Short coupled torsade de pointes: Critical timing of the ventricular premature beats.

In this case report, we describe a 73 year old female with structuraly normal heart that developed shortcoupled torsades de pointes (TdP) resulting in an electrical storm unresponsible to several antiarrhythmic drugs, but fully controlled with verapamil. The critical timing of the ventricular premature beats that initiated TdP corresponded to those that occurred at the peak of the previous T wave. This behavior differentiates this entity from other forms of malignant ventricular arrhythmias in patients with structurally normal heart. It is imperative that the clinical set-up and unique electrocardiographic fingerprint of this unusual malignant entity be assiduously recognized since verapamil can be life-saving in this condition.

Advanced management of ventricular arrhythmias in chronic Chagas cardiomyopathy.

Chagas cardiomyopathy is a parasitic infection caused by Trypanosoma cruzi. Structural and functional abnormalities are the result of direct myocardial damage by the parasite, immunological reactions, dysautonomia, and microvascular alterations. Chronic Chagas cardiomyopathy (CCC) is the most serious and important manifestation of the disease, affecting up to 30% of patients in the chronic phase. It results in heart failure, arrhythmias, thromboembolism, and sudden cardiac death. As in other cardiomyopathies, scar-related reentry frequently results in ventricular tachycardia (VT). The scars typically are located in the inferior and lateral aspects of the left ventricle close to the mitral annulus extending from endocardium to epicardium. The scars may be more prominent in the epicardium than in the endocardium, so epicardial mapping and ablation frequently are required. Identification of late potentials during sinus rhythm and mid-diastolic potentials during hemodynamically tolerated VT are the main targets for ablation. High-density mapping during sinus rhythm can identify late isochronal regions that are then targeted for ablation. Preablation cardiac magnetic resonance imaging with late enhancement can identify potentials areas of arrhythmogenesis. Therapeutic alternatives for VT management include antiarrhythmic drugs and modulation of the cardiac autonomic nervous system.

[Alternating bundle branch block in a supraventricular tachycardia: Which is the mechanism ?] / Bloqueo de rama alternante en una taquicardia supraventricular ¿ Cuál es el mecanismo subyacente ?

Functional bundle branch block during a supraventricular tachycardia can be observed with shorter cycle lengths and represent a physiologic response by the specialized intraventricular conduction system to accelerated AV nodal conduction. The present case corresponds to a young patient with exercise induced orthodromic A-V reentrant tachycardia and alternating bundle branch block. This unusual response is explained by the finding obtained during the electrophysiology study. An accelerated AV nodal conduction made the depolarizing wave front reach the bundle branches during their refractory period. Once block in one bundle was stablished, block persisted due to the linking phenomenon that is repetitive retrograde concealed conduction from the contralateral bundle. After catheter ablation of a concealed left-sided accessory A-V pathway, rapid atrial pacing at the same cycle length of the tachycardia reproduced the same aberrancies observed during tachycardia. This response proved that functional bundle branch block is due to the short cycle length and not the presence of an accessory A-V pathway.

El bloqueo de rama funcional durante una taquicardia supraventricular puede ser observado con longitudes de ciclo cortas y representa una respuesta fisiológica del sistema de conducción intraventricular por la existencia de conducción nodal auriculo ventricular acelerada. Presentamos el caso de un paciente joven con taquicardia reentrante aurículo-ventricular ortodrómica y bloqueo de rama alternante. Esta respuesta infrecuente se explica por el hallazgo obtenido durante el estudio electrofisiológico. Una conducción nodal aurículo-ventricular acelerada produce un frente de onda que despolariza las ramas durante sus períodos refractarios. Una vez que ocurrió el bloqueo en una de las ramas, dicho bloqueo persistió debido al fenómeno de linking, que es por conducción oculta retrógrada repetitiva de la rama contralateral. Después de la ablación transcatéter de una vía accesoria oculta lateral izquierda, el marcapaseo auricular rápido a la misma longitud de ciclo de la taquicardia, reprodujo la misma aberrancia observada durante la taquicardia. Este procedimiento demostró que el bloqueo de rama funcional fue debido a la longitud de ciclo corto y no a la presencia de una vía accesoria aurículo-ventricular.

Left ventricular noncompaction and orthodromic atrioventricular tachycardia observed in a patient with neurofibromatosis type 1.

