Saline Bag and TEE During Cardiac Displacement
Condition: Ischemic Heart Disease
MeSH terms: Heart Diseases; Myocardial Ischemia; Coronary Artery Disease
Study type: Observational

Summary: 
      During cardiac displacement for off-pump coronary artery bypass(OPCAB) surgery, the presence
      of air underneath the displaced heart compromises the transgastric (TG) window for
      transoesophageal echocardiography(TOE). The investigators hypothesised that placing a
      saline-filled glove would enhance TG transmission of ultrasound and facilitate TOE imaging
      for monitoring left-ventricular regional wall motion (LV-RWM). For left circumflex coronary
      artery (LCX) grafting in OPCAB surgery (n=13), mid-oesophageal (ME) and TG TOE images are
      recorded before cardiac displacement (T control), after displacing and stabilising the heart
      (T-displaced), and after placing a saline bag (saline-filled surgical glove) underneath the
      displaced heart (T-saline bag). Following data are determined by integrated TG and ME TOE
      views (ME+TG) at T-control, T-displaced and T-saline bag: number of readable segments (NRS)
      in a 17-segment model; NRSs in basal and mid-TG short axis views; NRS in 5-LV segments of the
      LCX territory; the incidence of inadequate monitoring of LV-RWM (NRS < 14/16 except for the
      apex in 17-segment model).
    

Detailed description: 
      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.

      Each LV segment is defined as readable/unreadable when more than 50% of the endocardial and
      epicardial borders were visible/invisible or more than 90% of endocardial border was visible
      or 10% was invisible.

      The primary objectives of the present study are to evaluate the efficacy of placing a saline
      filled glove in enhancing TOE's ability for global and regional LV RWM monitoring and to
      determine NRS out of the LV 17-segment model using ME views alone and integrated ME+TG views.

      As secondary objectives, NRS out of five LV segments in the LCX territory by using ME views
      alone vs. integrated ME+TG views as well as NRS out of six LV segments in the TG SAX view are
      determined, to confirm whether TG TOE imaging can be applied for regional LV RWM monitoring
      during cardiac displacement. The incidence (%) of inadequate RWM monitoring in 17-segment
      model using ME views alone vs. integrated ME+TG views is also compared to determine whether
      the possible increase in NRS facilitates the adequate TOE imaging.
    

Intervention name(s): placing saline bag during cardiac displacement
Intervention type(s): Procedure
Intervention description(s): For grafting to LCX territory, the heart is displaced using positioner and a suction-type epicardial stabiliser is applied to the target area. The degree of cardiac displacement and the LV compression by stabilisers are adjusted for maximal surgical access and minimal haemodynamic instability.
Other intervention name(s): displacing the heart for LCX grafting; placing the saline bag underneath the displaced heart
Observational model: Case-Only
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        elective OPCAB surgery patients
      
Keywords: Off-pump coronary artery bypass surgery; Transesophageal echocardiography