Immediate haemodynamic effects of a beta adrenergic blocking agent-propranolol-in mitral stenosis at fixed heart rates.

Previous haemodynamic studies in our laboratory have shown that pulmonary arterial and arterial wedge pressures in patients with isolated mitral stenosis decreased after administration of propranolol, without significant changes in right heart filling pressures or stroke volume.Reduction of heart rate with consequent prolongation of the diastolic filling period was thought to be the determining factor.These findings have been further confirmed in the present study by evaluating the effect ofpropranolol in such patients, paced at fixed heart rates.Propranolol pro- duced no signifcant haemodynamic effects during cardiac pacing.However, the post-pacing pul- monary vascular pressures were significantly reduced.These changes correlated well with reduc- tion of heart rate and prolongation of the diastolic filling period.It appears that the haemo- dynamic effects ofpropranolol in patients with mitral stenosis are mainly related to the negative chronotropic effect.Reduction of left heart filling and pulmonary arterial pressures in patients with mitral steno- sis by parenterally administered beta adrener- gic blocking agents has been documented by several investigators (Howitt, Tinker, and Wade, I965; Tsolkas, Davies, and Oram, I965; Cumming and Carr, I966; Goyle et al., I969).It has been, however, suggested that the negative inotropic effects of beta adrener- gic blockade, by reducing cardiac output (Howitt et al., i965; Stavropoulos, Davies, and Gazetopoulos, I965; Bensaid, Scebat, and Lenegre, I970), and the increase of ventricu- lar filling pressures (Cummuing and Carr, I966), may negate these beneficial effects.However, in our studies on patients with iso- lated mitral stenosis (Goyle et al., I969), the negative chronotropic effect of propranolol appeared to be the dominant factor respon- sible for the observed circulatory effects.The present study was designed to verify these observations further.Patients and methods of study Five patients, 2 men and 3 women, aged 2I to 38 years, with isolated rheumatic mitral stenosis were studied.Four patients were in normal sinus