Preliminary testing and evaluation of the renata minima stent, an infant stent capable of achieving adult dimensions

Objectives This study sought to obtain in vivo data on a new stent and delivery system specifically designed for implantation in infants with the ability to be enlarged to adult dimensions. Background There are no endovascular stents designed for or approved for use in infants, nor is there a stent capable of being implanted at infant vessel diameters and achieving adult size while maintaining structural integrity. The Minima stent was designed to address these needs. Methods This study was performed in 6 piglets who underwent implantation of 22 Minima stents into the following locations: aorta (n = 11), branch pulmonary arteries (n = 6), and central veins (n = 5). Results Successful deployment occurred in 21/22 attempts. Two instances of post-deployment migration occurred. Stents were re-expanded at 1, 2, 3 and 5 months after implant. All stents regardless of location could be re-dilated to the intended diameter to keep pace with somatic growth (implant diameter 6.9 +/- 1.2 mm; final diameter 16.1 mm +/- 1.4 mm). Histopathology at 1 and 5 months demonstrated widely patent vessel lumens with stent apposition to vessel wall, early mild inflammatory response surrounding stent struts, typical vascular damage and healing response to acute dilation and a progressive smooth neointimal growth covering stent struts over time. Conclusions In this in vivo study of the Minima stent, there was high implant success, predictable re-dilatability to adult diameters and favorable histopathology. Further study is warranted.