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J Thorac Cardiovasc Surg 2008;136:1243-1249
© 2008 The American Association for Thoracic Surgery
Surgery for Congenital Heart Disease |
a Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Ga
b Department of Cardiac Surgery, Children's Hospital at Boston, Boston, Mass
Received for publication January 29, 2008; revisions received April 8, 2008; accepted for publication May 16, 2008. * Address for reprints: Ajit P. Yoganathan, PhD, Wallace H. Coulter Distinguished Faculty Chair in Biomedical Engineering and Regents Professor, Wallace H. Coulter School of Biomedical Engineering, Georgia Institute of Technology, Room 2119 U. A. Whitaker Building, 313 Ferst Dr, Atlanta, GA 30332-0535. (Email: ajit.yoganathan{at}bme.gatech.edu).
Objective: Reoperation rates to correct left atrioventricular valve regurgitation after primary repair of atrioventricular canal defects remain relatively high. The causes of valvular regurgitation are likely multifactorial, and simple cleft closure is often insufficient to prevent recurrence.
Methods: To elucidate the mechanisms leading to regurgitation, we conducted hemodynamic studies using isolated native mitral valves. Anatomy of these valves was altered to mimic atrioventricular canal type valves and studied under pediatric hemodynamic conditions. The impact of subvalvular geometry, cleft closure, annular dilatation, and annular undersizing on regurgitation were investigated.
Results: Papillary muscle position did not have a significant effect on regurgitation. Cleft closure had a significant impact on valvular competence, with reduction in regurgitation volume with increased cleft closure. Regurgitation volume decreased from 12.5 ± 2.4 mL/beat for an open cleft to 4.9 ± 1.9 mL/beat for a partially closed cleft and to 1.4 ± 1.6 mL/beat when the cleft was completely closed. Annular dilatation had a significant impact on regurgitation even after cleft closure. A 40% increase in annular size increased regurgitation by 59% for a partially closed cleft and by 84% for a fully closed cleft. Reducing the annular size by 20% from the physiologic level decreased the regurgitation volume by 12% for a fully open cleft and by 58% for the partially closed cleft case.
Conclusions: Annular dilatation after primary repair has a potentially significant role in the recurrence of atrioventricular valve regurgitation. Reducing the annular size and restricting dilatation as an adjunct to cleft closure is a promising surgical approach in such valve anatomies.
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