[Treatment of ventricular tachycardia]. / Tratamiento de la taquicardia ventricular.

Evaluation and management of postinfarct ventricular tachycardia has changed dramatically in the past two decades. The introduction of the implantable cardioverter defibrillator has played a major role in this change, alternating both, the purpose of the patients evaluation and treatment options. Episodes of sustained ventricular tachycardia can occur in a variety of clinical settings; the most common of which is the patient who has suffered a myocardial infarction. In this paper, I explore the causes and effects of some of these changes and review current strategies, specially the radiofrequency catheter ablation, for the management of the patient with postinfarct ventricular tachycardia.

[Electrocardiographic changes during stress test in a patient with "Brugada syndrome"]. / Alteraciones electrocardiográficas durante el esfuerzo en un paciente con "síndrome de Brugada".

We report a 28 year old man with the Brugada syndrome characterised by an electrocardiographic pattern of a right bundle branch block and an ST segment elevation in the right precordial leads as well as syncope. During an exercise test, we observed a normalization of the ST segment in V2+ while in the postexercise phase, the ST segment elevation in the right leads was established. This is the first case reported of the Brugada syndrome in Mexico, with spontaneous changes on the EKG masked during exercise and apparent during postexercise phase.

[Malfunction of a permanent pacemaker]. / Disfunción de marcapaso definitivo.

Forty years have gone by since the first pacemaker implant; this fact had strong impact in the life of thousands of persons. The objective of this work is to report the case of definitive pacemaker malfunction with epicardiac lead and review the literature concerning the important aspects of the causes and diagnosis of pacemaker malfunction. We consider that physicians dealing with patients implanted these devices must be prepared to diagnose and treat them adequately.

[Radiofrequency ablation in the treatment of tachyarrhythmias. Experience concerning 1,000 consecutive patients]. / Ablación con radiofrecuencia en el tratamiento de las taquiarritmias. Experiencia en 1000 pacientes consecutivos.

Several reports have demonstrated that radiofrequency catheter ablation provides effective control of a variety of tachyarrhythmias. This report details the results of radiofrequency catheter ablation in 1,000 consecutive patients with a wide variety of tachyarrhythmias treated in the Instituto Nacional de Cardiología "Ignacio Chavez". Tachyarrhythmias were associated with the presence of an accessory pathway in 700 patients (70%). Dual accessory pathways were present in 21 patients, giving a total of 722 accessory pathways. The mechanism of the arrhythmia was AV nodal reentrant tachycardia in 204 patients (20.4%). Ablation of the reentrant circuit of atrial flutter within the right atrium was attempted in 56 (5.6%) patients and a primary atrial tachycardia in five patients (0.5%). AV node ablation and permanent pacemaker implantation were performed in 17 patients (1.7%). Finally we performed radiofrequency catheter ablation in 22 (2.2%) patients with ventricular tachycardia. Radiofrequency catheter ablation was successful in 630 of 700 (90%) patients with accessory pathways with a complication rate of 9/700 (1.2%) and a recurrence rate of 73 (12.4%). AV nodal reentry was successfully abolished in 190 of 204 (93%) patients by selective ablation of the slow pathway in 168/180 (93.3%) patients and the fast pathway in 22/24 (92%) patients. The complication rate of this group was 7/204 (3.4%) with a recurrence rate of 30 patients (14.2%). The reentrant circuit of atrial flutter was ablated successfully in 41 of 56 (73%). Four/five (80%) of patients with primary atrial tachycardia were successfully ablated. Complete AV block was achieved in 17/17 patients with atrial fibrillation or flutter treated by AV nodal ablation without complications or recurrence. The procedure was successful in 17/22 (77%) of patients with ventricular tachycardia. The results of this series of patients demonstrate the safety and efficacy of radiofrequency ablation for the treatment of a wide variety of tachyarrhythmias with high rate of success 899/1,000 (89.9%) and with an 1 1.8% of recurrence, low risk of complications (1.5%) and no mortality.

[Adenosine for suppression of paroxysmal supraventricular tachycardia in a newborn infant. First case in Mexico]. / Adenosina para la supresión de taquicardia supraventricular paroxística en un recién nacido. Primer caso en México.

