Physician-Modified Endografts Inner Branches Technique Using a Thoracic Endograft for Urgent Thoracoabdominal Aneurysm Repair

Preoperative Sizing and Planning

To prepare for the procedure, a computerized tomography angiogram (CTA) is first performed for planning purposes. Planning and sizing a PMEG require a contrast-enhanced CTA with a slice thickness of ≤1 mm for optimal resolution. Key measurements include vessel diameter, intervessel distance, and clock-face orientation. Illustrative examples for each of the 3 measurements are presented (Figure 1A–C).

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Figure 1.

Key measurements in technique planning with a contrast-enhanced computerized tomography angiography. (A) Clock position. (B) Intervessel distance. (C) Vessel diameter.

Diameter measurements are taken in 3 planes and iteratively adjusted to align the target vessels accurately in 2 perpendicular axes. Distances to target vessels are measured along the centerline, from the proximal edge of one vessel to the proximal edge of the next. Clock-face orientations are determined using the vertebral column as a reference, with the vertebrae defining the zero-degree position. The angle is then obtained and transported into the clock position to ensure precise fenestration planning for the graft. The Horos software (The Horos Project, Annapolis, MD, USA) is routinely used for planning.

Considering potential patient anatomical contraindications or challenges is crucial. Narrow aortic lumens, which are common to type IV or juxtarenal aneurysms, and sinuous aortas provide a significant challenge to regular PMEG techniques using fenestrations or conventional branches. These patients could potentially benefit from PCIBs, as conventional branches may not open properly in narrow lumens, and inner branches provide an advantage for sinuous aortas compared with fenestrations, which require precise apposition.

Device Modification

This technique is specifically developed for the use of PCIBs with a Valiant Captivia endograft (Medtronic, Minneapolis, MN, USA). Pictures were taken in the training lab. The Valiant Captivia system as an option for the PMEG technique offers advantages compared to other graft systems, making it particularly suitable for complex aortic repairs. In our experience, one notable feature is that the first bare stent in the Valiant graft is more stable than in other graft systems during the unsheathing and modification process, such as the Zenith graft system (Cook Medical, Bloomington, IN, USA), which allows the graft to be unsheathed while preserving the undelivered proximal bare stent (Figure 2A). This step allows much more stability for device modification and a smoother re-sheathing process. In addition, the Valiant Captivia endograft provides larger distances between stents, which can enhance fenestration allocation and durability while avoiding bending the grafts’ struts at the planned level.

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Figure 2.

Device modification. (A) First bare stent in the Valiant Captivia graft remained stable during device modification (arrow) and later re-sheathing process. (B) An assistant stabilizes the stent using forceps to facilitate the suture (arrow). The proximal bare stent is seen stable and positioned. (C) Inner branch demonstrated through transparency, stabilized with a proximal stitch and 1 stitch at the ostium.

Building on these advantages, as a first step for the technique, the graft is unsheathed while preserving the intact and undelivered proximal bare stent, which remains retained on its tip. To create fenestrations, an ophthalmic cautery is used. Typically, we opt for one of the thoracic endografts loaded into a 24Fr sheath. Then, we choose one of the 2 smallest diameters available, such as 34 or 36 mm. For this purpose, a 36 × 36 × 167 mm graft, the second smallest size of the 24Fr delivery shaft, is typically used. In the 22Fr sheath, we recommend using the 26 or 28 mm graft to ensure that the number of inner branches and pre-cannulated wires can fit within the shaft. Using the biggest graft sizes in the correspondent sheath can compromise the number of pre-cannulations and inner branches, which must be considered in urgent scenarios, where gaining safety and optimizing steps lead to faster hemostatic control. Short thoracic grafts are modified as necessary, preventing twisting while re-sheathing. A summary of the recommended configuration in our experience of the number of inner branches and pre-cannulated guidewires for graft sizes in relation to sheaths is presented (Table 1).

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Table 1.

