Fracture of the connecting bar of a stent graft in the thoracic aorta: a diagnosis by echocardiography

Computational investigation of interaction between stent graft and aorta in retrograde type A dissection after thoracic endovascular aortic repair for type B aortic dissection

OBJECTIVE

Retrograde type A dissection (RTAD) after thoracic endovascular aortic repair (TEVAR) has been a major drawback of endovascular treatment. To our knowledge, no studies have evaluated aortic injuries caused by stent grafts (SGs). Therefore, the aim of this study was to evaluate and to quantify the SG-aorta interaction and to analyze the risk factors for injury through computational simulation.

METHODS

The aortic geometry was extracted from an RTAD case. Five SG models were assembled based on Valiant and Talent (Medtronic Vascular, Santa Rosa, Calif) SGs, and modifications were made to the original SG design by adding and removing the connecting bar. TEVAR simulations were performed seven times for each SG model with 0% and 15% oversizing ratio (OSR), and the maximum aortic stress (MAS) was calculated and compared within the groups.

RESULTS

In all TEVAR models, MAS was seen at the proximal bare stent (PBS). The PBS in the Valiant and Talent SGs generated higher stress toward the aortic wall than other SG parts did. MAS was significantly higher for the 15% OSR (0.54 ± 0.07 MPa) than for the 0% OSR (1.32 ± 0.74 MPa) in 172.5-mm Valiant models. MAS was significantly higher in the Talent with connecting bar SG model (0.73 ± 0.24 MPa) than in the Talent without connecting bar SG model (0.51 ± 0.11 MPa). MAS was significantly higher in the Valiant with connecting bar SG model (0.82 ± 0.29 MPa) than in the Valiant without connecting bar SG model (0.54 ± 0.07 MPa). MAS was not significantly different in models with 172.5-mm and 140-mm Valiant SG implantations with 0% OSR (0.54 ± 0.07 MPa vs 0.60 ± 0.12 MPa) and 15% OSR (1.32 ± 0.74 MPa vs 1.12 ± 0.33 MPa).

CONCLUSIONS

The characteristic MAS distribution remained at the location where the apexes of the PBS interacted with the aortic wall at its greater curve. Both higher OSR and the presence of a connecting bar can significantly increase the MAS after SG implantation. Moreover, the chronic MAS at the PBS area may injure the aortic wall, causing RTAD.

Multidetector CT findings of complications of surgical and endovascular treatment of aortic aneurysms

Aortic aneurysms remain a significant problem in the population, and there is a concerted effort to identify, define, image, and treat these conditions to ultimately improve outcomes. The rapid development of diagnostic modalities, operative strategies, and endovascular techniques within the realm of this aortic disease has transformed the field and broadened the spectrum of patients that can be treated with minimally invasive techniques. This investigation has a broad spectrum of normal expected findings that must be differentiated from early or late complications in which intervention is required. In this article, normal and abnormal postoperative and post-TEVAR/EVAR MDCT findings are described.

Unusual complications of endovascular repair of the thoracic aorta: MDCT findings

With the development of minimally invasive surgical techniques, endovascular stent-graft placement has become an accepted and widely used alternative to the traditional surgical repair of aortic disease and is gaining acceptance as the treatment of choice. Many studies show that endovascular stent-graft therapy is safe and effective, although complications related to this treatment are also recognised. Although the incidence of major complication is low, neurological sequelae remain the major concern of endovascular repair. With growing experience, however, the spectrum of mid- and long-term complications has broadened to include potentially disastrous events, other than paraplegia or stroke, that require diligent surveillance. Three-dimensional data sets acquired quickly by multidetector computed tomography (MDCT) allow multiplanar reformations and 3D viewing, as well as quantitative assessment of vessel lumens, walls and surroundings. Although a large portion of radiologists will not be involved in the actual endograft deployment, many will be involved in the interpretation of postprocedural surveillance studies. Accordingly, the goal of this report is to summarise our experience with the presentation, diagnostic approach, management and outcomes of these unusual, but potentially catastrophic, postendovascular aortic repair complications to highlight their significance and increase familiarity with them among the imaging community. Increasing awareness of these complications may facilitate rapid diagnosis and/or triage and treatment.

Endovascular repair of thoracic stent-graft bulging rupture in a patient with multiple thoracic aneurysms due to Takayasu disease

Isolated aortic aneurysms in Takayasu arteritis (TA) are rare. Reported operative mortality and operative complication rates seem low, with an infrequent need for surgical revision, even though most reports concern occlusive disease. Treatment of aneurysms in TA requires therapeutic strategies that are different from the ones used for atherosclerotic vessel dilatations because the pathology and the extensive, progressive, relapsing nature of the disease are deeply different from the atherosclerotic process. We report a case of thoracic stent-graft bulging rupture, a device previously implanted to exclude a thoracic aneurysm, associated with two small aneurysms near the distal implantation site. Both were treated with three new-generation stent grafts implanted in a telescope fashion.