[The familial incidence of accessory atrioventricular pathways (the pre-excitation syndrome)]. / Frecuencia familiar de vías accesorias atrioventriculares (síndrome de preexcitación).

Cases of familial preexcitation syndrome represent a specific subgroup of patients that may result from diverse mechanisms: failure in development and genetic predisposition are the main mechanism involved. We determined the prevalence of this syndrome in first degree relatives of patients with proved accessory pathways by electrophysiologic study and compared such prevalence with the general population (0.15%). In five out of 469 patients (1.06%) we found an accessory pathway in one or more member of their family. Only 6 out of 3752 had preexcitation (0.15%); this prevalence was similar to the general population (P = NS). The identification of family members with this syndrome may be incomplete because we only chose for the study symptomatic patients. We did not observed multiple pathways and in one case we found atrial septal defect. Our data demonstrated familial preexcitation in five families suggesting hereditary predisposition.

[Late thrombolysis and electrical stability in acute myocardial infarction. Role of the collateral flow]. / Trombolisis tardía y estabilidad eléctrica en el infarto agudo del miocardio: importancia del flujo colateral.

We evaluated 249 patients (pts) with first acute myocardial infarction: 1. Pts without thrombolysis, n = 119, 2. Pts treated with thrombolysis within 6 hours following MI, n = 80 and 3. Pts treated with thrombolysis between 6-12 hours after MI. Arrhythmic events were evaluated during follow up. All underwent heart rate variability studies and coronary angiogram where anterograde flow (TIMI) and collateral flow (Rentrop scale 0-2 = poor collateral flow and 3 = good collateral flow) were determined. Pts in group 2 and 3 showed a better anterograde and collateral flow than group 1 (p < 0.001). A lower spectral power in the high frequency band and a higher ratio low/high frequency band were observed in group 1 (p < 0.05). Conjunctive consolidation analysis showed more malignant arrhythmias in TIMI 0-2 with poor collateral flow than TIMI 0-2 with good collateral flow (17/138-12.3% vs 0/14-0%). Kaplan Meier analysis was able to demonstrate more cardiac sudden death events in TIMI 0-2 with poor collateral flow than TIMI 0-2 with good collateral flow or TIMI 3 (x2 = 7.22, p = 0.028), independently of thrombolytic treatment.

[High-fidelity spectrocardiography for the diagnosis of ischemic cardiopathy. The validation of a new method for analyzing the spectral components of the QRS complex]. / Espectrocardiografía de alta fidelidad para el diagnóstico de cardiopatía isquémica. Validación de un nuevo método para el análisis de los componentes espectrales del complejo QRS.

BACKGROUND: Analysis of high-frequency QRS complex envelope has been suggested as a method that could detect myocardial ischemia but the characteristics of the turbulence spectral from an spectral-temporal mapping into the QRS complex has not been studied yet. This is a prospective study of phase I for the validation of a new diagnostic test. AIMS: The aims for this study are: 1) To validate a new method for the detection of transient myocardial ischemia by both, high-frequency QRS and spectral turbulence analysis, which we have named "high-fidelity spectrocardiogram" (HFS). 2) To compare the sensitivity, specificity and accuracy of this HFS versus those obtained from nuclear medicine (NM-MIBI) and a conventional exercise ECG test, in a highly selected population. PATIENTS AND METHODS: Twenty-five patients (P) were studied: 10 P (Group B) with risk factors for coronary artery disease, without previous infarct, who had atypical precordial pain and a conventional ECG considered as "normal" by two cardiologists. The group A was formed by 15 P without risk factors or another kind of heart disease. All patients underwent a conventional surface ECG, which had to be normal in order to be considered for this study. Echocardiogram, exercise testing ECG and a NM-MIBI study were also normal. The HFS recording was taken before and after Dipyridamole testing, similar to the conventional method for the NM-MIBI (dipyridamole 0.25 mg/Kg/doses) studies. Our software for the analysis of QRS-frequencies was constructed from a language Turbo C++. The Fourier's transform allowed the construction of 3-dimensional graphics. After the determination of the best wide band for detecting changes in the frequency contained of QRS, the determination coefficients (r2) were obtained and compared before and after the challenge with dipyridamole. These changes were compared between groups (A vs B) later. RESULTS: The r2 changed more than 30% after dipyridamole in those patients in whom myocardial ischemia was demonstrated later by NM-MIBI. The sensitivity (85%) and specificity (90%) of HFS were similar to the nuclear medicine for identifying myocardial ischemia, but higher than a conventional exercise ECG testing (p.001). The main change in HFS was in the frequency-contained QRS in the 130-260 Hz band. The accuracy of our method was increased when an analysis of each orthogonal lead was made. There was a clear tendency of the group B to increase the QRS duration, while the contrary was found in group A, being the QRS the shorter (p.064). The chronological responses were different in those patients with ischemia. CONCLUSION: This study suggests that an episode of myocardial ischemia is able to change in a dramatic manner the frequency-contained within of the QRS complex, in spite of an unchanged ST segment in the conventional exercise ECG. We suggest that the HFS could be a good method for identifying myocardial ischemia. Its advantages could be important, particularly when the conventional exercise ECG is non informative.

