Juan J. Sánchez-Muñoz

Fundamental Frequency and Regularity of Cardiac Electrograms With Fourier Organization Analysis

Dominant frequency analysis (DFA) and organization analysis (OA) of cardiac electrograms (EGMs) aims to establish clinical targets for cardiac arrhythmia ablation. However, these previous spectral descriptions of the EGM have often discarded relevant information in the spectrum, such as the harmonic structure or the spectral envelope. We propose a fully automated algorithm for estimating the spectral features in EGM recordings This approach, called Fourier OA (FOA), accounts jointly for the organization and periodicity in the EGM, in terms of the fundamental frequency instead of dominant frequency. In order to compare the performance of FOA and DFA-OA approaches, we analyzed simulated EGM, obtained in a computer model, as well as two databases of implantable defibrillator-stored EGM. FOA parameters improved the organization measurements with respect to OA, and averaged cycle length and regularity indexes were more accurate when related to the fundamental (instead of dominant) frequency, as estimated by the algorithm (p <; 0.05 comparing f0 estimated by DFA and by FOA). FOA yields a more detailed and robust spectral description of EGM compared to DFA and OA parameters.

Utilidad de la estimulación auricular progresiva para evaluar la efectividad de la ablación de la vía lenta perinodal

Introduccion y objetivos Estudiar la utilidad de la estimulacion auricular progresiva para evaluar el efecto de la ablacion con cateter sobre la conduccion por via lenta en pacientes con taquicardia por reentrada nodal comun. Metodos Estudio prospectivo en pacientes remitidos para estudio electrofisiologico en los que se indujo taquicardia por reentrada nodal comun, empleando como grupo control a los pacientes en los que no se indujo. La estimulacion auricular progresiva se practico mediante la disminucion paulatina del ciclo de estimulacion hasta obtener un intervalo PR > RR o bloqueo auriculoventricular. Durante la estimulacion auricular programada se evaluo la presencia de doble fisiologia nodal siguiendo el criterio estandarizado. En el grupo en que se indujo taquicardia se repitio el estudio electrofisiologico 30 min despues de la ablacion. Resultados En el grupo con taquicardia por reentrada nodal comun (n = 85), 52 pacientes (61%) mostraron criterios de doble via nodal durante la estimulacion auricular programada y 66 (78%) mantenian PR > RR durante la estimulacion auricular progresiva. En el grupo control, la incidencia de estos criterios fue de 10/56 (18%) y 7/56 (12%), respectivamente. Tras la ablacion eficaz de via lenta (81/85), 37 mostraban doble via nodal durante la estimulacion auricular programada y uno tenia PR > RR durante estimulacion auricular progresiva (valor predictivo positivo de la ausencia de PR > RR para ablacion eficaz de via lenta del 98%). Conclusiones La estimulacion auricular progresiva muestra un intervalo PR > RR en la mayoria de los pacientes en los que se induce taquicardia por reentrada nodal comun y puede emplearse como un metodo sencillo y rapido para evaluar el efecto de las aplicaciones de radiofrecuencia sobre la conduccion por via lenta.

Identificación del nervio frénico con tomografía computarizada cardiaca multidetector

Cryoballoon ablation of the pulmonary veins is a new technique that has proven useful in preventing paroxysmal and persistent atrial fibrillation recurrence. One of the most serious complications of this method is right phrenic nerve palsy. The usefulness of multidetector computed tomography to locate the right phrenic nerve and artery and predict the risk of phrenic nerve palsy during cryoablation according to the distance between the right phrenic neurovascular bundle and the right superior pulmonary vein ostium has recently been described. Fifty-five consecutive patients with paroxysmal atrial fibrillation (52 ± 12 years) underwent balloon cryoablation, following multidetector computed tomography to measure the pulmonary veins. We were able to identify segments of the right pericardiacophrenic artery (mean length 25 mm [range 7-68 mm]) in only 10 patients (20%).

ICD proarrhythmia as a consequence of an interaction with an algorithm to prevent atrial arrhythmias.

An episode of device‐related proarrhythmia is reported. Ventricular tachycardia was induced by ventricular pacing in a dual‐chamber implantable cardioverter‐defibrillator due to an inappropriate interaction of programmed device settings with the atrial preference pacing, an automatic algorithm designed to prevent atrial tachyarrhythmias.

Value of the “Standing Test” in the Diagnosis and Evaluation of Beta-blocker Therapy Response in Long QT Syndrome

INTRODUCTION AND OBJECTIVES Patients with congenital long QT syndrome (LQTS) have an abnormal QT adaptation to sudden changes in heart rate provoked by standing. The present study sought to evaluate the standing test in a cohort of LQTS patients and to assess if this QT maladaptation phenomenon is ameliorated by beta-blocker therapy. METHODS Electrographic assessments were performed at baseline and immediately after standing in 36 LQTS patients (6 LQT1 [17%], 20 LQT2 [56%], 3 LQT7 [8%], 7 unidentified-genotype patients [19%]) and 41 controls. The corrected QT interval (QTc) was measured at baseline (QTcsupine) and immediately after standing (QTcstanding); the QTc change from baseline (ΔQTc) was calculated as QTcstanding - QTcsupine. The test was repeated in 26 patients receiving beta-blocker therapy. RESULTS Both QTcstanding and ΔQTc were significantly higher in the LQTS group than in controls (QTcstanding, 528 ± 46ms vs 420 ± 15ms, P < .0001; ΔQTc, 78 ± 40ms vs 8 ± 13ms, P < .0001). No significant differences were noted between LQT1 and LQT2 patients. Typical ST-T wave patterns appeared after standing in LQTS patients. Receiver operating characteristic curves of QTcstanding and ΔQTc showed a significant increase in diagnostic value compared with the QTcsupine (area under the curve for both, 0.99 vs 0.85; P < .001). Beta-blockers attenuated the response to standing in LQTS patients (QTcstanding, 440 ± 32ms, P < .0001; ΔQTc, 14 ± 16ms, P < .0001). CONCLUSIONS Evaluation of the QTc after the simple maneuver of standing shows a high diagnostic performance and could be important for monitoring the effects of beta-blocker therapy in LQTS patients.

