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Heart Valve Dynamics
Published in Joseph D. Bronzino, Donald R. Peterson, Biomedical Engineering Fundamentals, 2019
Choon Hwai Yap, Erin Spinner, Muralidhar Padala, and Ajit P. Yoganathan
e bicuspid aortic valve is a congenital malformation that occurs in 1-2% of the population (Roberts, 1970). is type of valve is highly predisposed to calcication with 50% of aortic stenosis patients having bicuspid aortic valves (Ward, 2000). e predisposition to calcication has been shown to be related to an underlying genetic defect (Garg et al., 2005). However, it is argued that the drastic alteration of geometry and thus mechanical environment in the bicuspid aortic valve is in part responsible for calcication (Robicsek et al., 2004).
Bicuspid aortic valve aortopathies: An hemodynamics characterization in dilated aortas
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
Diana Oliveira, Sílvia Aguiar Rosa, Jorge Tiago, Rui Cruz Ferreira, Ana Figueiredo Agapito, Adélia Sequeira
Bicuspid aortic valve (BAV) is the most common form of congenital heart disease, affecting 0.5% to 1.4% of the population (Guntheroth 2008). It has high phenotypic heterogeneity (Kang et al. 2013), associated with valvular pathologies (stenosis, regurgitation), and with the development of ascending aortic dilation (Corte et al. 2006, 2007). The reported prevalence of dilation in these patients ranges from about 30 to 80% in the adult BAV population (Corte et al. 2007). Pathogenesis of aortic dilation in these patients is still controversial: the genetic basis supports the presence of a congenital defect in the aortic structure, which is backed by histopathological studies showing degeneration of the media layer of the ascending aortic wall (Grewa et al. 2014). The hemodynamic theory argues that the abnormal BAV dynamics causes perturbations on blood flow patterns and hemodynamic stress on the aortic wall, leading to aortic dilation (Mahadevia et al. 2014). According to current knowledge, the high heterogeneous expression of BAV aortopathy suggests that both genetic and hemodynamic factors coexist - a genetic predisposition in these patients may weaken the aortic wall, conferring it with susceptibility for dilation, and the presence of altered hemodynamic might act as a triggering and maintaining factor of that dilation (Padang et al. 2013).
How valvular calcification can affect the outcomes of transcatheter aortic valve implantation
Published in Expert Review of Medical Devices, 2020
Stephan Milhorini Pio, Jeroen Bax, Victoria Delgado
The majority of the data correlating the association of aortic valve calcification and these complications concern patients with tricuspid aortic valve. Extending this therapy to patients with intermediate and low risk may lead to a higher probability of bicuspid aortic valve since those patients are usually younger than patients with contraindications and high risk for surgery. Patients with bicuspid aortic valve were excluded from the main TAVI randomized clinical trials since they have peculiar anatomy of the valve and different distributions of calcification as compared to tricuspid aortic valve [1–3]. The higher burden of calcification of the annulus and cusps, abnormal cusp fusion with asymmetric orifice, and presence of raphe are postulated to affect transcatheter heart valve expansion which can lead to less optimal results [78–80]. In this population, MDCT is useful to provide information on leaflet morphology, symmetry of valve leaflets, presence of raphe, and location of calcification [81]. Data on aortic valve calcium score in this population are scarce and conflicting. Ferda et al. analyzed 37 patients with severe AS, 13 with bicuspid aortic valve and 24 with tricuspid aortic valve, who had non-contrast MDCT prior to valve surgery and showed that aortic valve calcium score was not significantly different between groups (1,168 ± 717 AU in bicuspid aortic valve vs 795 ± 530 AU in tricuspid aortic valve, p-value = 0.093) [82]. On the other hand, Watanabe et al. analyzed retrospectively 67 patients from a population of high-risk patients with severe AS treated with TAVI. Of 67 patients, 11 had bicuspid aortic valve morphology. Patients with bicuspid aortic valve had significantly higher aortic valve calcification volume and calcification index as compared to patients with tricuspid aortic valve (1,263 ± 396 AU vs 556 ± 462 AU, p < 0.01 and 744 ± 218 AU vs 313 ± 251 AU, p < 0.01, respectively) [83]. The reported rates of permanent pacemaker implantation after TAVI were similar for balloon- and self-expandable valves in patients with bicuspid aortic valves in two different studies: Mylotte et al. reported rates of 16.7% for balloon-expandable and 26.7% for self-expandable devices, while Jilaihawi et al. reported 25.5% for balloon-expandable and 26.9% for self-expanding devices [81,84,85].