Modified Aortic Root Enlargement Procedure

Inclusion Criteria: * 1\) Symptomatic severe AS patients aged 50-70 years who are planning to undergo biological valve replacement (diagnostic criteria for echocardiography are: mean transvalvular pressure gradient ≥ 40mmHg or flow velocity ≥ 4.0 m/s, aortic valve area (AVA) ≤ 0.8 cm2 or iEOA\<0.5 cm2/m2) 2) Merge SAA (defined as mean aortic annulus diameter ≤ 23 mm measured by CT) Exclusion Criteria: * 1\) High surgical risk, STS score\>8% 2) Severe lesions in multiple coronary arteries requiring PCI or CABG 3) Simultaneous surgical intervention is required for severe mitral and tricuspid valve disease 4) Combining other complex cardiovascular diseases requires simultaneous surgical treatment 6) Combined severe pulmonary arterial hypertension or left ventricular dysfunction (LVEF\<40%) 7) Severe respiratory, liver and kidney dysfunction, or other important organ dysfunction combined 8) Concurrent infective endocarditis in active phase 9) Previous history of cardiac surgery