Pre-Clinical Development of a Novel Catheter System for Chronic Postthrombotic Deep Vein Recanalization and Chronic In-Stent Restenosis

Patency rates and reinterventions for iliofemoral venous stents and percutaneous transluminal angioplasty (PTA) are inferior in postthrombotic etiology compared to nonthrombotic etiology. Intervening on chronically failed stents, resulting from both untreated or delayed intervention for acute thrombosis and chronic progressive lumen reduction leading to stenosis, is complex, often difficult with limited treatment options yielding reduced patency rates and more frequent secondary interventions. The practice of re-stenting/re-lining may induce paradoxical lumen loss, with maximum lumen size being compromised by accumulating stent layers during long-term care of patients.

Debulking and recanalization of chronic postthrombotic (collagenic) obstructive/occlusive tissue prior to PTA and native iliofemoral vein stent implantation may enhance patency and reduce secondary interventions. Furthermore, in the context of chronic in-stent restenosis (ISR), debulking and recanalization are postulated to improve patency, eliminating the need for re-stenting post-debulking of the obstructed/occluded stents.

Methods: A novel physician-adjustable spiral cutting, boring and debulking catheter system* was developed offering an endovenous solution analogous to open surgical endophlebectomy first reported by Comerota et al. This 12Fr image-guided system is intended to cut and recanalize a spectrum of chronic ISR and chronic native vein postthrombotic lesions, partial obstructions, full occlusions, and webbing-like trabeculae and synechiae. Included are means for collection of chronic emboli: an 18mm ipsilateral iliofemoral basket and 30mm caval-placement basket. The system also encompasses ipsilateral and contralateral lower extremity delivery and retrieval sheaths with 13 and 16Fr profiles. This facilitates debulking and recanalization of chronically obstructed/occluded venous stents, seeking patency restoration without stent re-lining. Additional applications include removal of wall-adherent, chronic obstruction encountered in 'late' thrombectomy along with re-establishment of inflow vessel patency facilitating iliofemoral venous stent implantation or enhancing pre-existing suboptimal inflow.

Results: The catheter system was tested within benchtop tissue, cadaveric, as well as in-vivo porcine animal models. Testing demonstrated the catheter's atraumatic nature on healthy cadaveric and porcine vein walls through routine utilization as well as intentional efforts to interact with the vein wall in combinations of significant curvature, angulation and compression. Further, testing within stented segments resulted in favorable outcomes with respect to crossing and debulking lumens with obstruction/occlusion.  Capability in excising chronic tissue was demonstrated across varied animal tissue(s) and polymer-based lesion types simulating diverse chronicity, density, hardness, and degree of luminal obstruction/occlusion.

Conclusions:

Pre-clinical evaluations suggest endovenous endophlebectomy and chronic ISR recanalization utilizing the novel system described herein is safe and feasible. New devices dedicated to challenging chronic postthrombotic pathology offer previously unavailable treatment options and improved outcomes to those suffering from chronic postthrombotic venous obstruction, occlusion, and ISR.

* Chronus venous system, Intervene, Inc.