Schurink Geert Willem H, Nijenhuis Robbert J, Backes Walter H, Mess Werner, de Haan Michiel W, Mochtar Bas, Jacobs Michael J
Department of Vascular Surgery, University Hospital Maastricht, Maastricht, The Netherlands.
Ann Thorac Surg. 2007 Feb;83(2):S877-81; discussion S890-2. doi: 10.1016/j.athoracsur.2006.11.028.
In thoracic stent graft repair, the importance of segmental artery (SA) occlusion and the role of blood pressure management during the intraoperative and directly postoperative period are not clear. To study these aspects in relation to spinal cord ischemia, our protocol in the endovascular treatment of descending thoracic aneurysms covering segmental arteries T8 and lower includes preoperative assessment of the spinal cord circulation using magnetic resonance angiography, intraoperative cerebrospinal fluid drainage, and spinal cord function monitoring using motor evoked potentials (MEPs).
Thirteen patients with thoracic aortic aneurysms and dissections needing stent graft coverage of T8 and lower were included. In 9 patients, spinal cord circulation was evaluated preoperatively by magnetic resonance angiography. In 12 patients, MEPs were recorded during the endovascular procedure. A combination of both techniques was used in 8 patients.
The distal stent graft landing zone covered the intercostal arteries up to T10 in 4 patients, up to T11 in 7 patients, up to T12 in 1 patient, and all SAs to the aortic bifurcation in 1 patient. In 6 patients, the SA feeding the Adamkiewicz artery was covered by the stent graft. In three patients, intersegmental collaterals were present to the SA feeding the Adamkiewicz artery. The MEPs decreased to 50% and 30% in 2 patients, recovering to levels above 50% by elevation of the mean arterial pressure. Postoperatively, no signs of paraplegia were present.
We believe that the presence of intersegmental collaterals decreases the risk of spinal cord ischemia during endovascular thoracic aortic aneurysm repair. Monitoring of MEPs during endovascular thoracic procedures shows no decrease in most cases. However, if a decrease of MEPs occurs, this can be reversed by elevation of the mean arterial pressure.
在胸主动脉覆膜支架修复术中，节段动脉（SA）闭塞的重要性以及术中及术后即刻血压管理的作用尚不清楚。为了研究这些与脊髓缺血相关的方面，我们在治疗累及T8及以下节段动脉的降主动脉瘤的血管内治疗方案中，包括术前使用磁共振血管造影评估脊髓循环、术中脑脊液引流以及使用运动诱发电位（MEP）进行脊髓功能监测。
纳入13例需要对T8及以下节段进行支架覆膜治疗的胸主动脉瘤和夹层患者。9例患者术前通过磁共振血管造影评估脊髓循环。12例患者在血管内手术过程中记录MEP。8例患者同时使用了这两种技术。
远端支架覆膜区覆盖至T10肋间动脉的有4例患者，覆盖至T11的有7例患者，覆盖至T12的有1例患者，覆盖至主动脉分叉处所有节段动脉的有1例患者。6例患者中，供应Adamkiewicz动脉的节段动脉被支架覆膜。3例患者中，存在至供应Adamkiewicz动脉的节段动脉的节段间侧支循环。2例患者的MEP下降至50%和30%，通过升高平均动脉压恢复至50%以上。术后，无截瘫迹象。
我们认为节段间侧支循环的存在降低了血管内胸主动脉瘤修复术中脊髓缺血的风险。血管内胸主动脉手术过程中对MEP的监测在大多数情况下未显示下降。然而，如果MEP下降发生，可通过升高平均动脉压使其逆转。
