Evaluation of venous anatomy after treatment with an intraluminal tissue debulking system in a porcine model.

BACKGROUND: Residual venous obstruction and in-stent restenosis are common and challenging complications that may occur after interventional procedures performed for acute deep vein thrombosis or chronic iliofemoral venous obstruction. A novel fully integrated thrombectomy system [Recana Thrombectomy Device (RTD)] was designed to treat (in-stent restenosis) and native vessel obstructions. The system includes a debulking catheter, collection baskets, and a family of sheaths. This report describes its use in animal models of native and stented veins to assess safety compared with currently available thrombectomy devices.

METHODS: The RTD was studied in comparison to two currently marketed thrombectomy devices, the Argon CLEANER 15 (CLEANER; Argon Medical Devices Inc.) and the Inari ClotTriever (ClotTriever Catheter; Inari Medical, Inc.). Devices were studied in a porcine iliac vein model used in a manner consistent with good laboratory practice for Nonclinical Laboratory Studies. A total of 26 iliac veins in 13 animals were studied to evaluate performance in normal veins (9 animals, 18 iliac veins) and in four animals with eight iliac veins pretreated with iliac stents implanted 21 days before device treatment. Twelve normal iliac veins were treated with the RTD, four normal veins were treated with CLEANER, and two with the ClotTriever. Five prestented iliac veins were treated with the RTD, and three prestented veins were treated with the CLEANER. Procedures were completed under fluoroscopic and intravascular ultrasound guidance. For each model, both iliac veins were treated with 10 passes of the test or control thrombectomy device through the length of the common and external iliac veins. Survival and sacrifice periods were completed at varied time points to evaluate peak histological injury potential, vein wall healing, and vein patency. Necropsy was performed at 5 ± 2 or 30 ± 2 days after catheter intervention for gross evaluation of the iliac veins and other related tissues. Histology was performed on representative sections of treated iliac veins to evaluate wall damage, thrombosis, or other effects of intervention.

RESULTS: All animals survived to their designated end points with no unexpected mortality. One common femoral vein access complication led to unilateral perivenous hematoma and thrombosis. Another animal showed postintervention venous constriction with eventual vessel occlusion. All other iliac veins (n = 24) remained patent without significant stenosis at necropsy. No clinically relevant lacerations, perforations, or hemorrhagic events were observed with either the Test or Control devices. Histology revealed intimal disruption and inflammation with all devices, more pronounced with the RTD compared with CLEANER but similar to those seen after use of the ClotTriever. Mild perivenous bruising occurred in some Test device cases, without evidence of transmural bleeding.

CONCLUSIONS: In an in vivo model of stented and native iliac veins, a novel venous tissue debulking system was able to engage intraluminal material without serious injury. Vein wall trauma was comparable to a commonly used mechanical thrombectomy device, with no transmural lacerations or device-related hemorrhage. These findings support continued development toward initial clinical trials in patients with venous obstruction.

CLINICAL RELEVANCE: This experimental study utilizes a porcine model for examination of a novel venous thrombectomy device in normal and stented iliac veins. The study examines the degree of injury occurring within the vein wall in normal and stented iliac veins after treatment with the test device compared with currently marketed thrombectomy devices. The feasibility of removal of the material causing in-stent restenosis is established using the Test device. The study also provides key information on the response of the iliac vein wall in this model to intraluminal devices that impact the wall during treatment.