TECHNICAL CONSIDERATIONS

The GORE TAG Conformable Thoracic Stent Graft with ACTIVE CONTROL System combines the familiar Conformable GORE^® TAG^® Device with a novel nested handle delivery system. The stent graft remains the same as the Conformable GORE TAG Device and therefore has the same conformable stent graft design with sutureless graft attachment, oversizing windows that enable optimized radial fit, and indications and anatomic requirements. The principle of operation is also maintained, with a fiber deployment mechanism that is actuated to release the self-expanding stent graft from a constraining sleeve.

The delivery system, however, is different and now features a nested handle that separates stent graft expansion into two deployment steps, each requiring actuation of a separate handle component (Figure 1). Deployment consists of four required steps and two optional angulation steps. Removal of the primary deployment handle deploys the stent graft to its intermediate diameter, initiating device opening from the leading to the trailing ends (Figure 2). At this intermediate stage, the angulation control dial is now accessible and the user has the first opportunity for optional angulation of the proximal end of the stent graft by rotating this dial. Removal of the secondary deployment handle deploys the stent graft to its full diameter, initiating deployment from the trailing to leading ends. The angulation control dial remains accessible even after full expansion, and the user has a second opportunity for optional angulation at full diameter. Throughout the deployment, the stent graft is secured onto the catheter via a lock wire. This ensures control of device positioning throughout the procedure until removal of the lock wire handle. Finally, the angulation assembly handle is removed to withdraw the angulation fiber mechanism.

The GORE TAG Conformable Thoracic Stent Graft with ACTIVE CONTROL System has two important features to improve deployment predictability through accuracy and control: staged deployment and in situ angulation control of the proximal end of the stent graft. With staged deployment, the nested handle delivery system design enables the stent graft to deploy in two distinct steps (Figure 3). Removal and actuation of the first primary deployment handle opens the device along its entire length to its intermediate diameter, which is approximately 50% of its nominal diameter. Importantly, this deployment to intermediate diameter is designed to allow continuous blood flow both through the lumen of the stent graft and around the device. This feature ensures hemodynamic stability throughout the procedure, even in the aortic arch with its characteristic high blood flow pressure and velocity. A unique advantage of this design is that blood pressure does not have to be aggressively reduced because the blood flow into the distal aorta is not compromised. The lack of windsocking forces that tend to push the device distally during device opening helps to ensure precise positioning of the stent graft in the aorta. Because there is little or no wall apposition at this intermediate diameter, it is possible to make refinements in the stent graft positioning. If required, it is also possible to modify the C-arm gantry angle to remove device parallax and maximize every millimeter of the landing zone. Removal and actuation of the secondary deployment handle opens the device to its full diameter. A lock wire secures the stent graft to the catheter, ensuring that the user maintains control of the device and its positioning throughout the procedure until the lock wire is removed as one of the final deployment steps.

Angulation of the proximal end of the stent graft is an optional feature that allows for more orthogonal placement of the stent graft. The benefit of angulation becomes evident in angulated aortic arch anatomies, where the wall apposition along the inner aortic curvature can sometimes lead to the formation of a bird beak. The GORE TAG Conformable Thoracic Stent Graft with ACTIVE CONTROL System allows the user to adjust the angulation and orthogonal placement of the proximal end of the stent graft in situ, depending on the individual anatomic needs of the patient. Angulation control is possible during the two phases of deployment, at intermediate diameter and after the stent graft has expanded to its full diameter (Figure 4). Because this is an optional feature, the clinician can decide during deployment whether and to what degree angulation is beneficial in that specific anatomy. This ability to optimize proximal device apposition may help to avoid complications such as type Ia endoleak.

CASE REPORT

A 79-year-old man with a documented medical history of a type B aortic dissection presented with thoracic pain (Figure 5). A CT scan revealed an aneurysm of the false lumen and collapse of the true lumen (Figure 6). Endovascular exclusion of the aneurysm was deemed to be appropriate to prevent aneurysm rupture. TEVAR planning was based on a thoracoabdominal thin-slice CTA. The preoperative maximum outer-outer thoracic diameter was 57 mm. Proximal neck length and diameter were measured using the vessel centerline-of-flow technique. 

The procedure was performed in a hybrid endovascular suite using fusion imaging under general anesthesia. The right femoral artery was accessed percutaneously using the preclose technique, which has been described elsewhere.4 During the procedure, intravenous heparin was administered to reach an activated clotting time corridor of 250 to 300 seconds. A 22-F GORE® DrySeal Sheath was placed. Under fluoroscopic guidance, two 34-mm-diameter GORE TAG Conformable Thoracic Stent Grafts were implanted. A permissive hypotension of < 100 mm Hg systolic blood pressure sufficed. The first 200-mm-long GORE TAG Conformable Device was placed with the proximal end just below the origin of the left subclavian artery (Figure 7). At intermediate diameter, it was observed that positioning of the device could be optimized by modifying the C-arm angle to remove device parallax. 

The device was then deployed to its full diameter, and angulation of the endograft was performed. The device conformed to the aortic arch, with no bird beak on the inner curvature. A second device was placed for distal extension with the same diameter and a length of 10 cm, aiming for an overlap of 5 cm. After deployment of the stent graft, completion angiography was performed to ensure adequate placement of the graft and to rule out endoleaks (Figure 8). Postoperatively, mean arterial blood pressure was kept between 80 and 100 mm Hg in order to reduce the risk of ischemic spinal cord injury. Cerebrospinal fluid drainage was not performed, as we abandoned it as a prophylactic measure several years ago.⁵