WJCD  Vol.5 No.6 , June 2015
Effect of Bicuspid Aortic Valve Cusp Fusion on Aorta Wall Shear Stress: Preliminary Computational Assessment and Implication for Aortic Dilation
The bicuspid aortic valve (BAV) is a major congenital valvular abnormality and is associated with a high prevalence of aortic dilation, whose expression depends on the type of leaflet fusion. Although BAV hemodynamics is considered a potential pathogenic contributor, the impact of BAV fusion on ascending aorta (AA) wall shear stress (WSS) remains largely unknown. A fluid-structure interaction approach was implemented to predict the hemodynamics and WSS characteristics in realistic AA models subjected to the flow of a normal tricuspid aortic valve (TAV) and three BAV morphotypes (left-right coronary cusp fusion (LR), right-non coronary cusp fusion (RN) and non-left coronary cusp fusion (NL)). TAV flow conditions subjected the proximal and middle AA to a streamlined flow typical of flows in bends, while BAV flow conditions generated increased flow helicity. The LR-BAV orifice jet generated flow abnormalities primarily in the proximal AA, which were marked by a uniform WSS overload along the wall circumference and contrasted WSS directionalities on the wall convexity and concavity. Flow abnormalities generated by the RN-BAV and NL-BAV inlet flow conditions were more diffuse and consisted of WSS overloads in the convexity of the proximal and middle AA and contrasted WSS directionalities in the anterior and posterior wall regions. This study demonstrates the impact of the BAV morphotype on AA hemodynamics and provides quantitative evidence for the existence of WSS abnormalities in aortic wall regions prone to dilation.

Cite this paper
Cao, K. and Sucosky, P. (2015) Effect of Bicuspid Aortic Valve Cusp Fusion on Aorta Wall Shear Stress: Preliminary Computational Assessment and Implication for Aortic Dilation. World Journal of Cardiovascular Diseases, 5, 129-140. doi: 10.4236/wjcd.2015.56016.
[1]   Ward, C. (2000) Clinical Significance of the Bicuspid Aortic Valve. Heart (British Cardiac Society), 83, 81-85.

[2]   Sabet, H.Y., Edwards, W.D., Tazelaar, H.D. and Daly, R.C. (1999) Congenitally Bicuspid Aortic Valves: A Surgical Pathology Study of 542 Cases (1991 through 1996) and a Literature Review of 2,715 Additional Cases. Mayo Clinic Proceedings, 74, 14-26.

[3]   Sievers, H. and Schmidtke, C. (2007) A Classification System for the Bicuspid Aortic Valve from 304 Surgical Specimens. The Journal of Thoracic and Cardiovascular Surgery, 133, 1226-1233.

[4]   Nkomo, V.T., Enriquez-Sarano, M., Ammash, N.M., Melton 3rd, L.J., Bailey, K.R., Desjardins, V., et al. (2003) Bicuspid Aortic Valve Associated with Aortic Dilatation: A Community-Based Study. Arteriosclerosis, Thrombosis, and Vascular Biology, 23, 351-356.

[5]   Girdauskas, E., Borger, M.A., Secknus, M.A., Girdauskas, G. and Kuntze, T. (2011) Is Aortopathy in Bicuspid Aortic Valve Disease a Congenital Defect or a Result of Abnormal Hemodynamics? A Critical Reappraisal of a One-Sided Argument. European Journal of Cardio-Thoracic Surgery: Official Journal of the European Association for Cardio-Thoracic Surgery, 39, 809-814.

[6]   Atkins, S. and Sucosky, P. (2014) The Etiology of Bicuspid Aortic Valve Disease: Focus on Hemodynamics. World Journal of Cardiology, 12, 1227-1233.

[7]   Hope, M.D., Meadows, A.K., Hope, T.A., Ordovas, K.G., Reddy, G.P., Alley, M.T., et al. (2008) Images in Cardiovascular Medicine. Evaluation of Bicuspid Aortic Valve and Aortic Coarctation with 4D Flow Magnetic Resonance Imaging. Circulation, 117, 2818-2819.

[8]   Barker, A.J., Lanning, C. and Shandas, R. (2010) Quantification of Hemodynamic Wall Shear Stress in Patients with Bicuspid Aortic Valve Using Phase-Contrast MRI. Annals of Biomedical Engineering, 38, 788-800.

[9]   Bauer, M., Siniawski, H., Pasic, M., Schaumann, B. and Hetzer, R. (2006) Different Hemodynamic Stress of the Ascending Aorta Wall in Patients with Bicuspid and Tricuspid Aortic Valve. Journal of Cardiac Surgery, 21, 218-220.

[10]   Bissell, M.M., Hess, A.T., Biasiolli, L., Glaze, S.J., Loudon, M., Pitcher, A., et al. (2013) Aortic Dilation in Bicuspid Aortic Valve Disease: Flow Pattern Is a Major Contributor and Dif-fers with Valve Fusion Type. Circulation Cardiovascular Imaging, 6, 499-507.

[11]   Saikrishnan, N., Yap, C.-H., Milligan, N.C., Vasilyev, N.V and Yoganathan, A.P. (2012) In Vitro Characterization of Bicuspid Aortic Valve Hemodynamics Using Particle Image Velocimetry. Annals of Biomedical Engineering, 40, 1760-1775.

[12]   Seaman, C., Akingba, A. and Sucosky, P. (2014) Steady Flow Hemodynamic and Energy Loss Measurements in Normal and Simulated Calcified Tricuspid and Bicuspid Aortic Valves. Journal of Biomechanical Engineering, 136, Article ID: 041001.

