Diagnostic challenges of Brugada Syndrome in pediatric patients.

Although most cases of Brugada syndrome have been described in adults, pediatric patients with the disease have been reported since the original article from Josep and Pedro Brugada. Herein is presented the case series of Brugada syndrome in pediatric population of the National Institute of Cardiology Ignacio Chavez. One boy and two adolescent males had palpitations as clinical presentation of the disease. Atrial arrhythmias were documented in two, in the third case there was a high clinical suspicion and quinidine abolished symptoms. The aim of this report is to highlight the importance of performing a detailed clinical history as well as the usefulness of high precordial leads for the diagnosis of this entity.

Corrected sinus node recovery time as a screening test in patients with typical atrial flutter post-ablation to predict pacemaker implantation.

OBJECTIVE: The objective of the study was to establish the prognostic value of CSNRT regarding the necessity for pacemaker implantation in patients with atrial flutter (AFL) post-ablation. METHODS: This prospective cohort study, conducted at the National Institute of Cardiology "Ignacio Chavez" in Mexico City, assessed patients who had undergone ablation procedures to correct AFL, posterior to which an autonomic blockade was performed, and CSNRT was measured. RESULTS: The sample for this investigation was 40 patients. These were subdivided into two study groups depending on their requirement of pacemaker implant post-ablation (Pacemaker P, No Pacemaker NP). Sinus node (SN) dysfunction was diagnosed in 13 (32.5%) of the 40 participants, 10 (71.43%) of which required a pacemaker implant, while only 4 participants (28.57%) with normal SN function required pacemakers. Ten out of the 14 patients (71.43%) who required a pacemaker had an elevated CSNRT > 500 ms (p ≤ 0.01). Post-ablation CSNRT mean was 383.54 ms ± 67.96 ms in the NP group versus 1972.57 ms ± 3423.56 ms in the P group. Furthermore, SN pause in the P group had a mean of 1.86 s ± 0.96 s versus the NP group with 1.196 s ± 0.52 s. CONCLUSION: CSNRT has the potential to be a quantitative prognostic tool for the assessment of future pacemaker implants in patients with AFL post-ablation. This could aid in the timely diagnosis of sinus node dysfunction, which could, in the long run, result in the reduction of cardiac functional capacity loss due to cardiac remodeling.

OBJETIVO: Establecer el valor pronóstico del TRNSC basado en la necesidad de marcapasos en pacientes diagnosticados con aleteo atrial, pos-ablación. MÉTODOS: Este cohorte prospectivo, realizado en el Instituto Nacional de Cardiología "Ignacio Chávez" en la Ciudad de México, evaluó pacientes sometidos a ablación para corregir el aleteo atrial; se midió el TRNSC post bloqueo autonómico. RESULTADOS: La muestra de 40 pacientes se subdividió en 2 grupos según su requerimiento de marcapasos posterior a la ablación (P y NP). Se diagnosticó disfunción del nodo sinusal en 13 participantes (32.5%), de los cuales 10 (71.43%) requirieron marcapasos en comparación a 4 (28.57%) con función normal. En el grupo P la pausa del nodo sinusal post-ablación tuvo una media de 1.86 ± 0.96 s versus el grupo NP con 1.196 ± 0.52 s. En relación con el TRNSC, el grupo NP tuvo una media de 383.54 ± 67.96 ms vs. 1972.57 ± 3423.56 ms en el grupo P. 10 pacientes (25%) obtuvieron un TRNSC > 500 ms, de los cuales 100% requirieron marcapasos; de los 14 pacientes que requirieron marcapasos 10 (71.43%) tenían un TRNSC elevado (p ≤ 0.01). CONCLUSIONES: El TRNSC tiene el potencial de ser una herramienta de pronóstico cuantitativo para la necesidad de futuros implantes de marcapasos en pacientes con disfunción del nodo sinusal, resultado de aleteo atrial pos-ablación. Esto podría ayudar a diagnosticar más temprano una disfunción del nodo sinusal, resultando en la reducción de la pérdida a largo plazo de la función cardíaca como efecto de la remodelación.

