Floating Stent-Graft as a Support to Bridge an Unfavorable Renal Artery During Postdissection TAAA Repair Using a Multibranched Thoracoabdominal Endograft

Abstract

Purpose: To report an unusual endovascular technique to manage unfavorable renal artery anatomy encountered in an urgent case of symptomatic postdissection thoracoabdominal aortic aneurysm (TAAA) treated with an off-the-shelf multibranched device. Technique: The technique is demonstrated in a 77-year-old woman who had a history of previous open abdominal aortic aneurysm repair and an emergent procedure to implant a thoracic endograft and an aortic bare Z-stent (PETTICOAT) for acute Stanford type B dissection 7 years prior. The patient presented with a symptomatic, rapidly growing, postdissection TAAA. Endovascular treatment with a Zenith t-Branch was planned. After standard catheterization techniques failed in the left renal artery, a bailout maneuver was utilized to place a “floating” Viabahn stent-graft in the aneurysm sac to create sufficient support to deliver the bridging stent-grafts through the bare stent to the target left renal artery. The procedure was successful in excluding the TAAA and preserving perfusion to all target vessels. No neurological complications occurred. Six-month imaging follow-up confirmed the patency of the bridging stents. Conclusion: Remodeling changes after complex endovascular TAAA procedures often require the use of innovative techniques and materials during secondary procedures. In this case, the presence of a post-PETTICOAT bare aortic stent and hostile target artery anatomy increased the technical difficulty of t-Branch implantation. A “floating” stent-graft could be useful to reach challenging target vessels by providing additional support to bridging stent advancement and deployment.

Keywords

bailout technique dissecting aneurysm endograft multibranched stent-graft PETTICOAT technique postdissection aneurysm stent-graft thoracoabdominal aortic aneurysm

Introduction

Endovascular repair for complicated acute type B aortic dissection (TBAD) has increasingly been accepted as the therapy of choice in high-volume endovascular centers.¹ Even in the presence of a re-expanded true lumen and a thrombosed thoracic false lumen after thoracic endovascular aortic repair (TEVAR), there is a continued risk of aortic rupture and a need for additional procedures due to progression of the dissection, aneurysm degeneration, or malperfusion.^2–5

In 2016, Barbante et al⁴ reported a case of relining with a fenestrated endograft (fEVAR) after the PETTICOAT (provisional extension to induce complete attachment) technique for TBAD, underlining the complexity of the procedure. In such challenging cases, planning is sometimes not suffi-cient to develop an optimal technique of implantation, and advanced endovascular skills are necessary to achieve best results.⁵ Bailout maneuvers might be required, mainly in case of secondary procedures, anatomical variants, or complex visceral vessel morphology.⁶ Our report concerns a case of postdissection thoracoabdominal aortic aneurysm (TAAA) in a patient previously treated with PETTICOAT for acute TBAD, successfully managed with the deployment of a multibranched endograft, overcoming a challenging renal bridging stent deployment with a “floating” stent-graft.

Technique

The technique is demonstrated in a 77-year-old woman who presented to the emergency department with acute thoracic pain. The patient had a surgical history of elective infrarenal aorta replacement with a Dacron graft for abdominal aortic aneurysm and an emergent procedure to implant a Zenith thoracic endograft (Cook Medical, Bloomington, IN, USA) and a PETTICOAT aortic bare Z-stent (Cook Medical) for acute TBAD 7 years prior in another institution. This last procedure was complicated by paraplegia treated with cerebrospinal fluid (CSF) drainage, culminating in persistent hyposthenia of the lower limbs.

At the current admission, thoracoabdominal computed tomography angiography (CTA) showed a non-ruptured postdissection TAAA (Figure 1) that had grown rapidly since the previous year (57 vs 50 mm) associated with disconnection of the thoracic endograft and the bare metal stent.

Figure 1.

Preoperative computed tomography angiography in (A) a maximum intensity projection reconstruction, (B) volume rendering reconstructions [(a) anteroposterior and (b) left laterolateral views], and (C) axial view of the postdissection thoracoabdominal aortic aneurysm maximum diameter. The arrow in B points to the disconnection of the thoracic endograft and the bare metal stent.

