[Transmitral flow velocity patterns as influenced by preload, afterload and heart rate alterations: pulsed Doppler...

The influences of preload, afterload and heart rate alterations on the pattern of left ventricular filling were investigated using pulsed Doppler echocardiography (PDE) in humans. Transmitral flow at the level of the valvular tip was recorded during dextran infusion, lower body negative pressure, angiotensin II infusion, and atrial and atrioventricular sequential pacings. Peak velocity of rapid filling (R), peak velocity of atrial contraction (A), the ratio of peak velocities (A/R), flow velocity integrals of the rapid filling phase (IR) and atrial contraction (IA) were obtained. PDE and the measurement of hemodynamics during lower body negative pressure (0, -10 mmHg, -20 mmHg) and dextran infusion (100 ml, 200 ml) were studied in 22 patients with ischemic heart disease. R decreased significantly after lower body negative pressure, and increased significantly during dextran infusion. Before and during angiotensin II infusion, PDE and the measurement of hemodynamics were studied in 14 patients with ischemic heart disease. The patients were categorized into 2 subgroups according to left ventricular function. During afterload stress, the A/R and IA increased in patients with normal left ventricular function; whereas, the A/R decreased in patients with poor left ventricular function. PDE was recorded during right atrial and atrioventricular sequential pacings at the heart rates of 60 to 100 beats/min in 29 patients with ischemic heart disease. When the heart rates increased, R decreased during atrial and atrioventricular sequential pacings. The A increased after the occurrence of the summation between the rapid and atrial filling waves. The A/R gradually increased with incremental heart rate. These results indicate that changes in the preload alter the peak velocity of left ventricular filling pattern of transmitral flow. The effects of the increasing afterload depend on the basal left ventricular function, with an increase in the peak velocity of atrial contraction being observed in the presence of normal left ventricular function. Both the peak velocity of rapid filling and atrial contraction were related to the heart rate and atrioventricular conduction delay. In assessing left ventricular filling dynamics using PDE, the influence of the preload, afterload and heart rate must be considered.