Comments regarding ‘Endovascular Stent-graft Treatment for Stanford Type A Aortic Dissection’

Abstract

It was only a matter of time before vascular surgeons attempted to treat type A aortic dissections using endovascular techniques. There is a clear need for a different approach to reduce mortality of standard surgical techniques. Only a proportion of patients with acute Type A dissection are offered surgery and for the fittest that are, recovery to pre-morbid health status is far from assured.1Rampoldi V. Trimarchi S. Eagle K.A. Nienaber C.A. Oh J.K. Bossone E. International Registry of Acute Aortic Dissection (IRAD) Investigators et al.Simple risk models to predict surgical mortality in acute type A aortic dissection: the International Registry of Acute Aortic Dissection score.Ann Thorac Surg. 2007 Jan; 83: 55-61Google Scholar The current series incorporates a mixed bag of patients with different pathologies, some of whom have classic acute type A dissection with an entry tear in the ascending aorta. Others had tears in the descending or arch of the aorta with retrograde extension. The study builds on previous sporadic cases of endovascular repair of type A dissection and the more commonly stent-grafted type B dissection.2Zimpfer D. Czerny M. Kettenbach J. Schoder M. Wolner E. Lammer J. Treatment of acute type a dissection by percutaneous endovascular stent-graft placement.Ann Thorac Surg. 2006; 82: 747e9Google Scholar Outcomes in the study were encouraging but significant challenges remain. Current classifications (Stanford, DeBakey) are helpful in the prognostication and management of dissections confined to the ascending and/or descending aorta. Confusion and uncertainty exists in the arch where these standard classification systems are less helpful. The advent of endovascular techniques are likely to further challenge the relevance of traditional classifications. Ultimately more appropriate schemes are required to help define management of dissections in the arch and the indications and timing of endovascular repair. As the authors have acknowledged imaging of the ascending and arch of the aorta is particularly important to define the location of the primary entry tear. Standard CT imaging is insufficient. Transoesophageal echocardiography or multidetector and cardiac gated CT improve visualization of the entry tear and their relationship to the coronary arteries and supra-aortic trunks. Preliminary European data suggest that half of patients undergoing open surgical repair would have been morphologically suitable for an endovascular repair.3Sobocinski J. O’Brien N. Maurel B. Bartoli M. Goueffic Y. Sassard T. et al.Endovascular approaches to acute aortic type A dissection: a CT-based feasibility study.Eur J Vasc Endovasc Surg. 2011; 42: 442-447Google Scholar The length and diameter of the proximal landing zones and competency of the aortic valve are key in assessing suitability. To increase this proportion further it is likely that either a hybrid approach will be required or stent-grafts manufactured which incorporate a new aortic valve or permit flow in to the coronary arteries and supra-aortic trunks. Total endovascular solutions are likely to be some years off yet. Questions remain regarding the most appropriate technique to deliver and deploy stent-grafts in the aortic arch. Femoral access is more convenient but supra-aortic trunks offer a more direct approach. Stroke is a significant risk with either approach. In contrast to the present authors, many find pacing the heart a more reliable solution to permit accurate stent-graft deployment rather than simply lowering the blood pressure. Aortic stent-grafts in current use were designed with aneurysms and the abdominal aorta in mind. They are generally rigid with high radial strength and poor conformability, characteristics which are not particularly suited to acute dissections with fragile membranes. Located in the arch, where forces and movement are considerable, these stent-grafts are going to have issues regarding durability. At present endovascular management of type A dissection must be regarded as experimental until the current limitations of technology can be surmounted and surgeons gain a better grasp of the indications, limitations and complications of the technique. It should only be employed in those patients turned down for conventional surgery as part of a properly conducted clinical trial or registry. Nevertheless, this technique represents a new and exciting chapter in the evolution of vascular surgery. Endovascular Stent-graft Treatment for Stanford Type A Aortic DissectionEuropean Journal of Vascular and Endovascular SurgeryVol. 42Issue 6PreviewThe aim of the study is to summarise our experience of endovascular stent grafting for Stanford type A aortic dissection. Full-Text PDF Open Archive