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Proximal Scallop in Thoracic Endovascular Aortic Aneurysm Repair to Overcome Neck Issues in the Arch
Eur J Vasc Endovasc Surg. 2015; doi:10.1016/j.ejvs.2015.09.012
To evaluate initial experience with a custom made proximal scalloped stent graft for thoracic endovascular aortic repair (TEVAR) of aortic aneurysms involving the arch.
Between September 2012 and November 2014, patients presenting with a thoracic aortic aneurysm (TAA) with short or angulated neck were selected for treatment by custom made proximal scalloped Relay Plus stent grafts (ABS Bolton Medical, Barcelona, Spain). Prospectively acquired data relating to patient demographics, procedure details, clinical outcomes, and complications were analyzed retrospectively.
Ten selected patients (50% male, mean age 77 ± 8 years) were treated using a thoracic custom made Relay Plus stent graft, three of whom underwent additional cervical supra-aortic trunk revascularizations. TAA were fusiform in four cases, saccular in three, and three patients were treated for proximal type I endoleaks after previous standard TEVAR. The graft was landed in zone 2 in 3 cases, in zone 1 in 4 cases, and in zone 0 in 3 cases. The custom made scallop was designed to preserve flow in the left subclavian artery in three patients, in the left common carotid artery in four, and in the innominate artery in three. No proximal type I endoleak occurred and proximal sealing was achieved in all cases, with a technical success rate of 100%. All targeted vessels were patent. During a mean follow up of 12 ± 5 months, no conversion to open surgical repair and no aortic rupture occurred. One patient died post-operatively from myocardial infarction and one patient suffered a stroke with complete recovery. One patient had a distal type I endoleak on the 6 month CT scan and is scheduled for distal extension. No paraplegia, retrograde dissection and no other aortic related complications were recorded.
Proximal scalloped stent grafts appear to be an effective additional tool for TEVAR of TAA when dealing with short or angulated proximal necks.
Keywords: Aortic, Arch, Aneurysm, Endovascular repair.
What this paper adds
Proximal scalloped stent grafts appear to be an effective additional tool for TEVAR when dealing with short or angulated proximal necks. More prospective and multicentre studies have been initiated to confirm these results.
Although thoracic endovascular aortic repair (TEVAR) is now an established treatment for descending aortic aneurysms,1 it is not so clear when considering the aortic arch. Management of the proximal landing zone remains challenging in cases of short proximal neck and severe angulation of the arch. During the last decade, short neck issues in TEVAR led surgeons to develop alternative techniques, such as hybrid arch repair with supra aortic debranching,2 chimneys,3 fenestrations,4 and branches.5 However, these procedures are still under evaluation and their results have been controversial.6 and 7 In the era of exclusive endovascular solutions for aortic arch lesions, stent grafts designed with a proximal scallop may provide an interesting approach. The concept of the proximal scallop aims to increase the proximal landing zone in the inner curvature of the arch without compromising supra aortic trunk (SAT) patency, thereby reinforcing proximal sealing at its weakest point. This study reports a single center experience using a custom made proximal scalloped stent graft for TEVAR of aortic aneurysms involving the arch.
Between September 2012 and November 2014, selected patients presenting with thoracic aortic aneurysm (TAA) with short or angulated neck were selected for treatment by custom made proximal scalloped Relay Plus stent grafts (ABS Bolton Medical, Barcelona, Spain). TAA included short proximal landing zone < 20 mm, significant angulation of the arch requiring up to 30 mm of proximal landing zone length, and patients with proximal type I endoleak after previous standard TEVAR. To be more specific, both in cases of fusiform and saccular lesions, it was considered that the minimum healthy aortic seal length had to be at least 15 mm from the expected position of the edge of the scallop, either distally or laterally (Fig. 1). All patients underwent high resolution computed tomography angiography (CTA) scan pre-operatively. All elective cases were discussed by a multidisciplinary team. Informed consent was obtained from all patients before intervention and data collection. After patient selection and approval, the custom made stent graft was ordered with a reinforced fenestration scallop to the left subclavian artery (LSA), the left common carotid artery (LCCA), or the innominate artery (IA). According to international recommendations,8 extra-anatomic revascularization of SATs was performed when indicated, prior to stent graft implantation.
As reported by Alsafi et al.,9 custom made scalloped stent grafts were designed on the basis of the CE marked Bolton Relay Plus, composed of self expanding nitinol stents sutured onto polyester vascular graft with proximal bare stent with capture. A curved nitinol catheter along the length of the stent graft supported the graft to place the scallop systematically on the upper side of the aortic arch, and to allow an easy positioning of the scallop around the origin of targeted SAT. In addition to radiopaque end markers, four more markers delineated the position of the scallop. The delivery system consisted of a series of coaxially arranged sheaths and catheters: a stiff hydrophilic introducer to deliver the device through the iliac arteries and a flexible sheath containing the stent graft, allowing the device to track through the tortuous course of thoracic aorta. If proximal readjustment was required, the delivery system allows distal tip recapture. Stent grafts were manufactured according to pre-operative CTA measurements, with a custom made scallop created in situ. Turnaround time from sizing to delivery was 3 weeks.
