Placing a Saline Bag Underneath the Heart Enhances Transgastric Transoesophageal Echocardiographic Imaging During Cardiac Displacement for Off-pump Coronary Artery Bypass Surgery

A multi-plane TOE probe (6T, GE Healthcare, Milwaukee, WI, USA) is inserted immediately after anaesthesia induction. One of authors (anaesthesiologist) performs the routine intraoperative TOE study, including analysis of RWM, using the 17-segment LV model 11-14 and a TOE imaging system (Vivid 7, GE Healthcare, Milwaukee, WI, USA) and the following six TOE images: ME 4-chamber (4-CH), ME 2-chamber (2-CH), ME long-axis (LAX), mid and basal TG short-axis (SAX), and TG LAX.

For the present study, the three-beat clips of two-dimensional (2D) mid-oesophageal (ME) views, including ME 4-chamber (ME 4-CH), ME 2-chamber (ME 2-CH), and ME long-axis (ME-LAX) views, and those of transgastric (TG) views, including the basal TG short-axis (basal TG SAX), mid short-axis (mid TG SAX), and TG-LAX views, are stored on the hard disc of the TOE imaging system as digital recordings at each of the following time points:

(i) T-control: during harvesting the vascular grafts after sternotomy. (ii) T-displaced: after completion of cardiac displacement and stabilisation for the distal graft construction to the LCX territory by stabilisers to maintain both maximal surgical access and minimal haemodynamic instability under the guidance of haemodynamic monitoring.

(iii) T-saline bag: after placing the saline bag underneath the displaced heart and further fine positioning.

Using a program (EchoPAC, GE Healthcare, Milwaukee, WI,), a cardiologist, who is unaware of the aim of the present study, undertook a postoperative off-line analysis of the stored images to determine the following data under T-control, T-displaced, and T-saline bag conditions: 1) NRS out of a LV 17-segment model using ME views only and integrated ME+TG views; 2) NRS out of five LV segments in the LCX territory including basal inferolateral, mid-inferolateral, basal anterolateral, mid anterolateral, and apical lateral segments using ME views only and integrated ME + TG views; 3) NRS out of six LV segments in the TG basal SAX view, including basal anterior, basal anterolateral, basal anteroseptal, basal inferior, basal inferolateral, and basal inferoseptal segment; 4) NRS out of six LV segments in the TG mid-SAX view, including mid-anterior, mid-anterolateral, mid-anteroseptal, mid-inferior, mid-inferolateral, and mid-inferoseptal segments; and 5) the incidence (%) of inadequate RWM monitoring, defined as fewer than 14 out of the 17 segment model (except for the apex) were readable, using the integrated ME + TG views.