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The differential diagnosis between orthodromic atrioventricular reentry tachycardia (AVRT) and atypical AV nodal reentrant tachycardia (aAVNRT) is sometimes challenging. We hypothesize that aAVNRTs have more variability in the retrograde conduction time at tachycardia onset than AVRTs.We aimed to assess the variability in retrograde conduction time at tachycardia onset in AVRT and aAVNRT and to propose a new diagnostic tool to differentiate these two arrhythmia mechanisms. We measured the VA interval of the first beats after tachycardia induction until it stabilized. The difference between the maximum and minimum VA intervals (∆VA) and the number of beats needed for the VA interval to stabilize was analyzed. Atrial tachycardias were excluded.A total of 107 patients with aAVNRT (n = 37) or AVRT (n = 64) were included. Six additional patients with decremental accessory pathway-mediated tachycardia (DAPT) were analyzed separately. All aAVNRTs had VA interval variability. The median ∆VA was 0 (0 - 5) ms in AVRTs vs 40 (21 - 55) ms in aAVNRTs (p 0.001). The VA interval stabilized significantly earlier in AVRTs (median 1.5 [1 - 3] beats) than in aAVNRTs (5 [4 - 7] beats; p 0.001). A ∆VA 10 ms accurately differentiated AVRT from aAVNRT with 100% of sensitivity, specificity, and positive and negative predictive values. The stabilization of the VA interval at 3 beats of the tachycardia onset identified AVRT with sensitivity, specificity, and positive and negative predictive values of 64.1%, 94.6%, 95.3%, and 60.3%, respectively. A ∆VA 20 ms yielded good diagnostic accuracy for DAPT.A ∆VA 10 ms is a simple and useful criterion that accurately distinguished AVRT from atypical AVNRT. Central panel: Scatter plot showing individual values of ∆VA in atypical AVNRT and AVRT. Left panel: induction of atypical AVNRT. The VA interval stabilizes at the 5th beat and the ∆VA is 62 ms (maximum VA interval: 172 ms - minimum VA interval: 110 ms). Right panel: induction of AVRT. The tachycardia has a fixed VA interval from the first beat. ∆VA is 0 ms.

Objectives The aim of this study was to assess the long-term efficacy and outcomes of retrograde venous ethanol ablation in treating ventricular arrhythmias (VAs). Background Retrograde co...

espanolIntroduccion: Se ha comunicado que algunos tratamientos utilizados para la infeccion por COVID-19 pueden ocasionar alteracionesdel intervalo QT y arritmias graves. La medicion por electrocardiograma (ECG) convencional requiere personaladicional y riesgo de contagio. Nuevas tecnologias para obtencion de un ECG conectados a telefonos inteligentes (smartphones)proporcionan una alternativa para evaluacion del QTc.Objetivo: El objetivo fue evaluar la factibilidad de un dispositivo para registro electrocardiografico de un canal, para la mediciondel intervalo QT en pacientes con sospecha o confirmacion de infeccion por COVID-19, antes de recibir drogas queprolongan el intervalo QT.Material y metodos: Se obtuvieron registros de ECG con un dispositivo Kardia Mobile (KM) con trasmision a un smarthphone.La seccion de electrofisiologia cardiaca centralizo la recepcion por medio electronico de los ECG en formato de archivo pdf yrealizo las mediciones de los intervalos QTm y QTc.Resultados: Se estudiaron 31 pacientes, edad promedio 61 anos (rango 20-95 anos), sospechosos de presentar infeccion porCOVID-19 enrolados para tratamiento con hidroxicloroquina, azitromicina, ritonavir y lopinavir. Los registros pudieron serleidos en todos los casos, y debieron repetirse en dos casos. Los valores del intervalo QTc promedio en varones y mujeres fue423 mseg (rango 380-457 mseg) y 439 mseg (rango 391-540 mseg), respectivamente. El tiempo de respuesta desde el enviodel ECG al grupo de analisis fue 11 min (rango 1-155).Conclusiones: Los registros ECG obtenidos con dispositivos KM, para trasmision a un smartphone a un grupo central delectura, permitieron la medicion del intervalo QTc en todos los pacientes. EnglishBackground: Some therapies used for COVID-19 can prolong the QT interval and produce severe arrhythmias. QT interval measuredfrom a standard electrocardiogram (ECG) requires additional personnel and risk of infection. Novel technologies to obtain anECG connected to smartphones provide an alternative for the evaluation of corrected QT interval (QTc).Objective: The aim of this study was to evaluate the feasibility of using a single-lead ECG device to measure the QT interval in patientswith suspected or confirmed COVID-19 before receiving treatment with drugs that can prolong the QT interval.Methods: The ECG was obtained with a KardiaMobile (KM) device and transmitted to a smartphone. The ECG recordings weresaved as pdf files and electronically submitted to the electrophysiology section which centralized the reception and assessed themeasured QT and QTc intervals.Results: A total of 31 patients (mean age 61 years, range 20-95 years) with suspected COVID-19 enrolled for treatment with hydroxychloroquine,azithromycin, ritonavir or lopinavir were analyzed. The recordings could be read in all the cases and had to be repeatedin two cases. The mean value of the QTc interval was 423 ms (range 380-457 ms) in men and 439 ms (range 391-540 ms) in women.The response time since the ECG recording was submitted for analysis was 11 min (range 1-155).Conclusions: The QTc interval could be measured from ECG recordings obtained with KM devices connected to a smartphone andtransmitted to a centralized reading center in all patients.

