Physiologic Determinants of Left Atrial Longitudinal Strain: A Two-Dimensional Speckle-Tracking and Three-Dimensional Echocardiographic Study in Healthy Volunteers.

BACKGROUND: Left atrial (LA) longitudinal strain (LS) using two-dimensional speckle-tracking echocardiography has emerged as an important diagnostic and prognostic parameter in various cardiovascular conditions. However, its reference values, their correlations with demographics characteristics, and its physiologic determinants remain to be established. METHODS: Accordingly, 171 healthy volunteers (mean age, 45 ± 12 years; 61% women) in whom LS was obtained from both apical four- and two-chamber dedicated views of the left atrium, considering the P-P interval on the electrocardiogram as the reference cardiac cycle, were prospectively studied. From the LA LS curve we measured the extent of the negative deflection (LSneg), representing LA active contraction, the positive deflection (LSpos) during LA filling, and total LS (LStot), as the sum of LSneg and LSpos values. RESULTS: Average values for biplane LA LSpos, LSneg, and LStot were 19.7%, -14.5%, and 33.3%, respectively. On multivariate analysis, age, left ventricular (LV) global LS and volume, and LV diastolic function were the main physiologic determinants of LA LSpos (R2 = 0.57) and LStot (R2 = 0.40), whereas systolic blood pressure, E/A ratio, global LS, and LV stroke volume were the main determinants of LA LSneg (R2 = 0.20). Women had higher LSpos and LStot than men, particularly before 50 years of age. LA LSpos and LStot decreased with aging, with different trends in men and women. CONCLUSIONS: LA LS values are different in men and women and should be interpreted taking into account patient age and LV function as well. These reference values may help identify subclinical LA dysfunction in several cardiovascular or systemic conditions.

Dynamic changes in tricuspid annular diameter measurement in relation to the echocardiographic view and timing during the cardiac cycle.

BACKGROUND: Tricuspid annular (TA) size and function play important roles in planning the need for associated TA annuloplasty in patients undergoing cardiac surgery for left-sided heart valve diseases. However, TA diameter normative values and the extent of TA dynamic changes during cardiac cycle remain to be established. METHODS: This was a prospective, cross-sectional study of 219 healthy volunteers (mean age, 43 ± 15 years; 57% women), using conventional two-dimensional transthoracic echocardiographic (2DE) imaging to assess the variability of TA diameter measurement in relation to 2DE view and timing during cardiac cycle. TA diameter was obtained from apical right ventricular (RV)-focused four-chamber, parasternal long-axis RV inflow, and parasternal short-axis at aortic plane 2DE views at five time points during the cardiac cycle. Right atrial and RV volumes were measured using three-dimensional echocardiography. RESULTS: TA diameters differed significantly among the three 2DE views and changed significantly during the cardiac cycle in all views. Moreover, mean fractional shortening of TA diameter was 24 ± 6% in the four-chamber view, 20 ± 7% in the parasternal long-axis RV inflow view, and 29 ± 11% in the parasternal short-axis at aortic plane view. One multivariate linear regression analysis, age, gender, and right atrial and RV volumes were independently correlated with TA diameters and accounted for 55% of the variance of midsystolic TA diameter in the four-chamber view. CONCLUSIONS: This study provides references values for TA diameters and dynamics using 2DE imaging. Age, gender, and right chamber sizes, as well as the 2DE view and time during the cardiac cycle, significantly influenced TA diameters in healthy individuals. These data may help better identify TA dilatation using 2DE imaging for surgical planning.