Evidence for a class 4 effect of cibenzoline "in vivo".

In anesthetized dogs, it has already been shown that cibenzoline (4 mg/kg i.v.) possesses class 1 anti-arrhythmic properties. In this work, the cardiac electrophysiologic effects of cibenzoline (1 mg/kg i.v.) were studied before and after propranolol (0.2 mg/kg i.v.) treatment. Cibenzoline caused a slight tachycardia, a reduction of conduction velocity in the His-Purkinje system and in the ventricle, but no significant effects in the atria and the atrioventricular node were detected. On the contrary, when dogs were given the beta-adrenoceptor blocking agent propranolol, cibenzoline produced major effects in the slow response structures, especially in the sinus node and the atrioventricular node (bradycardia and depression of the atrioventricular nodal conduction). No further effects were observed on the His-Purkinje system and ventricle as compared to administration of cibenzoline alone. In dogs, cibenzoline given i.v., had no effects on the slow response systems, probably because of sympathetic nervous system intervention since the class 4 effects of cibenzoline appeared after beta-adrenoceptor blockade.

[An experimental model of helicoid ventricular tachycardia (torsades de pointes). Preliminary report]. / Un modelo experimental de la taquicardia ventricular helicoidal (torsades de pointes). Comunicación preliminar.

Studies on twenty dogs were performed. With open thorax, aconitine was injected into the thickness of the interventricular septum. D2 and direct derivations were registered in the epicardium of the right atrium, on right and left septal surfaces and in the His bundle. As the experiment ended, the heart was taken out to determine the placement of the electrodes and the site of application of aconitine. "Torsades de pointes" were obtained in 15 dogs, with a rotation of 180 degrees during the episode. The rotation of A QRS occurred with a beat of intermediate direction which corresponded to a ventricular capture of a sinus beat or a ventricular echo after that beat, and a sequence of activation of AHV established in various beats, the first of which had a prolonged AH (p less than 0.01). The consecutive change of direction of QRS happened when that sequence of activation disappeared, and there was an A-V dissociation as in the beginning of the episode. In conclusion, in this experimental model, the Torsades de pointes were produced by double mechanism, an increased focus of automatism and a macro-re-entry that involves the two branches of the His bundle, the A-V node and the atrium.

[Pseudonormalization of repolarization during physical exercise and the hemodynamic findings]. / La seudonormalización de la repolarización durante el ejercicio físico y los hallazgos hemodinámicos.

The meaning of normalization of abnormal T waves during exercise is still unclear, twenty patients with this electrocardiographic pattern during treadmill stress test were studied with coronary arteriography. They were classified in two groups: Group I: In which 3 patients had isolated "pseudonormalization" of the T wave, and Group II with "pseudonormalization" of the T wave plus a positive stress test or an old myocardial infarction. Results allowed us to conclude that this phenomenon per se is not a diagnostic clue of coronary injury; however when we observe it associated with a positive stress test or an old myocardial infarction it may be indicative of severe and multiple coronary vessel injury.

[Cardiac involvement in ankylosing spondylitis]. / La afección cardíaca en la espondilitis anquilosante.

Ankylosing spondylitis is a rheumatic disease that affects the axial skeleton and has predilection for young men. Of its extraarticular manifestations, the cardiac involvement, reported up to 48%, has been pointed out in recent years. It seems to exist a racial variation in the features of the spondylitis and since most of the studies have been performed in northern countries therefore it appears inadequate to extrapolate the conclusions of such studies to our society. We studied 23 patients with definitive diagnosis of ankylosing spondylitis. All of them had a complete physical examination, electrocardiography and X-ray of the chest; eight patients underwent a Holter study of 24 hours and seven patients were examined by echocardiography. The mean age of the group was 36 years; there were 21 men and two women. The mean duration of the rheumatic disease was 11.5 years. In only 4 (17.4%) of the patients we found cardiac involvement that would not be related to another etiology. By the clinic examination we found two patients with isolated aortic insufficiency; one case had a right bundle branch block. The Holter study did not show modifications, except in the one with isolated aortic insufficiency and right bundle branch block, in whom this block became of variable degree. The echocardiographic study showed the mentioned aortic valvular lesions and did reveal the same lesion in another patient in which the other studies were normal. It is emphasized that it is adequate to search for signs of ankylosing spondylitis in every patient with isolated aortic insufficiency or/and conduction disturbances of unknown etiology and also to performe cardiac careful in each patient with ankylosing spondylitis examination.

[Fibrous fixed subaortic stenosis]. / Estenosis subaórtica fibrosa fija.

Fifty eight patients with isolated with discrete subaortic stenosis or in association with just another heart defect, were studied between 1961 and 1980. The age range was between 2 and 42 years. The evaluation of each case was done according to clinical manifestations, systolic overloading of the left ventricle and the amount of the systolic gradient. There is a poor correlation between the clinical, electrocardiographic and hemodynamic parameters according to the student t test in the preoperative evaluation. Forty-one patients were operated, two of them died in the early post-operative period. There was a good clinical evolution with significant values comparing pre and post-operative symptoms. The decrease in the systolic gradient in 26 cases after surgery was significative (p less than or equal to 0.005). Based on the natural history of this malformation and on the results obtained with the surgical treatment, we may conclude that there is surgical indication once the diagnosis is made, because this malformation has a completely different evolution compared with other forms of congenital aortic stenosis.

[New anti-arrhythmia drugs]. / Algunos aspectos de los nuevos medicamentos antiarrítmicos.

