Ann Thorac Surg 2008;86:689-690. doi:10.1016/j.athoracsur.2008.02.055
© 2008 The Society of Thoracic Surgeons
John A. Elefteriades, MD,
Arjet Gega, MD,
John A. Rizzo, PhD
Yale University School of Medicine, Section of Cardiothoracic Surgery, 121 FMB, 333 Cedar St, New Haven, CT 06510
To the Editor:
We appreciate Dr Augoustides'  kind comments and recognize his personal and institutional experience and insights of cerebral protection in aortic surgery.
With regard to retrograde cerebral perfusion, we present the following responses to Augoustides'  germane questions and comments:
- 1 Retrograde cerebral perfusion was not used for potential embolic washout in this series and thus does not represent a confounder to data analysis.
- 2 Although we believe it has been abundantly demonstrated in the literature that retrograde cerebral perfusion does not deliver oxygen in significant amounts to the brain, we have no objection whatsoever to its use for potential washout of cerebral debris. However, it should be noted that its usefulness in this regard remains a theoretical one. In fact, the results of clinical series using routine retrograde cerebral perfusion reveal no consistent stroke benefit compared with our series or other series with straight deep hypothermic arrest or antegrade cerebral perfusion. These are reviewed in Table 4 of our article . Retrograde perfusion is far from a panacea for prevention of stroke or embolic events.
With regard to the anesthetic management, we provide the following responses:
- 1 The volatile anesthetic isoflurane was used in all patients during cooling in the deep hypothermic arrest protocol. The concentration administered varied in response to its vasodilatory properties. We aimed for a blood pressure of about 50 to 60 mm Hg on bypass. In general, the concentration of isoflurane varied between 1% and 2%.
- 2 Because all patients received the same anesthetic with the same endpoint, we do not believe that bias was introduced by the anesthetic technique. As Augoustides  notes, there is a significant body of experimental work in animal models to show the potential for a neuroprotective effect from volatile anesthetics. However, to date there is no evidence in humans that these agents have cerebral protective effects [3, 4].
With regard to the use of aprotinin, we provide the following responses:
- 1 About two-thirds of the patients in our study received aprotinin, and the remainder received epsilonaminocaproic acid. We generally use full-dose aprotinin.
- 2 We did not analyze the impact of aprotinin on cerebral events in this study, although we did so in our prior investigation . That investigation disclosed no significant difference in stroke between the aprotinin or control groups.
- 3 Although our experience with aprotinin in aortic surgery has been favorable , we currently do not use the drug at all, and we follow the provisional market withdrawal by the United States Food and Drug Administration.
- Augoustides JGT. Contemporary conduct of adult deep hypothermic circulatory arrest: possible roles of retrograde cerebral perfusion, anesthetic preconditioning, and aprotinin Ann Thorac Surg 2008;86:689(letter).[Free Full Text]
- Gega A, Rizzo JA, Johnson JH, Tranquilli M, Farkas EA, Elefteriades JA. Straight deep hypothermic arrest: experience in 394 patients supports its effectiveness as a sole means of brain preservation Ann Thorac Surg 2007;84:759-767.[Abstract/Free Full Text]
- Clarkson AN. Anesthetic-mediated protection/preconditioning during cerebral ischemia Life Sci 2007;80:1157-1175.[Medline]
- Fukuda S, Warner DS. Cerebral protection Br J Anesth 2007;99:10-17.[Abstract/Free Full Text]
- Sedrakayan A, Wu A, Sedrakayan G, Diener-West M, Tranquilli M, Elefteriades J. Aprotinin use in thoracic aortic surgery: safety and outcomes J Thorac Cardiovasc Surg 2006;132:909-917.[Abstract/Free Full Text]
Contemporary Conduct of Adult Deep Hypothermic Circulatory Arrest: Possible Roles of Retrograde Cerebral Perfusion, Anesthetic Preconditioning, and Aprotinin
- John G.T. Augoustides
Ann. Thorac. Surg. 2008 86: 689.