Usefulness of ventricular sense response in last-generation cardiac resynchronization therapy devices.

OBJECTIVES: High percentages of pacing were associated to maximal symptomatic and mortality benefit from cardiac resynchronization therapy (CRT). Loss of CRT pacing is linked to intrinsic ventricular activation preceding biventricular pacing (BiV), as it occurs in patients with atrial fibrillation (AF). Last generation CRT devices incorporate the ventricular sense response (VSR) mechanism to maintain biventricular pacing in patients with atrial arrhythmias. This work aimed to characterize electrical dyssynchrony differences among baseline, BiV and VSR pacing, and determine whether the VSR mode is as beneficial as the BiV mode in terms of electrical dyssynchrony. METHODS: Thirty-two patients implanted with CRT devices were retrospectively studied. All patients presented non-ischemic dilated myocardiopathy and complete left bundle branch block (LBBB). Every patient went through baseline, BiV and VSR pacing while recording the 12­lead ECG. Electrical dyssynchrony was assessed by a dyssynchrony index (DIn) obtained from correlation analysis on the 12­lead ECG. RESULTS: When comparing with baseline, VSR pacing improved QRS duration (178 ± 22 ms vs 158 ± 43 ms, baseline vs VSR, p < 0.05) and so did BiV pacing (178 ± 22 ms vs 142 ± 20 ms, baseline vs BiV, p < 0.05). However, electrical dyssynchrony only improved at BiV pacing (2.86±0.6 vs 0.54±0.8, baseline vs BiV, p < 0.05) while VSR showed average DIn values similar to those at baseline. CONCLUSIONS: VSR pacing did not improve the electrical synchrony while did shorten QRS duration in this sample population. Therefore, VSR paced beats would fall in the category of inefficient BiV and may not be the preferred alternative in patients with CRT and AF.

Catheter ablation of left ventricle summit PVC using anterior interventricular vein approach.

A young female patient with normal ejection fraction. History of premature ventricular complex (PVC) radiofrequency ablation located in left ventricular outflow tract. Two years later frequent PVC is observed in a different location (> 47000 in 24 h Holter). Anti-arrhythmic drugs were used unsuccessfully. PVCs were located in left ventricular summit. Radiofrequency ablation through coronary sinus and anterior interventricular vein was performed. During follow up no recurrence was observed.A young female patient with normal ejection fraction. History of premature ventricular complex (PVC) radiofrequency ablation located in left ventricular outflow tract. Two years later frequent PVC is observed in a different location (> 47000 in 24 h Holter). Anti-arrhythmic drugs were used unsuccessfully. PVCs were located in left ventricular summit. Radiofrequency ablation through coronary sinus and anterior interventricular vein was performed. During follow up no recurrence was observed.

Estimulación parahisiana guiada por un índice de correlación cruzada con dos derivaciones electrocardiográficas / Parahisian stimulation guided by a cross-correlation index with two electrocardiographic leads

Introducción. La estimulación apical del ventrículo derecho (VD) produce un patrón de activación similar al bloqueo de rama izquierda, el cual retrasa la activación de la pared lateral del ventrículo izquierdo. El "índice de disincronía" (ID) correlaciona las derivadas DII y V6 como marcadores de la despolarización septal y lateral; en el presente reporte, se utilizó el ID para el implante del electrodo ventricular en la región "parahisiana". Métodos. Se incluyeron 6 pacientes a quienes se realizó un implante electivo de marcapasos bicameral, bajo indicaciones convencionales. En cada paciente se registró un electrocardiograma de 12 derivaciones en reposo, bajo estimulación apical en el (VD) y bajo estimulación septal "parahisiana"; en cada uno se obtuvo el ID. Resultados. Se analizaron 18 electrocardiogramas de 6 pacientes, edad promedio 72±16.7 años (48-91) 2 mujeres; en 4, la indicación del implante fue bloqueo atrioventricular completo y en 2, enfermedad del nodo sinusal. En todos los pacientes se observó mejoría del ID con estimulación parahisiana, con respecto al ápex del VD y en la mayoría también con respecto al ritmo de base. No se observó correlación entre la duración del complejo QRS y el ID. Conclusión. El uso del ID utilizando las derivaciones II/V6 permite valorar la disincronía eléctrica, en forma sencilla, no invasiva y en tiempo real.

