Propanolol reduces myocardial hypertrophy in the right cardiac chambers after infarction in rats

The effects of chronic propanolol (Prop) therapy on the post infarction myocardial hypertrophy of infarction rats were studied by histological techniques. male albino rats were submitted to left coronary artery ligation to produce infarction or to sham surgery (Con, N=6)., Infarction rats (Inf) were divided into 2 groups receiving Prop (2.5 mg/kg, twice a day, N+6) or saline (N=6) for one month, respectively. Myocyte diameters were measured in longitudinally oriented sections in the four heart chambers (60 cells/chamber). inf produced a significant increase in mean diameter of myocytes from the right atrium and ventricle and from the left atrium. In the right ventricle, myocyte diameter increased from 8.9 ñ 0.5 um in the Con group to 12.5 ñ 0.6 um in the the Inf group (P<0.05). Under Prop, myocyte diameter was reduced (P<0.05) to 9.8 ñ 0.9 um. Similar values were observed in the right atrium. In the left atrium, Prop produced only a partial reversion of the postinfarction hypertrophy. In the left ventricle, myocyte diameter was not significantly changed after Inf or Prop therapy. These data show that beta blockers reduce the myocardial hypertrophy in the right heart chambers after experimental infarcts in rats. This effect can be secondary to reduction of pulmonary hypertension or to blockade of direct effects of catecholamines on myocardial fibers or both

El efecto hemodinámico de la combinación propranolol y nifedipina en la paciente sometido a revascularización coronaria / Haemodinamyc effect with propranol-nifedipine treatment in the patient undergoing coronary bypass surgery

Se estudiaron 24 pacientes programados para revascularización coronaria. La técnica anestésica empleada fue Fentanil-Enflurano-Oxígeno-Pancuronio. Se comparó el comportamiento hemodinámico durante el período previo a la circulación extracorpórea en un grupo de pacientes bajo tratamiento con dinitrato de isosorbide y propranolol, un grupo bajo tratamiento con nifedipina y propranolol y un grupo control únicamente con dinitrato de isosorbide. La escasa literatura existente sugiere que la suspensión de la nifedipina antes de la cirugía disminuye la necesidad de emplear inotrópicos. El continuar con ella se ha asociado a un aumento en los requerimientos de vasodilatadores. En nuestro estudio no encontramos diferencia significativa entre ninguno de los 3 grupos estudiados. La literatura existente y los resultados obtenidos sugieren que no existe razón para suspender la nifedipina antes de la cirugía.