Yoshihiko Yokoi

Thoracic endovascular aneurysm repair in Japan: Experience with fenestrated stent grafts in the treatment of distal arch aneurysms

OBJECTIVES In the West, stent grafts for endovascular repair of thoracic aortic aneurysms have been commercially available for several years, whereas in Japan, a manufactured stent graft was not approved for this application until March 2008. Nevertheless, endovascular thoracic intervention began to be performed in Japan in the early 1990s, with homemade devices used in most cases. Many researchers have continued to develop homemade devices. We have participated in joint design and assessment efforts with a stent graft manufacturer, focusing primarily on fenestrated stent grafts used in repairs at the distal arch, a site especially prone to aneurysm. METHODS From 1995 to February 2008, we performed about 1100 endovascular procedures to treat thoracic aortic aneurysms and 682 cases were performed at Tokyo Medical University. In 435 out of 682 the aneurysm was located in the area from the distal arch to the proximal descending aorta. Fenestrated stent grafts were inserted in 288 cases. Computed tomography scans were performed at 3, 6, and 12 months postoperatively and annually thereafter. RESULTS The initial success rate in the entire series was 95.2%. Complications included 26 cerebral infarctions (3.8%), six of which (0.9%) resulted in serious paralysis and changes in consciousness. Among patients who received fenestrated stent grafts, paraplegia occurred in 2.6%, aortic injury in 1.2%, and iliofemoral artery injury in 6.0%. No complications resulted from occlusion of aortic arch branches. At >/=2 years after intervention, aneurysm diameter was reduced in 62% of patients, 33% had no change, and 5% had a diameter enlargement. The stent graft complication rate during follow-up was 8.4%, the device fracture rate was 1.4%, and the device migration rate was 7%. The 5-year survival rate was 62.4%, with follow-up in 96.8% of the patients. CONCLUSION Endovascular repair has promising results in the descending thoracic aortic region, although some stent grafts and their delivery systems can still be improved. Additional commercial developments and available stent grafts designed for use in the distal arch are urgently needed.

Blood coagulation and fibrinolytic response after endovascular stent grafting of thoracic aorta.

OBJECTIVE Thrombosis is common in aneurysms immediately after stent-grafting, because of exclusion from systemic blood flow. We studied changes in blood coagulation and the fibrinolytic system in patients with thoracic aortic aneurysm or dissection after stent-grafting to examine risk for consumption coagulopathy. METHODS Thirty-one thoracic aortic aneurysms were treated with stent-grafting (aneurysm group), and 29 aortic dissections were treated with entry closure with stent-grafting (dissection group). The stent-graft was constructed from a self-expanding Z stent and thin-walled woven polyester fabric. Platelet count, fibrinogen, antithrombin III (AT III), and thrombin-AT III complex were assayed as markers of coagulation. Plasminogen, alpha(2)-plasmin inhibitor, alpha(2)-plasmin inhibitor-plasmin complex, fibrin degradation products fragment E (FDP-E), and fibrin degradation products d-dimer were monitored as markers of fibrinolysis. Blood samples were collected before surgery and on postoperative days 1, 3, 7, and 14. RESULTS In both groups platelet count significantly decreased on postoperative days 1 and 3, and increased on postoperative day 14. AT III significantly decreased on postoperative day 1, but recovered after postoperative day 7. FDP-E significantly increased on postoperative day 1 in both groups. There was significant correlation of aneurysm diameter with alpha(2)-plasmin inhibitor-plasmin complex, fibrin degradation products, and d-dimer in the dissection group on postoperative day 1. CONCLUSIONS Activation of coagulation and fibrinolysis was observed after stent-grafting to treat thoracic aortic aneurysm and aortic dissection. However, no patients exhibited consumption coagulopathy postoperatively. Therefore we believe there is little risk for consumption coagulopathy after stent-grafting.

