Improved transcatheter aortic valve implantation for aortic regurgitation using a snare loop-assisted device: the first preclinical experience.

Abstract

Transcatheter aortic valve implantation (TAVI) is an effective percutaneous treatment for high-risk patients with severe symptomatic aortic stenosis. However, TAVI is rendered less effective in patients with noncalcified aortic valve disease because noncalcified aortic valves lack an anchor site for the implanted stent, causing the stent to relocate to an unexpected position. In this study, we developed an improved TAVI with a snare loop-assisted device, and evaluated the feasibility and safety of this strategy in noncalcified aortic valve disease. The balloon-expandable valve stent made of cobalt-chromium alloy was cut into a cylindrically shaped mesh configuration. The prosthetic valve was made of bovine pericardium. Ten healthy sheep (six males and four females with an average weight of 27·8 ± 1·18 kg) were selected to undergo transcatheter implantation of valved stents using the snare loop-assisted device. Aortic angiography and colour Doppler echocardiography were applied to assess the function of artificial valves immediately and 3 months after the operation. The snare loop-assisted TAVI was successfully implanted in all 10 sheep. The aortogram showed that the valve stent was fixed in the expected position. Among these 10 sheep, nine sheep survived for more than 3 months normally and one sheep died of infective endocarditis 1 week after the operation. Ultrasound and aortogram in the 3 months after operation showed proper positions of the prosthetic valves without stenosis and other apparent complications, and normal coronary artery openings. The snare loop-assisted TAVI approach can reduce stent shifting during valve stent implantation and improve the success rate of the TAVI in those with noncalcified aortic valves.