Abstract 16886: Wall Stress Profiles in Tricuspid Aortic Valve Associated Ascending Thoracic Aortic Aneurysms: The Effect of Surgical Threshold Diameter ≥5.5cm

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Axel Gomez ◽  
Zhongjie Wang ◽  
Yue XUAN ◽  
Liang Ge ◽  
Elaine E Tseng
Keyword(s):  
Aortic Valve ◽  
Systolic Pressure ◽  
Peak Stress ◽  
Wall Stress ◽  
Aortic Aneurysms ◽  
Patient Specific ◽  
Thoracic Aortic Aneurysms ◽  
Tricuspid Aortic Valve ◽  
Elective Repair ◽  
Longitudinal Wall

Introduction: Ascending thoracic aortic aneurysms (aTAAs) carry a risk of dissection. Elective repair guidelines are designed around size thresholds, but the one-dimensional parameter is insufficient to predict acute events in small aneurysms. Biomechanically, aortic events can occur when wall stress exceeds wall strength. Patient-specific aTAA wall stresses may be a better predictor of complications. Our aim was to compare wall stresses in aTAAs associated with a tricuspid aortic valve (TAV) based on diameter. Methods: Patients with TAV-aTAA and diameter >4.0cm (n=448) were divided into groups by 0.5 cm diameter increments. Pre-stress three-dimensional aneurysm geometries were reconstructed from ECG-gated computer tomography images. A fiber-embedded hyperelastic material model was applied to obtain longitudinal and circumferential wall stress distributions under systolic pressure. Medians with interquartile ranges are reported. The Kruskal-Wallis test is used for comparisons between size groups. Results: Peak longitudinal wall stresses for TAV-aTAA were 308[282-338] kPa for size 4.0-4.4cm vs 341[309-362] kPa for 4.5-4.9cm vs 339[289-370] kPa for 5.0-5.4cm vs 319[297-355] kPa for 5.5-5.9cm vs 373[364-449] for 6.0cm (p=0.003). Peak circumferential wall stresses were 487[448-579] kPa for size 4.0-4.4cm vs 516[473-619] kPa for 4.5-4.9cm vs 506[422-580] kPa for 5.0-5.4cm vs 540[468-591] kPa for 5.5-5.9cm vs 565[506-634] for >6.0cm (p=0.19) (figure). 95th-percentile longitudinal peak stress for TAV-aTAA <5.5cm vs ≥5.5cm is 408 vs 465 kPa. Conclusions: Longitudinal wall stresses are higher as diameter increases. The 95% percentile longitudinal peak stress for diameter ≥5.5cm is ~450 kPa, which correlates with established ~5% dissection risk for size ≥5.5cm. Wall stress thresholds may be a better predictor of patient-specific risk of dissection than diameter and require testing in clinical trials.

scholarly journals Wall stress on ascending thoracic aortic aneurysms with bicuspid compared with tricuspid aortic valve

2018 ◽  
Vol 156 (2) ◽  
pp. 492-500 ◽  
Author(s):  
Yue Xuan ◽  
Zhongjie Wang ◽  
Raymond Liu ◽  
Henrik Haraldsson ◽  
Michael D. Hope ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Wall Stress ◽  
Aortic Aneurysms ◽  
Thoracic Aortic Aneurysms ◽  
Tricuspid Aortic Valve

scholarly journals Difference in hemodynamic and wall stress of ascending thoracic aortic aneurysms with bicuspid and tricuspid aortic valve

2013 ◽  
Vol 46 (10) ◽  
pp. 1729-1738 ◽  
Author(s):  
Salvatore Pasta ◽  
Antonino Rinaudo ◽  
Angelo Luca ◽  
Michele Pilato ◽  
Cesare Scardulla ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Wall Stress ◽  
Aortic Aneurysms ◽  
Thoracic Aortic Aneurysms ◽  
Tricuspid Aortic Valve

The Relationship Between Diameter and Wall Stress in Ascending Thoracic Aortic Aneurysms With a Tricuspid Aortic Valve

2021 ◽  
Vol 5 (sup1) ◽  
pp. 14-14
Author(s):  
Axel O. Gomez ◽  
Zhongjie Wang ◽  
Yue Xuan ◽  
Liang Ge ◽  
Elaine E. Tseng
Keyword(s):  
Aortic Valve ◽  
Wall Stress ◽  
Aortic Aneurysms ◽  
Thoracic Aortic Aneurysms ◽  
Tricuspid Aortic Valve ◽  
The Relationship

Abstract 16111: Clinical Application of Deep Learning for Stress Analysis of Ascending Thoracic Aortic Aneurysms

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Imon Rahaman ◽  
Zhongjie Wang ◽  
Yue XUAN ◽  
Liang Ge ◽  
Elaine E Tseng
Keyword(s):  
Deep Learning ◽  
Stress Analysis ◽  
Wall Stress ◽  
Longitudinal Direction ◽  
Absolute Error ◽  
Aortic Aneurysms ◽  
Patient Specific ◽  
Accurate Estimation ◽  
Stress Distributions ◽  
Thoracic Aortic Aneurysms

