Geometric Modeling of Thoracic Aortic Surface Morphology - Implications for Pathophysiology and Clinical Interventions
Doctoral thesis, 2021

Vascular disease risk factors such as hypertension, hyperlipidemia and old age are all results of modern-day lifestyle, and these diseases are getting more and more common. One treatment option for vascular diseases such as aneurysms and dissections is endovascular aortic repair introduced in the early 1990s. This treatment uses tubular fabric covered metallic structures (endografts) that are implanted using a minimally invasive approach and placed to serve as an articial vessel in a damaged portion of the vasculature. To ensure that the interventions are successful, the endograft must be placed in the correct location, and designed to sustain the hostile biological, chemical, and mechanical conditions in the body for many years. This is an interaction that goes both ways, and keeping in mind that the endograft is a foreign object placed in the sensitive vascular system, it is also important that it does not disrupt the native conditions more than necessary.

This thesis presents a segmentation and quantication methodology to accurately describe the complex morphology and motion of diseased blood vessels in vivo through a natural and intuitive description of their luminal surfaces. After methodology validation, a series of important clinical applications are performed, all based on non-invasive imaging. Firstly, it is shown that explicit surface curvature quantication is necessary when compared to relying solely on centerline curvature and estimation methods. Secondly, it is shown that endograft malapposition severity can be predicted from preoperative geometric analysis of thoracic aortic surfaces. Thirdly, a multiaxial dynamics analysis of cardiac induced thoracic aortic surface motion shows how thoracic endovascular aortic repair affects the deformations of the dierent portions of the thoracic aorta. Fourthly, the helical propagation pattern of type B aortic dissection is determined, and two distinct modes of chirality are revealed, i.e., achiral and right-handed chiral groups. Finally, the effects of thoracic endovascular aortic repair on helical and cross-sectional morphology of type B dissections are investigated revealing how acuity and chirality affects the alteration due to intraluminal lining with endografts. Thus, the work presented in this thesis contributes by adding knowledge about pathology and pathophysiology through better geometric description of surface conditions of diseased thoracic aortas. This gives clinicians insights to use in their treatment planning and provides more nuanced boundary conditions for endograft manufacturers. Comprehensive knowledge about diseases, better treatment planning, and better devices are all crucial in order to improve the outcomes of performed interventions and ultimately the quality of life for the treated patients.

bird-beaking

helical morphology

Thoracic aorta

cardiac pulsatility

geometric modeling

stereolithographic 3D surfaces

chirality

aneurysm

endograft

type B aortic dissection

surface curvature

TEVAR

Details for the digital meeting can be found at: https://www.chalmers.se/sv/institutioner/m2/kalendarium/Sidor/Geometric-modeling-of-thoracic-aortic-surface-morphology---implications-for-pathophysiology-and-clinical-interventions.aspx
Opponent: Professor James E. Moore Jr. The Bagrit and Royal Academy of Engineering Chair in Medical Device Design, Department of Bioengineering Imperial College London, United Kingdom

Author

Johan Bondesson

Chalmers, Mechanics and Maritime Sciences, Dynamics

Automated Quantification of Diseased Thoracic Aortic Longitudinal Centerline and Surface Curvatures

Journal of Biomechanical Engineering,; Vol. 142(2020)

Journal article

Thoracic aortic geometry correlates with endograft bird-beaking severity

Journal of Vascular Surgery,; Vol. 72(2020)p. 1196-1205

Journal article

Multiaxial Pulsatile Dynamics of The Thoracic Aorta and Impact of Thoracic Endovascular Repair

European Journal of Radiology Open,; Vol. 8(2021)

Journal article

Quantification of True Lumen Helical Morphology and Chirality in Type B Aortic Dissections

American Journal of Physiology - Heart and Circulatory Physiology,; Vol. 320(2021)p. H901-H911

Journal article

Johan Bondesson, Ga-Young Suh, Neil Marks, Michael D. Dake, Jason T. Lee, and Christopher P. Cheng. "Influence of Thoracic Endovascular Aortic Repair on True Lumen Helical Morphology for Stanford Type B Dissections". Accepted for publication in the Journal of Vascular Surgery

A well-placed and durable implant can save your life
Vascular diseases are getting more and more common as a result of modern-day lifestyle.  Some of these can be treated with implants placed in the blood system using minimally invasive surgery. The implants are tightly packaged into a small catheter and inserted through the groin of the patient. Assisted by x-ray, the vascular surgeon can now steer the crimped implant through the vascular system and unfold it at the intended location.
 
In order to achieve a long-term successful outcome of the operation, two aspects are especially important: 1) that the implant is placed in at the intended and correct location, and 2) that it has a durable design. This is where the research presented in this thesis comes into play as it uses geometric modeling to describe how the vessels are shaped, and also how they move inside the body. Knowledge about the shape of the vessels will assist surgeons in where to place (and not to place) implants, and understanding about how vessels move is crucial to be able to design the implants so that they do not break during the lifetime of the patient. This thesis also describes how certain vascular diseases sometimes propagate in a spiraling manner. The fact that this is seen in other living organisms reminds us that the human body is very much a biological system defined by the fabric of nature.
 
This work will help improve the outcomes of interventions and ultimately the quality of life for treated patients.

Subject Categories

Surgery

Medical Engineering

Other Medical Biotechnology

Radiology, Nuclear Medicine and Medical Imaging

Areas of Advance

Health Engineering

ISBN

978-91-7905-472-4

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4939

Publisher

Chalmers University of Technology

Details for the digital meeting can be found at: https://www.chalmers.se/sv/institutioner/m2/kalendarium/Sidor/Geometric-modeling-of-thoracic-aortic-surface-morphology---implications-for-pathophysiology-and-clinical-interventions.aspx

Online

Opponent: Professor James E. Moore Jr. The Bagrit and Royal Academy of Engineering Chair in Medical Device Design, Department of Bioengineering Imperial College London, United Kingdom

More information

Latest update

5/18/2021