Fisiopatología del bloqueo interauricular y su rol como predictor de arritmias supraventriculares

El Bloqueo Interauricular (BIA) puede servir como un valioso marcador electrocardiográfico para evaluar el riesgo del desarrollo de arritmias auriculares, y nueva aparición de fibrilación auricular (FA). El BIA se produce por un deterioro en la conducción auricular que implica un retraso en la conducción del estímulo eléctrico desde la aurícula derecha a la aurícula izquierda. Las causas probables de interrupción del haz de Bachmann incluyen isquemia, enfermedad degenerativa del envejecimiento, enfermedades infiltrativas, enfermedad coronaria difusa y afecciones inflamatorias. Los factores de riesgo para el BIA avanzado, la fibrilación auricular (FA) y el accidente cerebrovascular (ACV) parecen ser muy similares, y la patogénesis subyacente probablemente se deba a fibrosis miocárdica y remodelación auricular. El bloqueo interauricular se relaciona clínicamente a la aparición de taquiarritmias supraventriculares y está relacionado al remodelamiento auricular. Aunque el agrandamiento auricular y el BIA comparten un patrón electrocardiográfico similar, son dos entidades separadas. Sin embargo, muchos autores aún asocian una duración de la onda P mayor a 120 ms con agrandamiento de la aurícula izquierda. El remodelamiento auricular modifica la velocidad de conducción, la arquitectura cardiaca, los canales iónicos dependientes de voltaje, y los componentes de resistencia y capacitancia, como son el espacio extracelular y las uniones celulares. La alteración de estas propiedades afecta las propiedades electrofisiológicas de la conducción auricular y favorece el BIA, los trastornos auriculares y la génesis de FA.

Interatrial block (IAB) can serve as a valuable electrocardiographic marker to assess the risk of developing atrial arrhythmias, and new onset of atrial fibrillation (AF). The IAB is produced by a deterioration in atrial conduction that implies a delay in the conduction of the electrical stimulus from the right atrium to the left atrium. Probable causes of Bachmann bundle interruption include ischemia, degenerative disease of aging, infiltrative diseases, diffuse coronary disease, and inflammatory conditions. The risk factors for advanced IAB, atrial fibrillation (AF), and cerebrovascular accident (CVA) appear to be very similar, and the underlying pathogenesis is probably due to myocardial fibrosis, and atrial remodeling. The interatrial block is clinically related to the appearance of supraventricular tachyarrhythmias and is related to atrial remodeling. Although atrial enlargement and IAB share a similar electrocardiographic pattern, they are separate entities. However, many authors still associate P wave duration greater than 120 ms with left atrial enlargement. Atrial remodeling modifies conduction velocity, cardiac architecture, voltage-gated ion channels, and resistance and capacitance components, such as the extracellular space and cell junctions. The alteration of these properties affects the electrophysiological properties of atrial conduction and favors IAB, atrial disorders, and the genesis of AF.

Arrhythmogenic right ventricular cardiomyopathy associated with arrhythmia-induced cardiomyopathy: A case report / 北京大学学报(医学版)

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a kind of inherited cardio-myopathy, which is characterized by fibro-fatty replacement of right ventricular myocardium, leading to ventricular arrhythmia. However, rapid atrial arrhythmias are also common, including atrial fibrillation, atrial flutter and atrial tachycardia. Long term rapid atrial arrhythmia can lead to further deterioration of cardiac function. This case is a 51-year-old male. He was admitted to Department of Cardiology, Peking University Third Hospital with palpitation and fatigue after exercise. Electrocardiogram showed incessant atrial tachycardia. Echocardiography revealed dilation of all his four chambers, especially the right ventricle, with the left ventricular ejection fraction of 40% and the right ventricular hypokinesis. Cardiac magnetic resonance imaging found that the right ventricle was significantly enlarged, and the right ventricular aneurysm had formed; the right ventricular ejection fraction was as low as 8%, and the left ventricular ejection fraction was 35%. The patients met the diagnostic criteria of ARVC, and both left and right ventricles were involved. His physical activities were restricted, and metoprolol, digoxin, spironolactone and ramipril were given. Rivaroxaban was also given because atrial tachycardia could cause left atrial thrombosis and embolism. His atrial tachycardia converted spontaneously to normal sinus rhythm after these treatments. Since the patient had severe right ventricular dysfunction, frequent premature ventricular beats and non-sustained ventricular tachycardia on Holter monitoring, indicating a high risk of sudden death, implantable cardioverter defibrillator (ICD) was implanted. After discharge from hospital, physical activity restriction and the above medicines were continued. As rapid atrial arrhythmia could lead to inappropriate ICD shocks, amiodarone was added to prevent the recurrence of atrial tachycardia, and also control ventricular arrhythmia. After 6 months, echocardiography was repeated and showed that the left ventricle diameter was reduced significantly, and the left ventricular ejection fraction increased to 60%, while the size of right ventricle and right atrium decreased slightly. According to the clinical manifestations and outcomes, he was diagnosed with ARVC associated with arrhythmia induced cardiomyopathy. According to the results of his cardiac magnetic resonance imaging, the patient had left ventricular involvement caused by ARVC, and the persistent atrial tachycardia led to left ventricular systolic dysfunction.

