Abstract: AIM: To evaluate the cardiac contractility and relaxation by Doppler tissue imaging (DTI) combined with myocardial contrast echocardiography (MCE) via injection of contrast media, Albunex. METHODS: Nineteen healthy mongrel dogs were conducted 60 min ligation of left anterior descending coronary artery (LAD), followed by reperfusion of 60, 120 and 180min to establish an acute myocardial ischemicreperfused canine model. (1) MCE was performed by bolus injection of Albunex at pre-reperfusion and at post-reperfusion. The perfused defect area defined by MCE at pre-reperfusion was regarded as risk area (RAMCE), while perfused defect area at post-reperfusion was regarded as no-reflow area (NRAMCE). When the ratio of NRAMCE to RAMCE exceeded 25 %, myocardial reperfusion was considered incomplete, i. e. , no-reflow group ;If the ratio was<25 %, myocardial reperfusion was considered adequate, i. e. , reflow group. (2) Left ventricular ejection fraction (LVEF) and wall thickness ratio (ΔT %) of LV anterior wall were determined. (3) S-wave, e-wave and awave velocities at the LV anterior wall were determined by DTI. The e a ratio was measured. RESULTS: The results of MCE showed 7 dogs in reflow group and 10 dogs in no-reflow group. (1) LVEF in reflow group gradually increased with time course after myocardial reperfusion, and in no-reflow group, however, LVEF increasingly declined with ongoing myocardial reperfusion. At the same reperfusion time point, LVEF of noreflow group was significantly lower than that of reflow group. (2) ΔT %in reflow group improved gradually, and however, it cannot come back to that of baseline at 180-min reperfusion. ΔT % in no-reflow group had no signal of recovery with progressive reperfusion. (3) S-wave, e-wave velocities measured by DTI significantly declined after ligation of LAD, and a-wave velocity increased, leading to decline of e a. After myocardial reperfusion, s-wave, e-wave velocities and e a in reflow group gradually increased at post-reperfusion, and a-wave velocity somewhat declined. In no-reflow group, on the other hand, s-wave, e-wave velocities and e a progressively declined and a significant difference was present between reflow group and no-reflow group (P<0.05). CONCLUSION: Cardiac contractility and relaxation cannot be recovered during myocardial microvascular impairment. This change may be further deteriorated with size enlargement of no-reflow area. DTI may provide a sensitive, reliable method for quantifying cardiac contractility and relaxation.

Key words: no-flow, doppler tissue imaging, contractility, relaxation, function