Preliminary feasibility and hemodynamic performance of a newly-developed self-expanding bioprosthesis and 16-F delivery system in transcatheter aortic valve implantation in sheep

Abstract

We sought to evaluate the feasibility and hemodynamic performance of a new self-expanding bioprosthesis and 16-F delivery system in sheep. A 23-mm new self-expanding aortic bioprosthesis was implanted in sheep (n = 10) with a 16-F catheter via the right common carotid artery. Each sheep underwent angiography and coronary angiography before intervention, immediately and 1 h after stent implantation. Electrocardiographic monitoring was carried out during and 2 h after the procedure. Transthoracic echocardiography was employed to detect hemodynamic performance before intervention, immediately and 1 and 2 h after stent implantation. All sheep were euthanized 2 h after successful implantation for macroscopic inspection. In all cases, the new self-expanding aortic bioprosthesis was successfully delivered to the aortic root and released with a 16-F catheter. Successful implantation was achieved in 8 of 10 sheep. Hemodynamic performance and device position of successful implantation were stable 2 h after device deployment. Atrioventricular block was not observed. We conclude that it is feasible to implant the new self-expanding aortic valve with a 16-F delivery system into sheep hearts via the retrograde route.

Keywords: aortic valve; percutaneous; self-expanding bioprothesis; sheep.

Fig. 1. The design of improved self-expanding bioprosthesis and its 16-F delivery system.

Fig. 2. The supra-aortic angiogram after implantation of a valved stent.

Angiography confirmed the well-anchored position of the device without evidence of aortic regurgitation or obstruction of coronary blood flow (arrows). In this case, we detected mild paravalvular aortic regurgitation after device deployment, but we selected this figure with no aortic regurgitation for clear visualization of coronary blood flow.

Fig. 3. Echocardiographic image of a 23-mm device implanted into an aortic root with a 19.1-mm aortic annulus (2 h post procedure).

Echocardiography showed that the device was in a good position and functioned normally. A: Long-axis, the stent (arrows) showed strong echo signals (LA=left atrium, LVOT=left ventricular outflow tract). B: Short-axis, the right coronary sinus (arrow) and left coronary sinus (arrowhead) were unaffected.

Fig. 4. Gross anatomy after successful implantation of the device.

The stent “fingerprint” on the aortic wall indicated high radial expansion of the stent.

Fig. 5. Echocardiographic image of moderate paravalvular aortic regurgitation after a 20-mm bioprothesis into an aortic root with a 19.6-mm native aortic annulus (long-axis, 2 h post procedure).

A: An increased trans-aortic gradient (15.1 mmHg vs 3.6 mmHg pre-procedure) and moderate paravalvular aortic regurgitation were observed. B: Echocardiography showed that there was a gap between the device and the left ventricular outflow wall (arrow).