189. A Novel Approach for Aortic Valve Bicuspidization: Integrating Computational and Ex-vivo Simulation Concepts of Free-edge Leaflet Length in a modified Schäfer's procedure.

Objective: Bicuspidization repair of the congenitally diseased aortic valve has been shown to be a promising, durable technique. However, the optimal gross morphology of this repair has yet to be defined. This study introduces a novel repair technique that combines simulation concepts and free-edge leaflet length (FEL), utilizing a modified Schäfer's procedure, to investigate the impact of FEL variation and valve function in bicuspidization repair techniques.
Methods: Model bicuspid valves were generated with varying FEL via fluid-structure interactions (FSI) in a single patient-specific model geometry (1.1 to 1.8 times the diameter, Figure 1). Based on results (Figure 2,3), three representative models (1.2D, 1.57D, 1.8D) were replicated in explanted porcine aortic roots (n=3), using bovine pericardium to adjust leaflets to desired FEL, valves were compared to a previously validated bicuspid control model, all within the same root. Valves were tested on a validated ex-vivo univentricular system under physiological conditions (Figure 4). Outcomes included transvalvular gradient, regurgitation fraction, and orifice area. Linear mixed effects model and pairwise comparisons to analyze outcomes across FEL were employed.
Results: FSI simulations established a clear correlation between FEL and stenosis, with FEL less than 1.3 times the diameter resulting in significant stenosis (>10mm Hg). Ex-vivo analyses similarly showed significant decrease in aortic regurgitation, an increase of aortic orifice, and a reduction in stenosis in the 1.57D repair model (p<0.01) compared to the baseline as well as both the 1.2D and 1.8D repair models. Pairwise revealed 1.57D was associated with lower gradient not only when compared to the control and 1.2D but also to 1.8D (p<0.01). In contrast to simulated results, 1.8D exhibited more stenosis (p<0.01) increased regurgitation (p=0.013) compared to the 1.57D model, and smaller orifice area than both 1.2D (p=0.04) and 1.57D (p<0.01) models.
Conclusions: Achieving an optimal FEL is imperative to avoid stenosis in aortic valve bicuspidization repair. However, excessive FEL extension can result in unfavorable outcomes, such as stenosis and regurgitation. Future investigations are warranted to determine the ideal FEL range, assess the outcomes of extended FEL, evaluate the long-term durability of these repairs, and consider the influence of various anatomic variations on the repair process.

Moussa HAIDAR (1), Perry Choi (2), Alexander D. Kaiser (3), Amit Sharir (4), Ntemena Kapula (5), Masafumi Shibata (6), Alison L. Marsden (3), Michael Ma (7), (1) Stanford Medicine, Palo Alto, CA, (2) Stanford Medicine, N/A, (3) Stanford University, Palo Alto, CA, (4) Stanford University, Stanford, CA, (5) Stanford University Medical Center, Stanford, CA, (6) Stanford University, United States, (7) Lucile Packard Children's Hospital, Stanford, CA

T-Y Hsia

Commentator

Dr. Tain-Yen Hsia is a board-certified pediatric cardiac surgeon and chief of service at The Heart Center at Orlando Health Arnold Palmer Hospital for Children. He performs all aspects of neonatal, pediatric and adult congenital cardiac surgery, including heart transplantation and mechanical cardiac support. 

Dr. Hsia earned his MD degree from the Stanford University School of Medicine and his Bachelor’s and Master’s degrees in mechanical engineering from the Massachusetts Institute of Technology.

He has extensive postgraduate training including: residencies in general surgery and cardiothoracic surgery at Johns Hopkins Hospital; a research fellowship and specialist registrar in cardiac surgery at the Great Ormond Street Hospital for Children in London, England; and a congenital cardiac surgery fellowship at the Children’s Hospital of Philadelphia.  Prior to his post at Arnold Palmer, Dr. Hsia was an attending cardiac surgeon at Medical University of South Carolina, Consultant Cardiac Surgeon at Great Ormond Street Hospital for Children, and Chief of Pediatric Cardiac Surgery at Yale School of Medicine.

Notably, Dr. Hsia has received $17.3 million dollars in research grants and served as the primary investigator for most of those studies. His primary research interest has been the application of engineering and computational modeling to improve congenital cardiac surgical performance and outcomes. He also has written more than 140 peer-reviewed articles and many medically-focused chapters and books.

Dr. Hsia is certified by the American Board of Surgery and American Board of Thoracic Surgery and a member of many professional organizations such as the Congenital Heart Surgeons Society, American Association for Thoracic Surgery, American College of Cardiology and more.

Perry Choi

Abstract Presenter

Dr. Perry Choi is a 4th year resident in Stanford's Integrated Cardiothoracic Surgery Residency Program. He received his MD at Harvard Medical School, where he spent time conducting research on mitral valve replacement options in the pediatric population under the mentorship of Dr. Sitaram Emani at Boston Children's Hospital. Currently, he is working as a research fellow in the labs of Dr. Michael Ma and Dr. Joseph Woo, investigating the biomechanics of ventricular remodeling and complex valvular repair techniques in congenital heart disease. His career interests include academic surgery, adult congenital cardiac disease, and surgical education. 

Specialties: Congenital