Recommended Configuration of the Number of Inner Branches and Precannulated Guidewires in Our Experience.

Sheath size (Fr)	Graft size (proximal diameter in mm)	Maximum number of inner branches	Maximum precannulated guidewire configuration
22	26 and 28	2	One 0.035″ hydrophilic guidewire (SMA or celiac trunk); 2 0.014″ or 0.018″ guidewires (renals)
22	26 and 28	3	Three 0.014″ or 0.018″ guidewires (SMA or celiac trunk and renals)
24	34 and 36	2	One 0.035″ hydrophilic guidewire (SMA or celiac trunk); 2 0.014″ or 0.018″ guidewires (renals)
24	34 and 36	3	Three 0.014″ or 0.018″ guidewires (SMA or celiac trunk and renals)

Abbreviation: SMA, superior mesenteric artery.

A Solaris stent (Scitech, Goiânia, Brazil) is then cut to the appropriate size to match the fenestration and the target vessel anatomy. One stent of 57 mm in length can be divided in half to make 2 inner branches. Specifically, the stent is shortened to ensure a length of 2 cm from its proximal tip to the start of the cannulation tip, which is the segment of the stent that aligns with the fenestration. In our experience, the Solaris stent has been demonstrated to be cost-effective and more rigid than other more commonly used options, enhancing the stability of the inner branches’ incorporation.

For renal arteries, a 7 mm covered stent is generally appropriate. The cutting process accounts for the diameter of the target vessel (6 mm in the displayed lab pictures), resulting in a 6 mm difference in length representing the distal portion of the stent removed to match the desired fenestration size. The tip of the stent is beveled during this process, ensuring a smooth fit and alignment with the fenestration edges. This beveled configuration helps reduce the risk of misalignment or damage during cannulation. The Solaris stent is sewn using a lock-stitch 4.0 Ethibond (Ethicon, Edinburgh, Scotland) suture over a coil, as a radiopaque marker, to reinforce the fenestration as previously described. ⁴ An assistant stabilizes the stent using forceps to facilitate the suture (Figure 2B). Two 3.0 Prolene fixation stitches are placed at the inner end of the branch to further secure the stent in place. One inner branch through transparency, stabilized with proximal and ostium stitches, is demonstrated (Figure 2C).

The procedure involves positioning one 0.035″ hydrophilic guidewire in the superior mesenteric artery (SMA) or the celiac trunk fenestration, and 1 or 2, 0.018″ or 0.014″, guidewires in the renal branches, as long as sizing requirements are observed. The guidewires are introduced through a small incision made with a number 11 scalpel on the graft of the delivery system, close to the handle. As SMA cannulation is critical, the hydrophilic 0.035″ is preferably inserted, allowing direct vessel cannulation and even inserting both sheath and stent, without further maneuvers. The 0.014″ was chosen for renal arteries to accommodate the 3 wires without re-sheathing issues. The positioned precannulated wires, critical to the success of the procedure, are demonstrated (Figure 3A–C).

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Figure 3.

Precannulated guidewires disposition. (A) One anterior 0.035″ hydrophilic precannulated guidewire in the superior mesenteric artery fenestration and celiac trunk fenestration above, not precannulated. (B) 0.014″ Precannulated guidewire in the right renal inner branch. (C) 0.014″ Precannulated guidewire in the left renal inner branch.

In light of this, fenestrations require more deployment precision than branches, and precannulation helps mitigate this challenge, leading to a preciser target vessel cannulation, especially if the graft has reducing ties. Conventionally, reducing ties should be proposed and planned for facilitating orientation of the graft inside the aorta. The technique for adding reducing ties involves making a loop around the stent’s struts using Prolene 3.0, which has been previously described. ⁴ As an additional step in device modification, radiopaque markers are applied built using coils, each stitched with 3.0 Ethibond suture on the endograft anteriorly, proximally and distally, aligned to the SMA for guidance on the endograft orientation during deployment.