The next generation of fenestrated endografts: results of a clinical trial to support an expanded indication for aortic arch aneurysm treatment

OBJECTIVES Short- and mid-term data regarding the use of precurved, fenestrated endografts have shown that these devices are both safe and effective in carefully selected patients. The first generation of the product was limited to patients with proximal landing zones (LZs) of >20 mm. The next generation of these endografts has been refined to enable the treatment of patients with shorter proximal seal zones (<20 mm), using smaller fenestrations and a greater diversity of skeletons. We reviewed the clinical studies involving the next-generation product and analysed the morphological characteristics of aortic arch aneurysms that were successfully treated. METHODS Next-generation endografts were used to treat 393 patients with aortic arch aneurysms at 35 medical institutions during 2010 and 2011. There were 371 (94%) patients with sealing zones <20 mm and 244 (62%) with sealing zones <15 mm. The proximal sealing length was 2-35 (14.2 ± 5.1) mm. RESULTS Technical success was achieved in 390 (99.2%) patients. Of the treated patient population, 6 patients died, 7 experienced strokes and 17 were subsequently identified to have Type I endoleaks. In cases with proximal LZs <15 mm, the aneurysm was more likely to develop an endoleak. The proximal sealing zones (11 ± 12 vs 9 ± 13 mm) were not significantly associated with the development of endoleaks, but the proximal aortic diameters were (34.0 ± 13.3 vs 36.6 ± 6.3 mm; P < 0.01), in the univariate analysis. In the discriminant analysis, the maximum length of the aneurysm was the only factor that was predictive of Type I endoleaks (73 ± 55 vs 97 ± 59 mm; P < 0.001). CONCLUSIONS The next generation of precurved, fenestrated endografts shows promise as devices for aortic arch aneurysms with a <15-mm proximal sealing zone. These devices have a significant advantage in cases where the LZ has a short neck. However, more refinement is necessary to prevent Type I endoleaks, so that these devices can be used with aortic vessels with large proximal diameters and large aneurysms.

Endovascular repair of ascending aortic rupture: effectiveness of a fenestrated stent-graft.

Purpose: To present a technique for endovascular treatment using a fenestrated stent-graft in a patient with ascending aortic rupture in the setting of methicillin-resistant Staphylococcus aureus infection. Case Report: A 62-year-old woman had undergone mastectomy and radiotherapy twice for breast cancer and then coronary artery bypass grafting (CABG). She developed sternal osteomyelitis 5 years after the CABG. Sternectomy and negative-pressure wound drainage were performed, but the infection did not resolve. Ascending aortic rupture occurred 5 months after sternectomy. Endovascular therapy was considered the only effective means of achieving hemostasis. A custom-designed fenestrated stent-graft was deployed from the ascending aorta to the proximal descending aorta via a femoral artery approach without transient cardiac arrest. Bleeding completely stopped after surgery. The postoperative course was uneventful, and the inflammatory activity subsided on antibiotic therapy. At 7 months after surgery, the patients recovery has been uneventful. Conclusion: Rupture of the ascending aorta associated with infection was successfully treated by stent-graft repair. The use of a custom-made, fenestrated stent-graft was an effective, lifesaving procedure for the management of this ascending aortic lesion.

Clinical results of endovascular stent graft repair for fifty cases of thoracic aortic aneurysms

Between February 1995 and December 1997, 50 cases (55 lesions) of thoracic aortic aneurysms including 20 cases of aortic dissections were treated with an endovascular technique using the stent grafts. All patients were treated in the operating room under general anesthesia and the stent grafts were implanted through 18 Fr. or 20 Fr. sheaths via femoral arteries under fluoroscopic guidance. The stent graft was composed of several units of self-expanding stainless-steel Z stents covered with an ultra-thin polyester fabric. Stent graft deployment was technically successful in 53 of 55 lesions (delivery success rate: 96.4%). Exclusion of the aneurysms and entry closing without endoleak were achieved within two weeks after the operation in 43 of 53 lesions (initial success rate: 81.1%). Endoleak was found in 10 lesions (minor endoleak: 8 and major endoleak: 2 lesions). Two patients died in the periopertive period of delivery failures as injury to external iliac artery and damage to the delivery sheath caused by tortuous and narrow access routes. Endovascular stent graft repair of thoracic aortic aneurysms is minimally invasive operation in comparison with conventional surgical graft replacement with extracorporeal circulation. These early results suggest that the stent graft repair is possibly safe and useful treatment for the patients of thoracic aortic aneurysms especially in high risk patients. However, careful long-term follow-up is necessary to prove the value and the effects of this endovascular treatment and improvement of the stent graft system and technical training of endovascular surgery for operators are required to reduce the delivery failure and to determine the stent graft repair is reliable treatment.

