Carlos Labadet

Supraventricular tachycardia coexisting with apparent Mobitz I and II atrioventricular block: a single mechanism?

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).

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.

Multiple morphologies of ventricular tachycardia assessed by implantable cardioverter-defibrillator electrograms in a patient with Chagas disease, successfully treated with catheter ablation: modern problems, old solutions

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

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.

Diagnóstico diferencial entre doble respuesta ventricular y extrasistolia hisiana bigeminada

We have read with attention the scientific letter published by Evertz et al. entitled ‘‘Dual Ventricular Response: Another Road to Supraventricular Tachycardia in Dual Atrioventricular Nodal Physiology’’. As the authors clearly explain, their case concerned a form of supraventricular ‘‘pseudotachycardia’’ in which they established a differential diagnosis involving 2 conditions: atrial tachycardia (quickly ruled out during the electrophysiological study) and bigeminy arising from the bundle of His. The latter diagnosis is not easily differentiated. The authors ruled out premature contractions of the bundle of His due to the consistent relationship of the His and ventricular action potentials to the preceding atrial action potential. However, in the description of the electrocardiographic recording shown in Figure 1 of their letter, the authors mention certain irregularity of up to 50 ms in the PR2 interval. As they state in the text, the diagnosis of dual nodal physiology was more evident once the dual ventricular response had disappeared following ablation of the slow pathway. Our group reported a case of frequent extrasystoles arising from the bundle of His in which, as in that described by Evertz et al., the patient had been referred to us with palpitations and supraventricular tachycardia. Our patient showed a wider variability in the H1-H2 interval, which contributed to the presence of a greater number of beats with aberrant conduction and facilitated the differential diagnosis. Moreover, in our case, the presence of blocked P waves and ‘‘pseudoblock’’ of atrioventricular conduction was incompatible with the existence of dual nodal physiology. By way of this letter, we wish to stress how difficult it is on occasion to differentiate between these two conditions during the diagnostic stage of the electrophysiological study performed prior to ablation. The diagnosis of premature beats arising from the bundle of His can be confirmed using a detailed map of the region

Should we test all defibrillators at the time of implantation? An unanswered question.

We read with great interest the study of Vischer et al. entitled “Role of defibrillation threshold testing in the contemporary defibrillator patient population.”1 This is an interesting paper on a timely and relevant topic that retrospectively reviews data on 436 patients undergoing implantable cardioverter defibrillator (ICD) insertion with defibrillation threshold testing (DFT) in all cases (309 de novo implantations and 127 generator replacements). The authors conclude that shock testing should be performed in all patients, based on the finding that 9 (2%) patients could not be defibrillated with their standard approach, which was a 10 J safety margin. However, external rescue shock was necessary in only 5 (1.1%) patients, assuming that in the remaining 4 patients ventricular fibrillation spontaneously terminated or was defibrillated by a maximal output ICD shock. This issue is not completely clear in the paper, and more information on those 4 patients may contribute to a better understanding of DFT outcomes. Moreover, owing the lack of a nontested control group and follow-up, the recommendation to routinely perform DFT in all ICD implantations appears to be overstated, according to the findings of the study. In terms of patients’ characteristics, amiodarone therapy, dilated cardiomyopathy, and low ejection fraction were associated with shock testing failure in univariate analysis. However, a multivariate analysis (not shown) will be helpful to more accurately identify those patients at risk of an unsuccessful DFT.

Value of the electrocardiographic signs in differential diagnosis of atrioventricular nodal reentrant tachycardia

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, …

Termination mode of a broad QRS complex tachycardia: is the surface electrocardiogram the key?

A 45-year-old man with a long history of palpitations and absence of pre-excitation in baseline electrocardiogram underwent a Holter recording, revealing several episodes of regular non-sustained broad QRS complex tachycardia that terminated following the occurrence of a narrow QRS. (Panel A). The analysis of the last narrow QRS showed a signal compatible with a retrograde P wave. An electrophysiological study was performed. During the procedure, short episodes of orthodromic tachycardia (OT) with functional left bundle branch block (LBBB) were reproduced and consistently interrupted following the occurrence of a single narrow QRS complex with exactly the same cycle length as that of the tachycardia (Panel B). The intracardiac recordings showed a 40 ms shortening of the ventriculo-atrial interval in the narrow beat and an-

Catheter Ablation in Patients with Electrical Storm. The Calm after the Tempest

Introduccion : La ablacion por cateter (AC) es beneficiosa en pacientes con taquicardia ventricular (TV) recurrente. Nuestro objetivo es revisar los casos de tormenta electrica (TE) tratados con AC. Metodos : Analisis retrospectivo de pacientes con TE debida a TV monomorfa sostenida (TVMS) tratados mediante AC. Se definio exito del procedimiento: ausencia de TV inducible al final del mismo; exito parcial: induccion de TV no clinica; no exito: inducibilidad de la TV clinica. Resultados: Se realizaron 16 procedimientos en 14 pacientes: 10 exitosos, 3 exito parcial y 3 no exitosos. Todos los pacientes evolucionaron sin arritmia ventricular inmediatamente post-ablacion. Diez pacientes (71,4%) evolucionaron sin TV y 86,7% sin TE (seguimiento 8 [3-30] meses). Cinco pacientes (35,7%) murieron de causa no arritmica. Conclusiones: La AC se asocia a una supresion aguda de TV en todos los pacientes con TE debida a TVMS y a una evolucion sin recurrencia en la mayoria de ellos.

Premature Ventricular Contractions Strike Back

Address for reprints: Dr. Carlos Labadet Av. Almirante Brown 240 CABA e-mail: clabadet@gmail.com A BIT OF HISTORY Historically, premature ventricular contractions (PVCs) were considered precursors of sudden cardiac death and, for many years, their mere presence was taken as an indication for prescribing antiarrhythmic agents. The concept that ventricular fibrillation (VF) and ventricular tachycardia (VT) are preceded by PVCs arose when coronary care units were created to treat the complications of acute myocardial infarction (AMI). For many years, this concept of premonitory arrhythmias was extended, despite the lack of evidence, to other heart diseases. In addition, the traditional studies evaluating AMI outcome showed that PVCs were independent predictors of sudden and nonsudden death. (1) Studies in the post-thrombolytic era concluded that ventricular arrhythmia was associated with adverse outcome. (2) Finally, studies in ischemic heart disease showed that PVC scould be suppressed with antiarrhythmic agents but at the expense of greater all-cause mortality. (3) Subsequent studies using amiodarone in ischemic heart disease, as the EMIAT or the CAMIAT trials, failed to demonstrate any benefit with this drug. (4, 5) Since then, no significant progress or working hypothesis has emerged about the role of PVCs in the outcome of patients. No new agents were developed in this field and the treatment of PVCs with drugs has remained as something trivial for the past 20 years. The concept of optimizing the treatment of the underlying condition has prevailed, especially with beta blockers, together with implantation of cardioverter defibrillator devices in patients at high risk of sudden death, with or without sustained ventricular tachycardia.