Valsalva manoeuvrel

Ten normal male volunteers received either TOO mg alprenolol or placebo in a double-blind randomized trial. Ninety minutes later they performed a standardized Valsalva manoeuvre 40: mmHg airway pressure for 12 seconds. Beat-to-beat measurements were made of heart rate, left ventricular ejection time (LVET), ejection time index (ETI), and' corrected ejection time' (LVET/Vye). After placebo, heart rate, left ventricular ejection time, and ejection time indexfollowed essentially the same beat-to-beat patterns as the normal response reported previously. fl-blockade produced qualitatively sinmlar curves, but with increased cycle length and reduced left ventricular ejection time per beat at all points. Both ejection time index and corrected ejection time curves did not differ sigmficantly between placebo and alprenolol for corresponding phases. fl-blockade, therefore, reduced control and subsequent heart rate so the Valsalva strain was sustained and completed withfewer heart beats during the standard time but with a pure rate effect