An endovascular procedure for TAAA exclusion was planned from CTA scans using a 3mensio Vascular workstation (Pie Medical Imaging, Maastricht, the Netherlands). According to the anatomical characteristics of the aorta and visceral arteries, considering also that the true lumen was expanded by the previously implanted bare stent (32-mm diameter), a Zenith t-Branch endograft (Cook Medical) was chosen. A 2-stage approach was planned to leave one branch open temporarily due to the high risk of spinal cord ischemia (SCI). Prompt procedure completion would have been considered if thoracic pain persisted after the first step. The patient gave informed consent both for treatment and research participation.

Both surgical steps were conducted in an operating theater equipped with a Ziehm Vision RFD C-arm (Ziehm Imaging GmbH, Nürnberg, Germany). Spinal cord protection was managed through CSF pressure monitoring and drainage.

First Step

With the patient under general anesthesia, the first step was performed via a left axillary and right iliofemoral surgical approach. Percutaneous puncture of the left femoral artery was performed for diagnostic purposes. The proximal sealing zone was created by the preliminary deployment of a thoracic endograft (ZTEC-2PT-42-32-165 PF; Cook Medical) overlapping the previous thoracic endograft. Then a Zenith t-Branch (TBRANCH-34-18-20; Cook Medical) endograft was deployed.

Access to the target vessels through their branches was obtained via the axillary access, using a 12-F, 45-cm-long Flexor Introducer (Cook Medical), with telescopic insertion of an 8-F, 70-cm-long Flexor Introducer (Cook Medical). A conflict with the struts of the previously implanted bare aortic stent made cannulation of the tortuous left renal artery very difficult. Several unsuccessful attempts led to the decision to leave the left renal artery unstented and proceed with bridging of the celiac trunk to maintain perfusion and reduce the risk of SCI, although the most accepted strategy is to leave the celiac trunk unstented.⁷ Four Viabahn VBX balloon-expandable stent-grafts (W. L. Gore & Associates, Flagstaff, AZ, USA) were safely positioned and delivered in the celiac trunk (BXAL 08-59-02-E, BXAL 08-39-02-E), superior mesenteric artery (BXAL 08-79-02-E), and right renal artery (BXAL 06-79-02-E).

Selective angiography of the visceral vessels and final angiography showed patency of the endograft and visceral bridging stents in the absence of stenosis. Perfusion of the left renal artery and part of the aneurysm sac was maintained through the non-stented left renal branch. The total procedure time was 300 minutes, the radiation dose was 23967 cGy·cm², and the contrast volume was 200 mL. Intensive care unit (ICU) stay was 3 days, and the patient was discharged on the eighth postoperative day with complete resolution of thoracic pain and no signs of visceral ischemia or worsening of the lower limb hyposthenia.

Second Step

The second procedure was performed after 21 days via a left brachial surgical approach. Because of the presence of the PETTICOAT stent, cannulation of the left renal artery was challenging. The target vessel was reached with the guidewire several times, but the support was not sufficient to advance a bridging stent into the left renal artery. A Rosen guidewire was left in the distal portion of the left renal artery, and a Viabahn stent-graft (VBCR070502A) was deployed suspended in the cul-de-sac (Figure 2). It was not connected to either the branch or the renal artery but was held distally by the struts of the bare stents as well as by the relatively small aneurysm sac. This maneuver allowed us to obtain sufficient support to advance and deploy one more Viabahn stent-graft (VBCR070502A) distally and another Viabahn VBX (BXAL087902A) proximally, connecting the branch to the bridging stents (Figure 3). A Protégé GPS (SECX-9-60-135; Medtronic, Santa Rosa, CA, USA) stent was deployed to support this complex bridging stent arrangement.

Figure 2.

Intraoperative images of the second step. (A) Forces and obstacles involved during left renal artery stenting included (a) the guidewire had a long and tortuous path to take, (b) the aortic bare metal stents, and (c) loss of pushability of the system. (B) The “floating” stent-graft technique involved (1) advancing the first Viabahn into the aneurysm sac; (2) the outline of the released stent-graft, and (3) proximal and distal landing zones of the “floating” stent-graft in the cul-de-sac are shown by the arrows.

Figure 3.

Improvement in sheath pushability was provided by (A) achieving adequate support with (a) the first Viabahn in the cul-de-sac and (b) the bridging Viabahn VBX to the branch. (B) Sufficient support (1) to advance and deploy another bridging Viabahn (2 and 3) to the target vessel was achieved.

