Objective:
Normative values for left ventricular (LV) end-diastolic area (EDA) and diameter (EDD) for intra-operative transoesophageal echocardiography (TOE) have not been established. We aimed to define the ranges of LV EDA and EDD for intra-operative TOE examinations in patients undergoing coronary artery bypass graft (CABG) surgery.
Methods:
A MEDLINE search for studies reporting LV EDA and EDD in patients undergoing CABG surgery was performed. Individual-level data set from 333 anaesthetised and ventilated patients with preserved LV function (study population) was obtained from eight studies. EDA and calculated EDD in the study population were compared with summary EDD values obtained using transthoracic echocardiography (TTE) in two studies of 500 awake patients with coronary artery disease (CAD). Further, the influence of pre-specified factors on EDD was evaluated in a multivariate regression model.
Results:
The EDA and EDD values measured using TOE in the anaesthetised CABG patients were 16.7±4.7 cm2 and 4.6±0.6 cm, respectively. TOE values of EDD in anaesthetised patients were 10%-13% less than those measured using TTE in two studies of awake patients (p<0.001). Body surface area, age and fractional area change, but not sex were factors that affected LV EDD.
Conclusion:
The values for LV EDD measured through intra-operative TOE in anaesthetised ventilated CABG patients were 10%-13% less than the corresponding values measured using TTE in awake CAD patients. This finding indicates that independent normative values specific for intra-operative TE should be established for guiding intra-operative clinical decisions.
Keywords: Echocardiography, transthoracic echocardiography, transesophageal echocardiography, cross-sectional, coronary artery bypass surgery