All Publications

  • Computational simulation-derived hemodynamic and biomechanical properties of the pulmonary arterial tree early in the course of ventricular septal defects. Biomechanics and modeling in mechanobiology Dong, M. L., Lan, I. S., Yang, W., Rabinovitch, M., Feinstein, J. A., Marsden, A. L. 2021


    Untreated ventricular septal defects (VSDs) can lead to pulmonary arterial hypertension (PAH) characterized by elevated pulmonary artery (PA) pressure and vascular remodeling, known as PAH associated with congenital heart disease (PAH-CHD). Though previous studies have investigated hemodynamic effects on vascular mechanobiology in late-stage PAH, hemodynamics leading to PAH-CHD initiation have not been fully quantified. We hypothesize that abnormal hemodynamics from left-to-right shunting in early stage VSDs affects PA biomechanical properties leading to PAH initiation. To model PA hemodynamics in healthy, small, moderate, and large VSD conditions prior to the onset of vascular remodeling, computational fluid dynamics simulations were performed using a 3D finite element model of a healthy 1-year-old's proximal PAs and a body-surface-area-scaled 0D distal PA tree. VSD conditions were modeled with increased pulmonary blood flow to represent degrees of left-to-right shunting. In the proximal PAs, pressure, flow, strain, and wall shear stress (WSS) increased with increasing VSD size; oscillatory shear index decreased with increasing VSD size in the larger PA vessels. WSS was higher in smaller diameter vessels and increased with VSD size, with the large VSD condition exhibiting WSS >100 dyn/cm[Formula: see text], well above values typically used to study dysfunctional mechanotransduction pathways in PAH. This study is the first to estimate hemodynamic and biomechanical metrics in the entire pediatric PA tree with VSD severity at the stage leading to PAH initiation and has implications for future studies assessing effects of abnormal mechanical stimuli on endothelial cells and vascular wall mechanics that occur during PAH-CHD initiation and progression.

    View details for DOI 10.1007/s10237-021-01519-4

    View details for PubMedID 34585299

  • The nested block preconditioning technique for the incompressible Navier–Stokes equations with emphasis on hemodynamic simulations Computer Methods in Applied Mechanics and Engineering Liu, J., Yang, W., Dong, M., Marsden, A. L. 2020; 367
  • Integrated Image-Based Computational Fluid Dynamics Modeling Software as an Instructional Tool. Journal of biomechanical engineering Stevens Boster, K. n., Dong, M. n., Oakes, J. n., Bellini, C. n., Rayz, V. n., LaDisa, J. n., Parker, D. n., Wilson, N. n., Shadden, S. C., Marsden, A. n., Goergen, C. n. 2020


    Computational modeling of cardiovascular flows is becoming increasingly important in a range of biomedical applications, and understanding the fundamentals of computational modeling is important for engineering students. In addition to their purpose as research tools, integrated image-based computational fluid dynamics platforms can be used to teach the fundamental principles involved in computational modeling and generate interest in studying cardiovascular disease. We report the results of a study performed at five institutions designed to investigate the effectiveness of an integrated modeling platform as an instructional tool and describe "best practices" for using an integrated modeling platform in the classroom. Use of an integrated modeling platform as an instructional tool in nontraditional educational settings (workshops, study abroad programs, in outreach) is also discussed. Results of the study show statistically significant improvements in understanding after using the integrated modeling platform, suggesting such platforms can be effective tools for teaching fundamental cardiovascular computational modeling principles.

    View details for DOI 10.1115/1.4047479

    View details for PubMedID 32529203

  • Image-based scaling laws for somatic growth and pulmonary artery morphometry from infant- to adulthood. American journal of physiology. Heart and circulatory physiology Dong, M. L., Yang, W. n., Tamaresis, J. S., Chan, F. P., Zucker, E. J., Kumar, S. n., Rabinovitch, M. n., Marsden, A. L., Feinstein, J. A. 2020


    Pulmonary artery (PA) morphometry has been extensively explored in adults, with particular focus on intra-acinar arteries. However, scaling law relationships for length and diameter of extensive pre-acinar PAs by age have not been previously reported for in vivo human data. To understand pre-acinar PA growth spanning children to adults, we performed morphometric analyses of all PAs visible in the computed tomography (CT) and magnetic resonance (MR) images from a healthy subject cohort (n=16; age: 1-51 years; body surface area, BSA: 0.49-2.01 m2). Subject-specific anatomic PA models were constructed from CT and MR images, and morphometric information - diameter, length, tortuosity, bifurcation angle, and connectivity - was extracted and sorted into diameter-defined Strahler orders. Validation of Murray's law, describing optimal scaling exponents of radii for branching vessels, was performed to determine how closely PAs conform to this classical relationship. Using regression analyses of vessel diameters and lengths against orders and patient metrics (BSA, age, height), we found that diameters increased exponentially with order and allometrically with patient metrics, and length increased allometrically with patient metrics, albeit weakly. The average tortuosity index of all vessels was 0.026 ± 0.024, average bifurcation angle was 28.2º ± 15.1º, and average Murray's law exponent was 2.92 ± 1.07. We report a set of scaling laws for vessel diameter and length, along with other morphometric information. These provide an initial understanding of healthy structural pre-acinar PA development with age, which can be used for computational modeling studies and comparison with diseased PA anatomy.

    View details for DOI 10.1152/ajpheart.00123.2020

    View details for PubMedID 32618514

  • Evolution of hemodynamic forces in the pulmonary tree with progressively worsening pulmonary arterial hypertension in pediatric patients BIOMECHANICS AND MODELING IN MECHANOBIOLOGY Yang, W., Dong, M., Rabinovitch, M., Chan, F. P., Marsden, A. L., Feinstein, J. A. 2019; 18 (3): 779–96