Assessment of Pull-out Forces in TEVAR & ANACONDA FEVAR Combination and Early Clinical Results: Creation of a Proximal Landing Zone for FEVAR in Patients with Type I and Type IV TAAAs

Abstract

Introduction: In certain cases of Type I thoracoabdominal aortic aneurysms (TAAA), endovascular treatment with off-the-shelf tube grafts is not feasible due to a lack of distal landing zone proximal to the celiac trunk. Likewise, the paravisceral segment of Type IV TAAAs is in certain cases not suitable for a branched endograft due to space restrictions. The creation of a proximal landing zone using a thoracic tube graft in combination with a distally implanted fenestrated Anaconda device may represent a feasible treatment option. The current investigation was performed to assess the stability of a fenestrated Anaconda device (FEVAR) implanted into a set of thoracic endografts from different manufacturers. We also evaluated our own clinical results with the TEVAR & FEVAR combination. Methods: The first part of the study was an experimental set-up. Pull-out forces were measured after docking the proximal end of an Anaconda graft within the distal end of a range of different TEVAR devices to assess the risk of migration and subsequent endoleak at the device interface. 30mm, 32mm and 34mm Anaconda devices were implanted in five different 28mm thoracic tube grafts (Cook Zenith, Medtronic Valiant, Jotec E-vita, Bolton Relay and Gore CTAG). The minimum overlap distance was 15mm. The device combination was mounted onto an Instron Tensile Tester and continuously increasing longitudinal pull forces of up to 100 Newton were applied. The initial break point and damage to the endografts were documented. For the second part of the study, a prospectively held database on FEVAR patients treated with the fenestrated Anaconda device at our institution was screened for cases where a suitable proximal landing zone had been created with a TEVAR device followed by aneurysm exclusion with a fenestrated device. Results: Median pull-out forces ranged from 1.05N to 55.0N. Pull-out forces were above 10.72N for all assessed combinations of grafts except for those including the 30mm Gore CTAG device and highest stability was achieved with 34mm Anaconda devices in 28mm thoracic tube grafts. While minor puncture holes caused by the downward-looking hooks of the Anaconda device were documented in all thoracic devices, the PTFE membrane of the Gore device and the Dacron material of the Jotec and Medtronic devices seemed especially vulnerable and fabric tears were observed. Between April 1st 2013 and December 31st 2018, in 28 out of 172 patients treated with a fenestrated Anaconda device, preliminary implantation of a thoracic tube graft was necessary to create a sufficient proximal landing zone. In 25 cases (89.3%), the aneurysm was successfully treated. Conclusion: The combination of a thoracic tube graft and a fenestrated Anaconda device is a viable option for the treatment of patients with Type I or IV TAAAs with no adequate landing zone above the celiac trunk. While pull-out testing has shown good stability with most assessed grafts, the Bolton and Cook thoracic devices seemed to be especially suitable. Disclosure: Jürgen Falkensammer & Afshin Assadian are have proctored fenestrated Anaconda implantations for Vascutek