We present the case of a 20-day old baby who was admitted with orthodromic supraventricular reentry tachycardia with a heart-rate of 300/minute. Suppression of the arrhythmia was tried with vagal maneuvers and digoxin. On failure to control the heart rate, a 0.05 mg/kg intravenous bolus of adenosine was given, with immediate response and subsequent normal heart rate and rhythm. In the following year he has been adequately controlled with oral digoxin. This is the first pediatric patient treated with adenosine in Mexico. Even though experience elsewhere in this age group is also limited, the properties of adenosine make it a valuable first-choice drug for the control of paroxysmal supraventricular tachycardia.

[Usefulness of the pre-excitation index to determine the mechanism of supraventricular paroxysmal tachycardia and the location of the anomalous pathway]. / Utilidad del índice de preexcitación para determinar el mecanismo de la taquicardia paroxística supraventricular y la localización de la vía anómala.

To evaluate the preexcitation index in determinate the mechanism of paroxysmal supraventricular tachycardia and localize accessory pathway, fifty nine patients with clinical and electrocardiographic supraventricular tachycardia were analyzed. There were thirty eight patients (64.4%) with orthodromic AV reentry using an accessory pathway for retrograde conduction and 21 patients (35.6%) with typical AV nodal reentrant tachycardia. Preexcitation of the atrium during tachycardia by premature ventricular complex at a time when anterograde His bundle activation was present in 30 o 38 (79%) patients with AV reentry while only 8 of 21 (38%) patients with AV nodal reentry demonstrated preexcitation during tachycardia. There was no significant difference between left and right accessory pathways and in mean tachycardia cycle length between the two groups. However, atrioventricular reentry demonstrated atrial preexcitation during tachycardia more frequently than AV nodal reentry. In conclusion, our findings show that the preexcitation index is a useful method for determinate the mechanism of supraventricular tachycardia and to localize accessory pathways.

[The effectiveness and safety of d,l-sotalol in the ambulatory treatment of atrial fibrillation and flutter]. / Eficacia y seguridad del d,l sotalol en el tratamiento ambulatorio de pacientes con fibrilación y flutter atriales.

Data on short and long term efficacy and safety of d,l sotalol in patients with atrial fibrillation or atrial flutter is limited. The aims of this study were to (1) assess the antiarrhythmic efficacy of d,l sotalol maintaining normal sinus rhythm in patients with refractory atrial fibrillation or flutter, (2) evaluate the efficacy of d,l sotalol in preventing recurrences of paroxysmal atrial fibrillation or flutter, (3) evaluate the control of ventricular rate in patients with paroxysmal or refractory atrial fibrillation or flutter unsuccessfully treated with other antiarrhythmic agents, (4) determine predictors of efficacy (5) assess the safety of d,l sotalol in this setting. Two hundred patients with chronic or paroxysmal atrial fibrillation or atrial flutter or both, who had failed one to six previous antiarrhythmic drug trials were treated with d,l sotalol 80 to 440 mg/day orally. Fifty four percent was female, age 47 +/- 16 years (range 7-79), follow up period 7 +/- 7 months (range 1 to 14 months), 79% of patients had the arrhythmia for more than one year. The atrial fibrillation in 37.5% of patients was chronic and paroxysmal in 23.5. The atrial flutter was chronic in 31% of patients and paroxysmal in 8%. Eighty two percent of patients was in functional class I (NYHA) and 82% had cardiac heart disease: left atrial (LA) size 44 +/- 10 mm, right atrial (RA) size 37 +/- 7 mm and left ventricular ejection fraction (LVEF) 58 +/- 8%. Total success was achieved in 58% of patients (atrial fibrillation 40% and 18% in atrial flutter), partial success in 38% (atrial fibrillation in 18% and 20% in atrial flutter) and 4% of patients failure. It was p < 0.07 when compared total success vs partial success among atrial fibrillation and atrial flutter groups. Patients with cardiac heart disease responded worst (p = 0.10) to the drug than those without it, specially if the heart was dilated. We concluded that d,l sotalol has moderate efficacy to convert and maintain normal sinus rhythm, as well as it acts controlling paroxysmal relapses and ventricular heart rate.

