Usefulness of the intracardiac electrocardiogram recorded using central venous catheters on P-wave magnification.

BACKGROUND: The detection of atrial electrical activity is extremely valuable in recognizing complex cardiac arrhythmias. However, P-wave detection on a surface electrocardiogram (S-ECG) can sometimes be challenging. The intracardiac electrocardiogram (IC-ECG), recorded by a central venous catheter loaded with saline solution, has proven to be a safe and effective method for amplifying atrial electrical activity. We aim to compare the P-wave amplitude recorded in the S-ECG and the IC-ECG in different venous accesses, catheters, heart rhythms, and atrial dimensions. METHODS: We compared the P wave amplitude obtained by the IC-ECG and the S-ECG recordings from cardiac intensive care unit patients. RESULTS: In 109 nonconsecutive patients, a total of 166 IC-ECG were collected. The median amplitude of the P wave was 0.1 (0.083-0.3) mV in the S-ECG and 0.4 (0.25-2.4) mV in the IC-ECG; p < 0.001. This difference remained significant regardless of the patient's heart rhythm, left atrial dimension, and catheter or vascular access used. CONCLUSION: The IC-ECG acquired using central venous catheters significantly increases atrial electrical activity signals. This technique might help identify complex cardiac arrhythmias.

The first Latin American Catheter Ablation Registry.

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.

Variability of the VA interval at tachycardia induction: a simple method to differentiate orthodromic reciprocating tachycardia from atypical atrioventricular nodal reentrant tachycardia.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Antegrade or retrograde accessory pathway conduction: who dies first?

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.

Value of Electrocardiography to Distinguish Fabry Disease from Sarcomeric Hypertrophic Cardiomyopathy.

Fabry disease (FD) is a rare genetic disorder that leads to left ventricular hypertrophy (LVH), frequently misdiagnosed as hypertrophic cardiomyopathy (HCM). We sought to assess the value of electrocardiography for distinguishing FD from HCM. We retrospectively reviewed and compared standard electrocardiograms and echocardiograms from 26 patients with FD and LVH and 33 sarcomeric patients with HCM, matched for gender, age, and degree of LVH. The mean age of patients with FD was 46 years (interquartile range) (28 to 53) and of HCM 50 (30 to 61) years (p = 0.27). Of them, 16 (61%) and 25 (76%) were male, respectively (p = 0.26). Indexed left ventricular mass was 166 g/m2 in FD versus 181 g/m2 in HCM (p = 0.88). All patients with FD and 30 (91%) with HCM were in sinus rhythm (p = 0.25). A higher prevalence of right bundle branch block (RBBB) was observed in FD (27%) versus HCM (6%) (p = 0.03). The PR interval was shorter in FD, 140 ms (120-160) versus 160 ms (140 to 180) (p = 0.004). P-wave duration was longer in patients with FD, 100 ms (80 to 120) versus 80 ms (80 to 100) (p = 0.01). The PQ interval (PR interval minus P-wave duration) was shorter in patients with FD, 40 ms (20 to 45) versus 80 ms (40 to 80) (p = 0.001). There were no differences regarding P-wave amplitude, QRS complex duration, corrected QT length, conduction or repolarization abnormalities, Sokolow-Lyon index, and Cornell index. After multivariate adjustments for RBBB, PR interval, P-wave duration, and PQ interval, a PQ interval ≤40 ms and RBBB were significantly associated with FD. In conclusion, there are electrocardiogram characteristics, such as the presence of RBBB or a PQ interval ≤40 ms, that may be helpful for screening and reducing the delay in FD diagnosis.

Catheter ablation of ventricular tachycardia in patients with electrical storm, with a special focus on patients with Chagas disease.

BACKGROUND: 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. METHODS: Prospective analysis of consecutive patients with ES due to monomorphic ventricular tachycardia (VT) treated with CA. RESULTS: 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 < 0.001) than the other patients. Long-term outcome of ChD patients was similar to that of the overall population. Only age and LVEF independently predicted mortality. CONCLUSION: CA was associated with acute ventricular arrhythmia suppression in all patients with ES. Freedom rates from ES and VT were 92.1% and 60.5% respectively. Despite having a lower-risk clinical profile, patients with ChD had a comparable outcome to that of the other patients.

Intramural Venous Ethanol Infusion for Refractory Ventricular Arrhythmias: Outcomes of a Multicenter Experience.

