Designanalyse von endovaskulären Aortenprothesen [thesis]

Anne Gebert de Uhlenbrock, Michael Morlock, TUHH Universitätsbibliothek, TUHH Universitätsbibliothek
In recent years minimally-invasive endovascular surgery of abdominal aortic aneurysms by means of stentgrafts has emerged alongside conventional open surgery as an alternative procedure for the prevention of vessel rupture. The degenerated vessel is bridged by a tubular prosthesis and is thereby decoupled from the systemic pressure. Despite the continuous evolution of endovascular stentgrafts over the last 15 years minimally-invasive treatment still suffers a re-intervention rate of 20% within
more » ... rate of 20% within 4 years. Inadequate sealing and migration of the prostheses rank among the most frequent failure causes. In this study, factors of stentgraft failure were identified, basic principles for component testing were established and design criteria for the development of prostheses were derived. Based on clinical data, parametric and patient-specific in vitro experiments and on mathematical models, fixation and flow forces were related to occurrence of migration in individual patients. Based on in vitro permeability measurements of thrombus and clotted grafts an analytical model was used to investigate the role of the thrombus as a sealing medium against pressure build-up in the aneurysm sac. Additionally, the influence of retrograde flow through the collateral vessels into the bridged aneurysm (endoleak II) on the pressure acting in the aneurysm was analyzed. In 80% of the patient data examined, a loss of fixation due to vessel dilation in the fixation region, or kinking of the prosthesis, were responsible for migration of the prostheses. The permeability of the thrombus was found to be sufficiently high to lead to pressurisation of the aneurysm sac and thus to a failure of the treatment for a permeable prosthesis and short attachment zones. Endoleak II was found topotentially lead to re-pressurization of the vessel wall up to the systemic pressure and was frequently found to be the cause for dilatation of the aneurysm clinically. Due to the high incidence of this leakage type a new design was proposed, to completely seal the co [...]
doi:10.15480/882.714 fatcat:cjacrkciqzgonkhthh3xpu6ub4