[Persistent atrial paralysis: reported of 2 cases]. / Parálisis atrial persistente: reporte de 2 casos.

Persistent atrial standstill is an uncommon clinical finding, this condition has no atrial electrical activity and do not respond to electrical stimulation. Electrophysiologic mapping of the heart, demonstrates two types of standstill: total and partial. There are three types of patients with this condition: patients with chronic cardiopathy, patients with muscular dystrophy and the third idiopathic group. In this article, we present two clinical cases, the fist one with dilated cardiomiopathy, in which we demonstrated total atrial standstill. The second patient with rheumatic heart disease, in which we demonstrated partial standstill that included the apical portion of the rigth atrium. We discuss the clinical and electrophysiological finding of both cases and we review the literature.

[Wolff-Parkinson-White syndrome with orthodromic supraventricular tachycardia associated with a "hyper-conductor" atrio-ventricular node. A therapeutic challenge]. / Síndrome de Wolff-Parkinson-White con taquicardia supraventricular ortodrómica asociado a un nodo auriculo-ventricular "hiperconductor". Un reto terapéutico.

One case of Wolff-Parkinson-White Syndrome with paroxysmal supraventricular tachycardia related to orthodromic atrioventricular reentry using an accessory pathway for retrograde conduction an a rapidly conducting AV node for anterograde conduction is present. The pharmacological therapy with Digoxin, Propranolol, Quinidine, Disopyramide and Propafenone was not effective. An electrophysiologic study showed a reciprocating tachycardia induced by spontaneous ventricular beats. Both the effective refractory period of the AV node and the anterograde effective refractory period of the accessory pathway were minor or equal to 220 msec which made the control of the arrhythmia difficult. Amiodarone was able to suppress the premature ventricular beats, depress conduction and prolong refractoriness in both, the AV node and accessory pathway to prevent recurrences of atrioventricular reentry. In this patient a false positive test with ajmaline was documented. The electrophysiologic study showed the association of Wolff-Parkinson-White Syndrome with an enhanced atrioventricular nodal-conduction and allowed the selection of an appropriate antiarrhythmic agent.

[Radiofrequency ablation of type I atrial flutter: combination of electrophysiological and anatomical techniques]. / Ablación con radiofrecuencia del flutter atrial tipo I: combinación de las técnicas electrofisiológica y anatómica.

Atrial flutter type I (FLA) is one of the most common arrhythmias found in clinical practice. Reentry into the right atrium (AD) is the mechanism of this arrhythmia. The reentry mechanism has critical sites where radiofrequency (RF) can act blocking the circuit. Both, electrophysiological and anatomical approaches using RF to FLA have demonstrated a success rate above 80%. Our group combined both techniques treating 35 patients with FLA type I (22 men and 13 women), with mean age of 40.8 +/- 15 years old (range 9-70). In 21 patients (60%) this arrhythmia was associated with cardiopathy. All patients had failed to respond to different antiarrhythmic therapy. The success rate was 82.8% (29/35). When compared failure vs success we observed that patients who failed were older (51.8 vs 38.5 years old, p < 0.05), had structural cardiopathy (83.3% vs 55.1%, p = NS), had FLA type I with P waves with shorter cycle length (195 vs 254 ms, p = 0.052), had the arrhythmia chronically (129.6 vs 68.1 month, p = NS), had great left atrium diameter (41.2 vs 36.7 mm, p = 0.052) and frequently had been associated with atrial fibrillation (33.3% vs 3.4%, p = 0.02). There were no complications. Six (20.6%) patients reverted to FLA. We followed our patients during mean time 8.37 +/- 8.8 months (1-36). Our results support the notion that FLA type I can be treated with high percentage of success and low risk of complications when both RF techniques are combined. Our predictors of failure were: gender and associated atrial fibrillation (p < 0.05). We conclude that RF is the treatment of choice in every patient with FLA type I who had failed to antiarrhythmic therapy. We recommend RF as soon as FLA has been diagnosed because the probability of success is higher in such instances.

[Radiofrequency ablation in multiple accessory pathways]. / Ablación con radiofrecuencia en vías accesorias múltiples.

