Differences between the effects of practolol and propranolol on the diastolic properties of the left ventricle

To elucidate the mechanism by which left ventricular end diastolic pressure (LVEDP) is reduced by practolol, ventricular volumes, hemodynamics, and diastolic elastic stiffness were determined before and 10 min after intravenous practolol (400 µg/kg) in 12 patients. Heart rate decreased in all patients after practolol (avg., −9/min, p < 0.02). There was an insignificant increase in stroke work index and decrease in cardiac index attributable to the fall in rate. Practolol did not change end diastolic volume or ejection fraction, but the average LVEDP fell from 21 to 15 mm Hg (p < 0.01) which was sustained even with atrial pacing to prepractolol heart rates. Diastolic elastic stiffness was also reduced after practolol (0.665 to 0.593, p < 0.0025). The data indicate that practolol exerts a negative chronotropic effect on the intact heart and, in contrast to other beta blockers such as propranolol, appears to decrease diastolic stiffness in the left ventricle.

Differences between the effects of practolol and propranolol on the diastolic properties of the left ventricle Journal Articles