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. 2021 Nov 4;8(11):175.
doi: 10.3390/bioengineering8110175.

Patient-Specific Analysis of Ascending Thoracic Aortic Aneurysm with the Living Heart Human Model

Salvatore Cutugno  1 , Valentina Agnese  2 , Giovanni Gentile  3 , Giuseppe M Raffa  2 , Andrew D Wisneski  4 , Julius M Guccione  4 , Michele Pilato  2 , Salvatore Pasta  1
Affiliations

Patient-Specific Analysis of Ascending Thoracic Aortic Aneurysm with the Living Heart Human Model

Salvatore Cutugno et al. Bioengineering (Basel). .

Abstract

In ascending thoracic aortic aneurysms (ATAAs), aneurysm kinematics are driven by ventricular traction occurring every heartbeat, increasing the stress level of dilated aortic wall. Aortic elongation due to heart motion and aortic length are emerging as potential indicators of adverse events in ATAAs; however, simulation of ATAA that takes into account the cardiac mechanics is technically challenging. The objective of this study was to adapt the realistic Living Heart Human Model (LHHM) to the anatomy and physiology of a patient with ATAA to assess the role of cardiac motion on aortic wall stress distribution. Patient-specific segmentation and material parameter estimation were done using preoperative computed tomography angiography (CTA) and ex vivo biaxial testing of the harvested tissue collected during surgery. The lumped-parameter model of systemic circulation implemented in the LHHM was refined using clinical and echocardiographic data. The results showed that the longitudinal stress was highest in the major curvature of the aneurysm, with specific aortic quadrants having stress levels change from tensile to compressive in a transmural direction. This study revealed the key role of heart motion that stretches the aortic root and increases ATAA wall tension. The ATAA LHHM is a realistic cardiovascular platform where patient-specific information can be easily integrated to assess the aneurysm biomechanics and potentially support the clinical management of patients with ATAAs.

Keywords: ascending aortic aneurysm; cardiac mechanics; finite element analysis; living heart human model.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Workflow showing the modification of the original LHHM to account for the ATAA; the green model (left) shows the original aortic model; measurements of ATAA diameter from CT images (middle-left); ATAA model showing the centerline and curve used for the loft protrusion surface (middle-right); ATAA model showing the coupling with the lumped-parameter model as boundary condition (right).
Figure 2
Figure 2
Sketch of LHHM implementation: (A) heart and great vessel geometries; (B) fiber architecture; (C) coupling with 1D lumped-parameter model; (D) structural mesh.
Figure 3
Figure 3
(A) Experimental stress–strain data (dots) and fitting (solid lines) from biaxial testing; (B) photography of experimental setup.
Figure 4
Figure 4
Circumferential (SC) and longitudinal stress (SL) map during systolic peak for unmodified LHHM healthy aorta.
Figure 5
Figure 5
Circumferential (SC) and longitudinal stress (SL) map during systolic peak for ATAA case.
Figure 6
Figure 6
Polar plot of stress distribution along three different sections for ATAA LHHM at systolic peak for both the inner aortic wall surface (red lines) and the outer aortic wall surface (blue lines).
Figure 7
Figure 7
Polar plot of stress distribution along three different sections for ATAA LHHM at late diastole for both the inner aortic wall surface (red lines) and the outer aortic wall surface (blue lines).
Figure 8
Figure 8
Polar plot of stress distribution along three different sections for healthy LHHM at systolic peak for both the inner aortic wall surface (red lines) and the outer aortic wall surface (blue lines).
Figure 9
Figure 9
Polar plot of stress distribution along three different sections for healthy LHHM at late diastole for both the inner aortic wall surface (red lines) and the outer aortic wall surface (blue lines).
Figure 10
Figure 10
Pressure–volume loop of the left ventricle for the healthy and ATAA LHHMs.
See this image and copyright information in PMC

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