Modified Octopus Technique for Thoracoabdominal Aortic Aneurysm

Summary

This study describes a modified octopus technique for endovascular treatment of thoracoabdominal aortic aneurysms, demonstrating favorable clinical outcomes.

Abstract

Thoracoabdominal aortic aneurysm (TAAA) involves both the thoracic and abdominal aorta and surgical treatment requires reconstructing several important visceral branch arteries. Open surgery is considered the standard treatment for TAAA, but it carries high risks and many complications. With the advancement of endovascular techniques, endovascular repair of TAAA has gradually become a new trend in treatment.

This article presents a case of a 61-year-old female with TAAA. The patient underwent a follow-up thoracoabdominal CTA after teratoma surgery, which revealed a thoracoabdominal aortic aneurysm (Crawford Type III) extending from the sixth intercostal space to 5 cm below the renal arteries. The challenge in treating this case lay in reconstructing the visceral arteries. The octopus technique, a type of parallel stenting, offers advantages but has inherent technical limitations, such as multiple access routes for simultaneous stent placement, the potential risk of gutter endoleaks, and mutual compression among parallel stents.

To avoid these drawbacks, modifications to the octopus technique are necessary. We connected multiple small stent grafts side-by-side and end-to-end to a single branch of the main aortic stent graft. This improved design effectively circumvented the gutter endoleaks and stent compression issues, allowing for sequential visceral artery reconstruction through single upper limb access. This modified octopus technique closely aligns with the design concept of branched stents. This article aims to describe a case of complete endovascular reconstruction of TAAA using the modified octopus technique combined with the external branch technique, providing an in-depth analysis of the specific procedural steps and their clinical application value.

Introduction

Thoracoabdominal aortic aneurysm (TAAA) is a severe vascular disease involving both the aorta's thoracic and abdominal segments. Although it is relatively rare, accounting for only 10% of all aortic aneurysms¹, its rupture rate and mortality are significantly high, and the 5-year survival rate is only 10%-20% if left untreated². Due to the need for careful management of the celiac trunk, superior mesenteric artery, and bilateral renal arteries during treatment, managing TAAA has long been a major challenge in vascular surgery. Since the first successful TAAA repair in 1955³, open surgery has been considered the standard treatment⁴. However, despite numerous advances and refinements in surgical techniques and perioperative management, open surgery still carries a relatively high mortality rate and complication incidence^5,6.

With the continuous advancement of medical devices and endovascular techniques, significant progress has been made in the endovascular treatment of TAAA. Based on different strategies for reconstructing branch vessels, fully endovascular repair methods can be categorized into fenestrated and branched endovascular aortic repair (F/B EVAR) or parallel stent techniques⁷. The octopus technique is a type of parallel stent technique that involves the placement of multiple small stent-grafts in parallel within a large stent graft. This approach reconstructs visceral branch arteries while excluding the aneurysm sac, achieving the dual goals of preserving visceral blood flow and sealing the aneurysm⁸.

The octopus technique utilizes existing stent grafts without requiring structural modifications, achieving treatment for complex aortic lesions through specific combination designs. However, it inevitably shares the limitations associated with parallel stent techniques^8,9. To overcome these shortcomings, this case employed a modified octopus technique. Multiple small stent grafts were aligned in parallel and connected end-to-end to a single branch of the main abdominal aortic stent graft. This modification makes the improved octopus technique closer to a branched stent graft approach.

We present a case of a 61-year-old female with TAAA. The patient, who underwent re-evaluation with chest and abdominal contrast-enhanced CTA following teratoma surgery, was found to have a Crawford type III TAAA. The proximal descending aorta appeared normal, with a diameter of 24 mm. However, aneurysmal dilation was observed in the middle and lower segments of the thoracic descending aorta, as well as the upper abdominal aorta, with the largest diameter measuring 65 mm. The celiac trunk, superior mesenteric artery, and bilateral renal arteries all originated from the aneurysmal wall, with diameters of 8 mm, 5.3 mm, 4.5 mm (left renal artery), and 5.5 mm (right renal artery), respectively. The infrarenal aorta measured 20 mm in diameter. The primary challenge of this case involved simultaneous aneurysm repair and revascularization of the celiac trunk, superior mesenteric artery, and bilateral renal arteries. Considering the patient's history of abdominal surgery for teratoma and her preference to avoid open surgery, a modified octopus technique was proposed for total endovascular repair.

Protocol

This study complied with all institutional, national, and international guidelines for human welfare. The patient gave written and verbal consent to using medical data and surgical videos for educational and scientific purposes.

1. Key considerations for surgical planning

1. Diameter measurements: Evaluate the diameters of the proximal thoracic aorta, distal abdominal aorta, aneurysm, the four visceral arteries, and the femoral artery access point.
2. Position and angulation: Determine the 12 o'clock position of each visceral artery's orifice and the approximate angles between branches and the proximal aortic axis.
3. Length measurements: Assess the length of the healthy anchoring zone in the thoracic aorta, the distance from the aneurysm's origin to each visceral artery, the aneurysm length, each visceral artery's anchoring zone length, and the length of the healthy anchoring zone in the distal abdominal aorta.