Completion angiography confirmed aneurysm exclusion, with good sealing and unhampered visceral perfusion (Figure 4). The total procedure time was 140 minutes, the radiation dose was 6988 cGy·cm², and the contrast volume was 50 mL. Neurological status was unchanged. ICU stay was 2 days. CTA on the third postoperative day demonstrated technical success of the procedure with the exclusion of the aneurysm. The postoperative course was regular without any complications, and the patient was discharged on the sixth postoperative day. The 6-month CTA confirmed the success of the procedure (Figure 5) without complications.

Figure 4.

Comparison between (A) the preprocedural and (B) poststenting angiograms. (C) The completion angiogram.

Figure 5.

(A) The final result is shown in a maximum intensity projection reconstruction of the 6-month computed tomography angiography (CTA) scan. (a) The sagittal cut shows the patency of the t-Branch endograft and the bridging stents through the aortic bare metal stents and (b) the detail of the left renal artery stenting. Volume rendering reconstructions from the follow-up CTA of the (B) left renal artery stents and (C) the complete view.

Discussion

Endovascular treatment for complicated acute TBAD is gaining widespread acceptance.⁸ TEVAR may induce positive aortic remodeling (growth of the true lumen, decrease of the false lumen) by covering the proximal entry tear. However, this remodeling is sometimes not reached. PETTICOAT has been revealed as a safe and feasible option to facilitate the exclusion of the false lumen by reapposing the intima at the distal reentry tear.^2,3 Nevertheless, component separation or device migration has been described,⁹ and the development of postdissection TAAA is not always avoidable, perhaps indicating the need for reoperation.^9,10

Fenestrated or branched endovascular aneurysm repair (f/bEVAR) techniques are recognized as a safe and effective solution for para-anastomotic AAAs or proximal aneurysmal degeneration after previous open or endovascular aortic repair in high-risk patients.¹¹ These f/bEVAR procedures could be even more challenging in the setting of previous endovascular treatment for acute TBAD.^4,12 Barbante et al⁴ described using fEVAR for postdissection TAAA in an asymptomatic patient who previously was treated with the PETTICOAT technique; however, custom-made endografts are not available for urgent cases such as the one we encountered. The off-the-shelf Zenith t-Branch option may be advantageous in reaching and cannulating visceral arteries without the orientation and repositioning restrictions associated with fenestrations¹² or previous bare aortic stents.

If a visceral vessel cannot be cannulated, embolization of the branch is always possible, and a multibranched thoracoabdominal endograft can still allow exclusion of the postdissection TAAA. In fact, the presence of bare aortic stents after a thoracoabdominal PETTICOAT procedure increases the technical difficulty of subsequent endovascular procedures.

Some authors describe the need for highly developed endovascular skills to overcome anatomical variants, perform complex secondary procedures, and address difficult situations that require bailout maneuvers,^5,6 describing the use of curved catheters or microcatheters and steerable sheaths, the balloon-grab technique, the use of aortic molding balloons, and the double guidewire-assisted technique as clever solutions to handle difficult situations.^6,13–16 In the current case, when the conflict of the bare stent prevented easy cannulation of the left renal artery, a longer and more tortuous pathway was chosen. In the search for a means to support and accurately reach a target vessel with unfavorable anatomy, we developed a “floating” stent-graft held distally by the struts of the bare stent. This technique, favored by the presence of a relatively narrow true lumen at that level, allowed the advancement and deployment of a complex bridging stent combination through the uncovered PETTICOAT stents to bridge to the tortuous renal artery. To our knowledge, this specific approach has not been previously described in the literature. A limitation of this technique may be that, in the presence of a larger true lumen, the stability of the stent-graft might not be sufficient.

Conclusion

Based on this experience, relining with a Zenith t-Branch endograft after PETTICOAT for TBAD is an option in urgent cases. However, the presence of a bare stent may interfere with catheterizing target vessels and could lead to the need for additional tricks when standard techniques fail. Deploying a “floating” stent-graft to improve support and pushability could be considered an option to add to the existing techniques portfolio regarding complex endovascular aneurysm repair.

Footnotes

Authors’ Note

This study was presented as poster at the 2019 Annual Meeting of the Italian Society for Vascular and Endovascular Surgery; October 21–23, 2019; Florence, Italy.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

Giulia Rossi

Paolo Perini

Claudio Bianchini Massoni

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