Safety and Effectiveness of a Triple-branched Stent Graft for Arch Repair During Open Aute Debakey Type I Dissection Surgery - a Randomized Controlled Multicenter Clinical Trial

Acute aortic dissection is a local rupture in the aortic intima. Blood flows into the middle layer from the rupture, causing the middle layer of the aortic wall to tear along the long axis, tearing the complete aortic wall into the dissected intima (intima + part of the middle layer) and the dissected outer wall (part of the middle layer + outer layer), and forming a true lumen (the original aortic lumen) and a false lumen (the cavity between the dissected intima and the dissected outer wall). The torn dissected outer wall bears the pressure of the entire aorta, which can easily cause aortic rupture. The clinical characteristics of this disease are acute onset and rapid progression, making it one of the most dangerous and fatal cardiovascular diseases. Acute type I aortic dissection involves the ascending aorta, aortic arch and the entire aorta, and is the most dangerous type of acute aortic dissection. At present, surgery is the only treatment for acute type I aortic dissection.

Since the most common rupture site of acute aortic dissection is in the ascending aorta, clinical trials have shown that simple ascending aortic replacement can effectively save the lives of most patients with acute type I aortic dissection, and this operation is simple and suitable for emergency rescue of such critically ill patients. Therefore, simple ascending aortic replacement has become a classic emergency surgical method for acute type I aortic dissection.

However, most patients with acute type I aortic dissection after simple ascending aortic replacement have residual false lumens in the aortic arch and its distal aorta (i.e., dissection lesions still exist). The expansion and rupture of these residual false lumens are the most important factors affecting the long-term efficacy after surgery.

During the operation, reconstruction of the aortic arch as much as possible, elimination of the intimal rupture of the arch and the proximal descending aorta, expansion of the true lumen, and promotion of thrombosis in the false lumen are the fundamental ways to improve the long-term effect after surgery. Therefore, for patients with a high probability of residual false lumen expansion and rupture, such as young patients, patients with a long postoperative survival time, and patients with multiple ruptures in the aortic arch, most scholars currently advocate that the aortic arch should be reconstructed at the same time as the ascending aorta replacement, and the four-branch artificial blood vessel is often used to replace the aortic arch, and the descending aorta fixed elephant trunk technique (Frozen Elephant Trunk Technique) is an effective method for the treatment of acute aortic dissection developed in recent years. It can effectively close the aortic intimal rupture, promote thrombosis in the false lumen, and expand the true lumen. In order to simplify the reconstruction of the aortic arch in acute type I aortic dissection, we designed an integrated three-branch covered stent system (referred to as the intraoperative stent system), which is implanted under direct vision during surgery to repair the aortic arch, that is, the three-branch covered stent is sent into the arch, the root of the branch artery and the descending part of the arch under deep hypothermic circulatory arrest to cover the rupture of the dissection in the arch, the root of the branch artery and the descending part of the arch, and the proximal end of the stent and the distal incision of the ascending aorta are directly anastomosed with the artificial blood vessel replacing the ascending aorta. This avoids the anastomosis of the three branches of the aortic arch, reduces the difficulty of surgery, and shortens the time of cerebral ischemia and lower body ischemia.

This clinical trial adopts a prospective, multicenter, randomized controlled method, with the marketed product descending aortic elephant trunk stent implantation (Frozen Elephant Trunk Technique) as a control, and evaluates the effectiveness and safety of the intraoperative stent system as a test device in the treatment of acute type I aortic dissection through a standardized experimental design.