SCOTTSDALE, Arizona (EGMN) –Surgeons have been pushing the boundaries of thoracic endovascular aortic repair to treat patients not covered in the instructions for use of thoracic endografts, a strategy that appeared to greatly increase the risk of treatment failure in a study of 303 patients.

Since the first thoracic stent-graft was approved in 2005 to treat aneurysm disease, surgeons have broadened the use of thoracic endovascular aortic aneurysm repair (TEVAR) to treat nonaneurysm aortic pathologies, according to Dr. Peter H. Lin.

He and his associates reviewed data on 284 successful TEVAR procedures and 19 failed TEVARs that required endograft removal to identify risk factors for failure. TEVAR failures were 12 times more likely in patients with a connective tissue disorder than in those without the disorder; 8 times more likely in patients with acute aortic dissection, compared with patients treated for other indications; and 5 times more likely when surgeons did not follow instructions for use when implanting the device, he said at the annual meeting of the Society for Clinical Vascular Surgery.

Neither connective tissue disorders nor acute aortic dissections are covered by the instructions for use of the three thoracic endograft instructions currently on the market, said Dr. Lin, chief of the division of vascular surgery and endovascular therapy at Baylor College of Medicine, Houston. When surgeons failed to follow instructions for device implantation, they most commonly implanted a device that was undersize for the patient or proceeded despite having an inadequate surgical landing zone, he added.

“We were surprised to see that, in patients who had concomitant aortic dissection and connective tissue disorders, the mean duration of implantation was 2 weeks before explantation was needed,” Dr. Lin said.

Four years after initial implantation, only seven patients (36%) in the explanted group were alive, compared with 86% of the successful TEVAR group. Nearly half of the patients who died had both aortic dissection and a connective tissue disorder.

“The simple take-home message from this study is that if you follow the instructions for use (IFUs) based on the FDA [Food and Drug Administration] or manufacturer recommendations, this is a fantastic treatment strategy,” he said. “If you want to apply this technology in patients outside the IFU treatment indications, you’ve got to be very careful. Beyond that, TEVAR should be avoided in patients with dissection and connective tissue disorders, as catastrophic complications can occur.”

The data came from successful TEVAR procedures at his institution during a 7-year period (July 2002 to April 2009) plus endograft removals performed there for 5 patients who originally underwent TEVAR at his institution and 14 patients who were transferred there from outside institutions after TEVAR failure. Patient characteristics did not differ significantly between the successful and failed TEVAR groups.

Connective tissue disorder was present in seven explant patients (37%), compared with 2% of the successful TEVAR group – the only comorbidity to differ significantly between groups. Rates of two treatment indications differed significantly: descending thoracic aortic aneurysm in nine explant group patients (47%) and 263 patients (93%) in the successful TEVAR group; and aortic dissection in seven explant group patients (37%) and 22 patients (7%) in the successful TEVAR group.

Among patients in the explant group, the average time from implantation to explantation was 8.7 months in three patients with aortic dissection, 2 weeks in the four patients with aortic dissection plus connective tissue disorder, 3.5 months in three patients with thoracic aortic aneurysm and connective tissue disorder, and 14 months in four patients with device infection.

The reasons for explantation included aortic thrombosis because of device migration in three patients, visceral malperfusion in nine, retrograde aortic dissection in three, aneurysm expansion in two, and device infection in five patients. (Some patients had more than one indication for explantation.)

Most complications occurred when only one thoracic stent-graft was approved, before two slightly larger ones reached the market in 2009, Dr. Lin said. CT scans of the TEVAR failures indicated that some surgeons implanted the device in patients who lacked the recommended aortic diameter or landing zone.

“They pushed the envelope a little further and put in a device hoping that it would seal. In the end, it didn’t. That led to device migration and aortic thrombosis,” Dr. Lin said.

Surgeons selected the device based on the instructions for use in 9 patients (47%) in the explant group and in 247 patients (87%) in the successful TEVAR group, a significant difference. Among device selections that were not based on the instructions for use, 5 patients (26%) in the explant group and 9 (3%) in the successful TEVAR group were undersize devices, 1 (5%) in the explant group and 7 (2%) in the successful TEVAR group were oversize, and 4 (21%) in the explant group and 21 (7%) in the successful TEVAR group had inadequate landing zones.

The study excluded patients who received TEVAR with the endograft extending into the aortic arch, requiring an innominate/carotid bypass. It also excluded patients in whom the endograft was implanted in the aortic arch via an elephant trunk reconstruction, and patients with visceral bypass for thoracoabdominal aortic aneurysm.

The investigators had no financial conflicts related to the study, Dr. Lin reported.