Introduction: Current guidelines for elective surgery of ascending thoracic aortic aneurysms (aTAAs) use aneurysm size as primary determinant for risk stratification of adverse events. Biomechanically, dissection may occur when wall stress exceeds wall strength. A widespread method for stress analysis is structural finite-element analysis (FEA). Patient-specific aortic geometries are easily obtainable and stress distributions can potentially predict risk of dissection. However, FEA is a time-consuming and difficult procedure. To bypass this issue, a recent study has developed the first deep learning (DL) approach for a fast and accurate estimation of aortic wall stress distributions. Hypothesis: In this study, we assessed the hypothesis that this deep learning approach can be applied to a large clinical dataset. Model performance was measured by comparing FEA and DL stress predictions in parallel. Methods: Patients with aTAA (n = 169) were studied. Patient-specific aneurysm geometries were obtained from ECG-gated computed tomography. Shapes were represented by hexahedral meshes with 9648 nodes and 6336 solid elements. FEA peak wall stresses and stress distributions were determined using LS-DYNA software with user-defined fiber-embedded material models under systolic pressure. The DL model was implemented in Julia and consisted of unsupervised and supervised learning algorithms. Training was performed on a training set of 152 shapes and testing set of 17 shapes with 10-fold cross-validation. Mean absolute error (MAE) and absolute error of peak stress values (APE) were used to compare DL model predictions with FEA values considered to be ground truth. Results: Average stress values predicted by our DL model were 175.64 ± 4.17 kPa and 95.69 ± 2.15 kPa in the circumferential and longitudinal direction, respectively. We computed a MAE of 5.06 ± 1.08 kPa and APE of 2.58 ± 1.39 kPa in the circumferential direction and MAE of 4.51 ± 0.98 kPa and APE of 2.32 ± 1.84 kPa in the longitudinal direction. Conclusions: DL model trained exclusively on clinical data was able to accurately predict stress distributions on complex aortic geometries. Fast and accurate stress predictions will facilitate real-time clinical applications for the risk assessment of aTAAs.

scholarly journals Wall Stress Distribution in Bicuspid Aortic Valve–Associated Ascending Thoracic Aortic Aneurysms

2020 ◽  
Vol 110 (3) ◽  
pp. 807-814 ◽  
Author(s):  
Axel Gomez ◽  
Zhongjie Wang ◽  
Yue Xuan ◽  
Andrew D. Wisneski ◽  
Michael D. Hope ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Stress Distribution ◽  
Bicuspid Aortic Valve ◽  
Wall Stress ◽  
Aortic Aneurysms ◽  
Thoracic Aortic Aneurysms

Abstract 16806: Changes in Wall Stress in Ascending Thoracic Aortic Aneurysms From Systole to Diastole

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Andrew Liu ◽  
Zhongjie Wang ◽  
Yue XUAN ◽  
Michael D Hope ◽  
Liang Ge ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Cardiac Cycle ◽  
Aortic Rupture ◽  
Wall Stress ◽  
Ascending Aorta ◽  
Aortic Aneurysms ◽  
Patient Specific ◽  
Imaging Data ◽  
Element Analysis ◽  
Thoracic Aortic Aneurysms

Introduction: Aortic rupture or dissection of ascending thoracic aortic aneurysms (aTAA) is a life-threatening pathology that can occur when wall stress exceeds wall strength. Surgical guidelines for repair is when aneurysm max diameter ≥5.5 cm. However, rupture has been documented at various sizes, including 60% <4.5cm. Wall stress may be a better predictor of dissection than diameter, using finite element analysis (FEA) of patient-specific aTAA models to assess patient-specific risk of dissection. The purpose of this study was to determine changes in aneurysm FEA peak wall stresses in patients during the cardiac cycle from systole to diastole. Methods: Preoperative aTAA patients (n = 20) underwent ECG-gated computed tomography (CT) scans at systolic and diastolic phases. Patient-specific 3D aneurysm geometries were reconstructed from the imaging data at both phases and after accounting for pre-stress, underwent FEA using LS-DYNA solver. Wall stress distribution and magnitude were determined using user-defined fiber-embedded material model at systole (120mmHg) and diastole (80mmHg). Aortic volume changes during the cardiac cycle were determined using computer-aided design tools. Results: From the diastolic model, the 99 th percentile circumferential stresses were 348.8 ±105.6 kPa and 186.6 ±31.4 kPa for the sinus and ascending aorta respectively, while for the systolic model, they were 500.7 ±183.7 kPa (p=0.00072) and 296.5 ±64.4 kPa (p < .00001), respectively. The 99th percentile longitudinal stresses from the diastolic model were 223.2 ±75.4 kPa and 126.1 ±20.4 kPa for the sinus and ascending aorta, respectively, while for the systolic model, they were 336.3 ±78.4 kPa (p < .00001), and 235.2 ±48.0 kPa (p < .00001), respectively. Mean volume change of the ascending aorta in percentage between systolic and diastolic phases was 6.34%. Conclusions: Peak circumferential and longitudinal stresses changed significantly from systole to diastole. For patients with significant hypertension, these differences in wall stress may be magnified such that sudden or significant hypertension may result in wall stress values that exceed tissue strength leading to dissection.

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