Isolated left ventricular noncompaction (LVNC) was described for the first time in 1984. It is a rare congenital disease, characterized by prominent trabecular meshwork pattern and deep intertrabecular recesses, communicated with the left ventricular chamber. Clinical presentation varies from asymptomatic patients, to those developing supraventricular and ventricular arrhythmias, thromboembolism, heart failure and sudden cardiac death. We present an unusual case, where the patient with Neurofibromatosis type 1 presented with a wide complex orthodromic atrioventricular reentrant tachycardia (AVRT) and a diagnosis of left posterior paraseptal accessory pathway in association with LVNC.

Cardiac automaticity: basic concepts and clinical observations.

PURPOSE: The purpose of this report was to review the basic mechanisms underlying cardiac automaticity. Second, we describe our clinical observations related to the anatomical and functional characteristics of sinus automaticity. METHODS: We first reviewed the main discoveries regarding the mechanisms responsible for cardiac automaticity. We then analyzed our clinical experience regarding the location of sinus automaticity in two unique populations: those with inappropriate sinus tachycardia and those with a dominant pacemaker located outside the crista terminalis region. RESULTS: We studied 26 patients with inappropriate sinus tachycardia (age 34 ± 8 years; 21 females). Non-contact endocardial mapping (Ensite 3000, Endocardial Solutions) was performed in 19 patients and high-density contact mapping (Carto-3, Biosense Webster with PentaRay catheter) in 7 patients. The site of earliest atrial activation shifted after each RF application within and outside the crista terminalis region, indicating a wide distribution of atrial pacemaker sites. We also analyzed 11 patients with dominant pacemakers located outside the crista terminalis (age 27 ± 7 years; five females). In all patients, the rhythm was the dominant pacemaker both at rest and during exercise and located in the right atrial appendage in 6 patients, in the left atrial appendage in 4 patients, and in the mitral annulus in 1 patient. Following ablation, earliest atrial activation shifted to the region of the crista terminalis at a slower rate. CONCLUSIONS: Membrane and sub-membrane mechanisms interact to generate cardiac automaticity. The present observations in patients with inappropriate sinus tachycardia and dominant pacemakers are consistent with a wide distribution of pacemaker sites within and outside the boundaries of the crista terminalis.

The mechanisms of spontaneous termination of reentrant supraventricular tachycardias.

BACKGROUND: Atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reentrant tachycardia (AVRT) often terminate spontaneously, presumably due to changes in the electrophysiological properties of the reentrant circuit. However, the mechanism of spontaneous termination of these arrhythmias is incompletely understood. METHODS: We included 70 consecutive patients with reentrant supraventricular tachycardias (35 AVNRT, 35 AVRT) in whom the arrhythmia ended spontaneously during the electrophysiologic study. We determined in each patient the duration of the induced arrhythmia, site of block, beat-to-beat oscillations in tachycardia cycle-length (CL), A-H, H-V, H-A and V-A intervals. RESULTS: In 21/34 (62%) patients with AVNRT and 19/30 (63%) with orthodromic AVRT, tachycardia termination was preceded by progressive increase in tachycardia CL due to prolongation of the A-H interval (Mobitz type-I pattern). In 13/34 patients with AVNRT (38%) and 11/30 with orthodromic AVRT (37%), termination occurred suddenly without a preceding change in CL, with block ensuing retrogradely either in the fast AV nodal pathway or the accessory pathway (Mobitz type-II pattern). In 4/5 patients with antidromic AVRT the tachycardia ended at the retrograde limb with previous prolongation of the VA interval. CONCLUSION: Spontaneous termination of AVNRT and AVRT is a time-related phenomenon. Despite different pathways being involved in these two reentrant tachycardias, termination can follow antegrade or retrograde block in similar ratio (60% antegradely and 40% retrogradely). Antegrade block is preceded by prolongation of the AH interval (Mobitz type-I), whereas retrograde block occurs unexpectedly in the retrograde limb (Mobitz type-II). Fatigue of conduction appears to be involved in this phenomenon.

Jesús Alanís and the first recording of the his bundle: the scientist and the man.

