Prospective, Multicenter, Randomized Controlled Clinical Study Evaluating the VitaFlow Liberty® Flex Transcatheter Aortic Valve Delivery System for the Treatment of Severe Aortic Stenosis Lesions

Inclusion Criteria: 1. Diagnosis of severe aortic stenosis, defined as: echocardiographically confirmed peak aortic valve velocity ≥4.0 m/s, or mean aortic valve gradient ≥40 mmHg, or aortic valve area (AVA) ≤1.0 cm2 (or AVA index ≤0.6 cm2/m2); 2. Preoperative cardiac and great vessel CT angiography (CTA) with 3D reconstruction demonstrating an aortic-left ventricular angle \>60°, indicating potential challenges for arch crossing and valve crossing; 3. New York Heart Association (NYHA) functional class ≥II; 4. Voluntary participation in the study with signed informed consent. Exclusion Criteria: 1. Known allergy or intolerance to components of the investigational or control devices (e.g., nitinol) or contrast agents; 2. Contraindication or known allergy to anticoagulant or antiplatelet therapy, rendering the patient unable to tolerate such treatment; 3. Known active infective endocarditis or other active infections; 4. Known severe vascular disease that would preclude safe prosthetic valve implantation; 5. Ascending aorta width ≥55mm; 6. Pre-procedural imaging shows aortic root anatomy unsuitable for transcatheter aortic valve implantation (including aortic root calcification that may affect proper valve expansion); 7. Pre-procedural echocardiography shows intracardiac mass, left ventricular or left atrial thrombus, or vegetation; 8. Acute myocardial infarction within 30 days prior to procedure (defined as Q-wave MI or non-Q-wave MI); 9. Concomitant severe mitral or tricuspid regurgitation; 10. Concomitant cardiogenic shock or hemodynamic instability requiring inotropic support, mechanical ventilation, or mechanical cardiac assistance; 11. Concomitant severe left ventricular dysfunction (defined as left ventricular ejection fraction LVEF\<20%); 12. Concomitant hematologic abnormalities defined as leukopenia (WBC count \<3×109/L), thrombocytopenia (platelet count \<30×109/L), history of bleeding diathesis or coagulopathy, or hypercoagulable state; 13. Female subjects known to be pregnant or breastfeeding; 14. Subjects currently participating in or planning to participate in other drug or device clinical studies within 12 months postoperatively; Any other condition that the investigator or heart team deems may hinder the subject's safe participation in the study.