Quantitative evaluation of left ventricular myocardial mechanics with volume overload

Abstract

Objective Evaluate myocardial strain of uremic patients after arteriovenous fistula (AVF) quantitatively by using 2-Dimensional Speckle Tracking Imaging (2D-STI), observe change of myocardial contractility of left ventricular after change of volume load. Methods Sixty-six uremic patients from the Nephrology Department of Shangxi Dayi Hospital from July 2012 to February 2015 were chosen as AVF group, and 30 age and gender matched healthy volunteers were chosen as healthy control group. Longitudinal stain (LS), circumferential stain (CS) and radial stain (RS) of each segment and global of systolic of left ventricular were obtained by using 2D-STI. Reference range of normal value is determined as 53-70 ml/m2 according to left ventricular end diastolic volume index (LVEDVI) of healthy control group. AVF group is divided into normal volume group (LVEDVI ≤70 ml/m2) and volume increase group (LVEDVI >70 ml/m2). Adopt ANOVA for myocardial stain of AVF group before operation and healthy control group, comparison in pairs shall adopt LSD-t test; comparison of AVF group before and after operation shall adopt paired t-test; correlation analysis of parameters of myocardial stain and volume load shall adopt curve fitting. Research of repeatability shall adopt Bland-Altman analysis chart and linear correlation; express with correlation coefficient (r) and D-value. Results (1) In healthy control group, left ventricular LS, CS increase gradually from basal segment to apical segment (F=14.19, 13.60, all P 0.05); (2) Each segment and global LS, CS, RS of left ventricular of AVF normal volume group and volume increase group before operation decrease compared with healthy control group; each segment and global LS, CS, RS of left ventricular of AVF volume increase group is higher than AVF normal volume group (apical-middle-basalt-global: LS: F=117.49, 61.66, 24.91, 80.70, CS: F=74.88, 43.91, 28.14, 57.08, RS: F=33.65, 96.09, 89.86, 85.85, all P<0.05); (3) Each segment and global LS of left ventricular decrease after AVF operation compared with pre-operation (t=24.05, 23.54, 16.64, 21.34, all P<0.05); (4) GLS and LVEDVI correlation of left ventricular: Y=-0.006X2+ 0.956X-25.719 (Y: GLS, X: LVEDVI, R2=0.703), X=80, Y value was maximum. Conclusions (1) Volume load has regular influence on myocardial contractility of left ventricular of uremic patients. When LVEDVI 80 ml/m2, myocardial contractility decreases gradually. (2) LS parameter of left ventricular is relatively sensitive to the change of volume load. The influence of volume load on myocardial mechanics of uremic patients can be evaluated by LS parameter of left ventricular. Key words: Echocardiography; Arteriovenous fistula; Volumetric overload; Speckle tracking; Strain