There are few reports on the benefits of catheter ablation (CA) in patients with electrical storm (ES). None of these publications included patients with Chagas disease (ChD). Our aims are to analyze (1) all the cases of ES treated with CA and (2) the subgroup of patients with ChD. Prospective analysis of consecutive patients with ES due to monomorphic ventricular tachycardia (VT) treated with CA. We included 38 patients: 28 males; median age of 63.5 (IQR 55–71) years old; ejection fraction (LVEF) 0.30 (0.25–0.40). Sixteen patients (42.1%) had ChD. The patients experienced 21 (15–37) VT episodes and received 7 (3–13) ICD shocks before CA. Forty-six procedures were performed (7 required epicardial access). All patients experienced ES suppression after CA. After 35 (10–64) months of follow-up (1.21 procedures per patient), 23 patients (60.5%) remain free from any VT; 35 patients (92.1%) were free from ES, and 11 patients (28.9%) died from non-arrhythmic causes. One patient underwent heart transplantation. Patients with ChD were younger (60 vs. 67 years old; p = 0.033), significantly more women (50% vs. 9.1%; p = 0.005), and had higher LVEF (0.40 vs. 0.28; p

Background: The noncontact mapping system facilitates the mapping of premature ventricular contractions (PVCs) and ventricular tachycardia (VT) using a 64-electrode expandable balloon catheter (ARRAY, St. Jude Medical). The aim of this study is to analyze the results and follow-up of the PVC ablation using this system. Methods and results: Prospective and consecutive patients with frequent PVCs (6,000 or more) or monomorphic VT, suspected to be originated on the right ventricular outflow tract (RVOT), were included. The balloon catheter was positioned in the RVOT. Eighteen patients, 9 women, mean age 48 years (youngest/oldest 19–65) were included. Sixteen patients presented no structural heart disease. The origin of the arrhythmia was RVOT (n = 15), right ventricular inflow tract (n = 1), and left ventricular outflow tract (n = 2). Acute success was achieved in 15 patients; in 2 patients radiofrequency was not applied due to security reasons (origin site close to left coronary artery origin). The mean follow-up was 15 months (min. 4, max. 26); 13 patients presented abolition of the arrhythmia without drugs and 1 patient required antiarrhythmic drugs for arrhythmia control (previously ineffective). As an only complication, a femoral artery-venous fistula was observed. Conclusions: The noncontact mapping system using a multielectrode balloon allows right ventricular arrhythmia treatment with a high rate of efficacy and safety.