Introduction. Right ventricle (RV) apical stimulation produces an activation pattern similar to the left bundle Branch block, which delays the lateral wall of the left ventricle activation. The "dyssynchrony index" (ID) correlates DII and V6 leads as surrogate markers of septal and lateral depolarization; in this report, the ID for the ventricular electrode implantin the "parahisian" region was used. Methods. Six patients were included who underwent an elective dual chamber pacemaker implant, under conventional indications. In each patient, a 12-lead electrocardiogram was recorded at rest, under RV apical stimulation and under "parahisian" septal stimulation; in each one, the ID was obtained. Results. Eighteen electrocardiograms of 6 patients were analysed, average age 72 ± 16.7 years (48-91) 2 women; in 4, the indication of the implant was complete atrioventricular block and in 2, sinus node disease. In all patients, improvement of the ID with parahisian stimulation was observed, with respect to the RV apex, and in most of them, also with respect to the base rhythm. No correlation was observed between the QRS complex duration and the ID. Conclusión The use of the ID using leads II/V6 allows the evaluation of electrical dyssynchrony, in a simple, non-invasive way and in real time.

ECG parameters to predict left ventricular electrical delay.

AIMS: Left ventricular (LV) dyssynchrony lengthens the left ventricular electrical delay (LVED), measured from QRS onset to the first peak of the LV electrogram. We constructed an ECG model to predict LVED noninvasively. METHODS: Intrapatient LVED was measured during a baseline vs nonselective His bundle pacing (nHBP) protocol. This setup provided paired synchronic/non-synchronic LVEDs, allowing intrapatient comparisons. Crosscorrelation of leads II and V6 was accomplished and extracted features together with age and gender fed a linear mixed effects model to predict LVED. RESULTS: Hemodynamic increments were consistent with LVED advances under nHBP in a subset of 17 patients (dP/dtmax, baseline: 938.82 ± 241.95 mm Hg/s vs nHBP: 1034.94 ± 253.63 mm Hg/s, p = 6.24e-4). The inclusion of the area under V6 (AV 6) and the time shift of R-peaks obtained from the crosscorrelation signal (CorS) grouped by patient significantly improved LVED estimation with respect to the model based only on QRS duration, age and gender (p = 1.7e-5). CONCLUSIONS: Interlead ECG changes explained LVED, providing clues about the electrical impulse conduction within the left ventricle noninvasively.

Non-selective His bundle pacing with a biphasic waveform: enhancing septal resynchronization.

Aims: His bundle pacing has shown to prevent detrimental effects from right ventricular apical pacing (RVA) and proved to resynchronize many conduction disturbances cases. However, the extent of His bundle pacing resynchronization is limited. An optimized stimulation waveform could expand this limit when implemented in His bundle pacing sets. In this work, we temporarily implemented RVA and Non-selective His bundle pacing with a biphasic anodal-first waveform (AF-nHB) and compared their effects against sinus rhythm (SR). Methods and results: Fifteen patients referred for electrophysiologic study with conduction disturbances, cardiomyopathy and ejection fraction below 35% were enrolled for the study. The following acute parameters were measured: QRS duration, left ventricular activation (RLVT), time of isovolumic contraction (IVCT), ejection fraction (EF), and dP/dtmax. QRS duration and RLVT decreased markedly under AF-nHB (SR: 169 ± 34 ms vs. nHB: 116 ± 31 ms, P < 0.0005) while RVA significantly increased QRS duration (SR: 169 ms vs. RVA: 198 ms, P < 0.05) and did not change RLVT (P = NS). Consistently, IVCT moderately decreased under AF-nHB (SR: 238 ms vs. RVA: 184 ms, P < 0.05 vs. SR) and dP/dtmax showed a 93.35 [mmHg] average increase under AF-nHB against SR. Also, T-wave inversions were observed during AF-nHB immediately after SR and RVA pacing suggesting the occurrence of cardiac memory. Conclusions: AF-nHB corrected bundle branch blocks in patients with severe conduction disturbances, even in those with dilated cardiomiopathy, outstanding from RVA. Also, the occurrence of cardiac memory during AF-nHB turned up as an observational finding of this study.

