Endovascular repair of thoracoabdominal aneurysms: design options, device construct, patient selection and complications.

The aim of this paper was to describe the current status of endovascular thoracoabdominal aortic aneurysm (TAAA) repair. This is a comparative review of current device designs and implantation techniques. A literature review of all reported results of endovascular TAAA repair has also been carried out, together with a comparison of clinical outcomes achieved with endovascular TAAA repair and those achieved in current series of standard open TAAA repair. Endovascular TAAA repair has been performed with both unibody and modular devices, but modular devices currently predominate. In modular devices the aortic component provides access to the target visceral artery either through a fenestration or a cuff. Cuffs increase device profile and the length of aorta that is covered, but easily accommodate variations in deployment position and provide a good seal zone. Fenestrations do not affect device profile or add length to the device, but deployment position tolerates little deviation and the seal zone is tenuous. A covered stent is used to bridge the gap between the fenestration or cuff in the aortic component and the target visceral artery. Balloon-expandable covered stent branch extensions are delivered from the femoral approach when fenestrations are used. Self-expanding covered stents are delivered from either the brachial or femoral approach when cuffs are used, depending on the orientation of the cuff. Some groups reinforce the self-expanding covered stent with an uncovered self-expanding stent to enhance flexibility and stability. The majority of endovascular TAAA repairs have been performed in three centers, accounting for 84% of all reported cases. The treated TAAAs were Type 1 31.8%, Type 2 14.2%, Type 3 14.2% and Type 4 37.5%. Perioperative mortality is 6.9% (N. = 20), late mortality 13.6% (N. = 38), spinal cord ischemia (SCI) 14.9% (N. = 29) permanent in 6.7% (N. = 6), transient in 10.0% (N. = 9). Deterioration of renal function was reported in 9.8% (N. = 8), and required initiation of dialysis in 5.1% (N. = 5). Reintervention was required in 18 patients (20.0%) early in 8.9% and late in 11.1%. Branch occlusion developed in 3.5% (N. = 9) and stenosis in 0.85% (N. = 2). Current single-center series of open surgical TAAA repair report mortality rates of 5-16%, spinal cord ischemia rates of 3.8-15.5% and new onset dialysis between 2-16.2%. Population-based series of open surgical TAAA repair report mortality rates between 19.2-26.9%, spinal cord ischemia rates between 7.3-16.0% and new onset dialysis rates of 14.2-18.2%. Final status of SCI neurologic deficit, reintervention rates and branch occlusion or stenosis rates for open TAAA repair are inconsistently available, if at all. In conclusion, endovascular TAAA repair is an evolving technique that is developing increasing consistency in device design and implantation technique. It is effective in eliminating aneurysm flow and in preserving visceral branch perfusion. These early outcomes are better than the results achieved with open TAAA repair in population-based studies and are at least equal to the results of open TAAA repair reported from centers of focused expertise. These results support expanding the indications for endovascular TAAA repair to include standard risk patients.

Double-barrel technique for preservation of aortic arch branches during thoracic endovascular aortic repair.

Thoracic endovascular aortic repair (TEVAR) may involve either planned or inadvertent coverage of aortic branch vessels when stent grafts are implanted into the aortic arch. Vital branch vessels may be preserved by surgical debranching techniques or by placement of additional stents to maintain vessel patency. We report our experience with a double-barrel stent technique used to maintain aortic arch branch vessel patency during TEVAR. Seven patients underwent TEVAR using the double-barrel technique, with placement of branch stents into the innominate (n = 3), left common carotid (n = 3), and left subclavian (n = 1) arteries alongside an aortic stent graft. Gore TAG endografts were used in all cases, and either self-expanding stents (n = 6) or balloon-expandable (n = 1) stents were utilized to maintain patency of the arch branch vessels. In three cases the double-barrel stent technique was used to restore patency of an inadvertently covered left common carotid artery. Four planned cases involved endograft deployment proximally into the ascending aorta with placement of an innominate artery stent (n = 3) and coverage of the left subclavian artery with placement of a subclavian artery stent (n = 1). TEVAR using a double-barrel stent was technically successful with maintenance of branch vessel patency and absence of type I endoleak in all seven cases. One case of zone 0 endograft placement with an innominate stent was complicated by a left hemispheric stroke that was attributed to a technical problem with the carotid-carotid bypass. On follow-up of 2-18 months, all double-barrel branch stents and aortic endografts remained patent without endoleak, migration, or loss of device integrity. The double-barrel stent technique maintains aortic branch patency and provides additional stent-graft fixation length during TEVAR to treat aneurysms involving the aortic arch. Moreover, the technique uses commercially available devices and permits complete aortic arch coverage (zone 0) without a sternotomy. Although initial outcomes are encouraging, long-term durability remains unknown.