Aims To assess the results of transcatheter ablation of cardiac arrhythmias in Latin America and establish the first Latin American transcatheter ablation registry. Methods and results All ablation procedures performed between 1 January and 31 December 2012 were analysed retrospectively. Data were obtained on the characteristics and resources of participating centres (public or private institution, number of beds, cardiac surgery availability, type of room for the procedures, days per week assigned to electrophysiology procedures, type of fluoroscopy equipment, availability and type of electroanatomical mapping system, intracardiac echo, cryoablation, and number of electrophysiologists) and the results of 17 different ablation substrates: atrio-ventricular node reentrant tachycardia, typical atrial flutter, atypical atrial flutter, left free wall accessory pathway, right free wall accessory pathway, septal accessory pathway, right-sided focal atrial tachycardia, left-sided focal atrial tachycardia, paroxysmal atrial fibrillation, non-paroxysmal atrial fibrillation, atrio-ventricular node, premature ventricular complex, idiopathic ventricular tachycardia, post-myocardial infarction ventricular tachycardia, ventricular tachycardia in chronic chagasic cardiomyopathy, ventricular tachycardia in congenital heart disease, and ventricular tachycardias in other structural heart diseases. Data of 15 099 procedures were received from 120 centres in 13 participating countries (Argentina, Bolivia, Brazil, Chile, Colombia, Cuba, El Salvador, Guatemala, Mexico, Peru, Dominican Republic, Uruguay, and Venezuela). Accessory pathway was the group of arrhythmias most frequently ablated (31%), followed by atrio-ventricular node reentrant tachycardia (29%), typical atrial flutter (14%), and atrial fibrillation (11%). Overall success was 92% with the rate of global complications at 4% and mortality 0.05%. Conclusion Catheter ablation in Latin America can be considered effective and safe.

Introduction and objective: The non-contact mapping system with expandable balloon catheter allows ventricular arrhythmia mapping with few ectopic beats. The aim of this study was to analyze ablation results with this system. Methods: Patients with ventricular arrhythmia were prospectively and consecutively studied with the non-contact mapping system. Results: The study included 10 patients, 8 women, with mean age of 45 years (range: 27 to 65). Arrhythmia origin was right ventricular outflow tract in 8 patients, right ventricular inflow tract in 1 and left ventricular outflow tract in 1. Acute success was obtained in 9/10 patients (90%). Mean follow-up was 6 months (range 1 to 16); 8 patients continued with obliterated arrhythmia without medication and 1 patient required pharmacologic treatment. The only complication was femoral arteriovenous fistula. Conclusions: The non-contact mapping system allows a highly efficient and safe approach of right ventricular arrhythmias. Future studies with more patients and comparing with other methods may confirm these results.

Introduction The CHADS2 score and the CHA2DS2-VASc score recently ad- opted by the medical community have been developed with in- ternational registry data a...

Aims Reciprocating atrioventricular tachycardia can be categorized into common slow–fast atrioventricular node re-entrant (AVNRT) and orthodromic atrioventricular reciprocating tachycardia (AVRT). The electrocardiogram (ECG) during tachycardia is useful in distinguishing these two mechanisms. The presence of a pseudo-R′-wave in lead V1 or pseudo-S-wave in the inferior leads has been widely used, although the value of an isolated aVL lead has not been evaluated yet. To determine whether an isolated aVL lead of the surface 12-lead ECG is useful for the differential diagnosis between AVNRT and AVRT. Methods and results Consecutive patients referred for paroxysmal regular supraventricular tachycardia radiofrequency ablation were prospectively evaluated. Patients with atrial tachycardia, bundle branch block, manifested pre-excitation, and those undiagnosed after electrophysiology study were excluded. We compared the standard criteria with the value of an isolated aVL lead to distinguish between AVNRT and AVRT. One hundred and one patients were included; 73.3% were AVNRT and 26.7% AVRT. Patients with AVNRT were older (49.4 ± 16.4 vs. 36.0 ± 18.7 years, P = 0.001). The aVL notch and the standard criteria were found more frequently in AVNRT than in AVRT (aVL notch: 51.3 vs. 7.4%, P ≤ 0.001; pseudo-S-wave 45 vs. 8.6% P = 0.001; and pseudo-R′-wave in V1 39.7 vs. 11.5%, P = 0.008, respectively). The aVL notch sensitivity and specificity to determine the final diagnosis were higher than the standard criteria (aVL notch 48.6 and 92.6%; pseudo-S-wave 45 and 91.3%; and pseudo-R′-wave in V1 39.7 and 88.5%, respectively). Conclusion The presence of a notch in aVL lead appeared to be as sensitive and specific as the standard electrocardiographic criteria for the differential diagnosis of AVNRT.

