Sri Krishna Sivakumar

BioE PhD Defense Presentation

Date: July 27th, 2023

Time: 2:15 pm

Zoom link: https://gatech.zoom.us/j/92830774480?pwd=VUcrOHI2aDhaaXBuQ2xZWnVXOE1jdz09

Committee Members: 

Lakshmi Prasad Dasi, PhD (Advisor) (School of Biomedical Engineering, Georgia Institute of Technology and Emory University) 

John Oshinski, PhD (Co-Advisor) (School of Biomedical Engineering, Georgia Institute of Technology and Emory University) 

Ajit P. Yoganathan, PhD (School of Biomedical Engineering, Georgia Institute of Technology and Emory University) 

Brandon Dixon, PhD (School of Mechanical Engineering, Georgia Institute of Technology)

Vinod H. Thourani, MD (Department of Cardiovascular Surgery, Piedmont Heart Institute) 

Biomechanics And Risk Of Coronary Obstruction In Transcatheter Aortic Valve Replacement

Transcatheter Aortic Valve Replacement (TAVR) has rapidly evolved into the preferred method of replacing aortic valves, taking over surgery in all patients over 65 years of age due to expansion of indication to all patients with aortic stenosis and great outcomes in long term studies. However, several complications have been reported to occur as a result of TAVR and therefore procedural planning is essential for good patient outcomes. Computational modeling can provide accurate predictions of the post-TAVR states of the device and native anatomy to assess risk for complications. However, computational modeling is not used in routine clinical practice due to insufficient data validating the models for current THV devices across a range of patient anatomies and long simulation times. For a successful TAVR in patients with difficult anatomies, cardiologists may employ adaptive strategies such as non-nominal deployment depths or balloon volumes, post-dilatation of the bioprosthesis and laceration of bioprosthetic valve leaflets to help mitigate the risk of complications. However, the impact of such adaptations on device shape or potential for other complications is not fully understood. Coronary obstruction is a serious procedural complication of TAVR associated with high mortality rates. Standardized assessment of the risk of coronary obstruction is necessary for TAVR planning and current clinical guidelines fail to achieve sufficient accuracy in predicting the complication.  

Computational deployment models for TAVR devices in patients with failed tricuspid aortic valves were developed and clinically validated. Changes to the implantation depth had no significant impact on the THV expansion or shape in native TAVR. Overfilling of the deployment balloon in SAPIEN showed improvement in device expansion and underfilling showed an increase in prosthesis deformation index. Post-dilatation of Evolut improved device expansion in the functional region. Successful application of the developed methods to predict deformation in valve-in-valve TAVR was demonstrated. Lower deployment worsened the functional area in Evolut, and a higher implant lowered inflow area of the SAPIEN in valve-in-valve TAVR. Both devices showed improved expansion with laceration of the bioprosthetic aortic valve leaflets. Coronary obstruction predictive models based on TAVR simulations were developed and validated against post-TAVR outcomes in both native and valve-in-valve TAVR. The impact of transcatheter valve type on the risk of coronary obstruction was studied. The outcomes of this work can help clinicians better visualize transcatheter valve deformations in native and valve-in-valve TAVR, better understand the impact of procedural adaptions and optimize patient and device selection to minimize the risk of coronary obstruction.