Copyright (c) 2009 Elsevier Global Medical News. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

亚利桑那州斯科茨代尔(EGMN)——一项纳入303例患者的研究显示，外科医生们一直在扩大胸主动脉腔内修复术的适用范围，并已将其用于治疗那些未包含在胸主动脉覆膜支架使用说明书范围内的患者，而该策略似乎极大地增加了治疗失败的风险。

 

自从2005年覆膜支架被首次批准用于治疗动脉瘤类疾病以来，外科医生已经将胸主动脉瘤血管腔内修复术(TEVAR)的使用范围扩展到用于治疗非动脉瘤类动脉病变，据Peter H. Lin博士说。

 

他及其同事对284例成功的和19例失败的(需要取出覆膜支架以确定手术失败的危险因素) TEVAR手术的相关数据进行了回顾。对患有结缔组织疾病的患者而言，其进行TEVAR手术的失败风险比未患该病的患者高出12倍。与那些因其他适应证而接受该手术治疗的患者相比，急性主动脉夹层患者的手术失败风险要高出8倍。如果外科医生在植入该设备时不遵守使用说明，则患者手术失败的风险要高出5倍，他在美国血管外科学会年会上发言说。

 

在目前上市的3种胸主动脉覆膜支架的使用说明书中既未包含结缔组织疾病，也未包含急性主动脉夹层，休斯顿市贝勒医学院血管外科与血管内治疗学系主任Lin博士说。当外科医生未能遵守该设备的植入操作指南时，发生的最常见情况是其为患者植入的设备尺寸过小，或是尽管完成了手术，但所植入设备的着陆空间不足，他补充说。

 

 “我们很惊讶地发现，对那些伴发主动脉夹层和结缔组织疾病的患者而言，在其需要将该设备移除前，其移植的平均持续时间为2周，” Lin博士说。

 

在最初的移植手术进行4年后，在设备移除组仅有7例患者(36%)存活，与之相比，在TEVAR手术成功组有86%的患者存活。近乎有一半的死亡患者同时患有主动脉夹层及结缔组织疾病。

 

 “该研究最关键的基本信息在于，如果你遵循基于FDA(美国食品药品管理局)要求或制造商建议的使用说明(IFU)，这将是一种极好的治疗策略，”他说“如果你想要将该技术用于IFU治疗适应证之外的患者，那么你就必须非常小心。除此之外，应该避免对患有主动脉夹层和结缔组织疾病的患者施行TEVAR手术，因为其有可能发生极其严重的并发症。”

 

该研究的数据来源于下述患者：在7年时间内(2002年6月~2009年4月)于研究者所在的机构成功施行TEVAR手术的患者，外加那些在此接受了覆膜支架移除术的患者，后者包括5例最初在该机构进行TEVAR手术的患者和14例TEVAR手术失败后从他处转诊至此的患者。

 

有7例接受设备移除术的患者存在结缔组织疾病(37%)，与之相比，在TEVAR手术成功组该数据仅为2%，该疾病是两组患者间存在显著差异的唯一合并症。两组患者的治疗适应证的构成比例也存在显著差异：设备外植组患有胸降主动脉动脉瘤的患者有9例(47%)，TEVAR手术成功组此类患者仅有263例 (93%)；外植组存在主动脉夹层的患者有7例(37%)，TEVAR手术成功组此类患者仅有22例(7%)。

 

在外植组的患者中， 3例存在主动脉夹层的患者从设备植入到取出的平均时间为8.7个月，其在同时患有主动脉夹层加结缔组织疾病的4例患者中为2周，在患有胸主动脉瘤和结缔组织疾病的3例患者中为3.5个月，在存在设备感染的4例患者中为14个月。

 

进行外植手术的原因包括：3例患者因设备移位诱发了动脉血栓形成，9例患者内脏血流灌注不足，3例患者存在逆行性主动脉夹层，2例患者存在动脉瘤扩张，还有5例患者出现了设备感染(有些患者存在不止一种外植手术适应证)。

 

患者出现这些并发症的时间大多在2009年2类尺寸稍大的支架进入市场前，当时仅有一种胸主动脉覆膜支架获得了批准，Lin博士说。对TEVAR手术失败患者进行的计算机断层扫描(CT)表明，某些外科医生对动脉直径或支架着陆空间小于推荐值的患者植入了该设备。

 

 “他们将动脉腔挤开得更大一些，然后植入支架并期望其可以封闭破口。而最终这未能奏效。这会导致设备移位和动脉血栓形成，” Lin博士说。

 

在外植组中，有9例患者(47%)的外科医生在为其选用设备时遵守了使用说明，而在TEVAR手术成功组有247例患者(87%)满足该要求，这构成了显著差异。在未遵守使用说明就进行设备选择的情况下，在外植组和TEVAR手术成功组的患者中分别有5例 (26%)和9例存在设备尺寸过小，分别有1例 (5%)和7例(2%)存在设备尺寸过大，还分别有4例(21%)和21例(7%)存在支架着陆空间不足。

 

该研究排除了那些覆膜支架延伸至主动脉弓的TEVAR手术患者，其需要进行无名静脉/颈静脉搭桥术。其还排除了那些通过象鼻重建术将支架植入主动脉弓的患者，以及那些因胸腹部动脉瘤而进行器官搭桥术的患者。

 

Lin博士报告说，研究者们无与该研究相关的经济利害关系。

 

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