Feasibility of an ex-vivo model for investigating the mechanistic performance of vessel preparation devices in tibial arteries.
Bright Benfor, Kavya Sinha, Alan B Lumsden, Trisha L Roy
Houston Methodist Debakey Heart and Vascular Center, Houston, TX
INTRODUCTION AND OBJECTIVES: Evaluating the safety and efficacy of vessel preparation devices (VPDs) in calcified tibial arteries has been a challenge thus far. The aim of this study was to demonstrate the feasibility of a novel experimental model for investigating the mechanistic performance of VPDs in tibial arteries.
METHODS:
Human amputated limbs were used to develop a model for testing orbital atherectomy (OA), intravascular lithotripsy (IVL) and plain balloon angioplasty (POBA) in tibial arteries. Limbs with evidence of concentric calcification (i.e. ≥ 270° circumference), and no history of prior revascularization in the targeted tibial artery were included. All amputated limbs were scanned in a 7T MRI with high resolution for histology-level plaque characterization prior to experiment. A retrograde through-through wire access was obtained by surgical cut-down, while the proximal end of the artery was transected to allow for flushing of contrast and pressurized saline infusion. Procedures were performed under fluoroscopic guidance, and intravascular ultrasound (IVUS) was used for balloon sizing. Lesions were treated with or without vessel preparation before POBA, depending on the availability of device and industry representative. Luminal gain was assessed with IVUS. The treated arterial segments and a control untreated segment were then harvested for ex-vivo processing which included imaging with microCT, decalcification, and histology (Fig1).
RESULTS:
The model was tested out in 15 limbs and was successful in 14 but had to be aborted in 1/15 case due to inability to achieve intraluminal wire access. The procedures were performed in the anterior tibial artery in 11/15 cases, the posterior tibial artery in 3/15 cases and the peroneal in 1/15 limb, with a total of 22 lesions treated. OA was performed on 3/22 lesions, IVL in 8/22 and POBA alone in the remaining 11/22. The mean reference vessel diameter and degree of stenosis were 2.9±0.2 mm and 52±6% respectively, while average luminal gain was estimated at 61±27%. The duration of experiment was 120 ±30 minutes. Histology showed degree of intimal disruption and vessel wall changes such as endothelial denudation, microcracks within calcium and uncontrolled dissections associated with each device (Fig. 2).
CONCLUSIONS:
An ex-vivo model using amputated limbs is feasible for evaluating the performance of VPDs in calcified tibial arteries and will potentially complement clinical data in investigating the safety and efficacy of these devices 
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