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 coronary venous ethanol ablation (RCVEA) can be effective for radiofrequency ablation (RFA)-refractory VAs, particularly those arising in the LV summit (LVS). METHODS: Patients with drug and RFA-refractory VAs were considered for RCVEA after RF failure attempts. Intramural coronary veins (tributaries of the great cardiac, anterior interventricular, lateral cardiac, posterolateral, and middle cardiac) were mapped using an angioplasty wire. Ethanol infusion was delivered in veins with appropriate signals. RESULTS: Of 63 patients (age 63 ± 14 years; 60% men) with VAs (71% extrasystole, 29% ventricular tachycardia, 76% LVS origin), RCVEA was performed in 56 patients who had suitable vein branches. These were defined as those amenable to cannulation and with intramural signals that preceded those mapped in the epicardium or endocardium and had better matching pace maps or entrainment responses. Seven patients had no suitable veins and underwent RFA. In 38 of 56 (68%) patients, the VAs were successfully terminated exclusively with ethanol infusion. In 17 of 56 (30%) patients, successful ablation was achieved using ethanol with adjunctive RFA in the vicinity of the infused vein due to acute recurrence or ethanol-induced change in VA morphology. Overall, isolated or adjuvant RCVEA was successful in 55 of 56 (98%) patients. At 1-year follow-up, 77% of patients were free of recurrent arrhythmias. Procedural complications included 2 venous dissections that led to pericardial effusions. CONCLUSIONS: RCVEA offers a significant long-term effective treatment for patients with drug and RF-refractory VAs.

Utility of the aVL lead in the electrocardiographic diagnosis of atrioventricular node re-entrant tachycardia.

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< or = 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.

Comportamiento del tiempo de conducción retrógrada al momento de la inducción de las taquicardias supraventriculares y su rol en el diagnóstico diferencial / Behavior of Retrograde Conduction Time at Supraventricular Tachycardia Induction and its Role in Differential Diagnosis

RESUMEN Antecedentes : El diagnóstico diferencial entre la taquicardia reentrante ortodrómica (TRO) y la taquicardia por reentrada nodal atípica (TRNa) puede ser dificultoso. Nuestra hipótesis es que las TRNa tienen más variabilidad en el tiempo de con ducción retrógrada al comienzo de la taquicardia que las TRO. Nuestros objetivos fueron evaluar la variabilidad en el tiempo de conducción retrógrada al inicio de la taquicardia en TRNa y TRO, y proponer una nueva herramienta diagnóstica para diferenciar estas dos arritmias. Métodos : Se midió el intervalo ventrículo-auricular (VA) de los primeros latidos tras la inducción de la taquicardia, hasta su estabilización. La diferencia entre el intervalo VA máximo y el mínimo se definió como delta VA (ΔVA). También contamos el número de latidos necesarios para que se estabilice el intervalo VA. Se excluyeron las taquicardias auriculares. Resultados : Se incluyeron 101 pacientes. Se diagnosticó TRO en 64 pacientes y TRNa en 37. El ΔVA fue 0 (rango intercuartílico, RIC, 0-5) milisegundos (ms) en la TRO frente a 40 (21-55) ms en la TRNa (p < 0,001). El intervalo VA se estabilizó significativamente antes en la TRO (1,5 [1-3] latidos) que en la TRNa (5 [4-7] latidos; p < 0,001). Un ΔVA < 10 ms diagnosticó TRO con 100% de sensibilidad, especificidad y valores predictivos positivo y negativo. La estabilización del intervalo VA en menos de 3 latidos predijo TRO con buena precisión diagnóstica. Los resultados fueron similares considerando sólo vías accesorias septales. Las TRN típicas tuvieron una variación intermedia. Conclusión : Un ΔVA < 10 ms es un criterio simple, que distingue con precisión la TRO de la TRNa, independientemente de la localización de la vía accesoria.

ABSTRACT Background : Differential diagnosis between orthodromic reentrant tachycardia (ORT) and atypical nodal reentrant tachy cardia (ANRT) can be challenging. Our hypothesis was that ANRT presents more variability in retrograde conduction time at tachycardia onset than ORT. Objectives : The objectives of this study were to assess retrograde conduction time variability at the start of tachycardia in ANRT and ORT, and postulate a new diagnostic tool to differentiate these two types of arrhythmias. Methods : The ventriculoatrial (VA) interval of the first beats after tachycardia induction was measured until stabilization. The difference between the maximum and minimum VA interval was defined as delta VA (ΔVA), and the number of beats needed for VA interval stabilization was also assessed. Atrial tachycardias were excluded. Results : In a total of 101 patients included in the study, ORT was diagnosed in 64 patients and ANRT in 37. ΔVA interval was 0 (interquartile range [IQR] 0-5) milliseconds (ms) in ORT vs. 40 (21-55) ms in ANRT (p <0.001). The VA interval significantly stabilized earlier in ORT (1.5 [1-3] beats) than in ANRT (5 [4-7] beats) (p<0.001). A ΔVA <10 ms diagnosed ORT with 100% sensitivity, specificity, and positive and negative predictive values. Ventriculoatrial interval stabilization in less than 3 beats predicted ORT with good diagnostic accuracy. The results were similar considering only accessory septal pathways. Typical NRTs presented an intermediate variation. Conclusion : Presence of DVA <10 ms is a simple criterion that accurately differentiates ORT from ANRT, independently of the accessory pathway localization.

