P269. Protective Biomechanical and Histological Changes in the False Lumen Wall in Chronic Type B Aortic Dissection
Presented During: POD Abstracts (Available for viewing in the exhibit hall for the duration of the meeting)
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Hai Dong, Ph.D., is an Assistant Professor in the Division of Cardiothoracic Surgery at Emory University School of Medicine. He received his Ph.D. in Solid Mechanics from Peking University in 2016. His research interests include risk prediction of aortic aneurysm/dissection, growth modeling of aortic tissues, and constitutive models of cardiovascular tissues.
Thursday, April 25, 2024: 5:38 PM - 7:00 PM
Sheraton Times Square
Room: Central Park
Description
Objective: The mechanical strength of the false lumen wall (FLW) prevents rupture in aneurysms secondary to Chronic Type B Aortic Dissection (CTBAD), despite having partial thickness. The FLW consists primarily of adventitia, a key component in the open repair of dissections. This study sought to elucidate mechanisms of FLW mechanical properties which remain unclear.
Methods: The FLW from 14 patients (9 CTBAD and 5 Acute Type A Aortic Dissection) who underwent open aortic replacement was analyzed, and compared to iatrogenically dissected, manually peeled FLW from 6 normal transplant donor descending aortas designated as a control group (C-FLW). Biaxial tension testing in the circumferential (Circ) and axial directions was performed on the CTBAD-FLW (n=9), Acute-A-FLW (n=5) and C-FLW (n=6) tissues. Stress-strain curves were created (Fig. 1a), and a lower and higher tangent modulus (LTM & HTM) was determined for each sample to assess tissue stiffness. A histologic analysis of the tissue microstructure was performed on the collagen and elastin fibers. Quantification of the composition of collagen and elastin fibers was performed by calculating the fibers' volume fraction (VF) from Z-Stack scans (n=106 locations in 15 FLW samples [5 per group], 4-9 locations per sample based on thickness).
Results: In Circ, both LTM and HTM of CTBAD-FLW were significantly larger than those of C-FLW and Acute-A-FLW (Fig. 1b, c). In axial, HTM of the FLW was also larger than that of C-FLW and Acute-A-FLW (Fig. 1c), and LTM of Acute-A-FLW was smaller than that of C-FLW (Fig. 1b). Histology demonstrated a higher concentration of organized collagen in CTBAD-FLW compared to C-FLW and Acute-A-FLW, and a lower concentration of elastin (Fig. 1d). Quantification of the collagen/elastin profile in the tissue demonstrated a significant increase in the VF of collagen fibers and a significant decrease in the VF of elastin fibers when comparing CTBAD-FLW versus Acute-A-FLW & control-FLW (Fig. 1e). The VF of collagen fiber is larger than that of elastic fibers within CTBAD-FLW, but smaller than that of elastic fibers within Acute-A-FLW & control-FLW (Fig. 1e).
Conclusions: The FLW is stiffer in CTBAD compared to either normal or acute aortic dissection tissue due to increased collagen and decreased elastin. This change in the composition of FLW extracellular matrix may be a protective adaption to prevent aortic rupture and explains the importance of the adventitia in the surgical repair of aortic dissection.
Authors
Hai Dong (1), Minliang Liu (1), Hannah Cebull (2), Marina Piccinelli (2), John Oshinski (3), John Elefteriades (4), Rudolph Gleason (1), Bradley Leshnower (5)
Institutions
(1) Georgia Institute of Technology, Atlanta, GA, (2) Emory University, Atlanta, GA, (3) Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, (4) Yale New Haven Hospital, New Haven, CT, (5) Emory University Hospital, Atlanta, GA
Methods: The FLW from 14 patients (9 CTBAD and 5 Acute Type A Aortic Dissection) who underwent open aortic replacement was analyzed, and compared to iatrogenically dissected, manually peeled FLW from 6 normal transplant donor descending aortas designated as a control group (C-FLW). Biaxial tension testing in the circumferential (Circ) and axial directions was performed on the CTBAD-FLW (n=9), Acute-A-FLW (n=5) and C-FLW (n=6) tissues. Stress-strain curves were created (Fig. 1a), and a lower and higher tangent modulus (LTM & HTM) was determined for each sample to assess tissue stiffness. A histologic analysis of the tissue microstructure was performed on the collagen and elastin fibers. Quantification of the composition of collagen and elastin fibers was performed by calculating the fibers' volume fraction (VF) from Z-Stack scans (n=106 locations in 15 FLW samples [5 per group], 4-9 locations per sample based on thickness).
Results: In Circ, both LTM and HTM of CTBAD-FLW were significantly larger than those of C-FLW and Acute-A-FLW (Fig. 1b, c). In axial, HTM of the FLW was also larger than that of C-FLW and Acute-A-FLW (Fig. 1c), and LTM of Acute-A-FLW was smaller than that of C-FLW (Fig. 1b). Histology demonstrated a higher concentration of organized collagen in CTBAD-FLW compared to C-FLW and Acute-A-FLW, and a lower concentration of elastin (Fig. 1d). Quantification of the collagen/elastin profile in the tissue demonstrated a significant increase in the VF of collagen fibers and a significant decrease in the VF of elastin fibers when comparing CTBAD-FLW versus Acute-A-FLW & control-FLW (Fig. 1e). The VF of collagen fiber is larger than that of elastic fibers within CTBAD-FLW, but smaller than that of elastic fibers within Acute-A-FLW & control-FLW (Fig. 1e).
Conclusions: The FLW is stiffer in CTBAD compared to either normal or acute aortic dissection tissue due to increased collagen and decreased elastin. This change in the composition of FLW extracellular matrix may be a protective adaption to prevent aortic rupture and explains the importance of the adventitia in the surgical repair of aortic dissection.
Authors
Hai Dong (1), Minliang Liu (1), Hannah Cebull (2), Marina Piccinelli (2), John Oshinski (3), John Elefteriades (4), Rudolph Gleason (1), Bradley Leshnower (5)
Institutions
(1) Georgia Institute of Technology, Atlanta, GA, (2) Emory University, Atlanta, GA, (3) Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, (4) Yale New Haven Hospital, New Haven, CT, (5) Emory University Hospital, Atlanta, GA
Presentation Duration
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