Procedure planning and device sizing were performed using a dedicated 3D vascular imaging work station (Vascular 4.2 software. 3mensio Medical Imaging BV, Bilthoven, The Netherlands) with centerline luminal reconstruction. The working landing zone included vessels around which the scallop fits. Scallops were custom made for each patient, according to the pre-operative CTA and 3D reconstructions. Three parameters were considered for their customization: width, length, and clockwise orientation of the targeted vessel. Generally, 20% oversizing of the stent graft, based on the proximal landing zone diameter, was recommended.
All procedures were performed under general anesthesia, through a surgical cutdown of the common femoral artery. The Relay Plus thoracic stent graft delivery system was inserted through a hydrophilic 60 cm, 22F to 24F sheath. Heparin 5000 IU, was administered at this point. Angiographic runs were performed through a pigtail catheter, introduced percutaneously through contralateral femoral or left brachial access and placed into the arch. The stent graft delivery system was inserted up to the mid descending thoracic aorta where the secondary sheath was further advanced into the arch. Using an arch angiogram, the distal marker of the scallop was aligned just distal to the targeted SAT (Fig. 2). Mean blood pressure at deployment was around 80 mmHg to optimize deployment accuracy. The steps of stent graft deployment were followed according to manufacturer instructions. Molding balloon angioplasty within the stent graft was optional. Completion angiograms were performed in all cases.
Morphological follow up consisted of CTA scans before discharge, at 1 and 6 months, and yearly thereafter. A detailed clinical examination was performed during the hospital stay and at outpatient visits at 1 and 6 months, and yearly thereafter. Prospectively acquired data relating to patient demographics, procedure details, clinical outcomes, and complications were analyzed retrospectively.
Out of 88 TEVAR performed at the study institution during the study period, 10 selected patients (50% male, mean age 77 ± 8 years) were treated using a thoracic custom made Relay Plus stent graft. Patient characteristics and pre-operative conditions are presented in Table 1. Considering anatomic lesions, TAA were fusiform in four cases (40%), saccular on a penetrating ulcer in three cases (30%), and three (30%) patients were treated for proximal type I endoleaks after previous standard TEVAR. Patient indications, anatomy, and procedure details are described in Table 2.
|Median age (range), years||77 (66–90)|
|Comorbidity, n (%)|
|Diabetes mellitus||1 (10)|
|Smoking history||4 (40)|
|Chronic renal failure||3 (30)|
|Previous open thoracic aortic surgery||2 (20)|
|Previous TEVAR||4 (40)|
|Previous infra renal aortic surgery||3 (30)|
CAD = coronary artery disease; COPD = chronic obstructive pulmonary disease; TEVAR = thoracic endovascular aortic repair.
|Pt||Indications||Original size, mm||Minimal sealing length, mm||Stent graft D/L, mm||Landing zonea||Scallop to preserve flow||Scallop design L/W, mm||Clock position||Associate procedure SAT revascularization|
|1||Descending TAA||60||15||36–32/109||1||LCCA||25/15||+21°||LCCA-LSA bypass and occluder in the LSA|
|2||Saccular aneurysm of the aortic isthmus||35||18||34–30/160||2||LSA||20/15||−4°||No|
|3||Type I endoleak after TEVAR||66||17||38/160||1||LCCA||30/20||−27°||No|
|5||Descending TAA||64||16||42/114||IA (BAA)||30/20||−1°||Occluder in the LSA|
|6||Penetrating ulcer of the aortic arch||36||15||34–30/140||2||LSA||30/20||−25°||No|
|8||Type I endoleak after hybrid arch repair with LCCA-LSA bypass||86||17||42/150||IA||20/20||+12°||Carotid-carotid and LCCA-LSA bypass|
|9||Type I endoleak after TEVAR||110||16||44–40/160||IA (BAA)||30/18||+12°||No|
|10||Penetrating ulcer with a pseudoaneurysm of the aortic arch||42||15||36–32/150||1||LCCA||30/20||+18°||LCCA-LSA bypass and occluder in the LSA|
a Proximal landing zone was reported using the classification of Ishimaru.
BAA = bovine aortic arch; D/L = diameter/length; LCCA = left common carotid artery; LSA = left subclavian artery; TAA = thoracic aortic aneurysm; TEVAR = thoracic endovascular aortic aneurysm repair.
