부산대학교 도서관

Left atrium (LA) is not just a passive chamber of the heart, its contractile capacity being as important as its reservoir and conduit functions. Newer echocardiographic techniques, such as deformation imaging, can be applied to characterize LA function. Aim. To evaluate LA systolic function and its determinants, by 2D speckle tracking, in 56 patients (57±8 years, 29 males) with type 2 diabetes, mild-to-moderate hypertension, and preserved LV ejection fraction (EF>50%).Methods: LA systolic function was evaluated from global LA longitudinal contraction strain (GLACS), LA ejection fraction, A wave velocity, mean 6 basal segments Aʼ velocity, lateral and septal mitral annular Am velocities, and atrial reversal velocity (Ar) from the PV flow. LA afterload was assessed from the LV diastolic parameters: E/Em, E/Vp, dur(Ar-A), IVRT, and mitral annular early (VTI-Eʼ) diastolic time-velocity integral; while LA preload from: pre-contraction LA volume, S time-velocity integral (VTI-S), D time-velocity integral (VTI-D), and their sum (from the PV flow) (VTI-S+D).Results: GLACS correlated with all indices of LA systolic function: LA ejection fraction (r=0.32), A wave velocity (r=0.31), mean Aʼ (r=0.38), Ar velocity (r=0.34), both Am (r=0.31 for septal, and r=0.32 for lateral), and Ar duration (r=-0.33)(all p<0.05). Surprisingly, GLACS did not correlate with parameters estimating LV filling pressure (see table), but correlated with IVRT (r=-0.33, p<0.05) and VTI-Eʼ (r=0.43, p<0.05). However, only 57% of all patients had impaired LV relaxation, and filling pressures were normal in all patients. Similarly, GLACS did not correlate with LA preload parameters (see table). By multiple stepwise regression analysis, best determinants of LA contractility were Aʼ, IVRT, D time-velocity integral, and VTI-E (r=0.72,R=0.52, p<0.001).Conclusion: In patients with type 2 diabetes, mild- to-moderate hypertension, normal LV ejection fraction, and normal or minimally impaired LV diastolic function, left atrial contraction is less dependent on LA preload, but it is closely related to LV relaxation and indices of early LV filling.