Effect of autonomic blockade, postural changes and isometric exercise on Doppler indexes of diastolic left...

Previous studies have demonstrated substantial changes in Doppler-derived indexes of left ventricular (LV) diastolic function in response to changes in loading conditions. To assess the influence of autonomic reflexes on these indexes, 2-dimensional and Doppler echophonocardiography were performed in 8 normal male subjects before and during autonomic blockade (0.2 mg/kg of propranolol and 0.04 mg/kg of atropine, intravenously) in the supine, passive upright 80 degree tilt and passive leg-raised positions, and during supine isometric exercise. During autonomic blockade in the supine position, there were significant increases in transmitral peak late filling velocity (A) (mean +/- standard error of the mean +34 +/- 7%) and isovolumic relaxation time (+18 +/- 9%), and significant decreases in transmitral peak early filling velocity (E) (-20 +/- 7%), deceleration time (-35 +/- 7%) and E/A ratio (-40 +/- 5%). E/A ratio decreased from 2.0 +/- 0.1 to 1.2 +/- 0.1 with autonomic blockade. When either upright tilt or isometric handgrip exercise was combined with autonomic blockade, the pattern of diastolic filling became distinctly "abnormal," with E/A ratio decreasing to 0.9 +/- 0.1. The effect of volume loading (increased end-diastolic volume and increased peak E) was seen in the legs-raised position only during autonomic blockade. It is concluded that autonomic blockade substantially alters the Doppler indexes of LV diastolic filling and modifies both hemodynamic response and Doppler indexes produced by positional changes and by isometric exercise.