Seven patients underwent stand alone scalloped TEVAR, and three patients underwent additional cervical SAT revascularizations (Fig. 3). According to the classification of Ishimaru,10 stent graft landed in zone 2 in three cases, in zone 1 in four cases, and in zone 0 in 3 cases. Therefore, the custom made scallop was designed to preserve flow in the LSA in three patients, in the LCCA in four, and in the IA in three (of whom two had a bi-carotid trunk). Dimensions of the scallops for each patient are reported in Table 2. The LSA was covered without revascularization in four patients. An Amplatzer plug for occlusion of the LSA was used in one case. Median minimal proximal sealing length was 16 mm (range 15–27 mm). The technical success rate was 100%. No SAT major coverage > 50% occurred in this series. Mean radiation dose was 3.4 ± 2.1 mGym.2 Mean contrast medium volume was 90 ± 24.5 mL. Median overall hospital length of stay was 4 days (range 3–7 days). The mean follow up was 12 ± 5 months. Post-operative complications are reported in Table 3.
|Retrograde dissection||0 (0)|
|Type II||0 (0)|
|Type III||0 (0)|
|Follow up in months, median ± SD||12 ± 5|
SD = standard deviation.
The 30 day mortality rate was 10%. Patient 7 died suddenly in the intensive care unit from massive myocardial infarction 3 days after the procedure. She had undergone stand alone scalloped TEVAR with a proximal scallop to the LCCA, without revascularization of the LSA. No retrograde dissection was found at post mortem. No other death was recorded during follow up.
There was one post-operative stroke (10%). Patient 1 was treated by a staged procedure with a first LCCA to LSCA bypass and a second scalloped stent graft to the LCCA. He suffered from a post-operative left hemiparesis secondary to multiple thalamic and posterior cerebral artery territory embolic infarcts, resulting in a posterior stroke. There was complete recovery at discharge on day 6.
No proximal type I endoleak occurred on completion angiography and a durable proximal seal was achieved in all cases during follow up. One distal type I endoleak was recorded in patient 1 on the 6 month CT scan, and is scheduled for distal extension.
No paraplegia, retrograde dissection, and no other aortic related complication were recorded. No conversion to open surgical repair and no aortic rupture occurred during follow up. All targeted SAT and all extra-anatomic revascularizations remained patent on completion angiograms and follow up CTA scans. No early or late re-intervention has been performed to date, although one was needed (patient 1, distal type I endoleak).
This study reports the single centre 2 year experience using the custom made Bolton Relay Plus proximal scalloped thoracic stent graft. This pilot series adds to the encouraging results previously published by Alsafi et al.,9 and precedes several clinical and anatomical investigations by the same study group on the subject of proximal scallop in TEVAR.
The paradox of aortic arch geometry is that to obtain a sufficient sealing zone by apposition of the proximal stent graft to the inner curvature, a much longer length needs to be covered in the outer curvature. That is why most failures of TEVAR are caused by proximal type I endoleaks originating from the inner curvature of the aortic arch.11 The concept of proximal scallop for TEVAR allows simple extension of the proximal sealing zone along the inner curvature of the aortic arch, while leaving SATs patent on the outer curvature. In this series, three patients presenting with proximal type I endoleaks after a previous standard stent graft were successfully treated mostly by increasing the proximal landing zone on the inner curvature of the arch (Fig. 4).
Although branched stent grafts appear to increase sealing on the outer curvature of the arch compared with scalloped ones, their deployment remains a complex and challenging procedure, even in expert hands.5 Endovascular maneuvers for catheterization or snaring of wires to access the SAT could be associated with a higher risk of stroke. The present authors believe that such complex procedures as branched stent grafts should be performed only in selected patients with aneurysms involving SAT ostia without sufficient sealing in the outer curvature of the arch. During the present study period, only one patient was treated with a double branched custom made stent graft (ABS-Bolton, Barcelona, Spain), and one other was screened who will be treated soon. The present authors have no experience with fenestrated stent grafts, but it is thought that the need for repositioning of fenestrations could lead to a higher risk of stroke. With the scallop concept, such maneuvers in the arch should be avoided because of a systematic positioning of the scallop in the outer curve of the aortic arch. In fact, the scallop is designed to be positioned directly in the outer curve of the arch because of its pre-curved nitinol catheter. The benefit is to limit endovascular maneuvers in the arch, which it is believed are associated with a higher risk of stroke. Misalignment risk cannot nevertheless be totally excluded, as the range of SAT clockwise positions varied from −27° to +21°, but this did not lead to any clinical issues. No major SAT coverage > 50% occurred in this series. Despite the potential risk, and with the aim of limiting dangerous maneuvers in the SAT, it was decided not to inflate a balloon at the level of the target vessel ostium nor wire the target vessel, which was the LCCA in four patients and the IA in three.
