Ann Thorac Surg 2007;84:715-716
© 2007 The Society of Thoracic Surgeons
Correspondence
Reply
Carl L. Backer, MD
A. C. Buehler Professor of Cardiovascular-Thoracic Surgery, Division of Cardiovascular-Thoracic Surgery, Children’s Memorial Hospital, 2300 Children’s Plaza, m/c Box 22, Chicago, IL 60614
(Email: cbacker{at}childrensmemorial.org).
To the Editor:
We would like to thank Dr Setty and colleagues [1] for their letter regarding the use of partial cardiopulmonary bypass in infants and children with coarctation and specifically the subgroup with an anomalous origin of the right subclavian artery. We were quite interested to hear about their anecdotal experience from other colleagues with 4 infants suffering postoperative paraplegia after coarctation repair, all with anomalous origin of the right subclavian artery. This is clearly not a complication that surgeons like to discuss, but is the type of information that is useful for possibly predicting and preventing this potential complication. As noted in our article we are also "aware" of an infant who had postoperative paraplegia related to anomalous origin of the right subclavian artery from the descending thoracic aorta [2].
We were pleased to hear that the authors agreed with our conclusion that anomalous right subclavian artery should be considered a potential risk factor for spinal cord injury during coarctation repair. The additional point that Setty and colleagues [1] make is that this risk is not only for older children, but may also be more important in infants than we and others had previously believed. The youngest child in our series to have cardiopulmonary bypass was 4.2 years and (until now) we have not routinely measured femoral artery pressure or considered using cardiopulmonary bypass for children less than 1 year of age. In our experience at Children’s Memorial Hospital (since 1990), we have operated on 7 patients with coarctation and anomalous origin of the right subclavian artery from either a preductal location as the last branch of the transverse aortic arch or from the descending thoracic aorta. In only 1 of those patients (4.2 years of age, described in our article) have we used cardiopulmonary bypass (5 of 7 patients were neonates and another was 3 months of age). None of those patients had a postoperative spinal cord injury.
Our current practice is not to use cardiopulmonary bypass, even if there is an aberrant origin of the right subclavian artery from the descending thoracic aorta in a neonatal or infant patient. We believe the neonatal and infant circulation physiology is different than older children and adults. This relates to the "sponge" theory of modified cerebral perfusion. The evidence for this practice is two-fold, the first being the 6 patients we have operated on without paraplegia. The other evidence can be found in the very low (nonexistent) incidence of paraplegia reported in other neonatal series of coarctation repair (ie, Great Ormond St, 77 patients with no paraplegia [3]; Planche, 307 patients with no paraplegia [4]; Wood, 181 patients with no paraplegia [5]; and Bove, 83 patients with no paraplegia [6]. Although the incidence of aberrant right subclavian artery is not stated in all of these series, it is probably similar to the incidences with our patients (3.5%). Most of these (neonatal) patients have a very short cross-clamp time (usually 15 to 20 minutes). We also take the usual precautions to cool the patient and increase the blood pressure on the cranial side of the clamp during the cross-clamp period.
However, for older patients (out of the neonatal or infant period) with an aberrant right subclavian artery, we highly recommend consideration for the use of partial cardiopulmonary bypass. We continue to use monitoring of the femoral artery pressure and its change with test clamp as the main indicator for using cardiopulmonary bypass. For example, in the patient who has an aberrant right subclavian artery from the descending thoracic aorta and a very tight coarctation, there may be sufficient collaterals developed that the femoral artery pressure still does not change with clamping of the aberrant right subclavian artery and the transverse arch.
The 4 patients reported by Setty and colleagues [1] (if there are no extenuating circumstances) would possibly predict that our current strategy is not correct. The neonates I am aware of that had postcoarctation paraplegia also had other confounding factors, such as intraoperative fever and the need for two-clamp applications. More information about the circumstances surrounding these 4 patients noted by Setty and colleagues [1] would be useful.
One technical detail on which we disagree with Setty and colleagues [1] is the cannulation of the left atrial appendage. We have not found this to be cumbersome, and in fact we have used this in all patients in this series (11 patients) with no complications related to this cannulation and no hindrances to the intraoperative conduct of the operation. Personally we would hesitate to cannulate the pulmonary artery for fear of injuring the pulmonary valve or creating supravalvar pulmonary stenosis, or both. The left atrial appendage clearly can be cannulated with essentially no risk of a postoperative issue regarding stenosis of that structure.
In summary, we appreciate Setty and colleagues [1] from Royal Children’s Hospital focusing our attention on the infant with anomalous origin of the right subclavian artery. Their experience that there are 4 infants they are aware of with an anomalous right subclavian artery that had postoperative paraplegia develop heightens our awareness of this as a potential risk factor for postoperative paraplegia. However, whether this means we should use partial cardiopulmonary bypass in all these patients remains to be seen. As Dr Setty states, "... the use of partial [cardiopulmonary bypass] CPB [in these patients] ... cannot be substantiated but we feel like it is justified" [1]. At the current time at Children’s Memorial Hospital we are still not routinely using cardiopulmonary bypass for neonates and infants with an aberrant right subclavian artery and coarctation.
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References
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- Setty SP, Brizard CP, d’Udekem Y. Partial cardiopulmonary bypass in infants with coarctation and anomalous right subclavian arteries(letter) Ann Thorac Surg 2007;84:715.[Free Full Text]
- Backer CL, Stewart RD, Kelle AM, Mavroudis C. Use of partial cardiopulmonary bypass for coarctation repair through a left thoracotomy in children without collaterals Ann Thorac Surg 2006;82:964-972.[Abstract/Free Full Text]
- van Heurn LW, Wong CM, Spiegelhalter DJ, et al. Surgical treatment of aortic coarctation in infants younger than three months: 1985 to 1990 J Thorac Cardiovasc Surg 1994;107:74-86.[Abstract/Free Full Text]
- Conte S, Lacour-Gayet F, Serraf A, et al. Surgical management of neonatal coarctation J Thorac Cardiovasc Surg 1995;109:663-675.[Abstract/Free Full Text]
- Wood AE, Javadpour H, Duff D, Oslizlok P, Walsh K. Is extended arch aortoplasty the operation of choice for infant aortic coarctation?Results of 15 years’ experience in 181 patients. Ann Thorac Surg 2004;77:1353-1358.[Abstract/Free Full Text]
- Wright GE, Nowak CA, Goldberg CS, Ohye RG, Bove EL, Rocchini AP. Extended resection and end-to-end anastomosis for aortic coarctation in infants: results of a tailored surgical approach Ann Thorac Surg 2005;80:1453-1459.[Abstract/Free Full Text]
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References