Development and initial in-vitro and in-vivo testing of a valved stent for percutaneous valve replacement

Objectives: The aim is to develop and evaluate a self expanding, stent-mounted valve for percutaneous pulmonary- and aortic valve replacement.

Methods: A newly designed tri-leaflet valve from equine pericardium was mounted in a self expanding 20mm stent. The valved stent was implanted in pigs by means of a 10 Fr catheter. During stent deployment the original pulmonary valve was pushed against the pulmonary artery wall by the self expanding force of the stent while the new valve was expanded. Performance of the valve was additionally tested in a computer controlled versatile pulse duplicator to assess pressure loss, closing and leakage volumes of the valve.

Results: In-vitro testing of the device yielded results comparable with commercially available stentless valves. It was possible to replace the pulmonary valve in the beating heart with no complication or relevant drop in blood pressure. The maximum peak to peak pressure gradient across the valve carrying stent reached a maximum of 10mm Hg under physiological conditions. No relevant regurgitation was detected by means of epicardial echocardiography. All pigs were sacrificed after valve replacement. Post mortem inspection of the right ventricle and the pulmonary artery showed no signs of malfunction of the implant and no damage of the vessel wall.

Conclusions: In-vitro tests of this newly designed self expanding pericardial valve showed promising results. The valved stent was successfully implanted in pulmonary valve position in the beating heart. In-vivo experiments are underway to evaluate the safety and efficacy of this concept.