Study of Anatomical Variations of Number of Pulmonary Veins and its Clinical Significance

Introduction: The pulmonary veins play an important rolein the pulmonary circulation by receiving oxygenated bloodfrom the Lungs and delivering it to the left atrium. Pulmonaryvein anatomy piqued curiosity of researchers off late afterthe discovery of its role in genesis of atrial arrhythmias andincreased incidence of pulmonary hypertension in COPD.The congenital variations in number of pulmonary veinsand their drainage patterns, encompass a wide spectrum ofanomalies and are not uncommon in general population. Theaim of the study was to observe the variations in the numberof pulmonary veins and pulmonary ostia.Material and Methods: The present study was done on 25formalin fixed hearts aged 18-70 years, obtained from thedepartment of anatomy, Sri Padmavathi Medical college forwomen, Tirupathi. These hearts were observed for the numberof pulmonary veins, their drainage into left atrium, variationsin pulmonary ostia on right and left sides and were comparedwith previous studies.Results: Out of the 25 specimens studied, 23 hearts (92%)had normal pattern of four pulmonary veins, two from eachlung extending to the left atrium and opening into it via twoseparate pulmonary ostia, on either side. In 2 (8%) out of 25specimens, variations in the number of pulmonary veins andthe pulmonary ostia were observed.Conclusion: The awareness of the variant anatomy ofpulmonary veins and their drainage is of paramountimportance to Radiologists, Electrophysiologist and Cardiothoracic surgeons while performing surgical procedures onHeart.

Efecto electromecánico de los antiarrítmicos clase Ic durante el tratamiento de arritmias auriculares en cardiopatías congénitas / Electromechanical effect of Ic class antiarrhythmic drugs during the treatment of atrial arrhythmias in congenital heart diseases

Introducción: los fármacos antiarrítmicos son la primera línea de tratamiento para el control de las taquiarritmias en el paciente pediátrico. La terapéutica con drogas clase Ic en los pacientes con cardiopatías congénitas ha sido limitada, por los reportes que demostraron incremento de la mortalidad en los sujetos con cardiopatías estructurales. Objetivo: valorar el efecto de los antiarrítmicos clase Ic sobre los fenómenos electro-mecánicos cardiacos en los niños con cardiopatías congénitas con arritmias auriculares. Métodos: se realizó un estudio analítico, observacional, longitudinal y prospectivo en los pacientes con cardiopatías congénitas que desarrollaron arritmias auriculares, tratados con antiarrítmicos clase Ic en el Cardiocentro Pediátrico William Soler . Se analizaron variables electrocardiográficas, así como estimación de la función sistodiastólica mediante el ecocardiograma. Resultados: fueron evaluados 46 pacientes, 25 tratados con flecainida (grupo I) y 21 con propafenona (grupo II) durante 4,57±0,86 años. La taquicardia por reentrada intraatrial fue la arritmia de mayor incidencia (58,69 por ciento), mientras que, la tetralogía de Fallot, el defecto cardiaco más común (36,9 por ciento). Las variables electrocardiográficas no sufrieron variaciones nítidas durante el seguimiento. El análisis comparativo intragrupal demostró la preservación de la función sistólica en la totalidad de los sujetos (I, p= 0,275; II, p= 0,262). Comportamiento análogo exhibió la función diastólica, expresada en el índice de Tei (I, p= 0,244; II, p= 0,286). Conclusiones: la utilización de antiarrítmicos clase Ic en los pacientes pediátricos con cardiopatías congénitas no se asocia a largo plazo con alteraciones electrocardiográficas significativas ni compromiso de la función sistodiastólica, por lo que se recomienda su uso en esta población(AU)