Re-sheathing

Regarding the speed and success of the repackaging process, we highlighted key factors experienced in our institution. First, returning the bare metal proximal stent into the nosecone requires considerable expertise, as 1 strut can escape while another is repositioned allowing potential damage to the device. Therefore, a stable proximal stent from the first steps of device unsheathing and modification, utilizing the tip capture as the Valiant Captivia endograft, significantly helps save time and prevent failures to return into the nosecone. Second, the first or second smallest size grafts of a delivery shaft should be preferred to facilitate re-sheathing. Third, a crucial step in the graft repackaging process is the sequential Rummel tourniquets for diameter reduction routinely performed. In our experience, the technique is aided by sequential loops of cardiac tape or silk sutures held by hemostatic clamps to allow a slow and progressive re-sheathing process as the clamps are sequentially removed. Additional caution is recommended to avoid twisting the graft, and for that reason 2 people are necessary, and each Rummel is removed for the graft to advance inside the sheath, sequentially and separately. An illustrative depiction of the routine sequential Rummel tourniquets applied to the described modified graft model is demonstrated (Figure 4). Furthermore, in a scenario where the proximal bare stent opens, a 2-person technique is utilized for returning it to the nosecone: one operator carefully repositions the struts back into the nosecone while the other holds them securely in position to ensure alignment for adequate re-sheathing.

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Figure 4.

Illustrative depiction of sequential Rummel tourniquets for diameter reduction facilitating repackaging applied to the described physician-modified endograft.

Deployment

The deployment of the modified Valiant Captivia endograft requires the establishment of bilateral femoral arterial accesses, preferably with ultrasound guidance. An additional upper arterial access, typically the axillary or brachial artery, is surgically exposed for anterograde manipulation of preloaded guidewires for the planned inner branches. Subsequently, a through-and-through femoro-axillary wire is created. Over this wire, a rigid guidewire is advanced through the femoral access allowing introduction of the modified endograft with PCIBs.

Under fluoroscopic guidance, the endograft is advanced, and once correctly oriented, partial deployment is performed to expose the inner branches. The preloaded guidewires are used to facilitate catheterization of the visceral arteries via the upper arterial access. Following successful deployment of the renal branches, the remaining portion of the modified endograft is fully deployed, ensuring accurate alignment with the remaining visceral arteries according to the positioned markers. The procedure concludes with angiographic confirmation of proper sealing and stent apposition, minimizing the risk of endoleaks and ensuring procedural success.

The technique is demonstrated in a case that presented a 4 cm thoracoabdominal pseudoaneurysm involving the origins of the SMA and the right renal artery, with a narrow aortic lumen diameter of 24 mm. The patient had a history of a descending thoracic aortic pseudoaneurysm endovascular repair using a Gore TAG (W.L. Gore, Phoenix, AZ, USA) 31 × 150 mm endograft and a previously occluded left renal artery.

In light of this, an endovascular repair was planned using a modified Valiant Captivia 28 × 28 × 150 mm endograft, selected into a 22Fr sheath. It was modified with inner branches created using Solaris 7 mm stents to direct flow to the celiac trunk and SMA, and a BeGraft (Bentley Innomed GmbH, Hechingen, Germany) 7 × 57 mm stent for the right renal artery. A distal extension was also performed with a 28 × 28 × 49 mm cuff to complete the repair. Customization of the graft was completed in 90 minutes, consistent with our experience in modified endografts with inner branches incorporation, in which the proximal bare stent stability of the Valiant Captivia significantly enhanced the ease and efficiency of device modification. Technical success was confirmed postoperatively and in a 4-year follow-up, which showed proper alignment and patency of the modified branches and complete exclusion of the pseudoaneurysm (Figure 5A–C).

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Figure 5.

Postoperative computerized tomography imaging of a case where the technique is demonstrated. (A–C) Sagittal, coronal, and axial views of the postoperative computerized tomography after 4 years of intervention with the 3 patent inner branches to the celiac trunk, superior mesenteric artery, and right renal artery.