Pulsed Doppler Echocardiographic Determination of Left Ventricular Pump Function by Analyzing of Flow Velocity Pattern in Left Ventricular Outflow Tract

To evaluate left ventricular (LV) pump function noninvasively, we analyzed the blood flow pattern in left ventricular outflow tract (LVOFT) with pulsed Doppler echocardiography (PDE) combined with 2-D echocardiography. The highest flow velocity in LVOFT was recorded. In 39 patients, except for valvular heart diseases, we compared variables from PDE data with those from cardiac catheterization. Peak flow velocity (PFV) of blood flow signal in LVOFT was proportionally correlated with stroke volume (SV) by thermodilution method (TDM) (r=0.444, p<0.01), but PFV was not correlated with ejection fraction (EF) and left ventricular end-diastolic volume (LVEDV). Ejection time (ET) and acceleration time of blood flow signal (AT) : the interval from the onset of the flow signal to PFV : were measured. The ratio of AT/ET was inversely correlated with LVEF (r=-0.647, p<0.001). A significant correlation was found between SV by PDE and SV by TDM (r=0.793, p<0.001). In 14 normal subjects, the effect of increase in, afterload (by angiotensin II) on the flow pattern in LVOFT was examined. Both PFV and SV by PDE were inversely correlated with peak systolic blood pressure, but there was no linear correlation between AT/ET and peak systolic blood pressure. In 7 anesthetized dogs, the simultaneous recording of flow and pressure was performed invasively for evaluation of the relation between AT/ET and peak systolic blood pressure in changing afterload. The ratio of AT/ET remained unchanged during slight increase in afterload, while AT/ET was increased progressively, when peak aortic pressure became higher than 20% of resting value. These results suggested that LV pump function could be estimated by analizing the blood flow pattern in LVOFT using PDE.