Intraoperative Ultrasound Assessment of Coronary Artery and Bypass Graft Blood Flow During CABG

Quantitative Assessment of Native Coronary Artery and Bypass Graft Blood Flow Using Intraoperative Ultrasound in Patients Undergoing Coronary Artery Bypass Grafting: A Single-Centre Prospective Feasibility and Safety Study

This single-centre, prospective observational feasibility and safety study will enrol 190 consecutive adults undergoing elective isolated coronary artery bypass grafting (CABG) at Nanjing Drum Tower Hospital. The study aims to evaluate the feasibility and safety of intraoperative ultrasound for the quantitative assessment of native coronary artery and bypass graft blood flow.

Transit-time flow measurement will be performed as part of routine intraoperative graft assessment. Additional ultrasound measurements will be obtained from major native coronary arteries before and after revascularisation and from bypass grafts after restoration of blood flow. The ultrasound findings will be collected for research purposes and will not influence graft revision or other intraoperative clinical decisions.

The co-primary outcomes are the participant-level technical success rate of the protocol-defined intraoperative ultrasound assessment and the incidence of adverse events related to the ultrasound device or measurement procedure. Secondary outcomes include agreement between ultrasound and transit-time flow measurements, changes in native coronary artery blood flow after revascularisation, measurement repeatability, and exploratory associations between intraoperative flow parameters and postoperative cardiac function and myocardial injury biomarkers. Participants will be followed for 30 ± 7 days after surgery.

Intraoperative assessment of bypass graft function is important for ensuring adequate myocardial revascularisation during coronary artery bypass grafting. Transit-time flow measurement is widely used for graft assessment but primarily evaluates blood flow within bypass grafts and provides limited information on changes in native coronary artery blood flow before and after revascularisation.

This study will evaluate a portable ultrasound platform with access to programmable raw radiofrequency data. The study-specific procedure consists of additional intraoperative ultrasound measurements obtained from the exposed epicardial surface without additional incision, vascular puncture or tissue penetration. Major native coronary arteries will be assessed before and after revascularisation, and individual bypass grafts will be assessed after completion of the graft anastomoses and restoration of blood flow. Transit-time flow measurements will be recorded according to routine clinical practice for subsequent agreement analyses.

The research ultrasound findings will not be used to guide graft revision, repeat anastomosis or other intraoperative clinical decisions. The study is designed to evaluate technical feasibility, safety, agreement with transit-time flow measurement, measurement repeatability and changes in native coronary artery blood flow. Associations between intraoperative flow parameters and postoperative cardiac function and myocardial injury biomarkers will be exploratory.

Inclusion Criteria:

• Aged 18 years or older.
• Confirmed coronary artery disease and scheduled to undergo elective isolated coronary artery bypass grafting at Nanjing Drum Tower Hospital.
• Able and willing to provide written informed consent before any study-specific procedures are performed.

Exclusion Criteria:

• Urgent, emergency, or salvage coronary artery bypass grafting.
• Prolonged preoperative fasting, as defined in the study protocol, or inability to maintain adequate oral intake without enteral or parenteral nutritional support.
• History of malignancy.
• Body weight below 50 kg.
• Preoperative hemodynamic instability requiring ongoing resuscitation or mechanical circulatory support, including intra-aortic balloon pump, extracorporeal membrane oxygenation, or left ventricular assist device support.
• Endotracheal intubation and invasive mechanical ventilation before surgery.
• Impaired consciousness, clinically significant central nervous system dysfunction, or evidence of cerebral malperfusion after hospital admission.
• End-stage renal disease requiring maintenance dialysis before hospital admission.
• Severe pulmonary disease considered to preclude tolerance of elective coronary artery bypass grafting or to confer an unacceptably high perioperative risk.
• Severe peripheral vascular disease or clinical evidence of limb malperfusion before surgery.
• History of gastrointestinal ulceration or chronic inflammatory gastrointestinal disease.
• Chronic inflammatory or autoimmune disease, or long-term treatment with systemic corticosteroids or non-steroidal anti-inflammatory drugs.
• Active infection or sepsis at screening.
• Severe uncontrolled arrhythmia requiring urgent treatment or expected to cause marked intraoperative hemodynamic instability.
• Previous cardiac surgery requiring repeat median sternotomy.
• Planned concomitant major cardiac or aortic surgery, including valve surgery, congenital heart defect repair, or aortic surgery.
• Inability to understand the study information or unwillingness or inability to provide written informed consent.
• Inability or unwillingness to complete follow-up at 30 ± 7 days after surgery.
• Pregnancy or breastfeeding.