# Developing Biomechanical Predictors of Ascending Thoracic Aortic Aneurysm Growth and Dissection

> **NIH VA I01** · VETERANS AFFAIRS MED CTR SAN FRANCISCO · 2022 · —

## Abstract

Veterans Affairs (VA) Healthcare System services >9 million veterans at 144 hospitals
nationwide. Aortic aneurysms are the 16th leading cause of death in patients >35 years old in
the United States. Dissection and rupture of aTAAs are catastrophic cardiovascular
emergencies carrying significant pre-hospital (40%) and operative (17-25%) mortality. Surgical
guidelines rely on aTAA maximum diameter, growth rate, and symptoms to guide elective
repair, which can be performed with low operative mortality. However, we and others have
demonstrated that diameter alone is not adequate to predict dissection or rupture—~60-90% of
type A dissection events occur in aTAAs with diameter <5.5cm and otherwise not meeting
elective surgical repair indications. From a biomechanics perspective, rupture or dissection is a
mechanical failure that can occur when aneurysm wall stress exceeds wall strength. Guidelines
simply use diameter as a surrogate for wall stress based on LaPlace’s Law for cylinders. Our
published studies showed that diameter was a poor predictor of wall stress due to the
complexity of individual aTAA geometries.
We propose to prospectively evaluate changes in aTAA wall stresses and distensibility to
determine their ability to improve on diameter criterion to predict dissection or death or need for
surgery in veterans with aneurysms that do not meet criteria for surgery. We propose to
prospectively evaluate changes in aneurysm wall shear stresses, flow velocities, and vortices in
veterans with nonsurgical sized aTAAs over time to determine their ability to predict aneurysm
growth and need for surgery. This proposal lays the foundation for practical clinical application
of patient-specific biomechanics and fluid dynamics to improve risk prediction of aortic
dissection, sudden death, aTAA growth, and need for surgery with the following aims:
Aim 1: To determine changes in longitudinal wall stresses using finite element analysis (FEA) to
correlate with clinical composite endpoint of aortic dissection, need for surgical repair, or sudden
death in prospectively followed veterans (n=400) with nonsurgical aTAA <5.5cm over 4 years.
Aim 2: To determine changes in aTAA wall strength using the surrogate of in vivo aortic
distensibility to correlate with clinical composite endpoint of aortic dissection, aTAA surgical
repair, or sudden death in prospectively followed veterans (n=400) with nonsurgical aTAA
<5.5cm over 4 years.
Aim 3: To determine changes in aTAA circumferential wall stresses and wall shear stresses,
flow velocities, and eccentricity using fluid structure interaction (FSI), validate with 4D flow
magnetic resonance imaging (MRI), and correlate with clinical composite endpoint of aortic
growth or need for surgical repair in prospectively followed veterans (n=400) with nonsurgical
aTAA <5.5cm over 4 years.
Aim 4: To develop a machine learning (ML) approach to determine biomechanical and fluid
dynamic parameters in Aim 1-3 in prospectively followed vete...

## Key facts

- **NIH application ID:** 10485645
- **Project number:** 1I01CX002465-01A1
- **Recipient organization:** VETERANS AFFAIRS MED CTR SAN FRANCISCO
- **Principal Investigator:** Elaine Evelina Tseng
- **Activity code:** I01 (R01, R21, SBIR, etc.)
- **Funding institute:** VA
- **Fiscal year:** 2022
- **Award amount:** —
- **Award type:** 1
- **Project period:** 2022-04-01 → 2026-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10485645

## Citation

> US National Institutes of Health, RePORTER application 10485645, Developing Biomechanical Predictors of Ascending Thoracic Aortic Aneurysm Growth and Dissection (1I01CX002465-01A1). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10485645. Licensed CC0.

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