Solaris

Clinical Trials

Optical Coherence Tomography and Histopathological Preclinical Evaluation of an Enhanced Polytetrafluoroetylene (PTFE) Covered Stent in a peripheral Swine Animal

Model: Addressing the Anatomical Challenges of the Lower Limb Stenting Procedure

 

Armando Tellez, Krista N. Dillon, Dane A. Brady, Luciano Curado, Eduardo Cordeiro, Alexander Moreira,
Serge D. Rousselle Alizée Pathology; Thurmont, Maryland; Scitech Medical, São Paulo Brazil

 

Introduction

Covered stents are widely used to address numerous areas of need in peripheral intervention including degenerated vein grafts, iatrogenic arterial perforations, aneurysm exclusion, iliac artery graft extension, and the chimney/snorkel technique to treat aortic aneurysm. However, PTFE covered stents have a known relative inflexibility which makes deliverability difficult in complex, tortuous, and heavily calcified anatomy. Additionally, current technologies tend to produce kinks resulting in device collapse. This, in turn, can be associated with a high restenosis rate post-implantation, particulary stent-edge restenosis, acute, and subacute thrombosis. In this study we aim to evaluate the performance and vascular response of a new, peripheral covered stent in a large animal model as compared to a commercially available PTFE-covered stent.

Methods

Six domestic swine were included in this study (45±1kg). Based on angiographic QVA, the superficial femoral arteries were randomized for either the implantation of Solaris (Scitech, São Paulo, Brazil) or Fluency (Bard, Tempe, AZ). Stents utilized were 40mm long for both groups and implanted aiming for a 1.1:1 ratio. Following implantation, animals were recovered and followed for 30 days. At 30 days post-implantation all stents were evaluated under optical coherence tomography (OCT), explanted and subjected to stent integrity analysis and histopathological evaluation.

Results

A total of 11 stents were evaluated (Solaris n=6, Fluency n=5), The operator described the Solaris stents as demonstrating a higher navigability when compared to the Fluency stent. The hydrophilic coated delivery system of the Solaris stent allowed a smoother release of the device without any sudden jump and greater geographical precision at implantation. At 30 days, OCT revealed a similar stent area for groups (Solaris 25.8±4,7 vs Fluency 24.7±5mm2) with a lower neointimal area (Solaris 7.8±1.8 vs Fluency 10.8±2.4mm2) compared to control. This led to a higher percentage stenosis in the control group (Solaris 31.9±7 vs Fluency 44.8±6%).

Device description

Low profile (5-7 mm diameter x 40-100 mm in length) self-expandable nitinol peripheral stent. Due to the cell design, the Solaris stent provides superior, ultidirectional flexibility and easy navigability. Three tantalum markers on the extremities allow for precision in delivery.The stent is covered by an ultra-thin, polytetrafluoroethylene (PTFE) membrane. The representative images above illustrate the SEM of the membrane at 170x (left) and 60x (right) objective magnification.

Histopathology showed a slightly lower amount of neointima formation in the Solaris (area percentstenosis ~ 30%) compared to the controls (~37%). There was optimal local biocompatibility in both groups. The Solaris and Fluency stent grafts showed optimal biocompatibility. Both groups showedinstances of increased mural inflammation (in the media and adventitia) primarily due to stent expansion.

Conclusion

The Solaris PTFE-covered peripheral stent demonstrated a resistance to fracture with increased flexibility and navigability and better conformability to artery curvature. The release system allowed for an accurate geographical delivery and the components of the device produced a lower OCT morphometrically – assessed neointimal response when compared to the control group.

 

http://www.onlinejacc.org/content/70/18_Supplement/B56.3