Effect of propranolol on the left ventricular response to the Valsalva maneuver in normal subjects.

Ten normal subjects performed the Valsalva maneuver before and after the administration of propranolol (1 mg/kg). Changes in left ventricular (LV) size and function were assessed with noninvasive techniques (echocardiography and sphygmomanometer). Data were obtained at baseline, at 20 seconds of the strain phase (phase II) and 10 seconds after the release of strain (phase IV). In the control state (before propranolol), blood pressure decreased during phase II and exceeded baseline after the release of strain ("overshoot") in phase IV; after the administration of propranolol, the pressure overshoot characteristic of phase IV was no longer present. End-diastolic dimension decreased during the strain phase, but returned to baseline values during recovery in both control and propranolol states. LV stress-dimension and stress-shortening relations before and after propranolol indicate that an increase in LV contractility beginning during phase II and extending into phase IV was attenuated after propranolol. Although the absence of phase IV blood pressure overshoot may be clinically useful in identifying patients with impaired left ventricular function, beta-adrenergic receptor blocking agents can also produce this hemodynamic response in the presence of normal ventricular function.