Congenital Heart Disease

1349168 - An Atlas-Based Analysis of Biventricular Mechanics in Tetralogy of Fallot

Wednesday, January 25, 2023

Location: E-POSTER

Presenting Author(s)

SG

Sachin Govil, MSc

PhD Candidate
University of California, San Diego, United States

Primary Author(s)

SG

Sachin Govil, MSc

PhD Candidate
University of California, San Diego, United States

Co-Author(s)

Sanjeet Hegde, MD, PhD

Director of Research, Heart Institute/ Medical Director of Cardiac MRI
UC San Diego/Rady Children's Hospital
San Diego, California, United States
JP

James C. Perry, MD

Pediatric Cardiologist, Clinical Professor
UC San Diego/Rady Children's Hospital
San Diego, California, United States
JO

Jeffrey H. Omens, PhD

Adjunct Professor
University of California, San Diego, United States
AM

Andrew D. McCulloch, PhD

Distinguished Professor
University of California, San Diego, United States

Disclosure(s):

Sanjeet Hegde, MD, PhD: No financial relationships to disclose

Background: The current study proposes an efficient strategy for exploiting the statistical power of cardiac atlases to investigate whether clinically significant variations in ventricular shape are direct determinants of differences in ventricular function or if they are indirect markers of altered myocardial mechanical properties.

Methods: This study was conducted in a previously identified cohort of 84 patients with repaired tetralogy of Fallot (rTOF). Deidentified datasets were contributed from multiple clinical centers with local IRB approval. A statistical atlas of systolic wall motion (SWM) was generated from displacements computed between patient-specific geometric models constructed at ED and ES. SWM modes that had the greatest effect on combined LV/RV EF were then identified, and linear regression was employed to identify significant associations between these SWM modes and previously identified, clinically significant ED shape modes. Finite element (FE) models of biventricular mechanics were then utilized to test the degree to which differences in ED shape are direct determinants of observed changes in SWM, and in the case of deviations, model contractility was adjusted to produce a better match.

Results: Features of ED shape associated with RV apical dilation and LV dilation (Figure 1A) and RV basal bulging and LV conicity (Figure 1B) correlated with components of SWM that contributed most to changes in global systolic function. The mechanisms of these shape-function relationships were then tested using FE models of biventricular mechanics. In the case of RV apical dilation and LV dilation, differences in the ED shape alone explained approximately 40% of the variation in SWM, and it was observed that greater RV apical dilation and less LV dilation were associated with greater contractility (Figure 2A). In the case of RV basal bulging and LV conicity, differences in the ED shape alone explained the opposite than expected change in systolic function (Figure 2B).

Conclusion: In this study, statistical shape models were integrated with cardiac biomechanics models to further investigate the degree to which clinically significant shape markers are direct determinants of systolic function in an rTOF patient cohort. Variations in ED shape explained differences in SWM to varying degrees. Specifically, greater RV apical dilation may be a surrogate for increased RV basal and apical contractility that may also serve as a compensatory mechanism to prevent LV dilation and preserve LV function. Overall, patients with rTOF may benefit from an atlas-based analysis of biventricular mechanics that can provide insight into mechanisms of pathophysiology and aid long-term clinical management.