[Comportamiento y decisión cardiovascular en el síndrome de MASS. Reporte de un caso y revisión de la literatura]. / Cardiovascular behavior and decision in MASS syndrome. A case report and literature review

MASS syndrome (disorder of connective tissue characterized by involvement of the mitral valve, aorta, skeleton, and skin) is a rare genetic disease with a phenotype similar to that of Marfan syndrome, but with important cardiovascular differences like the absence of aortic root aneurysm and marked mitral affection. We present a case of a patient with MASS syndrome and review the limited literature addressing these differences, and we discuss the impact this information may have in decisions regarding cardiovascular surgery.

El síndrome de MASS (que afecta a: válvula mitral [M], aorta [A], piel [S, skin], sistema musculoesquelético [S, skeletal]) es una rara enfermedad genética con un fenotipo similar al del síndrome de Marfan, pero con diferencias cardiovasculares importantes, como ausencia de afección de la raíz aórtica y marcada afectación mitral. Presentamos el caso de una paciente con síndrome de MASS y revisamos la limitada literatura con respecto a estas diferencias; finalmente discutimos acerca del impacto que pudiera tener esta información con respecto a las decisiones desde el punto de vista de la cirugía cardiovascular.

[Management of heart failure with His bundle pacing in right bundle branch block: case report]. / Manejo de la insuficiencia cardiaca con estimulación hisiana en bloqueo de rama derecha: reporte de caso.

La terapia de resincronización cardiaca mediante estimulación hisiana ha demostrado ser efectiva en pacientes con bloqueo de rama izquierda del haz de His e insuficiencia cardiaca. Paciente masculino, con 47 años de edad, con insuficiencia cardiaca, fracción de expulsión del 17% y miocardio dilatada idiopática, electrocardiograma en ritmo sinusal, bloqueo auriculoventricular de 1.er grado, intervalo PR 400 ms, bloqueo completo de rama derecha del haz de His, bloqueo del fascículo anterior de la rama izquierda del haz de His, duración del QRS 200 ms. Se decidió realizar estimulación selectiva del haz de His. La resincronización cardiaca biventricular convencional en pacientes con presencia de bloqueo completo de la rama derecha del haz de His no está indicada debido a la pobre respuesta al tratamiento. La estimulación hisiana permite reclutar la rama bloqueada y reestablecer la conducción a través de ella, de tal forma que, en ausencia de necrosis, se logre sincronía biventricular. En el caso presentado el reclutamiento de la rama derecha mediante estimulación hisiana se reflejó en el restablecimiento de la sincronía biventricular, medida por rastreo de marcas (speckle tracking) e incremento significativo de la fracción de expulsión del ventrículo izquierdo del 17 al 36.6%, con un incremento absoluto del 19.6%.Cardiac resynchronization therapy has proven to be an effective therapy in patients with left bundle branch block and heart failure. Male, 47 years old, heart failure with a left ventricle ejection fraction of 17%, idiopathic heart failure. ECG with sinus rhythm, 1st degree AV block, PR 400 ms, complete right bundle branch block, anterior hemi-fascicle of the left bundle of His, and QRS duration 200 ms. We decided to perform a selective His bundle pacing. In patients with right bundle branch block the biventricular cardiac resynchronization is not indicated due to low treatment response. His bundle pacing allows recruiting the blocked branch and restoring conduction throughout it, therefore, in the absence of necrosis the biventricular synchrony is achieved. We presented a case of His bundle pacing with recruitment of the right bundle branch, which reestablish biventricular synchrony measured by speckle tracking, and with a significant increase of the left ventricle ejection fraction from 17 to 36.6%, with an absolute increase of 19.6%.

[Case report: idiopathic ventricular tachycardia from the aortic sinus cusp]. / Informe de un caso: taquicardia ventricular idiopática en el seno de Valsalva izquierdo.