Introduction: antiarrhythmic drugs are the first line of treatment for the control of tachyarrhythmias in pediatric patients. Therapy with Ic class drugs in patients with congenital heart disease has been limited, mainly due to reports that showed an increase in mortality in patients with structural heart disease. Objective: to assess the effect of Ic class antiarrhythmic drugs on cardiac electro-mechanical phenomena in children with congenital heart disease with atrial arrhythmias. Methods: an analytical, observational, longitudinal and prospective study was performed in patients with congenital heart diseases who developed atrial arrhythmias treated with Ic class antiarrhythmic drugs in William Soler Pediatric Cardiocenter. Electrocardiographic variables were analyzed, as well as the estimation of systo-diastolic function by echocardiography. Results: 46 patients were evaluated, 25 treated with flecainide (group I) and 21 with propafenone (group II) during 4.57 ± 0.86 years. The intra-atrial reentrant tachycardia was the arrhythmia with the highest incidence (58.69 percent); while tetralogy of Fallot was the most common cardiac defect (36.9 percent). The electrocardiographic variables did not undergo sharp variations during the follow-up. The intergroup comparative analysis showed the preservation of systolic function in all subjects (I, p= 0.275; II, p= 0.262). Analogous behavior showed diastolic function, that was expressed in the Tei index (I, p= 0.244; II, p= 0.286). Conclusions: the use of Ic class antiarrhythmic drugs in pediatric patients with congenital heart disease is not associated in the long term with significant electrocardiographic alterations or compromise of systo-diastolic function, so its use is recommended in this population(AU)

EFECTO DEL REMODELADO ELÉCTRICO AURICULAR EN UN MODELO TRIDIMENSIONAL DE AURÍCULA HUMANA

Las arritmias cardíacas más frecuentes en humanos tienen origen auricular. El modelado de la actividad auricular se ha convertido en una importante herramienta en el análisis de arritmias como la fibrilación auricular. Estudios experimentales han demostrado que la fibrilación auricular tiende a perpetuarse, generando cambios electrofisiológicos denominados remodelado auricular. En este trabajo se presenta un modelo tridimensional geométricamente realista de la aurícula humana, al cual se le incorporan: anisotropía, dirección de las fibras y heterogeneidad en la conductividad. En un modelo del potencial de acción acoplado al modelo tridimensional, se estudió el efecto del remodelado auricular sobre el potencial de acción y su propagación teniendo en cuenta sus efectos sobre las corrientes iónicas. El modelo reprodujo el comportamiento de la actividad eléctrica en toda la superficie auricular. El remodelado redujo la duración del potencial de acción, el periodo refractario efectivo y la velocidad de conducción. Los resultados sugieren que en el modelo tridimensional desarrollado, es posible simular la actividad eléctrica auricular en condiciones fisiológicas y con remodelado eléctrico auricular.

The most common cardiac arrhythmias in humans originate in the atrium. Modelling of the atrial activity has become an important tool to analyze arrhythmias such as atrial fibrillation. Experimental studies have shown that atrial fibrillation tends to be perpetual, generating electrophysiological changes called atrial remodeling. In this study we present a geometrically realistic three-dimensional (3D) model of human atrium, which incorporates anisotropy, direction of the fibers and conductive heterogeneity. The effects of remodeling on the ionic currents were applied to an action potential model coupled to the 3D model. The effects of remodeling on the action potential and its propagation were studied the model reproduced the electrical activity behavior across the atrial surface. Remodelling induced a reduction in the action potential duration, the effective refractory period and the conduction velocity. Our results suggest that in the developed 3D model of human atrium is possible to simulate the atrial electrical activity under physiological conditions and with atrial electrical remodeling.

