Aorta Dynamics after Endovascular Aorta Repair

Background: Thoracic endovascular aortic repair (TEVAR) is the mainly used treatment for thoracic aorta pathologies (TAP) due to its less invasiveness compared to the conventional open surgical aneurysm repair. ‘Regular’ TEVAR is performed in pathologies of the descending thoracic aorta, while when the aortic arch is included in the pathology hybrid-TEVAR with a frozen elephant trunk (FET) or branched-TEVAR (BTEVAR) may be performed as well. Different types of endografts are developed for different procedures, including personalization options to fit best to the anatomy of each patient. Endografts of interest in the present study are the Relay(Branch) and Thoraflex Hybrid. Once implanted, the aorta dynamics and the device affect each other in ways that are currently not understood. Pre and post-operative imaging of aortic aneurysm is routinely performed using computerised tomographic angiography (CTA). However, these static techniques do not consider the aorta dynamics. Consequently, our understanding of the dynamic behaviour of the stent grafts and stented target vessels is limited. Electrocardiogram (ECG)-gated CTA is a technique that takes the patient’s heart cycle into account, enabling studies to the motion of aorta and implanted devices.

The objective of the study is to gain information on the dynamics and shape of the stent graft and stented target vessels, and how these change over time will improve our understanding about the fixation and/or sealing of the stent graft, which may help in stent graft selection and in designing stent grafts that are more durable.

Study design: Explorative observational cohort study with patients with an thoracic aorta pathology undergoing repair with the Thoraflex Hybrid graft (Hybrid-TEVAR) or the Relay(Branch) graft ((B)TEVAR). Included patients will undergo ECG-gated CTA preoperatively and at set points during follow-up to investigate geometry and dynamic changes over time and during the cardiac cycle.

Intervention: Present practise is that the patients undergo CTA of the aorta pre-operatively and post-operatively before discharge or after 6 to 8 weeks, after 3 to 6 months, after 12 months, and yearly thereafter. Patients included in this study receive an ECG-gated CTA before intervention and three ECG-gated CTs post-operatively: at discharge, after 6-8 weeks, and after 12 months. Thereafter the routine follow up scheme will be followed.

Main study parameters/endpoints: Of primary interest are the changes in the diameter of the (proximal) stent ring(s) due to hemodynamic forces and the changes in the dynamic interaction between the main body, the potential branches, and the native arteries. We distinguish between changes during the heartbeat (pulsatility) and changes over a period of several months (expansion). By relating the observed motions to computational models of the stent and the biomechanics of the vessel wall, the change in vessel compliance can be estimated.

Nature and extent of the burden and risks associated with participation, benefit and group relatedness: The ECG-gated CTA protocol results in a higher dose in comparison to a routine scan. However the additional risk on the chance of acquiring cancer as a result of this higher dose is estimated to be negligible, because the study population has a low life expectancy and only patients above 65 will be included.

Information on the dynamics and shape of the stent graft and stented target vessels, and how these change over time will improve our understanding about the fixation and/or sealing of the stent graft, which may help in stent graft selection and in designing stent grafts that are more durable.

-Inclusion of patients complete
-Each included patient is scanned pre-operatively and three times post-operatively until 12 months follow-up.

Present practise is that the patients undergo CTA of the aorta pre-operatively and post-operatively before discharge or after 6 to 8 weeks, after 3 to 6 months, after 12 months, and yearly thereafter. Patients included in this study receive an ECG-gated CTA before intervention and three ECG-gated CTs post-operatively: at discharge, after 6-8 weeks, and after 12 months. Thereafter the routine follow up scheme will be followed.