Endovascular treatment of thoracoabdominal aortic aneurysms.

Open surgical repair of thoracoabdominal aortic aneurysms (TAAA) bridges the aneurysm with a large, conventional, unstented graft and restores flow to the visceral arteries through short grafts or direct sutured connections between the visceral arterial orifices and the primary conduit. The combination of retrograde visceral bypass and endovascular aneurysm exclusion substitutes an endovascular stent-graft for a standard graft, stented overlaps for sutured anastomoses, and transluminal insertion for direct aortic exposure. Compared to open surgery, the combination treatment requires less dissection, and causes less hemodynamic instability, and lower complication rates, particularly paraplegia. The multi-branched stent-graft substitutes endovascular visceral bypass through branches of the stent-graft for surgical visceral bypass through branches of a conventional extraluminal graft, which has the potential to further reduce surgical dissection, hemodynamic instability, and complication rates. We favor a modular approach in which short, axially oriented cuffs are extended into the visceral arteries, using self-expanding covered stents. In the past year, we have used this approach to implant multi-branched thoracoabdominal stent-graft in 16 patients. In our opinion, this approach will eventually assume a prominent role in the management of TAAA.

Novel technique for placement of hemodialysis catheters using a combined open procedure with the Seldinger micropuncture technique.

Percutaneous placement of large-diameter dialysis catheters via the Seldinger technique can be technically challenging in patients with coagulopathy, difficult anatomy, or several previous central line insertions. We describe a method for achieving safer access by combining an open approach to delineate the venous anatomy of the chest wall, with a micropuncture device and smaller diameter guidewire to gain intravascular access to the cephalic vein or its major tributaries. Serial dilation of otherwise unusable vessels can then permit successful and safer hemodialysis catheter insertion in these difficult cases.

The choice of stent-graft for endovascular repair of abdominal aortic aneurysm.

The aim of this study was to explain variations in the results of endovascular aneurysm repair as a consequences of device design. Low profile, trackable systems, such as Zenith and Excluder, rarely fail to traverse the iliac arteries, even in the presence of iliac tortuosity or stenosis. In most patients, optimal sizing is only possible with systems, such as Zenith, Talent, and Quantum lp, that have a wide range of diameters. Short, angulated necks call for a high degree of flexibility and secure, barb-enhanced proximal fixation, which are features of Excluder, Zenith and Ancure. The main risk factors for rupture are migration, type III endoleak, and aneurysm dilatation. Migration rates are high for devices, such as AneuRx, that have neither barbs nor suprarenal stents. Aneurysm shrinkage occurs at high rates with non-porous stent-grafts, such as Zenith, Talent, and Ancure, but at far lower rates with porous stent-grafts, such as Excluder and AneuRx. Type III endoleak, due to fabric failure or component separation, was a common failure mode for the Vanguard device, but is rare with newer devices. Suture breakage, barb separation and stent breakage occur frequently, yet clinical consequences, such as endoleak or rupture, are rare. Graft thrombosis is also unusual when the prostheses is fully-stented. In conclusion, modern devices are more versatile, more effective, and more durable than their first generation counterparts.