Surgical aortic valvuloplasty in children and adolescents with aortic regurgitation: Acute and intermediate effects on aortic valve function and left ventricular dimensions
Surgical aortic valvuloplasty is increasingly employed in the management of children and adolescents with aortic regurgitation, but the durability of this approach and factors associated with outcome are not well defined.
From 1989 to 2005, a total of 81 patients younger than 19 years with moderate or severe aortic regurgitation underwent surgical aortic valvuloplasty. Aortic regurgitation was congenital in 20 cases, after treatment of aortic stenosis in 30, from other injuries to the aortic valve in 12, and from other causes in 19. Eighteen patients had moderate or severe aortic stenosis. Preoperative left ventricular end-diastolic dimension z score was 4.9 +/- 2.7.
After surgical aortic valvuloplasty with various techniques, including pericardial leaflet augmentation in 80%, aortic regurgitation was improved in 77 patients and was mild or less in 68. Ten of 18 patients with moderate or severe aortic stenosis before repair had a decrease to mild, whereas 2 had progression from mild to moderate. Left ventricular end-diastolic dimension z score decreased by 2.9 +/- 2.1 (P < .001). During follow-up (median 4.7 years), 33 patients underwent aortic valve reinterventions, including aortic valve replacement in 25. Estimated freedoms from aortic valve replacement were 72% +/- 6% at 5 years and 54% +/- 9% at 7.5 years and were shorter in patients with moderate or severe aortic stenosis before surgical aortic valvuloplasty. Among surviving patients who did not undergo aortic valve replacement, aortic regurgitation at follow-up was moderate in 21 and trivial or mild in 34; left ventricular and aortic root dimensions were preserved.
Surgical aortic valvuloplasty is a valid option with good intermediate results for children and adolescents with aortic regurgitation from a variety of causes, particularly for patients with less than moderate aortic stenosis.
Available from: ncbi.nlm.nih.gov
- "However, each of these options has drawbacks, including lifelong anticoagulant therapy (mechanical valves), limited durability (bioprostheses), and dilatation of the aortic root (pulmonary autograft). Valve repair avoids these disadvantages of valve replacement (Bacha et al., 2008; Jonas, 2010). Valve repair for AR involves reconstruction of the native leaflets in order to create an effective seal during diastole. "
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ABSTRACT: Aortic valve reconstruction using leaflet grafts made from autologous pericardium is an effective surgical treatment for some forms of aortic regurgitation. Despite favorable outcomes in the hands of skilled surgeons, the procedure is underutilized because of the difficulty of sizing grafts to effectively seal with the native leaflets. Difficulty is largely due to the complex geometry and function of the valve and the lower distensibility of the graft material relative to native leaflet tissue. We used a structural finite element model to explore how a pericardial leaflet graft of various sizes interacts with two native leaflets when the valve is closed and loaded. Native leaflets and pericardium are described by anisotropic, hyperelastic constitutive laws, and we model all three leaflets explicitly and resolve leaflet contact in order to simulate repair strategies that are asymmetrical with respect to valve geometry and leaflet properties. We ran simulations with pericardial leaflet grafts of various widths (increase of 0%, 7%, 14%, 21% and 27%) and heights (increase of 0%, 13%, 27% and 40%) relative to the native leaflets. Effectiveness of valve closure was quantified based on the overlap between coapting leaflets. Results showed that graft width and height must both be increased to achieve proper valve closure, and that a graft 21% wider and 27% higher than the native leaflet creates a seal similar to a valve with three normal leaflets. Experimental validation in excised porcine aortas (n=9) corroborates the results of simulations.
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ABSTRACT: This paper treats the computational solution of terminating stochastic games using concepts from deterministic matrix games and Markovian decision processes. The algorithms due to Shapley and Pollatschek/ Avi-Itzhak are discussed and a suboptimal approach suitable for large problems is presented. Numerical results are given from an example comparing the three approaches.
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