Electrical approach to improve left ventricular activation during right ventricle stimulation.

Coronary sinus mapping is commonly used to evaluate left atrial activation. Herein, we propose to use it to assess which right ventricular pacing modality produces the shortest left ventricular activation times (R-LVtime) and the narrowest QRS widths. Three study groups were defined: 54 controls without intraventricular conduction disturbances; 15 patients with left bundle branch block, and other 15 with right bundle branch block. Left ventricular activation times and QRS widths were evaluated among groups under sinus rhythm, right ventricular apex, right ventricular outflow tract and high output septal zone (SEPHO). Left ventricular activation time was measured as the time elapsed from the surface QRS onset to the most distal left ventricular deflection recorded at coronary sinus. During the above stimulation modalities, coronary sinus mapping reproduced electrical differences that followed mechanical differences measured by tissue doppler imaging. Surprisingly, 33% of the patients with left bundle branch block displayed an early left ventricular activation time, suggesting that these patients would not benefit from resynchronization therapy. SEPHO improved QRS widths and left ventricular activation times in all groups, especially in patients with left bundle branch block, in whom these variables became similar to controls. Left ventricular activation time could be useful to search the optimum pacing site and would also enable detection of non-responders to cardiac resynchronization therapy. Finally, SEPHO resulted the best pacing modality, because it narrowed QRS-complexes and shortened left ventricular activations of patients with left bundle branch block and preserved the physiological depolarization of controls.

Electrical approach to improve left ventricular activation during right ventricle stimulation

Coronary sinus mapping is commonly used to evaluate left atrial activation. Herein, we propose to use it to assess which right ventricular pacing modality produces the shortest left ventricular activation times (R-LVtime) and the narrowest QRS widths. Three study groups were defined: 54 controls without intraventricular conduction disturbances; 15 patients with left bundle branch block, and other 15 with right bundle branch block. Left ventricular activation times and QRS widths were evaluated among groups under sinus rhythm, right ventricular apex, right ventricular outflow tract and high output septal zone (SEPHO). Left ventricular activation time was measured as the time elapsed from the surface QRS onset to the most distal left ventricular deflection recorded at coronary sinus. During the above stimulation modalities, coronary sinus mapping reproduced electrical differences that followed mechanical differences measured by tissue doppler imaging. Surprisingly, 33% of the patients with left bundle branch block displayed an early left ventricular activation time, suggesting that these patients would not benefit from resynchronization therapy. SEPHO improved QRS widths and left ventricular activation times in all groups, especially in patients with left bundle branch block, in whom these variables became similar to controls. Left ventricular activation time could be useful to search the optimum pacing site and would also enable detection of non-responders to cardiac resynchronization therapy. Finally, SEPHO resulted the best pacing modality, because it narrowed QRS-complexes and shortened left ventricular activations of patients with left bundle branch block and preserved the physiological depolarization of controls.

El mapeo del seno coronario se utiliza comúnmente para evaluar la activación de la aurícula izquierda. Aquí, investigamos su utilidad para evaluar qué modalidad de estimulación ventricular derecha produce los menores tiempos de activación ventricular izquierda (R-LVtime). Se definieron tres grupos: 54 controles; 15 pacientes con bloqueo de rama izquierda y 15 con bloqueo de rama derecha. El ancho de QRS y los tiempos de activación fueron evaluados en cada grupo bajo las siguientes modalidades: ritmo sinusal, ápex del ventrículo derecho, tracto de salida del ventrículo derecho y alta salida en septum (SEPHO). El R-LVtime se midió como el tiempo transcurrido desde el inicio del QRS de superficie y la deflexión ventricular izquierda más distal del seno coronario. Durante las distintas modalidades de estimulación, el mapeo del seno coronario reprodujo diferencias eléctricas acompañadas por diferencias mecánicas que fueron evaluadas mediante Tissue Doppler Imaging. El 33% de los pacientes con bloqueo de rama izquierda mostró R-LVtime tempranos, lo que sugiere que estos pacientes no se beneficiarían con terapia de resincronización. SEPHO mejoró el ancho de QRS y el R-LVtime de todos los grupos, especialmente en los pacientes con bloqueo de rama izquierda. En conclusión, el R-LVtime serviría para identificar el sitio óptimo de estimulación y permitiría detectar ciertos no respondedores a la terapia de resincronización. Además, el SEPHO resultó la mejor modalidad de estimulación porque estrechó el QRS y acortó el R-LVtime de los pacientes con bloqueo de rama izquierda pero no alteró la despolarización fisiológica de los controles.

