Ann Thorac Surg 1998;65:1763
© 1998 The Society of Thoracic Surgeons
Original articles: cardiovascular
Invited commentary
Ralph S. Mosca, MDa
a Pediatric Cardiovascular Surgery, Department of Thoracic Surgery, Michigan Congenital Heart Center, F7830 Mott Children’s Hospital, 1500 E Medical Center Dr, Ann Arbor, MI 48109-0223 USA
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Invited commentary
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The optimal treatment of critical aortic stenosis in infants and neonates remains controversial. The study reported by Hawkins and colleagues adds more important information to the debate. Currently, treatment options include open surgical valvotomy, transventricular dilation, and percutaneous balloon aortic valve dilation.
Hawkins and colleagues describe 37 patients who underwent open aortic valvotomy for critical aortic stenosis. The hospital mortality was 10.8%, which represents an improvement over most previous surgical series and is comparable with reports of balloon valve dilation. In addition, 35% of patients required reintervention within 5 months, and the six late deaths occurred within 6 months of open valvotomy. Actuarial survival at 1 year after the operation was 74%. The majority of deaths occurred either as an immediate consequence of or as a result of the need for reintervention for residual aortic stenosis. Not included in the article is crucial quantitative information concerning the adequacy of relief of left ventricular outflow tract obstruction, and resultant aortic insufficiency in the perioperative period after aortic valvotomy.
This report is strengthened by the fact that it is data derived from treatment at a single institution, using a uniform approach to patients with critical aortic stenosis, and with follow-up over a relatively long period of time. Hawkins and colleagues rightly point out the importance of identifying those patients with hypoplastic left heart syndrome and excluding them from this mode of therapy. Although this distinction may be difficult, patients judged to have hypoplastic left heart syndrome will tend to do quite well after a Norwood-type palliation. The results after attempted valvotomy and subsequent Norwood palliation, however, have been much less rewarding. Hawkins and colleagues champion open surgical valvotomy because, in their opinion, it allows direct inspection of the valve and an "extended aortic valvuloplasty." This, they believe, will contribute to a more favorable long-term outcome by more completely relieving the left ventricular outflow tract obstruction. Yet, in their report, the need for reintervention occurs quite early and is at least as common as in series reporting the results of transventricular dilation or balloon dilation. For example, in a series reported from our institution comparing transventricular dilation and percutaneous balloon dilation of the aortic valve, the majority of patients (73%) were free of any form of reintervention at a mean follow-up of 53 months [1]. Hawkins and colleagues indicate that the patients requiring reintervention have been preferentially treated by balloon aortic valve dilation in the absence of significant aortic regurgitation. What were the results of these interventions, and why was this not used as their initial therapy?
As surgeons, our limitations in effectively treating critical aortic stenosis in the neonate and infant rest in the complexity of the anatomic substrate that is encompassed by the diagnosis. A heterogeneous mixture of commisural fusion, valvar myxoid dysplasia, and annular hypoplasia produces a spectrum of abnormalities ranging from a thickened, tricuspid aortic valve, to a bicuspid aortic valve, and finally a "unicuspid" valve. In many cases there are no recognizable cusps or commissures. Open valvotomy under these circumstances requires the surgeon to make a "best guess" as to where to incise the valve. This comes at the price of a major procedure involving cardiopulmonary bypass and myocardial ischemia imposed on an already dysfunctional left ventricle. The information provided by Dr Hawkins and colleagues once again underscores the difficulty of achieving adequate and durable relief of critical aortic stenosis via open valvotomy. Although the important information regarding residual aortic stenosis and aortic sufficiency in the early postoperative period is not available, it appears that Hawkins and colleagues’ contention that "direct exposure and extended aortic valvuloplasty" is a superior approach is not supported by their data. These results are no better than those described for transcatheter balloon valve dilation or transventricular dilation on cardiopulmonary bypass. Thus, the issue becomes one of durability of the procedure and its associated sequelae.
Procedures on the aortic valve for critical aortic stenosis in infants and neonates must be considered palliative. The challenge is to define the procedure with the fewest perioperative risks and best palliation. If we accept perforce that autograft replacement of the aortic valve is currently the best available surgical palliation for children with aortic valve disease, the challenge of earlier procedures is to sufficiently relieve left ventricular outflow obstruction and avoid inducing significant aortic regurgitation. This will allow us to perform the Ross procedure when the patient is at an age when allograft replacement of the right ventricular outflow tract may be more or less permanent and in the context of a left ventricle with optimal systolic and diastolic function. At present, it appears that the results of balloon valve dilation and open valvotomy are strikingly similar.
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References
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- Mosca R.S., Iannettoni M.D., Schwartz S.M., et al. Critical aortic stenosis in the neonate: a comparison of balloon valvuloplasty and transventricular dilatation. J Thorac Cardiovasc Surg 1995;109:147-154.[Abstract/Free Full Text]
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Invited commentary
References