Case planning and preparation are critical for seamless TEVAR execution in aTBAD. IVUS is critical in finalizing the procedural plan, and avoids “flying blind” at any point.
Commentary
We congratulate Dr. Murana and colleagues on their detailed description of their center’s approach to the management of acute Type B aortic dissection (aTBAD). In a concise and clear fashion they have summarized their treatment algorithm of aTBAD, consisting of optimal medical therapy for uncomplicated aTBAD, and thoracic endovascular aortic repair (TEVAR) for uncomplicated with high risk features, or aTBAD cases complicated by malperfusion or rupture. They also provide the technical details of their utilization of a bare metal stent in the abdominal aorta for patients with involvement of the visceral segment (the so-called STABILISE technique). ,
We agree with the majority of the technical details of their TEVAR procedure, and acknowledge that subtle variations exist between surgeons and institutions when performing TEVAR for aTBAD. However, the lack of utilization of intravascular ultrasound (IVUS) in the authors’ operative technique is surprising and does not represent “best practice.” Our group strongly believes that IVUS is mandatory for the endovascular treatment of aTBAD. It provides confirmation of true lumen access and avoids wire crossover between true and false lumens at secondary fenestrations. Furthermore, it provides accurate intraoperative measurements of the aortic diameter and distances of the aorta, which may be significantly different than the preoperative CT scans, and assists in limiting radiation exposure and contrast use which is essential in the setting of aTBAD with renal malperfusion. The use of fluoroscopy and transesophageal echocardiography (TEE) is an inadequate substitute for IVUS, as this combination does not provide comprehensive imaging of the entire aorta. TEE is limited in imaging the aortic arch and abdominal aorta. Effectively this leads to a blind approach to wire placement in several critical areas of the aorta, which can lead to unintended consequences. Indeed, we have had to explant thoracic aortic stent grafts in a patient who underwent TEVAR for aTBAD without IVUS at an outside institution. In that case, the stent grafts crossed over in the distal descending thoracic aorta from true to false lumen, causing severe compression of the true lumen resulting in celiac and SMA malperfusion and chronic mesenteric ischemia (Central Picture). The importance of IVUS is underscored by the most recent Society of Vascular Surgery (SVS) guidelines which assigned a Grade 1 recommendation for the use of TEVAR in the treatment of descending thoracic aortic aneurysms.
As with other endovascular procedures, emphasis remains on case planning and preparation for safe and seamless execution, and we strongly believe that IVUS serves a critical role in finalizing the intraprocedural plan, and avoids “flying blind” at any point before and after endograft deployment. While the accompanying operative technique by Murana and colleagues may serve as a roadmap, we would propose incorporating IVUS to help light the way Figure 1 .
