Intraoperative evaluation for endoleaks using the SCORPION procedure during endovascular aortic repair

Introduction

Endoleaks are important complications of endovascular aortic repair (EVAR). ¹ In general, endoleaks are judged indirectly by aortography (AG) or postoperative computed tomography (CT). However, findings from AG images or CT scans are difficult to distinguish because of the divergency of endoleaks. ² Few studies have reported direct visualization of endoleaks. Recently, in the field of aortic intervention, aortic angioscopy has been used to visualize cholesterol crystals ³ and intimal tears after aortic dissection. ⁴ Here, we introduce a direct procedure for intraoperatively evaluating endoleaks using angioscopy.

Methods

Patient enrollment

Characteristics of the enrolled patients are summarized in Table 1. Abdominal aortic aneurysm (AAA) was treated based on the enlargement of the abdominal aorta beyond 50 mm in the minor axis on an axial CT image or rapid expansion in cases where the diameter is less than 50 mm. EVAR was performed based on the anatomy of the patient. Consecutive patients, except for emergency cases and those with stenotic iliac arteries, underwent intraoperative angioscopy for the detection of endoleaks. The protocol for collecting and analyzing patient samples was approved by the Institutional Review Board of the Sunagawa City Medical Center (#2023-8). All patients provided informed consent in accordance with the principles of the Declaration of Helsinki.

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Table 1.

The characteristics of enrolled patients.

Pt	Age (y)	Gender	Height (cm)	BMI (kg/m2)	Sac diameter (mm)	Aneurysm type	Device	IMA emboli	LA emboli	Pre-eGFR (mL/min/1.73 m2)	Post-eGFR (mL/min/1.73 m2)	DEX (ml)	FT (min)	CM (ml)	OPT (min)	EL types
1	75	Male	167.3	23.0	47	Fusiform	Endurant	+	-	60.1	85.7	200	77	50	173	4
2	83	Male	157.0	23.9	42	Saccular	AFX2	+	-	51.7	48.2	200	63	50	156	-
3	75	Male	164.6	23.0	49	Fusiform	Endurant	-	+	48.7	63.1	200	65	50	157	4
4	82	Female	150.0	23.2	50	Fusiform	Endurant	+	-	42.8	58	300	123	100	260	-
5	77	Female	143.7	22.6	42	Fusiform	Excluder	+	-	63.9	61.8	100	73	50	182	3
6	77	Male	161.0	19.3	48	Fusiform	Excluder	+	-	97.5	103.1	200	91	105	231	2
7	75	Male	165.6	22.8	54	Fusiform	Excluder	+	-	42.9	45.6	100	67	75	181	-

BMI indicates body mass index; IMA, internal mesenteric artery; LA, lumbar artery; eGFR, estimated glomerular filtration rate; DEX, dextran; FT, fluoroscopy time; CM, contrast medium; OPT, operation time; EL, endoleak.

Results

The baseline characteristics of the seven consecutive patients (5 men and 2 women) who underwent EVAR in Sunagawa City Medical Center from April 2023 are shown in Table 1. Endoleaks were confirmed in cases #1, #3, #5, and #6 by the SCORPION procedure. Representative images (case #6) of the detection of a type 2 endoleak by the procedure are shown in Figure 2. In this case, the AAA had a patent IMA and several LAs (Figure 2(A)). An Excluder C3 (W. L. Gore & Associates, Inc., Santa Clara, CA, USA) was deployed after embolization of the IMA, and an angiographic catheter was positioned using the SCORPION procedure (Figure 2(B)). Embolization of the LA was unsuccessful. Intra-sac angiography showed contrast medium washout in the LA and pooling in the sac (Figure 2(C)). Simultaneously acquired findings from intra-sac angioscopy revealed a small hole with a pulsatile blood flow in the AAA wall (Figure 2(D) and Supplementary Video 1). These findings suggested a type 2 endoleak from the ostium of the LA. Postoperative CT showed that the endoleak persisted (Figure 2(E)) and tranexamic acid was prescribed. ⁶ On the other hand, using an Endurant 2 (Medtronic Vascular, Santa Rosa, CA, USA) with the same procedure in case #1, the ostium of the LA was observed without obvious blood flow (Figure 3). In this case, pulsatile blood leakage from the surface of the graft, indicating a type 4 endoleak, was also observed (Figure 4(A) and Supplementary Video 2). A type 4 endoleak was also indicated in case #3 (Table 1). Another endoleak was detected in case #5 using the Excluder C3. A small hole with pulsatile blood flow from the graft surface suggested a type 3 endoleak but uncertainly (Figure 4(B)). Because this finding was located near the leg and not the main body of the endograft, we suspected a type 3a endoleak and performed balloon inflation within the leg of the endograft. The endoleak was unclear in the final AG and undetected in the postoperative CT scan. No complications, including graft migration, access injury, acute kidney injury, and acute heart failure, were confirmed in the present study. In cases #2, #4, and #7, no apparent endoleaks were found (Table 1).OPEN IN VIEWER

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Figure 3.