Heterogeneous Phenotype of Long QT Syndrome Caused by the KCNH2-H562R Mutation: Importance of Familial Genetic Testing.

INTRODUCTION AND OBJECTIVES Long QT syndrome is an inherited ion channelopathy that leads to syncope and sudden death. Because of the heterogeneous phenotype of this disease, genetic testing is fundamental to detect individuals with concealed long QT syndrome. In this study, we determined the features of a family with 13 carriers of the KCNH2-H562R missense mutation, which affects the pore region of the HERG channel. METHODS We identified the KCNH2-H562R mutation in a 65-year-old man with a prolonged QTc interval who had experienced an episode of torsade de pointes. Subsequently, a total of 13 mutation carriers were identified in the family. Carriers (age 48 [26] years; 46% males) underwent clinical evaluation, electrocardiography and echocardiography. RESULTS The mean (standard deviation) QTc in carriers was 493 (42) ms (3 [23%] showed normal QTc); 6 (46%) had symptoms (4, syncope; 1, sudden death; 1, aborted sudden death [proband]). While under treatment with beta-blockers, 11 of 12 carriers (92%) remained asymptomatic at 5 years of follow-up (1 patient required left cardiac sympathectomy). The QTc shortening with beta-blockers was 50 (37) ms. There was 1 sudden death in a patient who refused treatment. CONCLUSIONS Family study is essential in the interpretation of a genetic testing result. This article describes the heterogeneous and variable phenotype of a large family with the KCNH2-H562R mutation and highlights the role of genetic study for the appropriate identification of at-risk individuals who would benefit from treatment.

Comparación del grado de opacificación auricular derecha con ecocardiografía intracardiaca tras inyecciones femoral y antecubital de contraste salino

Se asume que la superioridad de la inyeccion femoral de suero salino agitado para la deteccion del foramen oval permeable comparada con la antecubital se debe principalmente al efecto de las corrientes intrauriculares de la desembocadura de las cavas. Nos propusimos evaluar la influencia del lugar de inyeccion de contraste en el grado de opacificacion auricular derecha en ecografia intracardiaca. Se puntuo de 0 a 4 el grado de opacificacion obtenido tras inyecciones venosas por via antecubital y femoral de contraste salino en 21 pacientes. Se comprobo que el grado de opacificacion auricular derecha es mayor tras la inyeccion femoral que la antecubital (3,76 frente a 1,62; p

Multiple Interatrial Electrical Connection after Heart Transplantation

A 62‐year‐old woman who underwent heart transplantation 6 years later presented a regular atrial tachycardia. Electrophysiologic evaluation showed an atrial arrhythmia in the recipient atrium with 2:1 conduction to the donor atrium, with a confusing electroanatomical map. With the suspect of alternant conduction through two different breakthroughs, the map was split in two concordant maps, corresponding to two connections that were successfully ablated. Later on, a third connection was detected and therefore ablated. (PACE 2011; 1–3)

Duration of head-up tilt test for patients with suspected vasovagal syncope: a not-so-‘original article’

We have read with great interest the article published by Liu et al .1 about the duration of the tilt test in patients with suspected vasovagal syncope. We would like to highlight that a very similar paper (Head-up Tilt Test Potentiated with Nitroglycerin. What is the Optimal Duration of the Test after Administration of the Drug?2) was published by our group in 2002 in Rev Esp Cardiol , with an English …

Usefulness of Incremental Atrial Pacing for Evaluating the Effectiveness of Perinodal Slow Pathway Ablation

Introduction and objectives. To study the usefulness of incremental atrial pacing for evaluating the effect of radiofrequency catheter ablation on slow pathway conduction in patients with atrioventricular (AV) nodal reentrant tachycardia. Methods. A prospective study was carried out in patients either with (ie, AV nodal reentrant tachycardia group) or without (ie, control group) inducible AV nodal reentrant tachycardia who were referred for electrophysiologic study. Incremental atrial pacing involved gradually decreasing the pacing cycle length until the PR interval exceeded the R-R interval (ie, PR>RR) or AV nodal block occurred. The presence of dual anterograde AV nodal physiology was assessed during programmed atrial stimulation using standard criteria. In the AV nodal reentrant tachycardia group, electrophysiologic study was repeated 30 minutes after successful catheter ablation. Results. In the AV nodal reentrant tachycardia group (n=85), 52 patients (61%) exhibited dual AV nodal physiology during programmed atrial stimulation and 66 (78%) had a PR>RR during incremental atrial pacing. In the control group, the corresponding proportions were 10/56 (18%) and 7/56 (12%), respectively. After successful slow pathway catheter ablation (81/85), 37/81 exhibited dual AV nodal physiology during programmed atrial stimulation while 1/81 had a PR>RR during incremental atrial pacing. The positive predictive value of successful slow pathway ablation for the absence of a PR>RR was 98%. Conclusions. Incremental atrial pacing demonstrated that the PR interval exceeded the R-R interval in the majority of patients with inducible AV nodal reentrant tachycardia. This technique could provide a fast and simple way of evaluating the effect of radiofrequency catheter ablation on slow pathway conduction.