Magnitude and Direction of Pulsatile Displacement Forces Acting on Thoracic Aortic Endografts

Abstract

The orientation of the DF varies depending on curvature and location of the endograft, but in all instances, it is in the cranial rather than caudal direction on axial imaging. This is counter to the intuitive notion that displacement forces act in the downward direction of blood flow. Therefore, we postulate that migration of thoracic endografts may be different from abdominal endografts since it may involve upward rather than downward movement of the graft. Computational methods can enhance the understanding of the magnitude and orientation of the loads experienced in vivo by thoracic aortic endografts and therefore improve their design and performance.

Image-Based Modeling of Blood Flow and Vessel Wall Dynamics: Applications, Methods and Future Directions

“…More recently, Figueroa et al used image-based modeling techniques to demonstrate that, because all abdominal and thoracic aortic aneurysms are asymmetric and non-planar and many are tortuous, the dominant forces causing stent graft migration act in the lateral not longitudinal directions. 34,35 These results provide an explanation for the observed lateral movement of stent grafts into the aneurysm sac in some patients. 115 …”

Reporting standards for thoracic endovascular aortic repair (TEVAR)

“…Anatomy-Identify location in ascending, arch, or descending aorta, or use a standard classification scheme (eg, Stanford, DeBakey) -Include as much precision on length, location, and involvement of aortic branches as possible Etiology-Spontaneous dissection due to hypertension, Marfan syndrome, or other connective tissue disorder, or traumatic dissection (blunt, sharp, iatrogenic) Time course-Acute or chronic, using 14-day criterion 42 appropriate for aortic diverticulum (eg, Kommerell's diverticulum) but should be accompanied by a brief anatomic description to make the pathology clear, as well as associated abnormalities such as right-sided aortic arch and aberrant anatomy of other arch vessels. When multiple types of pathology coexist and are pertinent to repair, such as dissection with a corresponding aneurysm, the primary pathologic entity should be designated in addition to describing other pertinent pathology.…”

Initial clinical experience with a new low-profile thoracic endograft

“…Moreover, as mentioned before, vector forces act on the endograft as if "pushing" the proximal end and "pulling" the distal end into the aneurysm, resulting in either late proximal or late distal type I endoleaks. 27 These types of endoleaks were fairly common in short, single endograft implants using first-generation devices; however, long-term experience with TX2 devices deployed in a two-piece modular configuration has shown low migration rates and good adaptation of the devices to the modified aortic anatomy. 28 The proximal bare stent has a 15-mm length and six apices (in a 34-mm graft) with an apical radius of 3.75 mm (rounded apex).…”