Forces On Atrioventricular Valve Leaflets In Response To Annular And Ventricular Remodeling
Sumanth Kidambi, MD, Stephen C. Moye, James Y. Lee, BS, Teaghan H. Cowles, BS, Rob Wilkerson, BS, Michael J. Paulsen, MD, Joseph Woo, MD, Michael Ma, MD.
Stanford University, Stanford, CA, USA.
OBJECTIVES: We sought to identify the impact of two important causes of atrioventricular valve regurgitation, annular dilation and leaflet tethering, on valve biomechanics in hypoplastic left heart syndrome (HLHS).
METHODS: Fetal bovine tricuspid valves and right ventricles were sutured onto imaging-derived annular and ventricular mounts. The dilation model (AD) underwent dilation of the free wall annular perimeter (Fig 1A). The leaflet tethering model (LT) was created via apico-lateral traction of the anterior papillary muscle (Fig 1B). Control valves (CV) underwent no dilation or tethering. Specimens were placed in a simulator reproducing typical HLHS interstage hemodynamics. Forces at each leaflet edge were measured using strain sensors. Statistical significance was determined using t-tests.
RESULTS: Twenty-four specimens underwent testing. AD valves underwent average areal dilation of 55.6%. Tethering angle and volume in LT compared to CV were 109.5º vs 97.0º, p<0.001 and 3.2 mL vs 2.4 mL, p<0.001 respectively. Forces in the tricuspid valve anterior (TVAL), posterior (TVPL), and septal leaflets (TVSL) as a percentage change from CV were [TVAL: 56%, p<0.001| TVPL: 71%, p<0.001 | TVSL: 94%, p<0.001] in AD and [TVAL: 7.1%, p=0.04| TVPL: 18.4%, p=0.03 | TVSL: 14.4%, p<0.001] in LT (Fig 1C).
CONCLUSIONS: AD causes a larger increase in leaflet forces compared to LT, particularly in the septal leaflet. This simulation emphasizes the importance of addressing AD at the time of valve repair.
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