Intuitive visualization and quantification of intraventricular convection in acute ischemic left ventricular failure during early diastole using color Doppler-based echocardiographic vector flow mapping

The aim of this study was to make an intuitive visualization of intraventricular convection (IC) and quantification of intraventricular convection velocity (ICV) in acute ischemic left ventricular (LV) failure of open-chest canines during early diastole contrast to the baseline conditions using color Doppler-based echocardiographic vector flow mapping (VFM). The animal care committee approved this prospective study. In 6 anesthetized open-chest beagle models, the emergence time and the emergence sites of IC in the LV cavity during early diastole were visualized at the standard apical 3-chamber (AP3c) views with the VFM at baseline conditions and after coronary artery ligation. The global ICV and the ICV at the basal, middle and apical levels of LV at the AP3c views at T1, T2, T3, T4, and T5 between both states were compared respectively (T1: the beginning of LV rapid filling period; T2: the middle of LV rapid filling period; T3: the peak of LV rapid filling period; T4: the middle of period of reduced filling; T5: the end of early diastole.). Acute ischemic LV failure with a marked increase in LV end diastolic volume and LV minimal diastolic pressure was induced by coronary artery ligation. The IC appeared only during the period of reduced filling at baseline conditions, and limited to the basal level of LV cavity. But the IC appeared throughout all the early diastole, and was seen almost occupying whole LV cavity during ischemia. The peak of the global ICV for both states appeared at T4. The global ICV at the AP3c views in acute ischemic failure LV cavity increased than those of baseline conditions at the T1 (6.593 ± 0.834 cm²/s vs. 0.000 ± 0.000 cm²/s, P < 0.001), T2 (9.457 ± 0.852 cm²/s vs. 0.000 ± 0.000 cm²/s, P < 0.001), T3 (14.765 ± 1.791 cm²/s vs. 2.030 ± 0.502 cm²/s, P < 0.001), T4 (25.392 ± 4.640 cm²/s vs. 6.688 ± 1.343 cm²/s, P < 0.001), and T5 (15.890 ± 3.159 cm²/s vs. 2.518 ± 0.869 cm²/s, P < 0.001). And the ICV at the basal, middle and apical levels at AP3c views in acute ischemic failure LV cavity also increased than those of baseline conditions at the same phase of early diastole (P < 0.01), except for the ICV at the LV basal level at T1. VFM is a powerful tool for visualization IC and quantification of ICV on profiles of LV flow fields, which can give intriguing insights into the subtle, flow-associated LV fluid dynamics of normal and abnormal cardiac function. It will be of great practical importance to elucidate the accurate physiological and the pathophysiological significance of the IC in further studies, so as to determine whether the cardiac function can be precisely evaluated with IC related index, and to incorporate VFM into clinical routine practice in the future.