Fluid-Structure Interaction Models of Bicuspid Aortic Valves: The Effects of Nonfused Cusp Angles.

Bicuspid aortic valve (BAV) is the most common type of congenital heart disease, occurring in 0.5-2% of the population, where the valve has only two rather than the three normal cusps. Valvular pathologies, such as aortic regurgitation and aortic stenosis, are associated with BAVs, thereby increasing the need for a better understanding of BAV kinematics and geometrical characteristics. The aim of this study is to investigate the influence of the nonfused cusp (NFC) angle in BAV type-1 configuration on the valve's structural and hemodynamic performance. Toward that goal, a parametric fluid-structure interaction (FSI) modeling approach of BAVs is presented. Four FSI models were generated with varying NFC angles between 120 deg and 180 deg. The FSI simulations were based on fully coupled structural and fluid dynamic solvers and corresponded to physiologic values, including the anisotropic hyper-elastic behavior of the tissue. The simulated angles led to different mechanical behavior, such as eccentric jet flow direction with a wider opening shape that was found for the smaller NFC angles, while a narrower opening orifice followed by increased jet flow velocity was observed for the larger NFC angles. Smaller NFC angles led to higher concentrated flow shear stress (FSS) on the NFC during peak systole, while higher maximal principal stresses were found in the raphe region during diastole. The proposed biomechanical models could explain the early failure of BAVs with decreased NFC angles, and suggests that a larger NFC angle is preferable in suture annuloplasty BAV repair surgery.

Válvula aórtica bicúspide: resultados a largo plazo de la cirugía reparadora / Long-term Results with Reconstructiva Surgery of the Bicuspid Aortic Valve

Introducción: La válvula aórtica bicúspide es la anomalía congénita cardíaca más frecuente. En pacientes con requerimienro de cirugía, el tratamiento tradicional ha sido la sustitución valvular. La introducción del concepto de reparación de la válvula aórtica bicúspide ha llevado a nuestro grupo a reproducir las técnicas de reparación, las cuales se han estandarizado y aplicado de manera homogénea en nuestras instituciones. Objetivos: Revisar la experiencia conjunta de tres centros, con la presentación de los resultados a mediano y a largo plazos de la reparación valvular. Material y métodos: Entre octubre de 1995 y febrero de 2013 se intervinieron 666 pacientes con válvulas bicúspides e insuficiencia aórtica y/o aneurisma de la aorta. De ellos, 254 presentaban insuficiencia aórtica aislada y 412, aneurisma o disección. Se reconstruyó la válvula en todos los pacientes (en 254 como procedimiento aislado, en 281 "remodelación de la raíz", en 129 remodelación de la unión sinotubular y en 2 "reimplantación"). Resultados: La mortalidad fue de 3/666 (0,5%): 1/254 (0,4%) tras reparación valvular aislada y 2/410 (0,5%) tras reparación más reemplazo de la aorta. En pacientes con cirugía asociada (coronaria, reparación mitral/tricúspide) fue de 1/77 (1,3%). Durante el seguimiento murieron 12 pacientes (supervivencia a los 10 años: 95%). Las libertades de reoperación y de sustitución valvular a los 10 y 15 años fueron del 80% y 77% y del 86% y 83%, respectivamente. La libertad de reoperación a los 10 años fue superior en el reemplazo de la raíz (86%) o la aorta tubular (84%) en comparación con la reparación aislada (74%; p = 0,005). La libertad de cualquier complicación relacionada con la válvula fue del 80% y 77% a los 10 y 15 años, respectivamente, y fue mejor para reparación incluyendo "remodelación de la raíz" (87% y 82%) que para reparación aislada (77% y 77%; p = 0,04). Conclusiones: La reparación de la válvula aórtica bicúspide es un procedimiento seguro y duradero, con una incidencia baja de "complicaciones relacionadas con la válvula" a mediano y a largo plazos.

Introduction: Bicuspid aortic valve is the most common congenital heart disease. Traditionally, aortic valve replacement has been the approach for patients requiring surgery. After introduction of the bicuspid aortic valve repair concept, our group began reproducing these techniques, which have been standardized and homogeneously applied at our institutions. Objectives: The aim of this study was to review the conjoint experience of three centers and show the mid- and long-term results of bicuspid aortic valve repair. Methods: Between October 1995 and February 2013, 666 patients with bicuspid aortic valve underwent surgery for aortic regurgitation and/or aortic aneurysm. Isolated aortic regurgitation was present in 254 patients, and 412 had aortic aneurysm or dissection. The valve was reconstructed in all the patients (isolated valve repair in 254, "remodelling of the aortic root" in 281, remodelling of the sinotubular junction in 129 and "reimplantation" technique in 2). Results: Mortality was 3/666 (0.5%): 1/254 (0.4%) after isolated valve repair and 2/410 (0.5%) after valve repair plus aortic replacement. In patients with combined procedures (coronary revascularization or mitral/tricuspid valve repair), mortality was 1/77 (1.3%). During follow-up, 12 patients died (10-year survival: 95%). Freedom from reoperation and from aortic valve replacement at 10 and 15 years were 80% and 77%, and 86% and 83%, respectively Freedom from reoperation at 10 years was higher with aortic root (86%) or tubular aorta (84%) replacement, compared with isolated valve repair (74%; p = 0.005). Freedom from any valve-related complication was 80% and 77% at 10 and 15 years, respectively, and was better for valve repair including "remodelling of the aortic root" (87% and 82%) than for isolated repair (77% and 77%; p = 0.04). Conclusions: Bicuspid aortic valve repair is a safe, long-lasting procedure, with a low incidence of mid- and long-term "valve-related complications".