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Ann Thorac Surg 2002;73:1023
© 2002 The Society of Thoracic Surgeons

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Correspondence

Spinal cord protection during descending aortic aneurysm repair

^a First Department of Surgery, Hamamatsu University School of Medicine, 1-20-1, Handayama Hamamatsu, 431-3192, Japan

e-mail: tkazui{at}hama-med.ac.jp

To the Editor

I read with great interest the recent article by Dr Estrera and colleagues [1]. In a series of 148 patients, they found that the combination of cerebrospinal fluid (CSF) drainage and distal aortic perfusion protects the spinal cord more effectively than either of these methods applied alone during operations on descending aortic aneurysms. I have a few comments on some important aspects of this study.

The authors address a very pertinent issue in that CSF drainage with distal aortic perfusion has a role in protecting the spinal cord during operation for a thoracoabdominal aortic aneurysm or when the aortic cross-clamp time is too long. In fact, for longer and more extensive procedures, my colleagues and I also employ these adjuncts to ensure better spinal cord protection. However, in my opinion, their role during descending thoracic aneurysmal procedures that do not generally require aortic cross-clamping for more than 30 to 40 minutes needs to be critically evaluated.

Although the authors mention that the proximal aortic pressure was maintained within the normal range throughout the period of aortic cross-clamping, the exact values are not given. It is not clear why CSF pressure should rise when a normal proximal aortic pressure is maintained. According to the authors, CSF pressure was maintained at 10 mm Hg or less throughout the cross-clamp period by drainage. How much does the CSF pressure rise before drainage begins? More importantly, the distal aortic pressure, which has been identified by many investigators [2] as the key factor influencing spinal cord function, is also not provided in their article. I think spinal cord hemodynamics as well as CSF dynamics should have been clearly mentioned. This information would provide a better understanding of both the protective efficacy of distal aortic perfusion in this study and the possible role of CSF drainage in spinal cord protection.

In 1987, my associates and I [3] reported our experience with distal aortic perfusion (through right atrium-femoral artery bypass) alone during repairs of descending aortic aneurysms. Despite an average aortic cross-clamp time of about 80 minutes, there was no incidence of paraplegia in a series of 81 patients. Fifty percent of the patients had type C aneurysms (involvement of the entire descending aorta), and 50% had aneurysms caused by dissection. Up to 1996, we operated on a total of 228 patients with thoracic aortic aneurysms using essentially the same methods to protect the spinal cord. The 30-day mortality rate was 11%, and the incidence of spinal cord ischemia was zero [4].

The benefit of CSF drainage in the protection of the spinal cord, in addition to that offered by distal aortic perfusion, has yet to be clearly documented. From that point of view, the study by Estrera and co-workers [1] is very important. Their study lends some statistical support to the use of adjunctive CSF drainage during descending aortic aneurysm repair. However, the actual role of this method in spinal cord protection is difficult to prove because the mean cross-clamp time was relatively short in this series, and as always, a host of other factors (eg, extent of the aneurysm and adequacy of the distal aortic perfusion) were involved. The issue becomes particularly important when we consider that other investigators [5] have achieved equally good results without CSF drainage.

References

1. Estrera A.L., Rubenstein F.S., Miller C.C., III, Huynh T.T.T., Letsou G.V., Safi H.J. Descending thoracic aortic aneurysm: surgical approach and treatment using the adjuncts cerebrospinal fluid drainage and distal aortic perfusion. Ann Thorac Surg 2001;72:481-486.[Abstract/Free Full Text]
2. Laschinger J.C., Cunningham J.N., Jr, Nathan I.M., Knopp E.A., Cooper M.M., Spencer F.C. Experimental and clinical assessment of the adequacy of partial bypass in maintenance of spinal cord blood flow during operations on the thoracic aorta. Ann Thorac Surg 1983;36:417-426.[Abstract]
3. Kazui T., Komatsu S., Yokoyama H. Surgical treatment of aneurysms of the thoracic aorta with the aid of partial cardiopulmonary bypass: an analysis of 95 patients. Ann Thorac Surg 1987;43:622-627.[Abstract]
4. Morishita F., Kazui T., Komatsu S. Descending thoracic aneurysm surgery using partial cardiopulmonary bypass: experience with 228 cases without paraplegia. Presented at the 9th Annual Meeting of the Japan Chapter of the International Society of Cardio-Thoracic Surgeons 1996.
5. Borst H.G., Jurmann M., Buhner B., Laas J. Risk of replacement of descending aorta with a standardized left heart bypass technique. J Thorac Cardiovasc Surg 1994;107:126-133.[Abstract/Free Full Text]

This article has been cited by other articles:

				A. L. Estrera, C. C. Miller III, E. P. Chen, R. Meada, R. H. Torres, E. E. Porat, T. T. Huynh, A. Azizzadeh, and H. J. Safi Descending Thoracic Aortic Aneurysm Repair: 12-Year Experience Using Distal Aortic Perfusion and Cerebrospinal Fluid Drainage Ann. Thorac. Surg., October 1, 2005; 80(4): 1290 - 1296. [Abstract] [Full Text] [PDF]

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Teruhisa Kazui Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kazui, T. Search for Related Content PubMed PubMed Citation Articles by Kazui, T. Related Collections Cerebral protection