Objective: Verbal communication during coronary artery bypass graft (CABG) procedures is essential for safe and efficient cardiac surgery, yet sensitive to failure due to a current lack of standardization. The goal of this study was to improve communication during CABG by identifying critical items in verbal interaction between surgeons, anesthetists and perfusionists. Methods: Based on 6 video recordings, a list was assembled containing items of communication in CABG procedures. Personal interviews and a consecutive focus group meeting with surgeons, anesthetists and perfusionists revealed which of these items were considered critical. Afterwards, the recordings were systematically analysed on the communication of these critical items. Results: Practitioners considered 64 items to be critical to verbally communicate for safe CABG surgery. On average, these critical items were verbalized in 4.4 out of 6 recorded CABGs. Observations also show that the surgical subteam is the most verbally active subteam and the initiator of the majority of all exchanges. The exchange type involved was mainly ‘direction’ and ‘status’. The majority of communication during critical events is between two subteams and occurs in the form of call-back loops. Over half of the call-backs are substantive and communication is rarely directed at a specific team member by name. Conclusions: In this study, a list was developed containing 64 items that practitioners unanimously considered critical to verbalize during a CABG procedure. It forms the foundation of a quality standard for verbal communication during cardio-pulmonary bypass (CPB) and can increase safety and efficiency of cardiac surgery.