[Arrhythmia in acute myocardial infarction with involvement of the right ventricle]. / Disritmias en el infarto agudo del miocardio con extensión al ventrículo derecho.

Arrhythmias and conduction disorders were studied in 110 patients with posteroinferior myocardial infarction with right ventricular involvement. All the patients were hospitalized in the coronary care unit, and were compared with another 110 patients with posteroinferior myocardial infarction without extension to the right ventricle. 99% of the patients with right ventricular infarction and 96.3% of the patients with isolated inferior infarction had some type of arrhythmia. The disorders of automatism were similar in both groups (90% vs 91%, respectively). The conduction disturbances were observed in 68% of the infarctions extended to the right ventricle and in 20% of the isolated left ventricular infarctions (p greater than 0.01). A-V block occurred in 52% of the infarctions with right ventricular involvement and only in 10.9% of the control group. Intraventricular conduction disorders also were more frequent in right ventricular infarction (24.5% vs 10.9%) (p less than 0.02), especially the RBBB (18.2% vs 6.4%). Ventricular fibrillation was observed in 5.5% and 0.9%, and polymorphic ventricular tachycardia (torsades de pointes) in 12.7% and 1.9% respectively. In 62 patients with right ventricular infarction it was necessary to implant a pacemaker as compared to 12 patients in the control group. Mortality was higher in the patients with inferior infarction extended to the right ventricle (23 patients vs 2 patients). None of the deaths were due to arrhythmias. It can be concluded that conduction disorders and the number of pacemaker implants are more common in the infarctions with right ventricular involvement due to more severe damage to the conduction system.

[Long-term course of infarct of the right ventricle]. / Evolución a largo plazo del infarto del ventrículo derecho.

The long-term evolution of 36 patients surviving the phase of hospitalization after a postero-inferior infarction with extension to the right ventricle was studied. Patients included 7 women and 29 men with a mean age of 55 years. Follow-up time averaged 39 months (range: 4 to 78 months). The evolution of acute phase was analyzed and correlated with mortality, complications and long-term evolution of functional capacity. Mortality at the end of follow-up period was 5.5%. Five patients developed another myocardial infarctions (16%). No patient manifested right heart failure; in one case tricuspid regurgitation was evident. The majority of the patients (55.5%) were in functional class I of the NYHA, while 36.6% were in class II and 8.3% in class III. We conclude that long-term mortality of those patients with right ventricular infarction is not greater than that of other patients with myocardial infarction, and that the great majority have a favorable evolution in regard of functional capacity. Impared function is generally due to left ventricular failure secondary to the severity and extension of coronary lesions. The subgroup of patients with severe right ventricular dysfunction during the acute phase of the infarction did not have a worse long-term prognosis.

[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.

[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.