The deployment procedure of the custom made proximal scalloped Relay Plus remains as simple and precise as standard TEVAR.12 In the present study, stent grafts were inserted and advanced in the arch with no need to cross the aortic valve, and no additional catheterization maneuvers were required. The operator should focus on the distal marker of the scallop, which can be easily identified and positioned at the distal level of the targeted SAT. This deployment follows standard TEVAR conditions with the proximal tip capture system, as a mean blood pressure of 80 mmHg is recommended during stent graft release to optimize positioning precision. No ventricular rapid pacing was used in this series. It is believed that the simplicity of deployment of these custom made stent grafts in the arch is one of their main advantages compared with other endovascular techniques used in the field of aortic arch aneurysm repair, but here also experience is needed. Indeed, limiting the endovascular maneuvers in the arch is probably one of the key factors in minimizing stroke rates when dealing with such proximal anatomy. There was one stroke in this series. These results are comparable with Alsafi et al.’s series as they reported three strokes over 21 patients. Patient 1 suffered a stroke (left hemiparesis) caused by multiple embolic infarcts in both the posterior cerebral artery and thalamic territories, resulting in a posterior stroke. Clearly, too many re-positioning maneuvers had been done in the arch. In these first cases, the authors were keen to precisely align the markers of the scallop. Another possible etiology could be emboli from an angiogram pigtail catheter inserted through the LSA. Once comfortable with the markers on the scallop, the pigtail catheter was introduced via femoral access, and fewer maneuvers in the arch were necessary.
The necessity of covering SAT is not a rare situation when dealing with elective stent grafting of TAA.13 This becomes a greater concern for surgeons who treat acute aortic syndromes such as ruptured aneurysms or penetrating ulcers, acute aortic dissections or traumatic injuries of the thoracic aorta.14 In these acute settings the LSA might be covered in up to 46% of cases, with the regularly described complications.15 and 16 Unfortunately, such custom made scalloped or branched devices are not available in the emergency situation; for a custom made proximal scalloped Relay Plus stent graft, a period of 3 weeks is required from sizing to implant.
To widen clinical applications of such custom made devices from elective to emergent patients, work is under way on anatomical studies of SAT arising in the arch. The aim is to determine a standard scallop design to fit the anatomy of most patients treated for acute aortic syndromes, to obtain standardized “off the shelf” proximal scalloped devices.
Compared with open repair, SAT debranching or chimney procedures, scallops and branched stent grafts mix the advantages of a possible total endovascular repair, with the use of a labeled device designed to behave properly in the arch. The scallop concept might limit the number of cases in which complete or carotid debranching is needed. The present authors consider zone 0 debranching to be an aggressive procedure, because of the risks of retrograde aortic dissection, stroke, and the need for sternotomy. These early and mid-term results of pilot experiences with proximal scallop stent grafts need to be confirmed by larger multicentre studies. In January 2015, a national study was launched (REP: Relay Echancrure Proximale), which is a prospective observational multicentre study aiming to include 50 patients treated with the proximal scalloped Relay Plus stent graft during a 2 year period, with at least 1 year of follow up. Results of this larger prospective multicentre experience will help to further evaluate the potential benefits of proximal scallops in TEVAR. Longer term results will also be mandatory to confirm that the concept of proximal scallop in TEVAR is reliable to ensure durable sealing of stent grafts in the aortic arch. The present authors are also participating in an international prospective registry to report long-term follow up of patients treated in Europe.
Proximal scallop in TEVAR may become an additional tool for endovascular specialists dealing with complex thoracic aortic pathologies. The main potential benefit is extension of the proximal sealing zone in the inner curvature of the arch, while preserving physiological SAT vascularization. The simplicity of deployment with limited endovascular maneuvers in the arch probably makes this technique more accessible, reproducible and safe when dealing with a difficult aortic neck in the arch. Larger multicentre studies with longer follow up are mandatory.
Conflict of Interest
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a Service de Chirurgie Cardiaque et Vasculaire – Hôpital Européen Georges Pompidou, AP-HP, Paris, France
b Service de Radiologie Interventionnelle – Hôpital Européen Georges Pompidou, AP-HP, Paris, France
c Université Paris-Descartes, Faculté de Médecine, Paris, France
∗ Corresponding author. MCU-PH en Chirurgie Vasculaire, Service de Chirurgie Cardiaque et Vasculaire, Hôpital Européen Georges Pompidou 20, rue Leblanc – 75908 Paris Cedex 15, France.
© 2015 European Society for Vascular Surgery, Published by Elsevier B.V.
© 2015 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.
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