Representative images from intraoperative angioscopy and fluoroscopy in a patient without a type 2 endoleak from the ostium LA using the SCORPION procedure. The white arrowheads indicate the ostium of the LA (left panel). In this case, no apparent influx is observed. The black arrow shows the tip of the angiographic catheter (right panel). LA, lumbar artery; SCORPION, angioScopy-esCORted Perigraft and Intra-sac ObservatioN.

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Figure 4.

Representative images showing the detection of other endoleak types using the SCORPION procedure during intraoperative angioscopy and fluoroscopy. Oozing blood suggests a type 4 endoleak (left panel in A, dashed white line; the area of bleeding from the graft surface). A small hole in the graft surface with pulsatile influx indicates a type 3 endoleak (left panel in B, white arrowhead; small hole in the graft). The black arrowheads in the right panel both A and B represent the tip of the angiographic catheter. SCORPION, angioScopy-esCORted Perigraft and Intra-sac ObservatioN.

Discussion

The present study showed that intraoperative observation using perigraft-type angioscopy can detect endoleaks without complications. In the cases presented here, types 2, 3, and 4 endoleaks were evident directly by the procedure. Few studies have evaluated endoleaks directly. For the first time, angioscopy revealed an influx of blood from the LA from a type 2 endoleak. This finding suggests that type 2 endoleaks can affect intra-sac hemodynamics after implantation of an EVAR device. Direct intraoperative visualization using an angioscopy-based procedure may be used to clarify the pattern of endoleaks.

Type 2 endoleaks are recognized as a potentially significant entity if the AAA sac diameter enlarges. ⁷ In recent years, several studies have demonstrated the efficacy of embolization of the aortic side branch artery.^4,8 However, the optimal range of intervention remains controversial. Retrospective analyses show that the larger branch vessels (IMA diameter > 3 mm ⁹ and LA diameter > 2 mm) ¹⁰ were at high risk for significant type 2 endoleaks; however, the pathophysiological mechanism behind the relationship between the diameter of the side branch and sac growth has remained unclear. ¹¹ In this study, intra-sac angioscopy enables observation of the velocity and amount of blood flow from the arterial ostium (Supplementary Video 1), leading to the identification of type 2 endoleak functionality. Although cases without postoperative type 2 endoleaks showed no or little influx of blood from the LA by intraoperative angioscopy, pulsatile influx as in case #6 indicated significant type 2 endoleaks (Figure 2(E)). From direct findings by the SCORPION procedure, the larger branches might have contributed to the worse aortic outcome in terms of velocity and volume of blood flow. The proposed procedure could provide novel insights into the pathophysiology of type 2 endoleaks in terms of the direct visualization of intra-sac hemodynamics. Because this pilot study had a small sample size, further studies are needed to clarify the correlation between the functionality of type 2 endoleaks obtained from the procedure and the long-term outcome after EVAR with side branch embolization.

The study has several limitations. First, the observation area by intra-sac catheter-guided angioscopy is restricted owing to the sandwich between the arterial wall and leg graft. When another catheter with a larger diameter is added, the angioscopy may become more flexible. Second, the number of patients was small, and the selection bias of patients would have existed. Type 4 endoleaks are considered a rare phenomenon; however, 2 out of the 7 cases in our study were detected with type 4 endoleaks using the SCORPION procedure. Due to the small sample size in the study, we might have overestimated the incidence of type 4 endoleaks. Alternatively, occult small type 4 endoleaks may actually be more common than previously thought. In several months of outpatient follow-up, these patients have not shown sac expansion. Therefore, the long-term outcome of these endoleaks should be monitored with routine imaging studies. Finally, because the enrolled patients were only Japanese people, it is unclear whether the present findings can be generalized to other ethnicities.

Conclusion

In the present study, intraoperative NOGA enables visualization of endoleaks during EVAR for the first time. Direct findings by the procedure might provide information on the velocity and amount of endoleaks, leading to comprehensive insights for intra-sac hemodynamics after EVAR. Further studies are required to discern whether various patterns of endoleaks can be determined using the procedure.

Supplemental Material

Supplemental Material