Usefulness of fenestrated stent grafts for thoracic aortic aneurysms

OBJECTIVES Endovascular stent grafts (SGs) comprise a novel therapeutic approach to repairing aortic aneurysms. However, endovascular repair of the aortic arch remains challenging. Generally, the repair of sites with SGs requires an extra-anatomical bypass. We introduced SG repair of the aortic arch with strategically positioned fenestrations for each arch branch in 2006. An extra-anatomical bypass is not required for this procedure. This study evaluates the early and mid-term outcomes of fenestrated SG treatment. METHODS We retrospectively analysed the early and mid-term outcomes of 24 of 80 repairs with fenestrated SG among 383 single thoracic aortic aneurysm repairs that were undertaken at our department between January 2006 and March 2012. RESULTS Technical success was obtained in 100% of the patients. However, there was a 30-day perioperative mortality rate of 4.1% (1 of 24) due to a shower embolism. One patient developed a Type 2 endoleak without aneurysm enlargement within a median follow-up time is 25.1 months. However, migrations or device-related complications requiring additional procedures did not arise. CONCLUSIONS Treatment with fenestrated SGs does not require surgical transposition of the arch branches. The procedure is widely applicable and less invasive and outcomes are excellent.

A fenestrated stent graft for endovascular repair of an ascending aortic pseudoaneurysm.

Endovascular stent grafting is a novel therapeutic technique for repairing aortic aneurysms, and is especially useful for descending aortic aneurysm and aneurysm at the distal arch. However, no effective endovascular approach for the ascending aorta has been reported a remaining site for endovascular repair because of the anatomical restrictions and the presence of vital branches to the head and arms that are present in this region. This report describes an endovascular stent graft repair of a pseudoaneurysm at the ascending aorta using a fenestrated stent graft. The fenestrated stent graft is easy to use and less invasive for the endovascular repair of the ascending aorta.

Celiac artery coverage after occlusion test during endovascular stent grafting for thoracoabdominal aortic aneurysm

Previous investigators have reported favorable results with endovascular repair of thoracoabdominal aortic aneurysms by occlusion of the celiac artery (CA). Verification of collateral blood flow to the CA, however, is important to prevent postprocedural ischemic changes in the liver, stomach, and intestines. We describe the use of a CA occlusion test to investigate the collateral blood flow from the superior mesenteric artery (SMA) to the CA in a patient undergoing endovascular stent grafting for a thoracic and thoracoabdominal aortic aneurysm.

Successful treatment of multiple mycotic aortic aneurysms, using a hybrid procedure.

No generally accepted treatment of multiple mycotic aortic aneurysms of the thoracic and abdominal aorta has yet been established. We report a 67-year-old man with widespread mycotic aortic aneurysms previously treated for malignant lymphoma and interstitial pneumonia. He was successfully treated by a two-stage hybrid surgical procedure comprising open and endovascular methods. This is apparently the first report of repair of multiple mycotic aortic aneurysms using a hybrid procedure.

An innovative exclusion technique for ductus arteriosus with a novel stent graft.

A 72-year-old woman who had a patent ductus arteriosus that was anatomically unsuitable for catheter coiling was treated with a pre-curved fenestrated stent graft. This graft was custom-made to configure the patient’s whole aortic arch, and was capable of accurately adjusting its fenestrations to the arch branch orifices. The advantage of this fenestrated stent graft is close sealing, especially on the lesser curvature of the arch. This device could be an excellent option to treat an otherwise normal aortic arch with such a localized lesion.