograft leading to type III endoleak, injury to periaortic/caval structures, and aortocaval fistulas.

Conclusions

The TCE appears to be a safe and technically feasible management option for treatment of persistent T2E. In this small case series, the technical and clinical success rates of TCE are comparable to those of other reported treatment strategies. Thus, TCE provides a complementary technique to existing methods of endoleak management.