Visceral vessel relocation techniques

Abstract

It has been more than a decade since the first implantation of a thoracic stent graft was reported, and only recently has the first device been approved by the Food and Drug Administration. Even though the technology has been approved by the Food and Drug Administration for 5 years for infrarenal aneurysmal repair, devices for use in the thoracic aorta are considered first generation and are limited by constraints similar to those that infrarenal devices are subject to. Additionally, complicated devices that allow for fenestration or branched designs are lacking or are only in the initial phases of development. Providing adequate distal fixation and accomplishing aneurysm exclusion with an appropriate sealing region is the most challenging task in many patients. Almost all infrarenal devices require 1.5 cm of aortic neck length to provide adequate fixation and seal for aneurysmal exclusion. Additional length is needed in the thoracic aorta, however, given its larger size; 2.0 to 3.0 cm is generally thought to be sufficient. Some experts rely on a ratio calculation and target a fixation length of 0.75 times the aortic diameter as a minimal acceptable length. It is also crucial that the aortic walls be fairly parallel and free of significant calcification and thrombus. Although isolated thoracic aortic lesions can still meet these requirements, many thoracic aortic processes involve the entire descending thoracic aorta and end at, or near, the crus of the diaphragm or in the visceral section. In these cases, obtaining adequate fixation can be problematic. The angle of the descending thoracic aorta also plays a major role in the migration of thoracic stent grafts, possibly causing a cephalad migration of the caudal aspect of the device. It can also make precise deployment rather difficult; many times it is necessary to deploy an additional distal extension. Implanting the device in a region where significant angulation exists can jeopardize the durability of the endovascular repair. Finally, most stent graft deployment mechanisms are designed for precise proximal placement with minimal or no control over the distal attachment site or landing zone. Therefore, accurate deployment near the celiac artery becomes more challenging. Given the aforementioned issues,