In the most comprehensive analysis of publications about intraoperative transit-time measurement of bypass graft flow during coronary artery bypass grafting (CABG), Gabriele Di Giammarco from Chieti, Italy, sought an answer to a clinical question: Whether transit-time flow measurement (TTFM) can improve graft patency and clinical outcomes in patients undergoing coronary artery bypass grafting surgery using evidence-based information. Reviewed were 102 papers from which 10 that represented the best evidence to answer the clinical question were selected for analysis.

The papers focused on three major criteria: intraoperative graft verification with the aim of improving immediate graft patency, predictive power of early- and mid-term graft patency and clinical outcome. Among transit-time flow measurement parameters, according to different authors, mean graft flow was set at 10 or 15 ml/min; pulsatility index was set at three or five; insufficiency ratio was set at 3% or 4%.

The studies demonstrated the usefulness of intraoperative transit-time flow measurement as a method to improve intraoperative graft patency. Di Giammarco concluded that intraoperative transit time flow measurement is a reliable method to verify intraoperative graft patency. Also noted was that there is some evidence that checking graft patency intraoperatively may improve mid-term outcomes.

References: Di Giammarco A, Rabozzi R, “Best Evidence – Coronary: Can transit-time flow measurement improve graft patency and clinical outcome in patients undergoing coronary artery bypass grafting?” Interact Cardiovasc Thorac Surg. 2010;11(5): 635-40. (Transonic Reference # CV-9685AH).