Cath Lab Digest

I presented this topic during the recent ISET event (Figure 1), and I thought that further exposure and discussion were warranted, given the continuing relevance of the subject. While it is true that further clarity has been injected over the last few years, the matter remains largely unresolved. We could relatively easily find a number of international experts willing to defend the two extremes of the spectrum: on the one hand, there are those who maintain that the left subclavian artery (LSA) should be preserved essentially in all cases — all elective cases that is; on the other, there is a shrinking minority who still believes that LSA revascularization may be necessary in only a handful of instances — if at all. Between these two, we can probably find the vast majority of TEVAR operators today.

It is an important matter because of the ever-growing importance of TEVAR and the “promise” of larger numbers and better technologies yet to come. We are told it will revolutionize thoracic aortic surgery, and I believe it! Endograft proximal landing adjacent to or within the aortic arch is quite common, and Zone 2 (Figure 2) is a very frequent target site for proximal fixation and seal of the stent-graft device. Such a maneuver implies, of course, that the origin of the LSA will be covered and the vessel excluded from the aortic blood flow. Overstenting is another frequently used term to describe such a scenario. The potential consequences of LSA exclusion are well known and universally agreed upon (Figure 3). The real issue, though, is to identify (in a given case) those complications that may be likely to occur and could be prevented by revascularization performed prior to or at the time of TEVAR. Left arm ischemia is largely “inconsequential” in this regard because it can (almost) always be safely addressed later on with an elective carotid-subclavian or similar bypass operation. Hindbrain ischemia (and stroke) and paraplegia are of course in a different category. Recent evidence points to the fact that LSA revascularization may well be protective against spinal cord ischemia, but not so much to prevent brain ischemia or stroke (Ref. 1).

We are left, therefore, with a somewhat varied and ill-defined set of dangers that can be translated into indications for revascularizarion (Figure 4). While agreement and consensus escape us at this time, there is definitely an ongoing trend (among experts) in the direction of more and not less LSA revascularization in the context of TEVAR. Only one indication can be cited as mandatory for LSA revascularization and that is the patient who has a functional LIMA-coronary artery bypass. All the others are relative and more or less disagreed upon.

As to my own practice, I remain in the camp of selective (Figure 4) and not routine LSA revascularization, but I must admit to feeling increasingly inclined to preserve normal flow into the LSA rather than simple overstenting and exclusion. And this is especially so because of personal experience and growing confidence with chimney stents that can be used relatively easily and (mostly) percutaneously to maintain normal antegrade vessel patency (Figure 5). A similar technique is used at times for revascularization of the left common carotid artery in the same context. In the future, commercial off-the-shelf availability of branched endograft devices may well change some of these views and technical strategies.

Frank J Criado, MD, FACS, FSVM

Reference
1. Cooper DG, Walsh SR, Sadat U, et al. Neurological complications after subclavian artery coverage during thoracic endovascular aortic repair: A systematic review and meta-analysis. J Vasc Surg 2009;49:1594-601.

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Dr Frank J Criado is a Board-Certified Vascular Surgeon and Endovascular Specialist at the Union Memorial Hospital-MedStar Health in Baltimore, Maryland, USA.

Dr Criado is widely acknowledged to be a pioneer in endovascular therapy, with a 20-year + interventional experience. He has contributed extensively to the literature with more than 100 peer-review published articles – mostly on various vascular and endovascular subjects, and Editor-in-Chief of Vascular Disease Management (VDM). He has also been active in clinical research, with a major focus on aortic stent-graft and carotid interventions, and endovascular technologies in general. He was the National Principal Investigator (P.I.) for the Medtronic Talent AAA clinical trials in the U.S., and a member of the Executive Committee for the Medtronic Valor Thoracic trial.

He is a founding member and immediate past President of the International Society of Endovascular Specialists (ISES), founder and current President of the endovascular surgery society of Latinamerica (CELA), and a member of all major US and international vascular and endovascular societies. He is a Fellow of the American College of Surgeons (FACS) and of the Society of Vascular Medicine (FSVM), and a member of the Board of Directors of the Society for Vascular Surgery (SVS).