Ann Thorac Surg 2006;82:80
© 2006 The Society of Thoracic Surgeons
Original article: Cardiovascular
Invited commentary
Lars G. Svensson, MD, PhD
Marfan and Connective Tissue Disorder Clinic, The Cleveland Clinic Foundation, 9500 Euclid Ave, F25, Cleveland, OH 44195
(Email: svenssl{at}ccf.org).
In performing open aortic arch repairs, there are two main issues to consider: (1) the site of cannulation for hypothermic arrest, and (2) whether the antegrade brain perfusion will be adequate for neurologic safety if the arrest is not performed at deep hypothermic arrest (<20°C). If deep hypothermic arrest is planned, we have shown that the use of the right subclavian artery with a side graft reduces the risk of stroke by 40%. Furthermore, if antegrade brain perfusion is added to this through the inflow arterial line with balloon occlusion of the innominate and carotid arteries, it may also have some protective benefit for total arch replacements. Indeed we are studying this latter procedure in a randomized study of total arch replacements. Nonetheless, for hemi arch repairs, we have shown no benefit from using antegrade brain perfusion.
Increasingly, because multiple studies have demonstrated that pump time is the best predictor of stroke, less hypothermia is being used for arch repairs so as to shorten the pump time. Unfortunately this approach may be at the cost of a greater risk for multiple organ failure, as some retrospective studies have shown with more seizures and a questionable benefit in regard to bleeding. Furthermore, to do arch repairs at moderate hypothermia, antegrade brain perfusion has to be used, usually through the right subclavian artery. To do this safely, both the right vertebral artery and right carotid artery systems, in addition to either or both the anterior communicating artery and left posterior communicating arteries, are required to be intact. The important finding by Merkkola and colleagues [1] is that this method of perfusion is inadequate in as many as 14% to 16% of patients. To reduce the risk of malperfusion, the left carotid can be occluded intraoperatively, allowing "cross-over" collateral arteries (eg, thyrocervical trunk, thyroid, and external carotid arteries) to supply the left carotid artery system, although pressures may be low. Parenthetically we do not even know what right subclavian artery perfusion pressures we should be using. Because the left carotid artery is to be occluded anyway, placing a left carotid artery balloon catheter with a "Y" off the arterial line into the carotid artery is an option. We have previously reported this approach using an inflatable balloon type of retrograde cardiac perfusion cannula. Although this does somewhat interfere with the surgical field, it does obviate the danger of malperfusion in the 14% to 16% of patients with an incomplete Circle of Willis. In conclusion, perfusion of the right subclavian artery alone may be risky at moderate hypothermia, and thus the left carotid perfusion should be added for non-deep hypothermic arrest arch repairs.
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References
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- Merkkola P, Tulla H, Ronkainen A, et al. Incomplete circle of Willis and right axillary artery perfusion Ann Thorac Surg 2006;82:74-80.[Abstract/Free Full Text]
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