2. Surgical strategy

1. Stent main body
   1. Extend the 30-200 mm thoracic aortic stent graft for the proximal anchoring zone.
   2. Employ a modified "octopus" stent derived from an abdominal aortic stent graft for internal bridging.
   3. Adjust the release height of the branches appropriately to facilitate the seamless bridging of the covered stent grafts.
2. Modified octopus technique
   1. Divide a 6-150 mm stent graft into four segments of varying lengths and suture the branches accordingly.
   2. Suture the celiac trunk branch at the bifurcation of the abdominal aortic stent graft.
   3. Pair and securely suture the three branches of the superior mesenteric artery and the bilateral renal arteries.
   4. Create a common seam by suturing the areas between the three stent grafts, and then perform end-to-end anastomosis at the short branch of the abdominal aortic stent graft (Figure 1).
      NOTE: Preoperative calculations of the distances between branches and each artery are essential to ensure proper length. Stent modifications require meticulous handling, and precise suturing at the anastomotic site is crucial to prevent leaks.
3. Visceral artery reconstruction
   1. Deploy stent grafts of 8-100 mm and 7-100 mm to bridge the branches with the celiac trunk and superior mesenteric artery.
   2. Place a 6-100 mm stent graft to bridge the branches with the bilateral renal arteries.
   3. Insert an internal 6-60 mm peripheral bare metal stent to augment the anchoring strength between the octopus branches and the bridging stent.

3. Surgical procedure

1. Advance the main body of the abdominal aortic stent graft from the 20F delivery system. Deploy and section a 6-150 mm stent graft.
2. Utilize the modified octopus technique (as described in section 2.2) for stent adaptation, keeping it in reserve (Figure 2). After deploying the 30-200 mm thoracic aortic stent graft main body, use its 22F delivery system for placement.
   NOTE: Selecting the appropriate modified stent and the corresponding delivery system is crucial to ensuring the procedure's success.
3. Gain access through a puncture of the right common femoral artery and insert a 9F arterial sheath. Advance a centimeter-sizing catheter to the aortic arch, visualizing the descending aorta and the thoracoabdominal aortic aneurysm.
4. Bridge the proximal end initially with a thoracic aortic stent graft main body, followed by the placement of a modified octopus branch stent.
5. Gain access through a puncture of the left brachial artery and insert a 6F arterial sheath. Advance a guidewire and catheter to the stent's main body, then exchange the sheath for an 8F, 90 cm long sheath. Use an angiographic catheter to sequentially select the celiac trunk, superior mesenteric artery, and bilateral renal arteries.
   NOTE: Based on the branching locations of the visceral arteries, the appropriate direction and release position for the modified octopus anastomosis were selected to ensure that each branch corresponds roughly to the target artery.
6. Deploy stent grafts of 8-100 mm and 7-100 mm to reconstruct the celiac trunk and superior mesenteric artery, respectively. Place a 6-100 mm stent graft for the right renal artery and reinforce the junction with an additional 6-60 mm bare metal stent.
7. Address the acute angle of the left renal artery by deploying a 6-100 mm covered stent graft. Release a long-leg side abdominal aortic covered stent graft extension with trumpet legs measuring 16-24-124 mm, anchoring the distal end within the distal abdominal aorta. Deploy the left renal artery stent graft and reinforce the junction with a 6-60 mm bare metal stent.
8. Upon confirming satisfactory angiographic results, remove the catheter, guidewire, and sheath. Tighten the pre-placed sutures at the puncture site of the right femoral artery.
9. Achieve hemostasis at the left brachial artery puncture site through direct compression, followed by the application of a compressive dressing.

Results

Intraoperative angiography confirmed the successful exclusion of the thoracoabdominal aortic aneurysm, with no apparent endoleaks. The stent's shape and position were satisfactory, and blood flow within the stent and to the branch arteries was unobstructed. Six months later, the patient underwent routine follow-up with CTA, demonstrating good exclusion of the thoracoabdominal aortic aneurysm and patent blood flow in the celiac trunk, superior mesenteric artery, and bilateral renal arteries (Figure 3<...

Discussion

Kasirajan first reported using the octopus technique for reconstructing visceral artery branches in 2011, achieving favorable outcomes¹⁰. By utilizing existing stent grafts in a modular fashion, the octopus technique effectively excludes the thoracoabdominal aortic aneurysm while preserving visceral artery perfusion¹¹. This approach avoids the extensive trauma and high risks associated with traditional open surgery, providing a novel treatment option for patients who are un...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Angiographic catheter MP A1	Cordis	451-506P0	Aortic Angiography.
Centimeter Sizing Catheter	Cook	PIG-CSC-20	Length Measurement and Aortic Angiography.
Endurant stent graft	Medtronic	ETBF3616C145E	Reconstruction of abdominal aortic blood flow.
Endurant stent graft	Medtronic	ETLW1624C124E	Visceral artery reconstruction.
Hi-Torque Supra Core Guide Wire	Abbott	1002703-02	Place and exchange devices.
Lunderquist Extra-Stiff Wire Guide	Cook	TSCMG-35-300-7-LES	Place and exchange devices.
Perclose ProGlide Suture-Mediated Closure System	Abbott	12673-03	Suture-mediated vascular closure after percutaneous procedures.
S.M.A.R.T. Vascular Stent System	Cordis	C06060SL	Enhance stent anchoring strength.
Valiant Captivia Stent Graft	Medtronic	VAMF3030C200TU	Reconstruction of the thoracic aorta.
VIABAHN Endoprosthesis	Gore	VBCR060501A	Visceral artery reconstruction.
VIABAHN Endoprosthesis	Gore	VBCR071001A	Visceral artery reconstruction.
VIABAHN Endoprosthesis	Gore	VBCR081001A	Visceral artery reconstruction.
VIABAHN Endoprosthesis	Gore	VBCR061501A	Visceral artery reconstruction.
ZIPwire Hydrophilic Guide Wire	Boston Scientific	M00146151B0	Facilitates navigation in vascular paths.