The anatomy and physiology of the specialized conduction system has intrigued investigators since the 19th century and is still not fully understood. Dr. Wilhelm His Jr. is well known because he discovered the A-V bundle, and Dr. Sunao Tawara is rightly credited with the discovery of the atrioventricular (AV) node, but who was the first to record the electrical activity of the His bundle? This paper reviews the historical background and scientific contributions made by Dr. Jesús Alanís in the middle of the 20th century working at the National Institute of Cardiology in Mexico City. Collaborating with outstanding investigators such as Arturo Rosenblueth, Dr. Alanís recorded for the first time the electrical activity of the His bundle in the isolate canine heart. That the recorded electrogram was indeed the His bundle and not the AV node was confirmed by detailed studies that set the basis for modern clinical electrophysiology. The life and research contributions of this extraordinary man are reviewed in the context of a unique group of investigators who made significant advances in cardiac electrophysiology.

Spontaneous termination of ventricular fibrillation in a patient with congenital coronary anomaly.

Sudden death is common in patients with congenital coronary artery anomalies mainly when the left main coronary artery originates from the right coronary sinus. Ventricular fibrillation in these patients is irreversible unless defibrillation can be rapidly performed. We describe a 57-year-old male with an anomalous origin of circumflex and the left anterior descending coronary arteries from the right coronary sinus. He developed two episodes of ventricular fibrillation that terminated spontaneously, 10 hours after percutaneous revascularization of the circumflex coronary artery. Computed tomography angiography, in addition to confirming the anomalous origin of the coronary arteries, showed a muscle bridge over the midportion of the left anterior descending coronary artery. This is the first report of spontaneous termination of ventricular fibrillation in a patient with congenital anomaly of the coronary arteries.

Cardiac resynchronization therapy: evaluation of ventricular dysynchrony and patient selection.

Cardiac resynchronization therapy (CRT) is an established treatment modality for systolic heart failure. Aimed to produce simultaneous biventricular stimulation and correct the lack of ventricular synchrony in selected patients with congestive heart failure, CRT has shown to improve mortality and reduce hospital admissions when compared to medical treatment. At present, the indication criteria for the implantation of a CRT device include an ejection fraction of less than 35%, heart failure symptoms consistent with NYHA functional class III-IV and a QRS complex duration equal or longer than 120 milliseconds. It has been reported that 30% of patients who meet those criteria still may not derive clinical benefit from CRT. Due to the existing diversity of imagin modalities and resources for their process and analysis, a great expectation in terms of more accurate diagnosis of ventricular dyssynchrony has been raised. Reilable identification of dyssynchrony could allow us to better predict the favorable response of an individual patient to CRT and therefore offer this procedure to those individuals most likely to benefit. We review the available techniques for the study of ventricular dyssynchrony for CRT patient selection and the results of its application in clinical trials. Despite tremendous progress in the imaging technology available for the assessment and diagnosis of ventricular dyssynchrony, an ideal method has not been identified and the duration of QRS complex in the surface ECG remains the accepted criteria of dyssynchrony in the selection of patients for CRT.

Cardiac resynchronization therapy: evaluation of ventricular dysynchrony and patient selection / Terapia de resincronización cardiaca: evaluación de la disincronía ventricular y selección de pacientes

Cardiac resynchronization therapy (CRT) is an established treatment modality for systolic heart failure. Aimed to produce simultaneous biventricular stimulation and correct the lack of ventricular synchrony in selected patients with congestive heart failure, CRT has shown to improve mortality and reduce hospital admissions when compared to medical treatment. At present, the indication criteria for the implantation of a CRT device include an ejection fraction of less than 35%, heart failure symptoms consistent with NYHA functional class III-IV and a QRS complex duration equal or longer than 120 milliseconds. It has been reported that 30% of patients who meet those criteria still may not derive clinical benefit from CRT. Due to the existing diversity of imaging modalities and resources for their process and analysis, a great expectation in terms of more accurate diagnosis of ventricular dyssynchrony has been raised. Reliable identification of dyssynchrony could allow us to better predict the favorable response of an individual patient to CRT and therefore offer this procedure to those individuals most likely to benefit. We review the available techniques for the study of ventricular dyssynchrony for CRT patient selection and the results of its application in clinical trials. Despite tremendous progress in the imaging technology available for the assessment and diagnosis of ventricular dyssynchrony, an ideal method has not been identified and the duration of the QRS complex in the surface ECG remains the accepted criteria of dyssynchrony in the selection of patients for CRT.

