Endovascular Stent-Graft Placement for Vascular Failure of the Thoracic Aorta

It still remains undetermined whether endovascular stent-graft placement (ESGP) is the optimal initial treatment for elective cases of thoracic aortic disease because of unknown long-term results. However, it is also recognized that ESGP contributes to better outcome as an initial treatment for aortic emergency, such as rupture, aortic injury, and complicated acute type B aortic dissection. Despite the fact that most patients are elderly, early mortality rates of ESGP are reportedly around 10% in cases of ruptured degenerative thoracic aortic aneurysm. Postoperative morbidity is also superior in ESGP compared with conventional open repair. Postoperative paraplegia has rarely occurred with ESGP. In cases of blunt aortic injury (BAI), other complications may also be present because of other serious injuries. ESGP has changed the surgical strategy for BAI and partially resolved some of the clinical dilemmas. Early mortality rate is almost zero when a stent graft can be placed before re-rupture. While BAI is a very good indication for ESGP, young patients need careful management and attention because of the unknown long-term outcome. In cases of complicated acute type B aortic dissection, the two main determinants of death, shock from rupture and visceral ischemia, could be managed by ESGP with or without conventional endovascular interventions. Recent reports disclosed less than 10% early mortality with ESGP for complicated acute aortic dissection. Even if the possibility of endotension remains, ESPG seems to be beneficial for these critical patients as the preferable initial treatment. The importance of close follow-up should be stressed to avoid some devastating late complications following ESGP

合併症を有するB型大動脈解離に対するステントグラフト内挿術における腎動脈に対する治療戦略 : 多施設共同研究

Background: Management of abdominal branches associated with Stanford type B aortic dissection is controversial without definite criteria for therapy after thoracic endovascular aortic repair (TEVAR). This is in part due to lack of data on natural history related to branch vessels and their relationship with the dissection flap, true lumen, and false lumen. Purpose: To investigate the natural history of abdominal branches after TEVAR for type B aortic dissection and the relationship between renal artery anatomy and renal volume as a surrogate measure of perfusion. Materials and Methods: This study included patients who underwent TEVAR for complicated type B dissection from January 2012 to March 2017 at 20 centers. Abdominal aortic branches were classified with following features: patency, branch vessel origin, and presence of extension of the aortic dissection into a branch (pattern 1, supplied by the true lumen without branch dissection; pattern 2, supplied by the true lumen with branch dissection, etc). The branch artery patterns before TEVAR were compared with those of the last follow-up CT (mean interval, 19.7 months) for spontaneous healing. Patients with one kidney supplied by pattern 1 and the other kidney by a different pattern were identified, and kidney volumes over the course were compared by using a simple linear regression model. Results: Two hundred nine patients (mean age ± standard deviation, 66 years ± 13; 165 men and 44 women; median follow-up, 18 months) were included. Four hundred fifty-nine abdominal branches at the last follow-up were evaluable. Spontaneous healing of the dissected branch occurred in 63% (64 of 102) of pattern 2 branches. Regarding the other patterns, 6.5% (six of 93) of branches achieved spontaneous healing. In 79 patients, renal volumes decreased in kidneys with pattern 2 branches with more than 50% stenosis and branches supplied by the aortic false lumen (patterns 3 and 4) compared with contralateral kidneys supplied by pattern 1 (pattern 2 vs pattern 1: −16% ± 16 vs 0.10% ± 11, P = .002; patterns 3 and 4 vs pattern 1: −13% ± 14 vs 8.5% ± 14, P = .004). Conclusion: Spontaneous healing occurs more frequently in dissected branches arising from the true lumen than in other branch patterns. Renal artery branches supplied by the aortic false lumen or a persistently dissected artery with greater than 50% stenosis are associated with significantly greater kidney volume loss.博士（医学）・乙第1461号・令和2年6月30日Copyright © 2019 by authors and RSNA. This work is licensed under the Creative Commons Attribution International License (CC BY-NC-ND 4.0). https://creativecommons.org/licenses/by-nc-nd/4.0/

Mixed Chimerism Achieved by a Nonlethal Conditioning Regimen Induces Donor-Specific Tolerance to Lung Allografts

Graft rejection and toxicity associated with chronic immunosuppressive therapy remain a major problem in lung transplantation (Tx). Mixed hematopoietic chimerism has been shown to produce long-lasting donor-specific transplant tolerance without immunosuppressive drugs in animal models; however, most conditioning regimens required to achieve mixed chimerism are too toxic for clinical use. The aim of this study was to develop a nonlethal conditioning regimen to induce tolerance to lung allografts. Four to 6-wk old ACI (RT1.A a) and Wistar Furth (RT1.A u) rats were used as organ donors and recipients, respectively. The recipient conditioning regimen included: 10 mg/animal antilymphocyte globulin (on day-5), 1 mg/kg/d tacrolimus (days 1 to 10), total body irradiation (500 cGy; day 0), and donor bone marrow (DBM) Tx (100 × 10 6 T-cell depleted cells on day 0 following irradiation). Six weeks after DBM Tx, chimeric animals received orthotopic left lung Tx. Graft survival was monitored by chest X-ray and histology. Long-term DBM engraftment was observed: hematopoietic chimerism in the peripheral blood was 12.4 ± 3.4%, 36.7 ± 14.1%, and 31.9 ± 14.1% at 30 d, 6 mo, and 16 mo following DBM Tx, respectively. There was no graft versus host disease. Chimeric recipients (RT1.A u) permanently accepted (>400 d) donor-specific lungs (RT1.A a; n = 8), yet rapidly rejected (<8 d) third party hearts (RT1.A l; n = 5). Graft (lung) tolerant (>150 d) chimeric recipients accepted secondary donor-specific heart grafts (>150 d; n = 4) but rejected third party heart grafts (<7 d; n = 3). Graft tolerant recipients demonstrated reduced ( P < 0.05) in vitro donor-specific lymphoproliferative response and cytotoxicity, and no evidence of acute or chronic graft rejection. Mixed chimerism achieved by a nonlethal conditioning regimen induced long-term donor-specific tolerance to lung allografts