Caili Li^1,§, Christopher Baird², Jing Yao³, Chun Yang⁴, Liang Wang⁵, Han Yu⁵, Tal Geva⁶, Dalin Tang^5,*,7,§

Molecular & Cellular Biomechanics, Vol.16, Suppl.2, pp. 59-59, 2019, DOI:10.32604/mcb.2019.06872

Abstract Pulmonary valve stenosis (PVS) is one common right ventricular outflow tract obstruction problem in patients with tetralogy of Fallot (TOF). Congenital bicuspid pulmonary valve (BPV) is a condition of valvular stenosis, and the occurrence of congenital BPV is often associated with TOF. Dynamic computational models of normal pulmonary root (PR) with tri-leaflet and PR with BPV in patients with TOF were developed to investigate the effect of geometric structure of BPV on valve stress and strain distributions. The pulmonary root geometry included valvular leaflets, sinuses, interleaflet triangles and annulus. Mechanical properties of pulmonary valve leaflet were obtained from biaxial testing… More >

Han Yu¹, Tal Geva², Rahul H. Rathod², Alexander Tang², Chun Yang³, Zheyang Wu³, Kristen L. Billiar⁴, Xueying Huang⁵, Dalin Tang^1,*,3

Molecular & Cellular Biomechanics, Vol.16, Suppl.2, pp. 56-57, 2019, DOI:10.32604/mcb.2019.07257

Abstract Computational biomechanical models are widely used in cardiovascular research for better understanding of mechanisms governing disease development, quantitative diagnostic strategies and improved surgical designs with better outcome. Patients with repaired tetralogy of Fallot (TOF) account for the majority of cases with late onset right ventricle (RV) failure. The current surgical approach, which includes pulmonary valve replacement/insertion (PVR), has yielded mixed results. An innovative PVR surgical approach was proposed using active contracting bands to help ventricle to contract and improve RV function measured by ejection fraction [1]. Muscle active contraction caused by sarcomere shortening leads to change of zero-load configurations. In… More >

Caili Li^{1, §}, Christopher Baird², Jing Yao³, Chun Yang⁴, Liang Wang⁵, Han Yu⁵, Tal Geva⁶, Dalin Tang^{5*, 7, §}

CMES-Computer Modeling in Engineering & Sciences, Vol.119, No.1, pp. 227-244, 2019, DOI:10.32604/cmes.2019.06036

Abstract Pulmonary valve stenosis (PVS) is one common right ventricular outflow tract obstruction problem in patients with tetralogy of Fallot (TOF). Congenital bicuspid pulmonary valve (BPV) is a condition of valvular stenosis, and the occurrence of congenital BPV is often associated with TOF. Dynamic computational models of normal pulmonary root (PR) with tri-leaflet and PR with BPV in patients with TOF were developed to investigate the effect of geometric structure of BPV on valve stress and strain distributions. The pulmonary root geometry included valvular leaflets, sinuses, interleaflet triangles and annulus. Mechanical properties of pulmonary valve leaflet were obtained from biaxial testing… More >

Zhedian Zhou¹, Tal Geva², Rahul H. Rathod², Alexander Tang², Chun Yang³, Kristen L. Billiar⁴, Dalin Tang^1,*,3, Pedro del Nido⁵

Molecular & Cellular Biomechanics, Vol.15, No.2, pp. 99-115, 2018, DOI: 10.3970/mcb.2018.00558

Abstract Patients with repaired Tetralogy of Fallot (ToF), a congenital heart defect which includes a ventricular septal defect and severe right ventricular outflow obstruction, account for the majority of cases with late onset right ventricle (RV) failure. The current surgical approach, which includes pulmonary valve replacement/insertion (PVR), has yielded mixed results. A computational parametric study using 7 patient-specific RV/LV models based on cardiac magnetic resonance (CMR) data as "virtual surgery" was performed to investigate the impact of patch size, RV remodeling and tissue regeneration in PVR surgery design on RV cardiac functions. Two patch sizes, three degrees of scar trimming (RV… More >

