ABSTRACT
Objective: To evaluate the feasibility of implanting a new self-expanding valved stent for aortic valve implantation and its influence on coronary blood flow. Methods: We designed a self-expanding valved stent made from super-elastic memory nitinol alloy, with a tubular shape and a wide mesh in the cavate middle part. A valvular ring made of nitinol wire was sutured on the lower part. Fresh porcine pericardium was decellularized, treated with 0.6% glutaraldehyde solution for 36 h, trimmed into leaflets, and sutured by hand into the valvular ring. The valved stent was pulled into a 14-French sheath by a silk and positioned in the left ventricle of isolated pig heart via the ascending aorta, and then deployed over the native aortic valves by pulling back the outer sheath. Water was injected into the ascending aorta by a silicon tube to evaluate the competence of the prosthetic heart valves and its effect on coronary flow. Results: The prepared valved aortic stent could be stably positioned over the native valves and could be removed after deployment. The prosthetic heart valves showed a satisfactory function and had no influence on coronary flow and mitral valve motion. Conclusion: This self-expanding valved stent is well-designed and allows for aortic valve implantation over the native valves without interfering the coronary flow; it can be evaluated further in vivo.
ABSTRACT
Objective: To discuss the feasibility of using the off-pump antegrade transventricular route for aortic valved stent implantation in canines, and to observe the short-term outcomes. Methods: Fresh porcine pericardium was treated with 0.6% glutaraldehyde solution for 36 h; then it was trimmed and sutured into a valvular ring and fixed on a new self-expanding dumbbell-shaped nickel-titanium shape-memory alloy stent. The valved stents were then implanted off-pump in 8 canines. A limited or full sternotomy approach was used to access the apex of the heart. The crimped valve was introduced through a sheath in the left ventricular apex under ultrasound guidance. The function of valved stents was evaluated with electrocardiogram, echocardiography, computed tomography and DSA angiography early and 3 months after the procedure. Results: We successfully prepared the valved aortic stent. Five canines survived after implantation of the aortic valved stents. Angiographic and echocardiographic observation confirmed that the location and function of the stent were satisfactory, without influencing coronary blood flow and mitral valve function. CT examination showed no migration of the stent 3 months after the procedure, and there were no other prominent complications. Conclusion: Our new self-expanding valved stent can be deployed over the native aortic valves via transapical route, and the short-term outcome is satisfactory.