This single-center, randomized, controlled trial aims to evaluate whether intraoperative portable ultrasound monitoring can improve early postoperative outcomes in patients undergoing coronary artery bypass grafting (CABG).

A total of 380 patients scheduled for elective CABG at Nanjing Drum Tower Hospital will be randomly assigned in a 1:1 ratio to either the ultrasound group or the control group. In the ultrasound group, a trained surgeon or researcher will use a portable ultrasound device to assess distal graft perfusion and each coronary artery perfusion in real time before and after completion of graft anastomosis. In the control group, graft function is evaluated by the surgeon's standard clinical judgment without ultrasound monitoring.

The primary outcomes are two composite endpoints: (1) a composite of major adverse clinical events including operative death, perioperative myocardial ischemia or infarction, low cardiac output syndrome, stroke, acute kidney injury requiring dialysis, need for mechanical circulatory support, unplanned cardiac reoperation, cardiac arrest, multiorgan failure, prolonged mechanical ventilation (>72 hours), and postoperative hospital stay ≥30 days; and (2) a composite of ultrasound-detected graft perfusion abnormalities including diminished or absent graft flow signal, new segmental wall motion abnormalities, decline in left ventricular ejection fraction (LVEF) ≥10% from baseline, and graft-related reintervention.

Secondary outcomes include longitudinal changes in laboratory biomarkers (hematology, inflammation, coagulation, liver and renal function, myocardial injury, and cardiac function), intraoperative and perioperative surgical parameters, and diagnostic accuracy of ultrasound compared with postoperative imaging.

All participants will receive standard CABG surgery and perioperative care. Results are expected to provide evidence on the clinical utility of intraoperative ultrasound for real-time perfusion assessment during CABG.

Inclusion criteria: 1. Age ≥18 years; 2. Definitive diagnosis of coronary atherosclerotic heart disease, with intention to undergo elective coronary artery bypass grafting (CABG) at this center; 3. Able to perform real-time ultrasound blood flow measurement before and after bypass grafting during the operation, and obtain relevant blood flow parameters of the left anterior descending artery, left circumflex artery, right coronary artery, and bypass graft; 4. The subject or his/her legal guardian provides informed consent and signs a written informed consent form.

Exclusion criteria: 1. Patients undergoing emergency surgery, rescue surgery, or unable to complete standardized measurements according to the study protocol; 2. Patients with significant preoperative hemodynamic instability requiring intra-aortic balloon counterpulsation, extracorporeal membrane oxygenation, or other mechanical circulatory support; 3. Patients requiring concomitant valve surgery, major vascular surgery, or other complex cardiac surgeries; 4. Patients scheduled for or undergoing sequential coronary artery bypass grafting; 5. Patients unable to complete effective echocardiographic measurements due to severe adhesion, poor anatomical conditions, limited surgical field exposure, or other technical reasons during the operation; 6. Patients with severe arrhythmias, severe cardiac dysfunction, or other conditions that may significantly affect the accuracy of intraoperative blood flow measurements; 7. Patients with severe preoperative liver, kidney, lung, or other vital organ failure that may significantly affect the evaluation of study endpoints; 8. Patients lacking key baseline data before surgery or expected to be unable to complete follow-up of primary endpoint indicators after surgery; 9. Pregnant or lactating women; 10. Other situations deemed unsuitable for inclusion in this study by the investigator.

Definitive diagnosis of coronary atherosclerotic heart disease, with intention to undergo elective coronary artery bypass grafting (CABG) at this center