Fibrilación auricular en el atleta: ¿Adaptabilidad es sinónimo de riesgo? / Atrial Fibrillation in Athletes: Is Adaptability a Synonym of Risk?

RESUMEN La fibrilación auricular es la arritmia cardíaca más frecuente y de mayor interés debido a su alta morbimortalidad. Se encuentra asociada a los factores de riesgo cardiovascular, a la enfermedad cardíaca estructural y su prevalencia aumenta conforme a la edad. Su incidencia es mayor en deportistas de alta intensidad, en los que se plantea una fisiopatología diferente a la convencional, desde la base de una respuesta adaptativa hasta un exceso de ejercicio sostenido en el tiempo. Se evidencia además una clara diferencia entre sexos. Nuevas formas de diagnóstico se avizoran en el horizonte como el monitoreo con relojes inteligentes y la cuantificación de la fibrosis cardíaca con la resonancia magnética nuclear, que serán de gran utilidad. Su tratamiento es un gran desafío debido a la escasa evidencia y al impacto psicosocial que produce el cese del entrenamiento. El tratamiento definitivo y de elección hoy en día es la ablación de las venas pulmonares. Los bloqueantes cálcicos parecieran ser la mejor opción para el control de la frecuencia cardíaca, aunque aún son necesarios más estudios. Permanece además como interrogante el inicio o no de la anticoagulación.

ABSTRACT Atrial fibrillation (AF) is the most common cardiac arrhythmia and the most interesting due to its high morbidity and mortality. It is associated with cardiovascular risk factors and structural heart disease, and its prevalence increases with age. The incidence is higher in high-intensity athletes, with a pathophysiology different from conventional AF, from the basis of an adaptive response to an excess of sustained exercise over time. There is a clear difference between sexes. New diagnostic tools are on the horizon, such as smart watch monitors and quantification of cardiac fibrosis with nuclear magnetic resonance imaging, which will be very useful. Treatment of AF is a great challenge due to the scarce evidence and the psychosocial impact caused by stopping training. Pulmonary vein ablation is currently the definitive treatment of choice. Calcium channel blockers seem to be the best option for HR control; nevertheless, more studies. The initiation or not of anticoagulation also remains a question mark.

Radiofrequency catheter ablation of frequent premature ventricular contractions using ARRAY multi-electrode balloon catheter.

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.

Utilidad de un sistema de registro de una derivación electrocardiográfica y transmisión inalámbrica durante la pandemia por COVID-19 / Electrocardiographic Recording System and Wireless Transmission During the COVID-19 Pandemic

RESUMEN Introducción: Se ha comunicado que algunos tratamientos utilizados para la infección por COVID-19 pueden ocasionar alteraciones del intervalo QT y arritmias graves. La medición por electrocardiograma (ECG) convencional requiere personal adicional y riesgo de contagio. Nuevas tecnologías para obtención de un ECG conectados a teléfonos inteligentes (smartphones) proporcionan una alternativa para evaluación del QTc. Objetivo: El objetivo fue evaluar la factibilidad de un dispositivo para registro electrocardiográfico de un canal, para la medición del intervalo QT en pacientes con sospecha o confirmación de infección por COVID-19, antes de recibir drogas que prolongan el intervalo QT. Material y métodos: Se obtuvieron registros de ECG con un dispositivo Kardia Mobile (KM) con trasmisión a un smarthphone. La sección de electrofisiología cardíaca centralizó la recepción por medio electrónico de los ECG en formato de archivo pdf y realizó las mediciones de los intervalos QTm y QTc. Resultados: Se estudiaron 31 pacientes, edad promedio 61 años (rango 20-95 años), sospechosos de presentar infección por COVID-19 enrolados para tratamiento con hidroxicloroquina, azitromicina, ritonavir y lopinavir. Los registros pudieron ser leídos en todos los casos, y debieron repetirse en dos casos. Los valores del intervalo QTc promedio en varones y mujeres fue 423 mseg (rango 380-457 mseg) y 439 mseg (rango 391-540 mseg), respectivamente. El tiempo de respuesta desde el envío del ECG al grupo de análisis fue 11 min (rango 1-155). Conclusiones: Los registros ECG obtenidos con dispositivos KM, para trasmisión a un smartphone a un grupo central de lectura, permitieron la medición del intervalo QTc en todos los pacientes.

ABSTRACT Background: Some therapies used for COVID-19 can prolong the QT interval and produce severe arrhythmias. QT interval measured from a standard electrocardiogram (ECG) requires additional personnel and risk of infection. Novel technologies to obtain an ECG 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 patients with 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 were saved as pdf files and electronically submitted to the electrophysiology section which centralized the reception and assessed the measured 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 repeated in 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 and transmitted to a centralized reading center in all patients.

Brugada electrocardiographic pattern induced by fever.

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.