Introduccion y objetivos Nuestro proposito es caracterizar el modo de aparicion de la taquicardia ventricular monomorfica espontanea y sostenida en pacientes con miocardiopatia chagasica. Metodos Estudiamos 222 electrogramas procedentes de 14 pacientes con miocardiopatia chagasica y taquicardia ventricular monomorfica espontanea tratada con un desfibrilador cardioversor. Los complejos ventriculares prematuros previos a la taquicardia ventricular se clasificaron segun su morfologia y su numero. La aparicion se considero «subita» si no fue precedida de complejos ventriculares prematuros y «extrasistolica» si una extrasistole ventricular precedia al inicio de la taquicardia. La prematuridad se evaluo mediante el intervalo de acoplamiento y un cociente calculado de prematuridad (RR’/RR). Resultados Los complejos ventriculares prematuros de acoplamiento tardio (cociente de prematuridad > 0,5) iniciaron 209 (94%) episodios. El intervalo de acoplamiento medio del latido inicial fue de 565 ± 117 ms, con un cociente de prematuridad medio de 0,72 ± 0,15. La aparicion subita fue el patron de inicio de la taquicardia ventricular mas frecuente (129 episodios, el 58%). Entre aquellas de aparicion extrasistolica (93 episodios, el 42%), 48 se debieron a salvas de complejos ventriculares prematuros y en 88 la morfologia del complejo QRS (electrograma) de las extrasistoles ventriculares era diferente de las registradas durante la taquicardia ventricular posterior. En 95/222 episodios (43%), la arritmia fue precedida de una secuencia corto-largo-corto. Conclusiones En los portadores de desfibriladores automaticos implantables con miocardiopatia chagasica, los episodios de taquicardia ventricular monomorfica espontanea se inician de manera caracteristica por complejos ventriculares prematuros de acoplamiento tardio, que a menudo muestran una secuencia corto-largo-corto.

A 36 year-old man with Wolff Parkinson White syndrome due to a left-sided accessory pathway (AP) was referred for catheter ablation. Whether abolition of antegrade and retrograde AP conduction during ablation therapy occurs simultaneously, is unclear. At the ablation procedure, radiofrequency delivery resulted in loss of preexcitation followed by a short run of orthodromic tachycardia with eccentric atrial activation, demonstrating persistence of retrograde conduction over the AP after abolition of its antegrade conduction. During continued radiofrequency delivery at the same position, the fifth non-preexcitated beat failed to conduct retrogradely and the tachycardia ended. In this case, antegrade AP conduction was abolished earlier than retrograde conduction.

RESUMENEl desarrollo de arritmias supraventriculares es un hallazgo frecuente en el seguimiento depacientes sometidos a trasplante cardíaco. La ablación por radiofrecuencia del aleteo auricularha demostrado que es el tratamiento de elección en pacientes con cardiopatía subyacentey sin ella, en tanto que son escasas las comunicaciones en la bibliografía acerca de sueficacia postrasplante cardíaco.En esta presentación se describe el caso de un paciente de 26 años con antecedente detrasplante cardíaco que presentó aleteo auricular en la evolución. En el estudio electrofisiológico se observó un aleteo auricular típico antihorario dependiente del istmo en laaurícula derecha del donante. La aurícula derecha del receptor se encontraba disociada, enritmo sinusal. Durante la aplicación de radiofrecuencia en el istmo a la altura de la línea desutura auriculoauricular derecha se observó la interrupción del aleteo. Ambas aurículasderechas quedaron en ritmo sinusal, disociadas por bloqueo bidireccional a nivel de la anastomosis.REV ARGENT CARDIOL 2009;77:408-410.

A 28-year-old man with a history of palpita-tionswasreferredforevaluation.Initialevaluationshowed a normal resting electrocardiogram withsinus rhythm and absence of structural heart dis-ease.AmbulatoryHoltermonitoringdemonstratedseveral episodes of self-terminated narrow QRScomplex tachycardia, as well as episodes of atri-oventricular (AV) block (Fig. 1).