Idiopathic ventricular tachycardia is identified in 10% of the patients presenting with ventricular tachycardia, and they consist of various subtypes that can originate from different areas, including the aortic cusps which represent 0.7% of the total. Electrocardiographically, these ventricular tachycardias display a left bundle branch block pattern and inferior axis, and although rare, should be considered in the differential diagnosis with tachycardias originating from the septal region of the right ventricular outflow tract, which comprise 80% of the idiopathic ventricular tachycardias. Despite the vicinity of the left coronary artery ostium, radiofrequency catheter ablation can be curative in more than 90% of cases with a low risk (< 1% of serious complication). Therefore, it must be considered first-line therapy in patients who have failed or are intolerant to therapy with antiarrhythmic agents. The aim of this article is to describe the first case reported in Mexico of a successful ablation idiopathic ventricular tachycardia from the aortic sinus cusp in a patient with incessant ventricular tachycardia.

Association of congenital, diffuse electrical disease in children with normal heart: sick sinus syndrome, intraventricular conduction block, and monomorphic ventricular tachycardia.

INTRODUCTION: Rhythm disturbances in children with structurally normal hearts are usually associated with abnormalities in cardiac ion channels. The phenotypic expression of these abnormalities ("channelopathies") includes: long and short QT syndromes, Brugada syndrome, congenital sick sinus syndrome, catecholaminergic polymorphic ventricular tachycardia, Lènegre-Lev disease, and/or different degrees of cardiac conduction disease. METHODS: The study group consisted of three male patients with sick sinus syndrome, intraventricular conduction disease, and monomorphic sustained ventricular tachycardia. Clinical data and results of electrocardiography, Holter monitoring, electrophysiology, and echocardiography are described. RESULTS: In all patients, the ECG during sinus rhythm showed right bundle branch block and long QT intervals. First-degree AV block was documented in two subjects, and J point elevation in one. A pacemaker was implanted in all cases due to symptomatic bradycardia (sick sinus syndrome). Atrial tachyarryhthmias were observed in two patients. The common characteristic ventricular arrhythmia was a monomorphic sustained ventricular tachycardia, inducible with ventricular stimulation and sensitive to lidocaine. In one patient, radiofrequency catheter ablation was successfully performed. No structural abnormalities were found in echocardiography in the study group. CONCLUSION: Common clinical and ECG features suggest a common pathophysiology in this group of patients with congenital severe electrical disease.

Corrected sinus node recovery time as a screening test in patients with typical atrial flutter post-ablation to predict pacemaker implantation / Tiempo de recuperación del nodo sinusal corregido como prueba de tamizaje en pacientes con aleteo atrial típico postablación para predecir la implantación de marcapasos

Abstract Objective: The objective of the study was to establish the prognostic value of CSNRT regarding the necessity for pacemaker implantation in patients with atrial flutter (AFL) post-ablation. Methods: This prospective cohort study, conducted at the National Institute of Cardiology "Ignacio Chavez" in Mexico City, assessed patients who had undergone ablation procedures to correct AFL, posterior to which an autonomic blockade was performed, and CSNRT was measured. Results: The sample for this investigation was 40 patients. These were subdivided into two study groups depending on their requirement of pacemaker implant post-ablation (Pacemaker P, No Pacemaker NP). Sinus node (SN) dysfunction was diagnosed in 13 (32.5%) of the 40 participants, 10 (71.43%) of which required a pacemaker implant, while only 4 participants (28.57%) with normal SN function required pacemakers. Ten out of the 14 patients (71.43%) who required a pacemaker had an elevated CSNRT > 500 ms (p ≤ 0.01). Post-ablation CSNRT mean was 383.54 ms ± 67.96 ms in the NP group versus 1972.57 ms ± 3423.56 ms in the P group. Furthermore, SN pause in the P group had a mean of 1.86 s ± 0.96 s versus the NP group with 1.196 s ± 0.52 s. Conclusion: CSNRT has the potential to be a quantitative prognostic tool for the assessment of future pacemaker implants in patients with AFL post-ablation. This could aid in the timely diagnosis of sinus node dysfunction, which could, in the long run, result in the reduction of cardiac functional capacity loss due to cardiac remodeling.

