Abstract:

Objective   To investigate the feasibility and value of tissue Doppler imaging (TDI) in evaluating early myocardial dysfunction using HFB in a mouse model of dilated cardiomyopathy (DCM). Methods     A total of 33 mice carrying the ZASP4 mutation found in a DCM family were studied by using HFB with a Vevo 770 system and a 40 MHz transducer. The sample volume of TDI was placed on the posterior wall of the left ventricle, which was divided into basal, middle and apical segments to obtain systolic and diastolic peak velocities (S′, E′ and A′). The mice were divided into 3 groups according to ages: Group 1 (G1， 3 months， n=12)， Group 2 (G2， 6 months，n=11), and Group 3 (G3， 9 months，n=10). Global cardiac function was evaluated by Mmode and twodimensional echocardiography to obtain fractional shorting (FS) and ejection fraction (EF). Results    Both FS and EF in Bmode and Mmode echocardiograms showed no significant difference between G1and G2，but significantly decreased in G3. The TDI S′ were significantly decreased in G2 than in G1 in the basal ［(28.62±4.32)  vs  (45.8±12.04) mm/s, P<0.01］ and middle segments ［(26.32±5.35)  vs  (38.63±12.62) mm/s, P<0.01］, and further diminished in  G3 compared with G1and G2 in the two segments (P<0.01). Conclusion    TDI using HFB is feasible, and TDI velocities are probably more sensitive to early myocardial dysfunction in the mouse model of DCM.

Key words: High frequency ultrasound biomicroscopy; Tissue Doppler imaging; Dilated cardiomyopathy; Myocardial dysfunction