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A 60-year-old man with Chagas disease, implanted with an implantable cardioverter defibrillator (ICD), experienced electrical storm. The ICD-stored electrograms revealed several ventricular tachycardia (VT) episodes with two different morphologies, confirmed thereafter by surface electrocardiogram. Both VTs originated from two different re-entry circuits and were successfully ablated. This case highlights the usefulness of ICD electrograms in identifying two VTs as having different sites of origin. Analysis of implantable cardioverter-defibrillator electrograms (ICD-EG) showed that monomorphic ventricular tachycardia (VT) with different QRS morphologies during different episodes (multiple morphologies, MM) predicted higher mortality. 1 A 60-year-old man implanted with an ICD (Medtronic Maximo-VR7232) for secondary prevention of death, with Chagas disease and left ventricular ejection fraction (LVEF), 0.45 was hospitalized for electrical storm. The ICD interrogation revealed 62 episodes of monomorphic VT. Analysing ICD-EG, a difference in morphology was seen only in the HVA/HVB electrogram (a QS complex in Figure 1A; a Qr complex in Figure 1B). During hospitalization he experienced several VT episodes and surface-electrocardiogram Figure 1 Schematic representation of the endocardial surface of the left ventricle. (A) and (B) Implantable cardioverter defibrillator- stored electrograms showing two different morphologies of the HVA/HVB electrogram. Note that this difference is not evident in the Vtip-Vring electrogram. (C) and (D) Twelve-lead surface electrocardiogram from two different spontaneous episodes of monomorphic ventricular tachycardia. (E) and (F) Surface and endocardial recordings from the two ventricular tachycardias induced at electrophysio- logicalstudy.NotethatQRSconfigurationsofinducedventriculartachycardiasmatchthoseofthespontaneousventriculartachycardias. There is a mismatch in lead V6 from ventricular tachycardia 1, probably due to different electrode position.

Paroxysmal atrial fibrillation (AF) initiation often occurs from pulmonary vein (PV) ectopy. We describe the case of a young patient with multiple episodes of refractory AF who had, almost permanently, left inferior PV extrasystoles in a pattern of bigeminy. At the beginning this focal arrhythmia was concealed due to exit block, going unnoticed on the electrocardiogram. Subsequently PV couplets were expressed as atrial extrasystoles and finally disorganization of this phenomenon led to AF. PV isolation was performed and after 4 months of follow-up the patient remains free from AF and supraventricular extrasystoles on Holter monitoring.

Introduction and objectives We sought to demonstrate the mode of spontaneous onset of sustained monomorphic ventricular tachycardia in patients with Chagas' cardiomyopathy. Methods We studied 222 stored electrograms in 14 patients with Chagas cardiomyopathy and spontaneous monomorphic ventricular tachycardia treated with a cardioverter defibrillator. Premature ventricular complexes before ventricular tachycardia were classified by morphology and number. The onset was considered “sudden” if no previous premature ventricular complexes were present, and “extrasystolic” if a ventricular extrasystole precedeed SMVT initiation. Prematurity was evaluated by the coupling interval and a calculated prematurity ratio (RR′/RR). Results Two-hundred and nine episodes (94%) were initiated by late-coupled premature ventricular complexes (prematurity ratio >0.5). The mean coupling interval of the initiating beat was 565 (117) ms with a mean prematurity ratio of 0.72 (0.15). A sudden onset was the most frequent pattern of ventricular tachycardia initiation (129 episodes, 58%). Among the extrasystolic onset (93 episodes, 42%), 48 were due to multiple premature ventricular complexes and 88 had a different QRS complex (electrogram) morphology of the ventricular extrasystoles than that recorded during the subsequent ventricular tachycardia. The arrhythmia was preceded by a short-long-short sequence in 95/222 episodes (43%). Conclusions In implantable cardioverter defibrillator recipients with Chagas cardiomyopathy, spontaneous monomorphic ventricular tachycardia episodes are typically initiated by late-coupled premature ventricular complexes, which often show a short-long-short sequence.

We read with great interest the article: ‘Value of the aVR lead in differential diagnosis of atrioventricular nodal reentrant tachycardia’ by Haghjoo et al. 1 in a recent issue of the journal. We would like to comment that the specificity of an electrocardiographic sign guarantees that in the presence of this sign, the likelihood of the disease in question is high. On the contrary, the sensitivity of a particular sign guarantees that in the absence of this sign, …

Brugada syndrome is a major cause of sudden death in young adults. Fever has been described to induce a Brugada-type electrocardiogram in asymptomatic patients with a negative family history, to disclose Brugada syndrome and to increase the risk of death and induce T wave alternans in patients with diagnosed Brugada syndrome. Risk stratification is challenging and demands a careful evaluation. Here we present 2 case reports and review the literature.