Resumen Objetivo: Establecer el valor pronóstico del TRNSC basado en la necesidad de marcapasos en pacientes diagnosticados con aleteo atrial, pos-ablación. Métodos: Este cohorte prospectivo, realizado en el Instituto Nacional de Cardiología "Ignacio Chávez" en la Ciudad de México, evaluó pacientes sometidos a ablación para corregir el aleteo atrial; se midió el TRNSC post bloqueo autonómico. Resultados: La muestra de 40 pacientes se subdividió en 2 grupos según su requerimiento de marcapasos posterior a la ablación (P y NP). Se diagnosticó disfunción del nodo sinusal en 13 participantes (32.5%), de los cuales 10 (71.43%) requirieron marcapasos en comparación a 4 (28.57%) con función normal. En el grupo P la pausa del nodo sinusal post-ablación tuvo una media de 1.86 ± 0.96 s versus el grupo NP con 1.196 ± 0.52 s. En relación con el TRNSC, el grupo NP tuvo una media de 383.54 ± 67.96 ms vs. 1972.57 ± 3423.56 ms en el grupo P. 10 pacientes (25%) obtuvieron un TRNSC > 500 ms, de los cuales 100% requirieron marcapasos; de los 14 pacientes que requirieron marcapasos 10 (71.43%) tenían un TRNSC elevado (p ≤ 0.01). Conclusiones: El TRNSC tiene el potencial de ser una herramienta de pronóstico cuantitativo para la necesidad de futuros implantes de marcapasos en pacientes con disfunción del nodo sinusal, resultado de aleteo atrial pos-ablación. Esto podría ayudar a diagnosticar más temprano una disfunción del nodo sinusal, resultando en la reducción de la pérdida a largo plazo de la función cardíaca como efecto de la remodelación.

[Supraventricular tachycardial ablation supported with an electroanatomical system]. / Ablación de taquicardias supraventriculares apoyadas con el sistema de mapeo electroanatómico.

UNLABELLED: In 1992 the radiofrequency ablation program was started, with very good results in patients with supraventricular tachycardias and normal hearts or minimal structural defects. Nevertheless, the results are not as good for the patients with structural defects, that are actually seen more frequently, those are cases with more complex arrhythmias, are patients with cardiac surgery that show a complex arrhythmogenic substrate or patients previously treated with conventional ablation which tachycardia recurs. In these cases, the electroanatomic Carto system has been very useful. RESULTS: In the last two years, 74 procedures with the Carto system were performed, of which 56 have been supraventricular arrhythmias, improving substantially the success rates CONCLUSIONS: The electroanatomical mapping allows the more accurate identification of the arrhythmogenic substrate, achieving better success rates in recurrent tachycardia after conventional ablation, or in cases with more complex arrhythmogenic substrates.

Postintervention Dyspnea after Radiofrequency Catheter Ablation: Think of a Phrenic Nerve Injury.

Phrenic nerve injury (PNI) is a rare complication of catheter ablation therapy, most commonly observed in cryoablation of the right side pulmonary veins. We present a case of PNI after radiofrequency catheter ablation that developed acute dyspnea 24 hours after the intervention. Dyspnea is the main symptom of PNI, so the diagnosis should always be suspected if it appears after any type of catheter ablation involving the trajectory of the phrenic nerve. There is no specific treatment for PNI. The only maneuver that has been reported to accelerate the recovery of PNI is early stopping of the ablation therapy.

[Electroanatomic mapping system (CARTO) to perform catheter ablation of atrial fibrillation]. / La cartografía electroanatómica (CARTO) en la ablación de la fibrilación auricular.

Since the first report of radiofrequency catheter ablation curing atrial fibrillation (AF) nearly a decade ago, numerous techniques have evolved, from linear ablation to modify the reentrant sustrate for AF, to electrical isolation of pulmonary vein to eliminate triggers of AF, to hibrid approaches of circunferential ablation around and between the pulmonary veins and mitral valve annulus to modify both the triggers and sustrate for AF. We describe the electroanatomic mapping system (CARTO, Biosense Webster) and its use in patients undergoing catheter ablation for AF.

