Type A Aortic Dissection

The goal of this multicenter, double-blind, randomized controlled trial is to learn if sivelestat sodium (Siv) can protect the organ function in patients suffered operation for acute type A aortic dissection. The main questions it aims to answer are: * Can the 3-day-treatment of Siv enlarge the Day-0-to-Day-5 drop in the organ-health score (SOFA score)? * Can this treatment significantly shrink the area under the SOFA curve from first dose to Day 5? * Can this treatment significantly improve the end of patients in 28 days (clinical outcomes)? Researchers will compare drug Siv to a placebo (a look-alike substance that contains no drug) to see if drug Siv works. Participants will: * Take drug Siv or the placebo through vein continuously for 72 hours * Receiving regular intensive care in ICU after the operation

This is a national, multicenter, open-label, randomized, controlled, endpoint-blinded clinical trial of patients diagnosed with ATAAD and undergoing "Sun's procedure" coordinated by the First Affiliated Hospital of Xi'an Jiaotong University, China. Per the protocol, "Sun's procedure" combined with "XJ-Procedure" in the anastomosis of the aortic root and Sun's procedure combined with regular suturing methods of the aortic root will be compared.