Background
Cases of coronary heart disease have been increasing in recent years and appearing in younger patients [1]. Coronary artery revascularization can improve long-term patient prognosis and quality of life. Ever since the American College of Cardiology Foundation and American Heart Association (ACCF/AHA) revised the Guidelines for Coronary Artery Bypass Grafting (GABG) in 2011[2], CABG procedures have been significantly more numerous and in situ left internal mammary artery (IMA)-anterior descending branch bypass grafting has become the first choice for clinicians, with the treatment rate increasing from 31% in 1988 to 91% in 2008 [3], leading to better immediate and long-term postoperative outcomes (i.e., lower rates of mortality, myocardial infarction, and reoperation) than venous grafts, and 90–97% 5-year patency rates [3,4]. Although coronary angiography is the gold standard for evaluating the patency of vascular grafts, ultrasound, a non-invasive and reproducible method of examination, has been adopted in clinical practice. It would be of great value for evaluating the preoperative related parameters of IMA and the postoperative graft patency to effectively assess the success rate of surgery and the prognosis of the patients. In this study, we mainly used ultrasound to evaluate the changes in related parameters of IMA before and after the in situ CABG in IMA and the factors affecting the postoperative flow of the vascular grafts.