[Electrophysiologic study and ablation therapy in idiopathic paroxystic atrial fibrillation]. / Estudio electrofisiológico y ablación de actividad eléctrica anormal en venas pulmonares de pacientes con fibrilación auricular paroxística idiopática.

OBJECTIVE: To analyze the results of radiofrequency catheter ablation (RFCA) of the pulmonary veins (PV) in patients with paroxysmal atrial fibrillation (PAF). MATERIAL AND METHODS: We describe 4 patients (38 +/- 12 years, interval 8-52; 11 men) with symptomatic PAF, refractory to antiarrhythmic drugs. Special mapping catheters were used and ablation was performed at the ostium/antrum of those veins with abnormal electrical activity (AEA). RESULTS: AEA in one or more PV was identified in 13 patients (86%); in one patient AEA was also found in the superior vena cava (6.6%). One procedure was complicated by unstable ventricular tachycardia and was notfinished. Success was accomplished in 10, in 5 after the first ablation, in 4 after the second, and in one after a third procedure. One patient had pericarditis with a small pericardial effusion that did not require intervention. CONCLUSIONS: RFCA is a useful and relatively safe procedure for the treatment of PAF and the only one with curative potential. The long-term rate of success (with or without antiarrhythmics) in this series was 71%. These results justify catheter ablation in selected patients with symptomatic PAF unresponsive to medical treatment.

Manejo de la insuficiencia cardiaca con estimulación hisiana en bloqueo de rama derecha: reporte de caso / Management of heart failure with His bundle pacing in right bundle branch block: case report

Resumen La terapia de resincronización cardiaca mediante estimulación hisiana ha demostrado ser efectiva en pacientes con bloqueo de rama izquierda del haz de His e insuficiencia cardiaca. Paciente masculino, con 47 años de edad, con insuficiencia cardiaca, fracción de expulsión del 17% y miocardio dilatada idiopática, electrocardiograma en ritmo sinusal, bloqueo auriculoventricular de 1.er grado, intervalo PR 400 ms, bloqueo completo de rama derecha del haz de His, bloqueo del fascículo anterior de la rama izquierda del haz de His, duración del QRS 200 ms. Se decidió realizar estimulación selectiva del haz de His. La resincronización cardiaca biventricular convencional en pacientes con presencia de bloqueo completo de la rama derecha del haz de His no está indicada debido a la pobre respuesta al tratamiento. La estimulación hisiana permite reclutar la rama bloqueada y reestablecer la conducción a través de ella, de tal forma que, en ausencia de necrosis, se logre sincronía biventricular. En el caso presentado el reclutamiento de la rama derecha mediante estimulación hisiana se reflejó en el restablecimiento de la sincronía biventricular, medida por rastreo de marcas (speckle tracking) e incremento significativo de la fracción de expulsión del ventrículo izquierdo del 17 al 36.6%, con un incremento absoluto del 19.6%.

Abstract Cardiac resynchronization therapy has proven to be an effective therapy in patients with left bundle branch block and heart failure. Male, 47 years old, heart failure with a left ventricle ejection fraction of 17%, idiopathic heart failure. ECG with sinus rhythm, 1st degree AV block, PR 400 ms, complete right bundle branch block, anterior hemi-fascicle of the left bundle of His, and QRS duration 200 ms. We decided to perform a selective His bundle pacing. In patients with right bundle branch block the biventricular cardiac resynchronization is not indicated due to low treatment response. His bundle pacing allows recruiting the blocked branch and restoring conduction throughout it, therefore, in the absence of necrosis the biventricular synchrony is achieved. We presented a case of His bundle pacing with recruitment of the right bundle branch, which reestablish biventricular synchrony measured by speckle tracking, and with a significant increase of the left ventricle ejection fraction from 17 to 36.6%, with an absolute increase of 19.6%.

[Sudden death. Role of the electrophysiologic study]. / Muerte súbita. El papel del estudio electrofisiológico.

