Left ventricular energy loss in patients with 2 type diabetes during diastole detected by ultrasonic vector flow mapping

Objective To quantitatively evaluate left intraventricular blood flow patterns and explore the value of energy loss (EL) of left ventricle in patients with type 2 diabetes mellitus (D2M) for diastolic dysfunction using ultrasonic vector flow mapping. Methods Randomly selected 62 patients with D2M as case group and 39 normal adults for control group. Acquired 2D gray-scale echocardiographic images and standard dynamic apical 3 chambers (AP3c) Doppler flow images for 3 completed cardiac cycles for the measurement of general parameters of left ventricular structure and diastolic function. The AP3c Doppler flow dynamic images were analyzed using off-line workstation for acquiring the EL parameters and time-flow curve (T-F curve) of left ventricular inflow tract during diastole. Diastole of left ventricle was divided into the isovolumic relaxation phase (P1), early diastolic phase (P2), rapid filling phase (P3), slow filling phase (P4), atria contract period (P5) and late diastolic phase (P6) based on T-F curve, with recording EL of each phase (Pn-EL, n=1-6). The difference of general parameters and EL value and the correlation between EL and diastolic hemodynamic parameters of above 2 groups were analyzed. Results (1) EL: The value of P1-EL, P2-EL, P3-EL, P4-EL, P5-EL, P6-EL were dividedly 5.233, 4.328, 17.249, 9.043, 13.829, 9.765 N/(m•s) in D2M group, and were dividedly 3.191, 2.587, 16.025, 6.324, 8.858, 8.093 N/(m•s) in normal group; Compared between D2M group and normal group, the EL of all periods were higher with statistical significance in P1, P2, P4, P5, P6 phases (Z=-3.042, -2.386, -2.103, -2.763, -2.107, all P<0.01 or 0.05). (2) Correlation analysis: In D2M group, a significant positive correlation existed between P3-EL and E, E/A (r=0.741, 0.599, both P<0.01), and there were positive correlations between P3-EL and e, E/e (r=0.3, 0.253, both P<0.05); There was a significant positive correlation between P5-EL and A, a (r=0.578, 0.384, both P<0.01), and significant negative correlations between P5-EL and E/A, e/a (r=-0.427, 0.537, both P<0.01). In normal group, there were a significant positive correlation between P3-EL and E (r=0.732, P<0.01) and positive correlations between P3-EL and E/A, e (r=0.4, 0.321, both P<0.05); There were a positive correlation between P5-EL and A, a (r=0.688, 0.399, both P<0.05), and negative correlation between P5-EL and E/A (r=-0.406, P<0.05). Conclusion The higher diastolic EL of left ventricle in patients with D2M during most phases of diastole indicate that EL might be used as a quantitative index for evaluating the left ventricular diastolic dysfunction, and there is a close correlation between EL parameters and left ventricular hemodynamics in specific phases of diastole. Key words: Ultrasonic vector flow mapping; Diabetes mellitus, type 2; Energy loss; Ventricular function, left