Resincronización electromecánica con estimulación septal de alta energía / Electromechanical Resynchronization with High Energy Septal Pacing

Introducción: La estimulación cardíaca estándar en el ápex del ventrículo derecho altera la sincronía eléctrica por la generación de un bloqueo de rama izquierda, provocando en algunos casos disincronía mecánica. Una estimulación que respete la anatomía (estimulación septal) y tenga la energía suficiente para generar un angostamiento del QRS podría tener un efecto beneficioso, que se evidencia por la mejoría de la sincronía eléctrica y mecánica con mejoramiento de la función miocárdica. Objetivo: Evaluar el comportamiento eléctrico, mecánico y hemodinámico agudo en pacientes con trastornos graves de la conducción intraventricular ante la estimulación de alta energía a nivel septal, comparándola con otros sitios de estimulación en el ventrículo derecho (ápex y tracto de salida). Material y métodos: Se analizaron en forma continua 30 pacientes con edad promedio de 65 años, divididos en: Grupo I (n = 15), con trastornos graves de la conducción, bloqueo completo de rama izquierda o bloqueo completo de rama derecha asociado con hemibloqueo anterior izquierdo, todos con miocardiopatía dilatada con fracción de eyección (FEy) < 35%; y Grupo II (n = 15), sin trastornos de la conducción con FEy conservada. A todos se les realizó un estudio electrofisiológico en el que se constataron parámetros en agudo de duración del QRS en mseg, distancia entre el inicio del QRS de superficie o espiga y las porciones más distales de la pared basal del ventrículo izquierdo (VI) a través del seno coronario (R-LV), el tiempo de contracción isovolumétrica (TIV) por ecocardiografía tisular, la FEy por eco-Doppler (mediciones realizadas off-line por un especialista en imágenes ecocardiográficas) y la evaluación de la dP/dt del VI por catéter Miller intracavitario (solo 18 casos). Estas variables se evaluaron en estado basal (sin estimulación), con estimulación septal de alta energía (7,5 V y 1 mseg de ancho de pulso), con estimulación en el ápex del ventrículo derecho y estimulación en el tracto de salida del ventrículo derecho. En la estimulación con alta energía se evaluaron umbrales de "angostamiento" del QRS. Resultados: El tiempo del QRS, del R-LV y de contracción isovolumétrica mejoraron en el Grupo I con estimulación septal de alta energía, no así en otros sitios, incluso con mejoría de la FEy, mientras que en el Grupo II sin trastornos de la conducción la estimulación septal de alta energía no prolonga el QRS, el R-LV o el TIV ni mejoran la FEy, como sí lo hacen otros sitios de estimulación. La dP/dt del VI presentó un incremento promedio del 14% en 16 de los 18 pacientes evaluados en agudo. Conclusiones: En pacientes con trastornos graves de la conducción con deterioro de la FEy, la estimulación septal de alta energía permite la resincronización electromecánica y la mejoría de la FEy y la dP/dt á . En pacientes sin trastornos de la conducción, esta estimulación septal no altera la sincronía eléctrica, mientras que en otros sitios de estimulación como el ápex y el tracto de salida la deteriora.

Obstructive membrane at the base of the left atrial appendage, a multi-imaging approach.

The left atrial appendage (LAA) is a small muscular extension that grows from the anterolateral wall of the left atrium, in the proximity of the left pulmonary veins. The presence of a membrane in the LAA is a rare clinical entity whose origin is not known. Its clinical implication in the genesis of atrial arrhythmias and thromboembolic risk remains unknown. We report a case of an obstructive membrane located at the base of the LAA, found incidentally in a young patient who was initially undergoing a transesophageal echocardiogram prior to an invasive treatment for atrial fibrillation.