At present, sudden death is considered a major health problem, DeBoer in 1935, recognized the clinical importance of ventricular fibrillation as the cause of sudden cardiac death. Sudden death due to cardiovascular problems has been established as one of the main causes of death in the developed countries and in developing countries as ours, where the deaths caused by cardiovascular diseases represent 15% of the total, exceeding other causes of death. The frequency of sudden death in our country is unknown, but more frequently we hear about cases of patients that have been reanimated for cardiac arrest; in the United States of America the frequency has been estimated between 400,000 at 500,000 per year although, recently, 250,000 at 300,000 events are being mentioned. It is convenient to comment that the causal arrhythmias are diverse and may vary depending on the underlying disease, although, generally, it can be pointed out that 80% of them are due to tachyarrhythmias. It's important to point out that there is a strong relationship between left ventricular dysfunction, the frequency of ventricular arrhythmias, and fatal cardiac events due to cardiac rhythm disturbances. The recommendations for electrophysiological studies are: 1) patients surviving cardiac arrest, occurring without evidence of an acute Q-wave myocardial infarction and 2) patients surviving cardiac arrest occurring more than 48 hours after the acute phase of myocardial infarction in the absence of a recurrent ischemic event.

[Hypertrophic cardiomyopathy. Arrhythmia in hypertrophic cardiomyopathy]. / Cardiomiopatía hipertrófica. Las arritmias en la cardiomiopatía hipertrófica.

Hypertrophic cardiomyopathy is a relatively common genetic disorder with heterogeneity in mutations, forms of presentation, prognosis and treatment strategies. Hypertrophic cardiomyopathy is recognized as the most common cause of sudden cardiac death that occurs in young people, including athletes. The clinical diagnosis is complemented with the ecocardiographic study, in which an abnormal myocardial hypertrophy of the septum can be observed in the absence of a cardiac or systemic disease (arterial systemic hypertension, aortic stenosis). The annual sudden mortality rate is 1% and, in selected populations, it ranges between 3 and 6%. The therapeutic strategies depend on the different subsets of patients according to the morbidity and mortality, sudden cardiac death, obstructive symptoms, heart failure or atrial fibrillation and stroke. High risk patients for sudden death may effectively be treated with the automatic implantable cardioverter-defibrillator.

[Electrocardiogram in the differential diagnosis of wide-QRS tachycardias]. / El electrocardiograma en el diagnóstico diferencial de las taquicardias con QRS ancho.

The surface ECG constitutes an invaluable tool for the differential diagnosis in those cases in which the QRS complex exceeds the normal duration (120 mseg or more) and a heart rate of 100 bpm or more. Most of the arrhythmias with wide QRS complexes are ventricular in origin, and frequently related to heart disease; nevertheless, in those patients with hemodynamic stability it is frequently misdiagnosed as supraventricular tachycardia. The importance of the surface ECG resides in the fact that the correct diagnosis can be done with high probability when the analysis is orderly made. To be able to perform such an analysis it is necessary to count upon a good quality ECG, besides it is very important if, in addition, a transesophageal record is available to establish the precise relation between the "p" wave and the ventricular activation. There are the traditional morphologic criteria, with their limited usefulness, but the observations of Brugada et al. increased the sensitivity, which can reach up to 98% with a high degree of specificity (96%). The clinical data plus an adequate ECG analysis can lead to the differential diagnosis with a high grade of certainty.

[Atrioventricular nodal reentrant tachycardia: Radiofrequency ablation]. / Taquicardia por reentrada nodal atrioventricular: ablación con radiofrecuencia.

Atrioventricular nodal reentrant tachycardia is the most frequent regular supraventricular tachycardia. It is generally a benign arrhythmia and usually it is no associated with heart disease. It is more often seen in middle-aged women but it is no infrequent in younger and older patients. The development of radiofrequency with catheter ablation has provided the possibility to definitely cure the arrhythmia and moreover permit a better comprehension of the underlying electrophysiologic and anatomic substrate.

[Follow-up of a group of patients with automatic implantable defibrillator]. / Seguimiento de un grupo de pacientes con desfibrilador automático implantable.

