Aekaansh Verma1, Mahdi Esmaily2,3, Jessica Shang4, Richard Figliola5, Jeffrey A Feinstein6,7, Tain-Yen Hsia8, Alison L Marsden6,7,9. 1. 1 Department of Mechanical Engineering, Stanford University, Stanford, CA, USA. 2. 2 Center for Turbulence Research, Stanford University, Stanford, CA, USA. 3. 3 Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, USA. 4. 4 Department of Mechanical Engineering, University of Rochester, Rochester, NY, USA. 5. 5 Department of Mechanical Engineering, Clemson University, Clemson, SC, USA. 6. 6 Department of Pediatrics, Stanford University School of Medicine, Lucile Salter Packard Children's Hospital, Palo Alto, CA, USA. 7. 7 Department of Bioengineering, Stanford University, Stanford, CA, USA. 8. 8 Cardiothoracic Unit, Great Ormond Street Hospital for Children NHS-Trust, London, UK. 9. 9 Institute for Computational and Mathematical Engineering, Stanford University, CA, USA.
Abstract
BACKGROUND: First-stage single-ventricle palliation is challenging to manage, and significant interstage morbidity and mortality remain. Prior computational and in vitro studies of the assisted bidirectional Glenn (ABG), a novel first-stage procedure that has shown potential for early conversion to a more stable augmented Glenn physiology, demonstrated increased pulmonary flow and oxygen delivery while decreasing cardiac work, as compared to conventional stage-1 alternatives. This study aims to identify optimal shunt designs for the ABG to improve pulmonary flow while maintaining or decreasing superior vena caval (SVC) pressure. METHODS: A representative three-dimensional model of a neonatal bidirectional Glenn (BDG) was created, with a shunt connecting the innominate artery to the SVC. The shunt design was studied as a six-parameter constrained shape optimization problem. We simulated hemodynamics for each candidate designs using a multiscale finite element flow solver and compared performance against designs with taper-less shunts, the standalone BDG, and a simplified control volume model. Three values of pulmonary vascular resistance (PVR) of 2.3, 4.3, and 7.1 WUm2 were studied. RESULTS: Increases in pulmonary flow were generally accompanied by increases in SVC pressure, except at low PVR (2.3 WUm2), where the optimal shunt geometry achieved a 13% increase in pulmonary flow without incurring any increase in SVC pressure. Shunt outlet area was the most influential design parameter, while others had minimal effect. CONCLUSION: Assisted bidirectional Glenn performance is sensitive to PVR and shunt outlet diameter. An increase in pulmonary flow without a corresponding increase in SVC pressure is possible only when PVR is low.
BACKGROUND: First-stage single-ventricle palliation is challenging to manage, and significant interstage morbidity and mortality remain. Prior computational and in vitro studies of the assisted bidirectional Glenn (ABG), a novel first-stage procedure that has shown potential for early conversion to a more stable augmented Glenn physiology, demonstrated increased pulmonary flow and oxygen delivery while decreasing cardiac work, as compared to conventional stage-1 alternatives. This study aims to identify optimal shunt designs for the ABG to improve pulmonary flow while maintaining or decreasing superior vena caval (SVC) pressure. METHODS: A representative three-dimensional model of a neonatal bidirectional Glenn (BDG) was created, with a shunt connecting the innominate artery to the SVC. The shunt design was studied as a six-parameter constrained shape optimization problem. We simulated hemodynamics for each candidate designs using a multiscale finite element flow solver and compared performance against designs with taper-less shunts, the standalone BDG, and a simplified control volume model. Three values of pulmonary vascular resistance (PVR) of 2.3, 4.3, and 7.1 WUm2 were studied. RESULTS: Increases in pulmonary flow were generally accompanied by increases in SVC pressure, except at low PVR (2.3 WUm2), where the optimal shunt geometry achieved a 13% increase in pulmonary flow without incurring any increase in SVC pressure. Shunt outlet area was the most influential design parameter, while others had minimal effect. CONCLUSION: Assisted bidirectional Glenn performance is sensitive to PVR and shunt outlet diameter. An increase in pulmonary flow without a corresponding increase in SVC pressure is possible only when PVR is low.
Authors: Jessica K Shang; Mahdi Esmaily; Aekaansh Verma; Olaf Reinhartz; Richard S Figliola; Tian-Yen Hsia; Jeffrey A Feinstein; Alison L Marsden Journal: Ann Thorac Surg Date: 2018-11-22 Impact factor: 4.330
Authors: Casey M Fleeter; Gianluca Geraci; Daniele E Schiavazzi; Andrew M Kahn; Alison L Marsden Journal: Comput Methods Appl Mech Eng Date: 2020-04-21 Impact factor: 6.756