Pathology of explanted novel expanded polytetrafluoroethylene pulmonary valved conduits reveals paucity of leaflet tissue response but frequent nonadherent thrombus formation.

Abstract

Durable and biocompatible pulmonary valved conduits remain a challenge in congenital cardiac surgery. The GORE PV1 device is a fully synthetic expanded polytetrafluoroethylene-based conduit designed to improve durability and reduce calcification. This study characterizes the gross and histopathologic findings in explanted PV1 conduits. Six GORE PV1 conduits explanted from pediatric patients (median age: 13.5 years) were evaluated. All patients were part of a previously reported cohort. Clinical data, imaging, and operative notes were reviewed. Gross and histologic examinations assessed leaflet integrity, thrombus, inflammation, calcification, and tissue overgrowth. Sections were stained with hematoxylin and eosin and reviewed by an experienced pediatric cardiac pathologist. All patients had undergone multiple previous cardiac surgeries and received anticoagulation after conduit implantation. Explantation was prompted by thrombus formation, with pulmonary emboli in 4 of 6 patients (66.7%), including 2 with progression despite therapeutic anticoagulation. Leaflets appeared thin, transparent, and intact with no calcification or degeneration. Nonadherent thrombi, often filling the sinuses, were present in all conduits. Histology showed no leaflet inflammation, fibrosis, calcification, or endothelialization. Thrombi demonstrated laminated fibrin with inflammatory cells; 2 showed foreign-body giant cell reaction. Fibrous overgrowth along suture lines was minimal to moderate. The GORE PV1 conduit retained excellent structural integrity after midterm implantation. However, frequent nonadherent thrombi, despite anticoagulation, were associated with embolic events. These findings underscore the need for long-term monitoring and device design improvements, and may guide anticoagulation strategies in patients receiving synthetic valved conduits.