[Left ventricular diastolic properties in dogs evaluated by stress pulsed Doppler echocardiography]

We examined diastolic properties of the left ventricle (LV) of 12 anesthetized open-chest dogs. The heart was paced at a fixed rate of 100 beats/min. The time constant (T) was calculated from the LV pressure curve, and the A/R was measured from LV diastolic velocity curves using pulsed Doppler echocardiography (PDE). Both were used as indexes of the LV diastolic properties. The afterload increased by occluding the descending aorta; the preload decreased by occluding the inferior vena cava. Both T and the A/R increased significantly (p less than 0.01) when the afterload was increased. However, when the preload was decreased, T was not significantly changed. The A/R increased significantly due to a smaller decrement of A than that of R, when the preload was decreased. The percent change of T correlated significantly with that of the A/R, when the afterload was increased (r = 0.687, p less than 0.05). However, there was no correlation between them, when the preload was decreased. We conclude that LV diastolic properties are affected by afterload and preload, and that percent changes of T do not always correlate well with percent changes in the A/R. Thus, it is important to evaluate the preload and afterload states when ever LV diastolic properties are measured clinically.