La terapia de resincronización cardiaca es una modalidad de tratamiento bien establecida para la insuficiencia sistólica cardiaca. Dirigida a producir una estimulación biventricular simultánea y a corregir la falta de sincronía ventricular en pacientes seleccionados con insuficiencia cardiaca congestiva, la terapia de resincronización cardiaca ha mostrado ser capaz de mejorar los índices de mortalidad y reducir las admisiones hospitalarias cuando se compara con el tratamiento médico. Actualmente, los criterios para la implantación de un dispositivo de terapia de resincronización cardiaca incluyen una fracción de eyección menor a 35%, síntomas de insuficiencia cardiaca consistentes con la clase funcional NYHA III-IV, y una duración del complejo QRS igual o mayor de 120 milisegundos. Se ha reportado que 30% de los pacientes que cumplen con estos criterios pueden inclusive no obtener beneficio clínico de la terapia de resincronización cardiaca. Debido a la diversidad existente de los estudios de imagenología y de los recursos para su proceso y análisis, ha surgido una gran expectativa en términos de un diagnóstico más exacto de la asincronía ventricular. La identificación confiable de la asincronía nos podría permitir predecir mejor la respuesta favorable de un paciente en particular a la terapia de resincronización cardiaca y así ofrecer este procedimiento a aquellos pacientes con mayores probabilidades de beneficiarse de dicha terapia. Hacemos una revisión de las técnicas disponibles para el estudio de la asincronía ventricular para la selección de pacientes para esta terapia y los resultados de su aplicación en pruebas clínicas. A pesar de los grandes progresos alcanzados en la tecnología de imágenes disponibles para la evaluación y diagnóstico de la asincronía ventricular, no se ha identificado un método ideal y la duración del complejo QRS en el ECG de superficie sigue siendo el criterio aceptado de asincronía en la selección de pacientes para terapia de resincronización cardiaca.

Reversal of primary and pseudo-primary T wave abnormalities by ventricular pacing. A novel manifestation of cardiac memory.

AIMS: "Cardiac memory" refers to abnormal T waves (TW) appearing after transient periods of altered ventricular depolarization. The aim of the study was to test the hypothesis that in the presence of abnormal TW, short periods of tailored ventricular pacing (VP) can be followed by normalization of ventricular repolarization. METHODS: Ten patients with normal TW (control group) and 18 patients with abnormal TW (study group) underwent 15 min of VP at a cycle length of 500 ms. In the control group, VP was performed from the right ventricular apex, and in the study group from right or left ventricular sites that resulted in paced QRS complexes of opposite polarity to that of the abnormal TW. Before and after VP, atrial pacing was maintained at a stable cycle length. Simultaneous 12-lead electrocardiography (ECG) was recorded before, during, and following VP to assess changes in TW polarity, amplitude, electrical axis, QTc interval, and QTc interval dispersion. RESULTS: As expected, VP was followed by memory-induced changes in TW in eight of ten patients in the control group. Mean T wave axis shifted from +60 degrees + or - 21.2 degrees to +23.5 degrees + or - 50.7 degrees (p = 0.01) in the frontal plane. In the study group, complete or partial normalization of TW occurred in 17 of 18 patients. Mean T wave axis shifted from -23.7 degrees + or - 22.9 degrees to +19.7 degrees + or - 34.7 degrees (p < 0.0002) in the frontal plane when paced from right ventricular outflow tract. The QTc interval shortened after VP both in the control group (424 + or - 25 vs. 399 + or - 27 ms; p = 0.007) and in the study group (446 + or - 26 vs. 421 + or - 22 ms; p < 0.0002). No significant changes were found in QTc interval dispersion. CONCLUSIONS: Transient changes in the sequence of ventricular activation may either induce or normalize abnormal TW. The background of preceding ventricular depolarization needs to be taken into account before determining the clinical significance of a given pattern of ventricular repolarization.

Doença de Ebstein: ausência de bloqueio de ramo direito como preditor de via anômala manifestada / Ebstein disease: absence of right branch block as a predictor of manifested anomalous way

O desenvolvimento anormal da válvula tricúspide na doença de Ebstein resulta em uma série de anormalidades na ativação, que inclui condução intra-atrial demorada, bloqueio de ramo direito(BRG) e pré-excitação ventricular. O objetivo desse tabalho era definir as características do ECG antes e depois da ablação de uma via anômala atrioventricular. De 226 pacientes consecutivos com anomalia de Ebstein, 64 apresentavam taquicardia documentada...

Flecainide suppresses bidirectional ventricular tachycardia and reverses tachycardia-induced cardiomyopathy in Andersen-Tawil syndrome.

