An experimental evaluation of the device/arterial wall compliance mismatch for four stent-graft devices and a Multi-layer Flow Modulator (MFM) device for the treatment of abdominal aortic aneurysms

Abstract

Purpose: To experimentally investigate the arterial wall/device compliance mismatch of four stent-graft devices and a multi-layer flow modulator within the supra- and infra-renal locations for the treatment of Abdominal Aortic Aneurysms (AAA). Methods: Five devices (MFM™, Endurant II™, Excluder™, Zenith™ and Fortron™) were tested under physiologically flow conditions within a flow simulator system comprising of a patient-specific thin-walled flexible AAA perfusion model with replicated intraluminal thrombus (ILT), supported by the spinal column. Devices were submitted to circumferential force tests and implanted in the perfusion model for circumferential arterial pressure/diameter measurements. Parameters, including: radial resistive force, supra-/infrarenal compliance, pulsatile arterial energy loss (PAEL), pulse wave velocity (PWV) and waves reflection coefficient (Γ), were computed to characterise the device performance. Results: The Zenith™ and Endurant II™ devices had the highest radial resistive force (up to 3 N/cm), while the Fortron™ device had the lowest (0.11 N/cm). The compliance varied between 6.9 to 5.1×10-4/mmHg (suprarenal), and between 4.8 to 5.4×10-4/mmHg (infrarenal). Two devices (Endurant II™ and Excluder™) significantly decreased the infrarenal compliance by 13 – 26% (p<0.001). Four devices increased the PAEL by 13 – 44% (p<0.006). The PWV ranged from 10.9 m/s (MFM™, p=0.164) to 15.1m/s (Endurant II™, p<0.001). There was an increase of 8 – 238% (p<0.001) in the reflection coefficient for all devices. Conclusions:

Commercially available endovascular devices lower the aortic wall compliance after implatation. The MFM™ was found to be the most compliant in the surprarenal region, while the Fortron™ device was the most compliant in the infrarenal region.