Sinus node function in patients operated for mitral valve disease: indirect evaluation with epimyocardial electrodes / Função do nó sinusal em pacientes submetido a correção cirúrgica da valvopatia mitral: avaliação indireta com eletrodos epimiocárdicos

PURPOSE: To study the interatrial conduction times and atrial node performance in patients submitted to mitral valve surgery with the aid of temporary atrial epicardic electrodes. METHODS: The atriograms were carried out in the first postoperative day and before the hospital discharge of ten consecutive patients. RESULTS: Sixty percent of the patients could complete the post-operative study protocol. The main results were: a) Post-operative arrhythmias were detected in 50 percent of the patients; b) There were no statistical differences between the pre and post-operative 12 lead EKGs. c) The interatrial conduction time (IACT) ranged from 90 to 140ms in the first post-operative day, and from 110 to 130ms at hospital discharge; d) The sinus node recovery time (SNRT) ranged from 250 to 560 ms in the first post-operative day and from 180 to 360ms at hospital discharge; e) The sinus atrial conduction time (SACT) remained between 70 and 140ms, both in the first post-operative day and at hospital discharge, and; f) The IACT was normal in patients whose left atrium (LA) was less than 50mm in diameter but supra normal in the remaining cases. CONCLUSIONS: Sinus node function and inter-atrial conduction are not altered by mitral valve operation. Post-operative programmed epicardic atrial stimulation is easy and safe.

OBJETIVO: Estudar os tempos de condução interatrial e a função do nó sinusal em pacientes submetidos a tratamento cirúrgico. MÉTODOS: Foram estudados 10 pacientes adultos consecutivos submetidos à operação de correção de valvopatia mitral. Registraram-se atriogramas usando eletrodos epimiocárdicos cirurgicamente implantados. Os atriogramas foram obtidos no primeiro dia do pós-operatório e antes da alta hospitalar. RESULTADOS: Os principais achados foram: a) A incidência de arritmias atriais até alta hospitalar foi de 50 por cento; b) O tempo de condução interatrial (TCIA) variou de 90 a 140 ms no 1°PO e 110 a130 ms antes da alta hospitalar; c) O tempo de recuperação do nó sinusal (TRNS) variou de 250 a 560 ms no 1°PO e180 a 360 ms antes da alta hospitalar; d) O tempo de condução sinoatrial (TCSA) variou de 70 a 140 ms tanto no 1ºPO, como antes da alta hospitalar e; d) O tempo de condução interatrial (TCIA) foi normal em pacientes com átrio esquerdo menores do que 50 mm e supranormal nos outros casos. CONCLUSÃO: As funções do nó sinusal e a condução interatrial não foram alteradas pelo tratamento cirúrgico da valvopatia mitral. A estimulação atrial epicárdica programada é segura de fácil realização.

Catheter Ablation of Atrial Fibrillation

Atiarrhythmic drugs that are currently in use are not only frequently ineffective at eliminating atrial fibrillation (AF), but also life-threatening in some patients. However, the accumulating clinical experience along with the remarkable advancement in the technology has made the catheter ablation (CA) of AF more effective and safe. The application of circular mapping catheters that can identify pulmonary vein (PV) potentials (PVPs) within the PVs has allowed the effective guidance of the electrical isolation of the PVs from the left atrium (LA). The widespread utilization of 3-dimensional (D) mapping systems has facilitated the improvement of the outcomes after CA in patients with paroxysmal (PAF) and even chronic AF (CAF). Different strategies that are currently in use are as follows segmental ablation of each PV ostium guided by PVPs, pure anatomic approach of circumferential PV ablation (CPVA), CPVA with electrical isolation, complex fractionated atrial electrograms during AF guided ablation, and ablation of ganglionated plexuses, etc. The efficacy of each approach varies according to the investigators and subsets of AF. CPVA with electrical isolation is known to be more effective and is widely used. With further development of new energy sources of ablation and mapping systems, it is important to simplify, standardize, and shorten the procedures, which may enable the CA to become more effective, safe, and applicable to many different subsets of AF. CA of AF has evolved rapidly and has become accepted as one of the therapeutic modalities to cure AF.

Efficacy and safety of intravenous cediland and esmolol and daltiazem for controlling rapid atrial arrhythmias / 中国实用内科杂志

ObjectiveTo evaluate the efficacy of intravenous cediland(lanatoside C) and esmolol and daltiazem for controlling rapid atrial arrhythmias.MethodsA total of 94 patients with rapid atrial arrhythmias were randomized to receive intravenous cediland(n=29) and esmolol(n=30) and daltiazem(n=35),respectively.ResultThe total efficacy rate were 86%,83% and 85%,with a mean decrease in heart rate by 30.4%,29.3 and 27.6% compared to baseline,and mean response times was 34.3?21.0min、8.1?2.1min and 11.3?3.8min,respectively.ConclusionThree drugs are all effective、rapid and safe in slowing rapid ventricular rate in patients with rapid atrial arrhythmias.