Radiofrequency ablation were performed in 465 consecutive patients with Wolff-Parkinson-White syndrome. We demonstrated evidence of multiple accessory pathways in 18 patients (3.9%); 17 had two, and one had three accessory pathways. In three of these there was additional right atrio-fascicular connection. There were 27 manifest and 10 concealed accessory pathways. Six patients had Ebstein's anomaly associated with accessory pathways. The location of the accessory pathways was in the right posterior portion of the ventricular septum in 16, the left posterior portion of the ventricular septum in 5, the right free wall in 5, the left wall in 7, the right anteroseptal in 3, the midseptum in 1, and one right anterolateral. Of the 37 pathways, 32 (86%) accessory pathways were ablated successfully without complications. Duration of the procedure was 100 +/- 58 minutes, and fluoroscopic time 40 +/- 17 minutes. The mean applications were 26 +/- 17 and the power level of the radiofrequency current 41 +/- 6 W. A follow-up of 80 +/- 40 days after ablation demonstrated incidence of recurrent conduction in 3 accessory pathways (8%). In conclusion, patients with multiple accessory pathways can be treated by radiofrequency ablation in a single session with a high success rate although slightly less than that in patients with a single accessory pathway.

[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.

[Experience in 1,500 patients undergoing radiofrequency ablation in the treatment of tachycardias]. / Experiencia en 1,500 pacientes sometidos a ablación con radiofrecuencia en el tratamiento de las taquicardias.

Several reports have demonstrated that radiofrequency catheter ablation provides effective control of a variety of supraventricular and ventricular tachycardias. This report details the results of radiofrequency catheter ablation in 1500 consecutive patients with a wide variety of supraventricular and ventricular tachycardias treated in the Instituto Nacional de Cardiología "Ignacio Chavez", between April 22, 1992 until December of 1999. Tachycardias were associated with the presence of an accessory pathway in 987 patients (65.8%). Dual accessory pathways were present in 24 patients giving a total of 1,012 accessory pathways. The mechanism of the arrhythmia was atrioventricular nodal reentrant tachycardia in 321 patients (21.4%). Ablation of the reentrant circuit of atrial flutter within the right atrium was attempted in 109 (7.2%) patients and a primary atrial tachycardia in 13 patients (0.8%). Atrioventricular node ablation and permanent pacemaker implantation were performed in 26 patients (1.7%). Finally we performed radiofrequency catheter ablation in 37 (2.4%) patients with ventricular tachycardia. Radiofrequency catheter ablation was successful in 908 of 1012 (89.7%) patients with accessory pathways with a complication rate of 10 (0.98%) and a recurrence rate of 92 (9%). AV nodal reentry was successfully abolished in 319 of 321 patients by selective ablation of the slow pathway in 297/321 (92.5%) patients and the fast pathway in 22/24 (92%) patients. The complication rate of this group was 8/321 (2.4%) with a recurrence rate of 34 patients (10.5%). The reentrant circuit of atrial flutter was ablated successfully in 86 of 109 (76.8%) patients with a recurrence flutter in 14 (12.8%) patients. Five of 13 (38.4%) cases of primary atrial tachycardia were successfully ablated. Complete AV block was achieved in 26 of 26 (100%) patients with atrial fibrillation or flutter treated by AV nodal ablation. The procedure was successful in 28 of 37 (75.6%) patients with fascicular ventricular tachycardia. The results of this series of patients demonstrates the safety and efficacy of radiofrequency ablation for the treatment of a wide variety of taquicardias with high rate of success 1375 of 1500 patients (91.6%), with 142 recurrences (9.4%), 15 complications (1%), and no mortality.

[A new electrocardiographic algorithm for localizing accessory pathways using only the polarity of the QRS complex]. / Un nuevo algoritmo electrocardiográfico para la localización de las vías accesorias utilizando únicamente la polaridad del complejo QRS.