In this paper some of the new antiarrhythmic drugs are reviewed. The origin, electrophysiologic effects, mechanisms of action, pharmacokinetic properties, hemodynamic changes, clinical utilization with indications and contraindications as well as the collateral effects of: Verapamil Amiodarone, Aprindine, Encainide, Mexiletine and Tocainide are analyzed. A conclusion is drawn for each one of these drugs in accordance with the available information in the literature and the author's criteria and experience.

[Effect of intravenous disopyramide in supraventricular paroxysmal tachycardia refractory to vagal maneuvers]. / Efecto de la disopiramida intravenosa en la taquicardia paroxistica supraventricular refractaria a maniobras vagales.

The objective of this study was to prove the efficacy of intravenous disopyramide in the treatment of paroxysmal supraventricular tachycardia resistant to vagal maneuvers. Nine patients with this condition were admitted to the emergency service of the Instituto Nacional de Cardiología Ignacio Chávez. They were given an intravenous bolus of 2 mg/kg of the drug a maintenance dose of 0.4 mg/kg during 3 hours. The undesirable effects of the drug were arterial hypotension, dizziness, dry mouth, transient A-V dissociation and scape-capture rhythm. In conclussion, disopyramide is an excellent drug in the treatment of paroxysmal supra-ventricular tachycardia resistant to vagal maneuvers, but an strict monitorization of the arterial pressure and electrocardiogram should be kept during its administration.

Efecto de la disopiramida intravenosa en la taquicardia paroxistica supraventricular refractaria a maniobras vagales. / Effect of intravenous disopyramide in paroxysmal ventricular tachycardia resistant to vagal maneuvers

El objetivo del presente estudio fue comprobar la eficacia de la disopiramida intravenosa en el tratamiento de las taquicardias paroxisticas supraventriculares que no respondieron a maniobras vagales.Se seleccionaron nueve enfermos atendidos en el servicio de urgencia del Instituto Nacional de Cardiologia Ignacio Chavez, a los cuales se les interno en la Unidad Coronaria y se les administro una dosis de 2 mg/kg, seguida de otra dosis para un mantenimiento de 0,4 mg/kg por hora durante tres horas. Los resultados obtenidos mostraron el cese del trastorno del ritmo en el 100% de los enfermos. Todos ellos fueron dados de alta del hospital en ritmo sinusal. Como efectos indeseables secundarios al uso del farmaco, se encontro hipotension arterial, manero, sequedad de mucosas, asi como alteraciones electrocardiograficas transitorias que consistieron en disociacion auriculo-ventricular y ritmo de escape-captura. Se concluye que el medicamento es muy eficaz en el tratamiento de este trastorno del ritmo, pero se requiere vigilancia estrecha de las cifras de tension arterial y de las alteraciones electrocardiograficas durante la administracion del mismo

Algunos aspectos de los nuevos medicamentos antiarritmicos. / Some aspects of new antiarrhythmic drugs

En este trabajo se hace una revision de algunas nuevas drogas antiarritmicas.Se analizan el origen, los efectos electrofisiologicos, los mecanismos de accion, las propriedades farmacocineticas, los efectos hemodinamicos, el uso clinico, con sus indicaciones y contraindicaciones, asi como los efectos colaterales de: el verapamil, la amiodarona, la aprondina, la encainida, la mexiletina y la tocainida. Se establece una conclusion sobre cada uno de estos farmacos de acuerdo con los informes de la literatura y la experiencia y el criterio de los autores

Estenosis subaortica fibrosa fija. / Fibrous fixed subaortic stenosis

Entre 1961 y 1980 se estudiaron 58 pacientes con estenosis subaortica fibrosa fija aislada o asociada a una sola cardiopatia.La edad oscilo de 2 a 42 anos. La valoracion de cada caso se hizo en base a la severidad de las manifestaciones clinicas, a la sobrecarga sistolica del ventriculo izquierdo y a la magnitud del gradiente sistolico. Se operaron 41 enfermos de los que dos murieron en el transoperatorio. Se observo una evolucion clinica favorable con valores significativos al comparar los sintomas antes y despues de la operacion.La reduccion del gradiente sistolico en 26 casos valorados con cateterismo cardiaco despues de la cirugia, fue significativa (p < ou = 0.005). Al considerar la evolucion natural de la cardiopatia y los resultados obtenidos con el tratamiento, concluimos que la indicacion quirurgica existe una vez hecho el diagnostico ya que esta malformacion tiene una evolucion diferente a la observada en las otras formas de estenosis aortica congenita. Finalmente, se enfatiza la escasa correlacion existente entre los parametros clinicos, electrocardiograficos y hemodinamicos por medio de la prueba t de Studen

Comisurotomia mitral cerrada durante el embarazo. / Mitral commissurotomy during pregnancy

El objetivo del presente trabajo ha sido revisar la experiencia y resultados obtenidos en la comisurotomia mitral cerrada en mujeres embarazadas. Se estudiaron 50 pacientes con estenosis mitral pura o predominante que han sido operadas mediante tal procedimiento y durante el curso del embarazo, en el Instituto Nacional de Cardiologia Ignacio Chavez, desde 1953 hasta 1980. Los datos obtenidos permiten afirmar que si bien el procedimiento quirurgico fue un tratamiento de relativa urgencia en la mayoria de estas pacientes, los resultados son satisfactorios para la madre y el producto, con morbimortalidad ligeramente mayor que en pacientes sometidas al mismo tratamiento fuera del embarazo. Se encontro mortalidad materna del 2% y del producto de 8%. La morbilidad estuvo representada principalmente por amenaza de aborto y de parto prematuro. Se concluye que llevar a cabo este tratamiento en pacientes embarazadas no encierra un riesgo significativamente mayor y si en cambio tiene resultados excelentes al mejorar el compromiso hemodinamico de la cardiopatia exacerbado por el estado gravidico