UNLABELLED: The automatic implantable defibrillator (AID) is the treatment of choice for primary and secondary prevention of sudden death. At the Instituto Nacional de Cardiología, since October 1996 until January 2002, 25 patients were implanted with 26 AID. There were 23 men (92%) and the mean age of the whole group, was 51.4 years. Twenty-three patients (92%) presented structural heart disease, the most common was ischemic heart disease in 13 patients (52%), with a mean ejection fraction of 37.8%. One patient without structural heart disease had Brugada Syndrome. The most frequent clinical arrhythmia was ventricular tachycardia in 14 patients (56%). The mean follow-up was of 29.3 months during which a total of 30 events of ventricular arrhythmia were treated through AID; six of them were inappropriate due to paroxismal atrial fibrillation; 10 AID patients (34%) have not applied for therapy. Three patients (12%) of the group died due to congestive heart failure refractory to pharmacologic treatment. CONCLUSION: The implant of the AID is a safe and effective measure for primary and secondary prevention of sudden death. World-wide experience evidences, that this kind of device has not modified the mortality rate due to heart failure in these patients, but it has diminished sudden arrhythmic death.

[Usefulness of adenosine to detect advanced paroxysmal atrioventricular block as a cause of syncope]. / Utilidad de la adenosina para evidenciar bloqueo auriculoventricular avanzado paroxístico como causa de síncope.

We present the case of a 66 years old man with recurrent episodes of syncope, up to three times during the last two months without previous symptoms. An ECG after the syncope showed a bilateral block (left anterior fascicle block and right bundle branch block) and first grade atrioventricular block. The exercise test did not demonstrate either AV conduction disorders or tachyarrhythmia episodes. Holter monitoring showed premature ventricular complexes; tilt testing and carotid sinus massage were normal. The electrophysiologic study revealed no alteration in the conduction system. Throughout atrial and ventricular stimulation documented no tachyarrhythmias. However, intravenous administration of 12 mg of adenosine induced complete AV infra-His block with ventricular asystolia of 7.2 sec duration. Adenosine testing can identify patients with syncope due to paroxysmal AV block even when the electrophysiological findings and other conventional tests are not conclusive.

[Trans-septal puncture for radiofrequency ablation of left accessory pathway]. / Punción transeptal para la ablación con radiofrecuencia de una vía accesoria izquierda.

We present the case of an 18-year-old male patient with diagnosis of Wolff Parkinson-White syndrome due to a left free wall accessory pathway. We performed an electrophysiology study and transseptal punction guided by transesophageal echocardiogram to via access to the left atrium. We performed successful radiofrequency ablation of the accessory pathway, observing disappearance of the delta wave on the first attempt. There were no complications. In follow-up a 10 months, the patient had no clinical nor electrocardiographic evidence of recurrence. Transseptal radiofrequency ablation is an alternative for treatment of some arrhythmias localized in the left side of the heart.

[Long-term follow-up of 413 patients with atrioventricular accessory pathway who underwent radiofrequency catheter ablation]. / Seguimiento a largo plazo en 413 pacientes con vía accesoria atrioventricular sometidos a ablación con radiofrecuencia.

OBJECTIVE: The aim of this study was shown clinical characteristics and follow-up of patients with atrioventricular reentrant tachycardia (AVRT) who underwent radiofrequency catheter ablation (RCA) therapy. MATERIAL AND METHODS: From April 1992 to December 1995, 413 patients with AVRT underwent RCA therapy. RESULTS: Two hundred thirty four men (57%) and one hundred seventy nine women (43%) aged 31.3 +/- 16.3 years were studied. 437 single accessory pathways were found; 24 had multiple accessory pathways. Ablation therapy was successful in 381 accessory pathways. During follow-up of 7 years, AVRT recurred in 51 patients (13%) and in 80% this occurred within the first 3 months after the procedure. 56 patients underwent a second RCA therapy with success in 35 patients (83.5); two reoccurred (5.7%); 365 accessory pathways (83.5) remained without evidence of preexcitation AVRT. CONCLUSIONS: During follow-up, these patients with successful ablation therapy remained without symptoms. In patients who underwent a second RCA therapy, atrioventricular reentrant mechanism was always present.