[Clinical study of a new anti-arrhythmic drug: propafenon. Short and long-term results]. / Estudio clínico de un nuevo fármaco antiarrítmico: propafenona.

Fifty patients with atrio-ventricular arrhythmias were treated with the new antiarrhythmic drug propaferon. A dose of 70 mg (1-1.5 mg/kg), was injected slowly into a vein (2-3 min), in 16 cases. In the other 34 cases a dose of 450-900 mg/24 hours was given orally. Propafenon is a drug which acts on the permeability of the membrane and also as a local anaesthetic. Its efficiency has been demonstrated in the treatment of arrhythmias. In our series, ventricular arrhythmias were suppressed in 76.8% of the cases (33 patients), while the ventricular extrasystoles were reduced in 18.6% of the cases (8 patients). There was no action in 4.6% of the cases (2 patients). The drug was not useful in the treatment of atrial arrhythmias. Unwanted side-effects (arterial hypotension, conduction disorders, etc.), were not seen when intravenous doses of less than 2 mg/kg, were administered. However, electrocardiographic changes (widening of the QRS, prolongation of the PQ interval, etc.), were observed in those patients who received doses greater than 450 mg/24 hours. In these patients, there was a close correlation between the dose administered and the prolongation between the dose administered and the prolongation of the conduction times. We believe that the amount of myocardial degradation and the age of the patient are directly related to the appearance of conduction disorders. This relation is greater when a larger dose is administered. The advantages that this new drug has over other antiarrhythmics are the methods of administration (oral and intravenous). Both these methods may be used simultaneously to maintain a stable sinus rhythm or the rapid intravenous method may be followed by the oral maintenance one.

[The influence of cardiac frequency on the hemodynamic consequences of mitral stenosis (author's transl)]. / Influencia de la frecuencia cardiaca en la repercusión hemodinámica de la estenosis mitral.

In eleven patients with isolated mitral stenosis and regular sinus rhythm a right cardiac catheterization was performed and the wedged pulmonary capillary pressure recorded at rest and during electrical pacing of the right atrium at successive frequencies of 100, 120, 140, and, occasionally, 160 and 180 beats/min, while cardiac output was estimated by the Fick's principle. In all cases a significant elevation of pulmonary capillary pressure with a simultaneous reduction in cardiac output was obtained. The rise of wedged pulmonary pressure was proportional to the increment in cardiac frequency and related also to the calculated area of the mitral valve. The influence of active atrial contraction upon pulmonary pressure and cardiac output is discussed and comparisons with other studies are made. Emphasis is made on the value of atrial pacing as a diagnostic method in mitral stenosis, especially in cases in whom classical effort manoeuvres can not be applied or are insufficient to rise cardiac frequency.