From 250 consecutive patients who underwent radiofrequency ablation of accessory pathways, we studied 102 patients with successful ablation of a single overt accessory pathway. All patients had manifested preexcitation on a baseline 12 lead electrocardiogram. None of this patients had additional congenital or acquired cardiac abnormalities which could have affected the QRS morphology. A new algorithm for localizing the AP site was developed, based only on the polarity of the QRS complexes in DIII, V1 and V2, without analysis of the delta wave. We could localize the accessory pathway in five sites with 88% of probability of success. This simplify the electrocardiographic analysis of Wolff Parkinson White and improvement the results of radiofrequency ablation.

[The response of ventricular tachycardia to adenosine administration]. / Respuesta de la taquicardia ventricular a la administración de adenosina.

Ten patients with ventricular tachycardia were studied. Two groups were formed. Group A included 5 patients with idiopathic ventricular tachycardia and group B included 5 patients with coronary heart disease. In all patients an electrophysiologic study was performed and monomorphic sustained ventricular tachycardia was induced through programmed stimulation. All patients received 12 mg of intravenous adenosine. The response was satisfactory in 3 of 5 patients in group A, with the presence of sinus rhythm. No response was seen in the other 2 patients. None of the patients in group B responded to the administration of intravenous adenosine. We concluded that adenosine may be useful in patients with cyclic AMP-mediated triggered activity ventricular tachycardia, in contrast to the coronary heart disease patients in which the mechanism is reentry. This interpretation is supported by results obtained in 15 experiments in canine heart.

Infectious endocarditis in pacemaker endocardial leads: report of three cases.

Three cases of endocarditis affecting endocardial leads of permanent pacemakers are presented with a review of the literature. Vegetations were identified using transesophageal echocardiography. Infection of pacemaker leads is far less common than infection at the site of the pulse generator with greater morbidity and mortality and generally requiring surgical removal of both electrodes and power source. The most frequent infective agents are stahylococcus varieties.

Kearns-Sayre syndromes an absolute indication for prophylactic implantation of definitive pacemaker?

Kearns-Sayre syndrome is a mitochondrial cytopathy characterized by chronic progressive external ophthalmoplegia, retinitis pigmentosa and heart block, the last of which determines the survival of these patients. The case of a 23 year old man with Kearns-Sayre syndrome, conduction disturbances and mitral valve prolapse is presented. The characteristics of this syndrome are described and the criteria for prophylactic installation of a pacemaker discussed.

[Auricular flutter associated with an interatrial septal aneurysm submitted to radiofrequency ablation]. / Flutter auricular asociado a un aneurisma del septum interatrial, sometido a ablación con radiofrecuencia.

We present the case of a young man who began with type I atrial flutter, he had no response to antiarrhythmic drugs. The echocardiogram showed an atrial septal aneurysm in the region of the fossa ovalis. We performed an electrophysiologic study which showed an atrial flutter with atrial rate of 257 bpm, and 2:1/3:1 AV conduction. The flutter waves were negatives in leads II, III and a VF (type I atrial flutter). An endocardial mapping was obtained in order to localize the area of slow conduction. It was located in the isthmus of atrial tissue bounded by the inferior vena cava and the tricuspid valve annulus in the low posterior septal right atrium. In this area we applied radiofrequency energy in 10 occasions but the arrhythmia was not suppressed. With atrial pacing we achieve a concealed entrainment and then resumption of atrial flutter after cessation of pacing. After another 6 applications of radiofrequency in this same area in sinus rhythm, we paced the atrium without inducing any form of arrhythmia. He was asymptomatic 15 days later, but one month after the ablation, the flutter reappeared, we performed a second successful radiofrequency ablation. In this time he was asymptomatic.

[Changes in auriculoventricular conduction due to the effect of ethanol]. / Modificaciones de la conducción auriculoventricular por efecto de etanol.

Transcoronary ablation of atrioventricular conduction by dehydrated alcohol was attempted in one patient with refractory ectopic atrial tachycardia. Ethanol (1.5 ml) was delivered after selective catheterization of the atrioventricular nodal artery in a patient in whom the artery could be identified by cineangiography. The mean creatine kinase (MB fraction) at four hour to six hour after ablation was 40 U. No electrocardiographic QRS changes was seen. The procedure was successful. The patient is asymptomatic 3 months after procedure. Transcoronary alcohol ablation of atrioventricular conduction should be considered in patients in whom electrical techniques have been unsuccessful.