Assessment of left ventricular wall motion in diabetic rats using velocity vector imaging combined with stress echocardiography

Objective: The aim of this study was to investigate whether velocity vector imaging (VVI) combined with stress echocardiography could detect potential diffused myocardial impairment of the left ventricle (LV) in diabetic rats. Methods: Thirty-five male SD rats were randomly divided into either the control group or the diabetes mellitus (DM) group (induced with STZ). VVI was performed both at rest and after dipyridamole stress in all rats 12 weeks later. Segmental peak systolic velocity (V_s), diastolic velocity (V_d), radial strain (ɛ_r), circumferential strain (ɛ_c), systolic and diastolic radial strain rate (SR_r), and circumferential strain rate (SR_c) were measured from six segments at the mid-level of the LV. Results: At rest, systolic and diastolic SR_c in the DM group were significantly lower than those in the control group. After dipyridamole stress, all VVI parameters in the DM group were significantly lower than those in the control group, although all values increased significantly after dipyridamole stress compared to those at rest in both groups. Conclusions: The VVI-derived V_s, V_d, ɛ_r, ɛ_c, systolic and diastolic SR_r and SR_c, combined with dipyridamole stress are all effective parameters in evaluating potential myocardial impairment due to ultrastructural alterations of cardiocytes and microcirculation disturbances in DM rats. Systolic and diastolic SR_c may be more sensitive indices that could be useful in detecting myocardial impairment at rest.