Quantitative Analysis Of Left Ventricular Blood Flow Energy Loss During Diastole By Ultrasonic Vector Flow Mapping In Beagles Models Of Acute Myocardial Ischemia

Objective Aim of this study was to assess the left ventricular (LV) blood flow patterns and hemodynamics during diastole in beagles models of acute myocardial ischemia using vector flow mapping (VFM), and to investigate the value of flow energy loss (EL),in the attempt to find novel sensitive and accurate indicators of hemodynamics for myocardial ischemia.Methods Ten anesthetized open-chest beagle models were underwent VFM inspection at baseline conditions and after coronary artery ligation. The LV global EL and the EL at the basal, middle, apical levels of LV, and the vortex area, vortex circulation during isovolumic relaxation period, early diastolic period, rapid filling of early diastole period, middle diastole period, atrial contraction of late diastole period and rapid filling of late diastole period between both states were acquired. The qualitative observation of flow velocity vector, vorticity streamline, distribution of energy loss were compared respectively. The pertinent parameter test and non-parameter test were applied for comparing the same kind quantitative parameters of both states. The linear correlation analyses were applied respectively between the LV fluid global EL and the vortex area, as well as the vortex circulation.Results (1) The qualitative observations:the intraventricle were filling in a sequence time, the development of vortex and the flow velocity vector were stable and regular, and the distribution of EL was small and centered during diastole in baseline. The sequential time of flow filling in intraventricle was destroyed, Typical turbulant flow and vorticity fluctuation caused by irregular blood motion were observed, and the distribution of EL was large and dispersal during diastole in acute ischemia. (2) ① The LV global EL in acute ischemia significantly increased than that of baseline conditions during the isovolumic relaxation period,middle diastole period, atrial contraction of late diastole period and rapid filling of late diastole period:(5.74±2.01) vs (0.88±0.09) N/m2/s, (16.00±3.55) vs (8.82±1.76) N/m2/s, (15.44±3.37) vs (9.08±2.93) N/m2/s, (7.12 ±1.28) vs(4.65±0.66)N/m2/s,(t= 2.236、2.997、2.682、2.620, P<0.05). And the EL at the basal, middle and apical levels of LV in acute ischemic also increased than that of baseline conditions at the same phase of diastole (P<0.05). ② The vortex area and circulation in acute ischemia significantly increased than those of baseline conditions during the middle diastole period, atrial contraction of late diastole period and rapid filling of late diastole period:(98.34±16.89) vs (66.32±14.33) mm2, (131.04 ±16.38) vs (107.86±15.08) mm2, (180.76±18.21) vs (94.90±8.58) mm2, (67.35±9.67) vs (37.93±9.30) cm2/s, (62.53±11.72) vs (38.72 ±10.01) cm2/s, (75.11±13.09) vs (39.01±10.12) cm2/s, (t=3.412、 9.776、10.018, t=8.542、9.751、10.358, P<0.05)。③ Significant linear correlations were found between EL and vortex area, vortex circulation in both states during the middle diastole period, atrial contraction of late diastole period and rapid filling of late diastole period (P<0.05).Conclusion The sequence of intraventricular fluid modulation and reformation during diastole are destroyed by ischemia. The typical turbulant flow and abnormal vorticity induce the process of high fluid energy loss. The parameter of energy loss derived from VFM is a novel parameter for visualization and quantification LV hemodynamics, which can provide sensitive and accurate fluid dynamics index, and may contribute its advantages to the theranostic of ischemia in basic and clinical studies and applications.