The Gore TAG stent graft used for endovascular aortic aneurysm repair procedures.
Here are several considerations for physicians when choosing endovascular stent grafts used to treat aortic aneurysms. Multiple devices are available on the market, each with unique features.
Improved graft technology has allowed for treatment with short landing zones down to 1.5 cm in some configurations. In addition, each stent-graft employs a design to improve conformability to aortic curvature, reducing the risk of birds-beaking or wind-socking at the proximal landing zone. Multiple configurations including tapered components allows for treatment of aortas with proximal – distal size discrepancy. Finally, lower-profile delivery systems allow for safer transfemoral access.
There are indications for thoracic endovascular aortic repair (TEVAR) in the descending thoracic aorta (DTA). Both American and European guidelines [1,2] list the following pathologies of the DTA as treatment indications for TEVAR:
• Aneurysm (>5.5 cm);
• Penetrating aortic ulcer (>20 mm in diameter and 10 mm neck);
• Intramural hematoma and aortic dissection; and
• Pseudo-aneurysm and traumatic aortic injury.
TEVAR can be a life-saving procedure in the acute setting for patients with aortic rupture or type B aortic dissection complicated by malperfusion. Patients with chronic aortic aneurysm with appropriate anatomy can be effectively treated with TEVAR with outcomes comparable to open aortic repair. Contraindications for TEVAR include connective tissue disorder, active infection, absence of retrograde access to aorta (transfemoral or transiliac).
Below is a description of several of the TEVAR devices available on the U.S market.
This device was approved by the U.S. Food and Drug Administration (FDA) in September 2012. It is indicated for endovascular repair of aneurysms (fusiform and saccular) and penetrating ulcers in descending thoracic aorta. The delivery system does not require a separate sheath and the stent-graft is contained within a two-sheath system. Deployment is multi-staged. The primary outer sheath is advanced to just below the distal landing zone. The secondary inner sheath is advanced to the proximal landing zone. The secondary inner sheath is retracted to expose the stent-graft.
The stent-graft can be repositioned while the bare stent of the first covered stent is exposed. The remainder of the stent-graft is deployed after confirmation of final position. The apex holder is then released from the proximal end of the stent-graft and the delivery system is removed from the body.
Unique features of the Bolton Relay-Plus are a bare metal stent proximally and spiral support strut along the graft to be aligned with the greater curve of the aorta. The stent-graft is available in 25 cm in both straight and tapered configurations, the longest on the market. Stent-grafts with diameters of 28 mm or less can be placed with proximal landing zones as short as 15 mm.
Cook Medical TX2
The TX2 was approved by FDA in May 2008. The device is indicated for endovascular repair of aneurysms (fusiform and saccular) and penetrating ulcers in descending thoracic aorta. This stent graft does not require a separate sheath and is contained within a proprietary Flexor introducer sheath. The device is advanced to the proximal landing zone and the stent-graft is partially unsheathed. The partially-deployed stent-graft can be repositioned by advancing proximally but not distally due to the presence of proximal fixation barbs. Completion of the sheath retraction is performed once desired position is achieved. The trigger-wires slowly releases the proximal trifold configuration for complete deployment.
The Cook TX2 device consists of a modular design with proximal and distal components. The proximal component has no uncovered stent but does have proximal barbs for fixation. The distal component has distal bare springs.
Cook Medical Zenith Alpha
The Zeith Alpha was approved by FDA for commercial use in September 2015. The device is indicated for aneurysm and penetrating ulcer in the descending thoracic aorta. Deployment is performed in a similar fashion as the Cook TX2 but the proximal portion of the graft is released by turning a rotation handle rather than direct unsheathing. The design is also modular. The proximal component has an uncovered stent (15 mm long) at the proximal end as well as fixation barbs. The distal component also has fixation barbs on the proximal end and uncovered stent on the distal end. The unique feature of this device is the low-profile delivery system (16 to 20 Fr sheaths), the smallest on the market.
Gore TAG Conformable
The TAG Conformable was approved by FDA in September 2013. The device is indicated for treatment of aneurysm, penetrating ulcer, blunt aortic injury and dissection. This device does require a separate sheath and the proprietary Gore Dry-Seal sheath is recommended. Deployment is single-staged and is performed by pulling a deployment string. The stent graft is release from the middle of the stent graft, towards either end simultaneously. This stent-graft is the only ePTFE graft on the market and has uncovered stent protruding proximally for improved fixation.
The Valiant was approved in January 2014. The device is indicated for treatment of aneurysm, penetrating ulcer, blunt aortic injury and dissection.
This stent-graft does not require a separate sheath. Deployment is performed by retracting a graft cover. The partially-deployed stent-graft can be repositioned distally but not proximally. After the stent-graft is deployed, the Captivia tip capture mechanism releases the proximal uncovered stent. The device is modular. The proximal component has an uncovered stent proximally.
Distal components are available in two configurations — either with covered or uncovered stents at the distal end. A unique feature is the availability of both proximal and distal components in straight and tapered configurations.
A comparison chart highlighting key characteristics of each stent-graft has been created to help the physician choose the appropriate device based on indication and anatomy. View the TEVAR Stent Grafts Comparison Chart (www.dicardiology.com/content/tevar-stent-grafts). It will require a login to access the specifications, but it is free and only takes a moment to complete the form.
Editor's Note: Andrei Churyla, M.D., is an assistant professor of cardiac surgery, and S. Chris Malaisrie, M.D., is an associate professor of cardiac surgery, division of cardiac surgery at Northwestern University. Malaisrie also is an attending cardiac surgeon at Northwestern Medicine, Bluhm Cardiovascular institute, and is co-director of the Marfan Clinic, Bicuspid Aortic Valve Clinic and Thoracic Aortic Surgery Program.
Related Endovascular Aortic Repair Content:
1. Hiratzka LF, Bakris GL, Beckman JA, et al. American College of Cardiology Foundation/ American Heart Association Task Force on Practice Guidelines; American Association for Thoracic Surgery; American College of Radiology; American Stroke Association; Society of Cardiovascular Anesthesiologists; Society for Cardiovascular Angiography and Interventions; Society of Interventional Radiology; Society of Thoracic Surgeons; Society for Vascular Medicine. 2010 ACCF/AHA/AATS/ ACR/ASA/SCA/SCAI/SIR/STS/SVM Guidelines for the diagnosis and management of patients with thoracic aortic disease. A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines, American Association for Thoracic Surgery, American College of Radiology, American Stroke Association, Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, Society of Interventional Radiology, Society of Thoracic Surgeons,and Society for Vascular Medicine. Circulation. 2010;121:e266–369. doi: 10.1161/CIR.0b013e3181d4739e.
2. Erbel R, Aboyans V, Boileau C, Bossone E, et al. ESC Committee for Practice Guidelines (2014) ESC Guidelines on the diagnosis and treatment of aortic diseases: document covering acute and chronic aortic diseases of the thoracic and abdominal aorta of the adult. The Task Force for the Diagnosis and Treatment of Aortic Diseases of the European Society of Cardiology (ESC). Eur Heart J 35:2873–2926.