[Infusion of fluids into the pulmonary artery in the treatment of acute myocardial infarction extending to the right ventricle. Evaluation of the method]. / La infusión de líquidos en la arteria pulmonar en el tratamiento del infarto agudo del miocardio extendido al ventrículo derecho-Valoración del método.

Seventeen patients with diagnosis of acute myocardial infarction with right ventricular extension were studied. All of them had evidence of contractile impairment of the right ventricle as shown by elevated filling pressure of the right ventricle, low systolic pulmonary pressure and low left ventricular filling pressure and cardiac output. These patients were treated with fluid infusion into the pulmonary artery besides other treatment measures for myocardial infarction in order to improve the filling pressure of the left ventricle and the cardiac output without stressing the right ventricle. The results obtained with this approach, which was maintained for 22 hours, showed a significant improvement in the stroke work indices of both ventricles and also in the cardiac output with a decrease in peripheral resistence without ever loading the ventricles. We analyze the physiological basis for using this procedure and also the complications that can occur. Our results show that the infusion of fluid into the pulmonary artery improves the hemodynamic situation of these patients and protects a damaged right ventricle.

La infusion de liquidos en la arteria pulmonar en el tratamiento del infarto agudo del miocardio extendido al ventriculo derecho-valoracion del metodo. / Liquid infusion into pulmonary artery in the treatment of acute myocardial infarction with right ventricular extension - evaluation of the method

Se estudiaron 17 pacientes con diagnostico de infarto agudo del miocardio con extension al ventriculo derecho y que tuvieron datos de falla mecanica de este ultimo, caracterizada por presion de llenado del ventriculo derecho elevada, presion sistolica pulmonar disminuida, junto con datos de bajo gasto cardiaco. A estos enfermos se les infundieron liquidos en la arteria pulmonar como parte del tratamiento del infarto con el fin de mejorar el llenado del ventriculo izquierdo y el gasto cardiaco, sin sobrecargar volumetricamente al ventriculo derecho. Los resultados obtenidos con este sistema de tratamiento por un lapso promedio de 22 horas indican una mejoria significativa en los indices de trabajo de ambos ventriculos y en el gasto cardiaco con una disminucion de las resistencias perifericas, sin evidencia de sobrecarga ventricular. Se analizan los mecanismos fisiologicos que justifican este procedimiento y tambien las complicaciones atribuibles al mismo. Nuestros resultados indican que la infusion de liquidos en la arteria pulmonar mejora las condiciones hemodinamicas de los pacientes y protege a un ventriculo derecho lesionado

[Myocardial damage following cardioversion]. / El daño miocárdico secundario a electroversión.

In order to ascertain myocardial damage secondary to D.C. cardioversion, we studied 20 patients from the National Institute of Cardiology Ignacio Chávez, in whom an elective electric countershock was applied because of rythm abnormalities. We studied the patients before and after the procedure with E.C.G., enzyme levels (SGOT, LDH, CKMB), and myocardial scintigraphy to detect possible myocardial lesions. Only in two patients the CKMB rose to a significant level. The ECG changes were significant in 40 per cent, and myocardial scintigraphy was positive in a diffuse pattern in 50 per cent of the cases. The interpretation of the three studies as a whole, showed an absolute lack of correlation between them. We conclude that DC countershock is a safe and innocuous procedure, to which no myocardial damage can be attributed, if it is used within the normal limits of clinic.

El dano miocardico secundario a electroversion. / Secondary myocardial damage and electroversion

En el Servicio de Urgencias y Unidad Coronaria del Instituto Nacional de Cardiologia Ignacio Chavez, se estudio un lote de 20 enfermos a quienes se les hizo electroversion electiva. Se hicieron determinaciones de enzimas sericas, centelleografia del miocardio y electrocardiogramas tratando de demonstrar lesion miocardica imputable al procedimiento terapeutico. En ningun enfermo habia datos de patologia que pudiese alterar los resultados de laboratorio. Los resultados obtenidos permiten aseverar que la electroversion es un procedimiento eficaz, seguro e inocuo ya que no encontramos datos que sugiriesen dano sobre la fibra miocardica atribuible al uso de corriente electrica