[13]   Seaman, C. and Sucosky, P. (2014) Anatomic versus Effective Orifice Area in a Bicuspid Aortic Valve. Echocardiography, 31, 1028.

[14]   Chandra, S., Rajamannan, N.M. and Sucosky, P. (2012) Computational Assessment of Bicuspid Aortic Valve Wall- Shear Stress: Implications for Calcific Aortic Valve Disease. Biomechanics and Modeling in Mechanobiology, 11, 1085-1096.

[15]   Nathan, D.P., Xu, C., Plappert, T., Desjardins, B., Gorman, J.H., Bavaria, J.E., et al. (2011) Increased Ascending Aortic Wall Stress in Patients with Bicuspid Aortic Valves. The Annals of Thoracic Surgery, 92, 1384-1389.

[16]   Pasta, S., Rinaudo, A., Luca, A., Pilato, M., Scardulla, C., Gleason, T.G., et al. (2013) Difference in Hemodynamic and Wall Stress of Ascending Thoracic Aortic Aneurysms with Bi-cuspid and Tricuspid Aortic Valve. Journal of Biomechanics, 46, 1729-1738.

[17]   Atkins, S.K., Cao, K., Rajamannan, N.M. and Sucosky, P. (2014) Bicuspid Aortic Valve Hemodynamics Induces Abnormal Medial Remodeling in the Convexity of Porcine Ascending Aortas. Biomechanics and Modeling in Mechanobiology, 13, 1209-1225.

[18]   Fazel, S.S., Mallidi, H.R., Lee, R.S., Sheehan, M.P., Liang, D., Fleischman, D., et al. (2008) The Aortopathy of Bicuspid Aortic Valve Disease Has Distinctive Patterns and Usually Involves the Transverse Aortic Arch. The Journal of Thoracic and Cardiovascular Surgery, 135, 901-907, 907.e1-2.

[19]   Kang, J.-W., Song, H.G., Yang, D.H., Baek, S., Kim, D.-H., Song, J.-M., et al. (2013) Association between Bicuspid Aortic Valve Phenotype and Patterns of Valvular Dysfunction and Bicuspid Aortopathy: Comprehensive Evaluation Using MDCT and Echocardiography. JACC Cardiovascular Imaging, 6, 150-161.

[20]   Hope, M.D., Hope, T.A., Meadows, A.K., Ordovas, K.G., Urbania, T.H., Alley, M.T., et al. (2010) Bicuspid Aortic Valve: Four-Dimensional MR Evaluation of Ascending Aortic Systolic Flow Patterns. Radiology, 255, 53-61.

[21]   Olufsen, M.S., Peskin, C.S., Kim, W.Y., Pedersen, E.M., Nadim, A. and Larsen, J. (2000) Numerical Simulation and Experimental Validation of Blood Flow in Arteries with Structured-Tree Outflow Conditions. Annals of Biomedical Engineering, 28, 1281-1299.

[22]   Lantz, J., Renner, J. and Karlsson, M. (2011) Wall Shear Stress in a Subject Specific Human Aorta—Influence of Fluid-Structure Interaction. International Journal of Applied Mechanics, 3, 759-778.

[23]   Donea, J., Guiliani, S. and Halleux, J.P. (1982) An Arbitrary Lagrangian-Eulerian Finite-Element Method for Transient Dynamic Fluid Structure Interactions. Computer Methods in Applied Mechanics and Engineering, 33, 689-723.

[24]   Mahadevia, R., Barker, A.J., Schnell, S., Entezari, P., Kansal, P., Fedak, P.W.M., et al. (2014) Bicuspid Aortic Cusp Fusion Morphology Alters Aortic 3D Outflow Patterns, Wall Shear Stress and Expression of Aortopathy. Circulation, 129, 673-682.

[25]   Hope, M.D., Hope, T.A., Crook, S.E.S., Ordovas, K.G., Urbania, T.H., Alley, M.T., et al. (2011) 4D Flow CMR in Assessment of Valve-Related Ascending Aortic Disease. JACC Cardiovascular Imaging, 4, 781-787.

[26]   Barker, A.J., Markl, M., Bürk, J., Lorenz, R., Bock, J., Bauer, S., et al. (2012) Bicuspid Aortic Valve Is Associated with Altered Wall Shear Stress in the Ascending Aorta. Circulation Cardiovascular Imaging, 5, 457-466.

[27]   Cotrufo, M., Della Corte, A., De Santo, L.S., Quarto, C., De Feo, M., Romano, G., et al. (2005) Different Patterns of Extracellular Matrix Protein Expression in the Convexity and the Concavity of the Dilated Aorta with Bicuspid Aortic Valve: Preliminary Results. The Journal of Thoracic and Cardiovascular Surgery, 130, 504-511.

[28]   Della Corte, A., Quarto, C., Bancone, C., Castaldo, C., Di Meglio, F., Nurzynska, D., et al. (2008) Spatiotemporal Patterns of Smooth Muscle Cell Changes in Ascending Aortic Dilatation with Bicuspid and Tricuspid Aortic Valve Stenosis: Focus on Cell-Matrix Signaling. The Journal of Thoracic and Cardiovascular Surgery, 135, 8-18.e2.

[29]   Sucosky, P., Padala, M., Elhammali, A., Balachandran, K., Jo, H. and Yoganathan, A.P. (2008) Design of an ex Vivo Culture System to Investigate the Effects of Shear Stress on Cardiovascular Tissue. Journal of Biomechanical Engineering, 130, 35001-35008.