**5.1 The birth of no clamp technique**

Although OPCABG avoids cardiopulmonary bypass and greatly reduces brain damage caused by cerebral air embolism and insufficient perfusion, the incidence of neurological complications (including stroke, transient ischemic attack, coma, postoperative delirium or epileptic attack, etc.) remains one of the most common postoperative complications [28]. Cerebral infarction is mostly related to atheromatous plaque or calcification breaking and detachment in the aorta caused by operating on it, and cerebral hemorrhage may also be related to post infarction hemorrhage [29–30]. Patients often show delayed awake or coma for longer time as this kind of disease often occurs in the operation or the early postoperative period. However, patients could hardly move and remain in the state of respiratory assistance; as a result, computed tomography (CT) or magnetic resonance imaging (MRI) diagnose and further treatment are often delayed with more serious consequences. Among all the risk factors, calcification plaque shedding caused by clamping the ascending aorta is the most important risk factor [31]. Thus, using proximal anastomotic device to assist or complete proximal aortic anastomosis without side wall clamp can effectively avoid the complications caused by clamping ascending aorta during traditional proximal aortic root anastomoses, such as the damage of the aortic wall and the detachment of atheromatous plaque. Therefore, avoiding the ascending aorta clamping is the key to reduce the incidence of aortic dissection and nervous system complications in OPCABG, and thus improving the postoperative survival rate. Indicators of severe ascending aortic calcification include carotid stenosis, hypertension, peripheral vascular disease or abdominal aortic aneurysm, male gender, renal insufficiency and being over 65 years old. As an innovative suture method, the no clamp suture method can minimize the incidence rate of systemic infarction caused by the detachment of atherosclerotic plaques. The operation process is simple, effective, accurate and cost-efficient. Therefore, in the OPCABG for patients with severe ascending aortic calcification, the method without clamp has its practical and generalization value.

## **5.2 Operation process**

The method without clamp refers to that when the great saphenous vein is anastomosed with ascending aorta, and the aortic wall is not clamped with side wall clamp. The specific operation process is as follows:

