Assessing left ventricular early diastolic velocities with tissue doppler and speckle tracking by transesophageal and transthoracic echocardiography

BACKGROUND: Assessing diastolic dysfunction is essential and should be part of every routine echocardiography examination. However, clinicians routinely observe lower mitral annular velocities by transesophageal echocardiography (TEE) under anesthesia than described by awake transthoracic echocardiography (TTE). It would be important to know whether this difference persists under constant loading conditions. We hypothesized that mean early diastolic mitral annular velocity, measured by tissue Doppler imaging (TDI, E-TDI') would be different in the midesophageal 4-chamber (ME 4Ch) than in the apical 4-chamber (AP 4Ch) view under unchanged or constant loading conditions. Secondarily we examined (1) in an alternative transesophageal view with presumed superior Doppler beam alignment, the deep transgastric view (DTG), compared to those in the AP 4Ch, and (2) early diastolic speckle tracking-based strain rate (E-SR'), in the ME 4Ch and in the AP 4Ch. METHODS: Twenty-five consecutive adult patients undergoing on-pump cardiac surgery from February 2017 to July 2017 were included. Both TTE and TEE measurements were obtained under anesthesia in a randomized order in the AP 4Ch, ME 4Ch, and DTG views. Within-patient average values were compared by paired t tests with a Bonferroni adjustment. Box plots, correlation, and agreement by Bland-Altman were examined for all 3 comparisons. A second echocardiographer independently acquired and analyzed images; images were reanalyzed after 4 weeks. Image quality and reproducibility were also reported. RESULTS: Averaged E-TDI' measurements were lower in the ME 4Ch than in the AP 4Ch (6.6 +/- 1.7 cm/s vs 7.0 +/- 1.5 cm, P = .028; within-patient difference mean +/- standard deviation: 0.6 +/- 1.2 cm/s). An alternative TEE view for E-TDI', the DTG, also exhibited lower mean values (6.0 +/- 1.6 cm/s, P = .006; within-patient difference mean +/- standard deviation: 1.1 +/- 1.8 cm/s). E-SR' strain rate showed a low degree of bias, but greater variability (ME 4Ch: 0.87 +/- 0.32%/s vs AP 4Ch: 0.73 +/- 0.18%/s, P = .078; within-patient difference mean +/- standard deviation: -0.1 +/- 0.2%/s). CONCLUSIONS: This study confirms that TEE modestly underestimates E-TDI' but not to a clinically relevant extent. While E-TDI' in the DTG is not a promising alternative, the future role for speckle tracking-based early diastolic strain rate is unknown