Influence of Variable Loading Conditions on Pulsed Doppler Indices of Left Ventricular Ejection Dynamics

To investigate the influence of changes in loading conditions on Doppler echocardiography determination of left ventricular ejection dynamics (peak aortic flow velocity and mean acceleration), pulsed Doppler was performed on 20 patients from apical 5-chamber view. Doppler aortic flow velocity curves and hemodynamic values (left ventricular pressure, wedge pressure, and cardiac output) and the first derivative of ventricular pressure (dPIdt) by tip-transducer catheter were simultaneously recorded at baseline and during intravenous infusion of nitroglycerin as well as at baseline and immediately following left ventriculography. During nitroglycerin infusion, the hemodynamic values were reduced and peakdPIdt remained constant, Doppler aortic peak velocity and mean acceleration decreased significantly compared with baseline (0.87 ± 0.11 mlsec vs 1.01 ± 0.14 mlsec and 8.86 ± 1.68 ml sec² vs 10.17 ± 1.88 mlsec² respectively; bothP < 0.001). After ventriculography, the hemodynamic values increased and peak dPIdt was still constant, Doppler aortic peak velocity and mean acceleration increased significantly compared with baseline (1.15 ± 0.17 mlsec vs 0.98 ± 0.16 mlsec and 11.44 ± 2.06 mlsec² vs 9.79 ± 1.88 mlsec² respectively;both P < 0.001). In conclusion, left ventricular ejection dynamics, as evaluated by pulsed Doppler echocardiography, is modified by mild changes in loading conditions. Therefore, when serially evaluating the inotropic state of the left ventricle by the Doppler aortic flow velocity pattern, the potential influence of loading conditions should be takeninto account.