Temporal healing patterns and coverage dynamics after new Polish transcatheter PFO occluder implantation in a swine

Although currently used devices for interventional closure of patent foramen ovale (PFO) are widely used due to the minimally invasive nature of this technique and high success rate, there is still a need to look for new materials and designs in order to improve the treatment outcomes.

To evaluate the safety, biocompatibility, temporal healing patterns, and coverage dynamics of the new Polish PFO occluder (Balton, Warsaw, Poland) in a swine model - an observation that may assist the decision with regard to its first-in-human use and duration of anticoagulation therapy.

In total, 12 pigs were scheduled for 28-day (n = 6) and 90-day follow-up (n = 6). In each animal, using a standard femoral venous approach, one PFO occluder was implanted and subsequently, in order to verify device position stability, the Minnesota manoeuvre was performed. At follow-up, all devices underwent a comprehensive evaluation with the use of high-resolution radiography (Faxitron MX-20 system), scanning electron microscopy (SEM), and standard histopathological techniques.

All PFO occluders were implanted successfully with no complications. The Faxitron revealed that all nitinol portions of the frame appeared intact and breaks were not detected at both studied time points. Overall, the device appeared to be well deployed in the atrial septum. At 28 days the average neointimal coverage of the right side of the PFO occluder by SEM was 92%; while in contrast the left side had less coverage, at 63%. At 90 days, the coverage of the right side of the occluder was 96.8%, while the left side of the PFO occluder improved and had similar coverage of 93.3%. By histology the endothelialisation process was virtually complete at 90 days. At the early time-point the overall inflammatory infiltrate was moderate and subsequently it diminished and was only mild or occasionally moderate at 90-day follow-up. At both time points the inflammatory reaction was limited to the neointimal tissue surrounding the device.

Our study confirmed safety and good overall biocompatibility of the new Polish PFO occluder, which is comparable to other devices available on the market - an observation that supports the decision with regard to its first-in-human application. Neoendothelialisation was virtually completed at 90 days, suggesting that similarly to other widely used devices a minimum of three to six months of anticoagulation therapy should be recommended.