Background: Intraoperative evaluation of left ventricular (LV) myocardial function using transesophageal echocardiography (TEE) has become routine during anaesthesia for major surgical procedures. Current practice for quantification of LV function includes fractional shortening (FS) and fractional area change (FAC), which are suggested by published guidelines.  Contractility or systolic function is load dependent and should ideally be assessed over a range of prelaod and afterload. Two-dimensional strain echocardiography (2DSE), a relatively new method for assessment of myocardial function, which is based on measurement of myocardial deformation using speckle tracking from B mode images. [5, 10] This study examined LV function using FS, FAC and 2DSE radial strain during different loading conditions in patients undergoing non-cardiac surgery to assess if 2D radial strain (2DRS) derived from 2DSE is superior to FS and FAC for evaluation of left ventricular function. Methods: Patients undergoing non-cardiac surgery with a minimum duration of 30 minutes and endotracheal intubation were included. TEE studies were performed at 3 different time points and at each time point patients were positioned differently by tilting the operating table in the three different loading conditions - zero-position (=horizontal position), Trendelenburg position (10cm head down from horizontal position) and anti-Trendelenburg position (10 cm head-up from horizontal position).
Sequence of positioning followed a random order. After a delay of 3 minutes to allow a steady state in loading conditions 3 cardiac cycles of the transgastric mid-papillary short-axis view (TG SAX) were stored and FS, FAC and 2DRS were calculated offline. Results: We included 33 patients and we observed no adverse events or hemodynamic instability. Considerable correlation above 0.5 was found for FAC and FS in zero- and Trendelenburg (r=0.629, r=0.587) and for RS and FAC in anti-Trendelenburg position (r=0.518). In the repeated measures analysis significant differences between the values measured at the three positions were found for FAC and FS (p=0.0033, p=0.0271). For FAC there were differences between position anti-Trendelenburg and the other two positions. For FS only the difference between position zero and anti-Trendelenburg was significant. For 2DRS the differences between positions were not significant (p=0.8956). Conclusion: RS remained unchanged during different loading conditions, whereas FAC was the parameter, which detected preload changes best. 2DRS is not a useful parameter for assessing left ventricular function during different loading conditions in the operating room.