Dalin Tang^1,*,2, Heng Zuo^2,*, Chun Yang², Zheyang Wu², Xueying Huang³, Rahul H. Rathod⁴, Alexander Tang⁴, Kristen L. Billiar⁵, Tal Geva⁴

Molecular & Cellular Biomechanics, Vol.14, No.3, pp. 137-151, 2017, DOI:10.3970/mcb.2017.014.137

Abstract Patients with repaired tetralogy of Fallot (TOF) account for the majority of cases with late onset right ventricle failure. Comparing TOF patients with healthy people may provide information to address this challenge. Cardiac magnetic resonance (CMR) data were obtained from 16 TOF patients (patient group, PG) and 6 healthy volunteers (healthy group, HG). At begin-of-ejection, better patient group (n=5, BPG) stress was very close to HG stress (54.7±38.4 kPa vs. 51.2±55.7 kPa, p=0.6889) while worse patient group (n=11, WPG) stress was 84% higher than HG stress (p=0.0418). Stress may be used as an indicator to differentiate BPG patients from WPG… More >

Heng Zuo^*, Dalin Tang^*,†,‡, Chun Yang^*,§, Glenn Gaudette^¶, Kristen L. Billiar^¶, Pedro J. del Nidok^II

Molecular & Cellular Biomechanics, Vol.12, No.2, pp. 67-85, 2015, DOI:10.3970/mcb.2015.012.067

Abstract Right ventricular (RV) dysfunction is a common cause of heart failure in patients with congenital heart defects and often leads to impaired functional capacity and premature death. Myocardial tissue regeneration techniques are being developed for the potential that viable myocardium may be regenerated to replace scar tissues in the heart or used as patch material in heart surgery. 3D computational RV/LV/Patch models with fluid-structure interactions (FSI) were constructed based on data from a healthy dog heart to obtain local fluid dynamics and structural stress/strain information and identify optimal conditions under which tissue regeneration techniques could achieve best outcome. RV/LV/Patch geometry… More >

Dalin Tang^*, Chun Yang^†, Tal Geva^‡,§, Pedro J. del Nido^¶

Molecular & Cellular Biomechanics, Vol.4, No.3, pp. 159-176, 2007, DOI:10.3970/mcb.2007.004.159

Abstract A single-layer isotropic patient-specific right/left ventricle and patch (RV/LV/Patch) combination model with fluid-structure interactions (FSI) was introduced in our previous papers to evaluate and optimize human pulmonary valve replacement/insertion (PVR) surgical procedure and patch design. In this paper, an active anisotropic model with two-layer structure for ventricle wall and tissue fiber orientation was introduced to improve previous isotropic model for more accurate assessment of RV function and potential application in PVR surgery and patch design. A material-stiffening approach was used to model active heart contraction. The computational models were used to conduct ``virtual (computational)'' surgeries and test the hypothesis that… More >

Dalin Tang¹, Chun Yang^1,2, Tal Geva^3,4, Glenn Gaudette⁴, and Pedro J. del Nido⁵

CMES-Computer Modeling in Engineering & Sciences, Vol.56, No.2, pp. 113-130, 2010, DOI:10.3970/cmes.2010.056.113

Abstract Right and left ventricle (RV/LV) combination models with three different patch materials (Dacron scaffold, treated pericardium, and contracting myocardium), two-layer construction, fiber orientation, and active anisotropic material properties were introduced to evaluate the effects of patch materials on RV function. A material-stiffening approach was used to model active heart contraction. Cardiac magnetic resonance (CMR) imaging was performed to acquire patient-specific ventricular geometries and cardiac motion from a patient with severe RV dilatation due to pulmonary regurgitation needing RV remodeling and pulmonary valve replacement operation. Computational models were constructed and solved to obtain RV stroke volume, ejection fraction, patch area variations,… More >