Bidirectional ventricular tachycardia (BVT), although a rare arrhythmia in the general population, is frequently observed in patients with Andersen-Tawil syndrome and long QT interval. However, the pharmacologic treatment of this arrhythmia remains unknown. In the present study, we documented the favorable antiarrhythmic action of flecainide in a young woman with sustained BVT and Andersen-Tawil syndrome. She presented with incessant BVT that could only be terminated with flecainide. During sinus rhythm, a prolonged QT interval was observed. Genetic studies revealed a mutation in the K(+) channel gene KCNJ2. Over a 4-year follow-up period, recurrence of her arrhythmia occurred twice. The first episode was due to noncompliance and resolved with resumption of flecainide therapy. The second recurrence was associated with a tachycardia-induced cardiomyopathy and resolved when the dose of flecainide was increased from 200 to 300 mg daily. This report suggests that flecainide can be effective in controlling BVT associated with Andersen-Tawil syndrome and indicates that the left ventricular dysfunction is secondary to the arrhythmia and not due to an associated phenotypic manifestation of the disorder.

Electrocardiographic characteristics of patients with Ebstein's anomaly before and after ablation of an accessory atrioventricular pathway.

UNLABELLED: The abnormal development of the tricuspid valve in patients with Ebstein's anomaly results in several activation abnormalities including delayed intraatrial conduction, right bundle branch block (RBBB), and ventricular preexcitation. The aim of the present study was to define the ECG characteristics before and after ablation of an accessory A-V pathway (AP) in patients with Ebstein's anomaly. METHODS: A series of 226 consecutive patients with Ebstein's anomaly was studied. Sixty-four patients (28%) had documented tachycardia. Thirty-three patients with recurrent tachycardia were found to have a single right-sided AP that was successfully ablated (study group). Thirty patients without tachycardia served as the control group. RESULTS: Only 21 of 33 patients (62%) had a typical ECG pattern of preexcitation. In addition, none of the patients had an ECG pattern of RBBB during sinus rhythm. In contrast, 28 of 30 (93%) patients in the control group had RBBB (P < 0.001). Radiofrequency catheter ablation resulted in appearance of RBBB in 31 of 33 (94%) patients. The absence of RBBB in patients with Ebstein's anomaly and recurrent tachycardia had a 98% sensitivity and 92% specificity for the diagnosis of an AP. The positive predictive value was 91% (0.77, 0.97 CI 95%) and the negative predictive value was 98% (0.85, 0.99 CI 95%). CONCLUSION: One-third of patients with Ebstein's anomaly and symptomatic tachyarrhythmias have minimal or absent ECG features of ventricular preexcitation. In these patients, the absence of RBBB pattern is a strong predictor of an AP.

Mechanism of the inhibitory effect of 11ß hydroxypregna 1,4 diene 3,20 dione (delta HOP) at high concentrations in RNA synthesis / 303-12

La potente inhibición de la síntesis de ARN en timocitos de rata por la 11ß -hidroxipregna-1,4-dien-3,20-diona (DeltaHOP) demostrado recientemente, cumple las tres condiciones requeridas para un efecto no-genómico: no perdurabilidad del efecto después de ser retirado el esteroide por lavado, acción instantánea y efecto en presencia de inhibidores de la síntesis de ARN. La inyección intraperitoneal de DeltaHOP en ratones (2 mg/100 gm) provoca un 32% de inhibición de la síntesis de ARN en los timocitos; queda por aclarar si esta inhibición es debida también a un efecto no-genómico (AU)

Mechanism of the inhibitory effect of 11ß hydroxypregna 1,4 diene 3,20 dione (delta HOP) at high concentrations in RNA synthesis / 303-12

La potente inhibición de la síntesis de ARN en timocitos de rata por la 11ß -hidroxipregna-1,4-dien-3,20-diona (DeltaHOP) demostrado recientemente, cumple las tres condiciones requeridas para un efecto no-genómico: no perdurabilidad del efecto después de ser retirado el esteroide por lavado, acción instantánea y efecto en presencia de inhibidores de la síntesis de ARN. La inyección intraperitoneal de DeltaHOP en ratones (2 mg/100 gm) provoca un 32% de inhibición de la síntesis de ARN en los timocitos; queda por aclarar si esta inhibición es debida también a un efecto no-genómico