Trigeminia de la bigeminia ventricular por mecanismo reentrante: reentrada de la reentrada / Trigeminy of ventricular bigeminy caused by reentrant mechanism: reentry of reentry

El proceso post-infarto agudo de miocardio genera el sustrato apropiado para la formación de circuitos de reentrada, los cuales son considerados como el mecanismo más frecuente de las extrasístoles y taquiarritmias ventriculares. Presentamos el trazado electrocardiográfico de un paciente con infarto agudo de miocardio en quien se observó la inusual concurrencia de una trigeminia ventricular acoplada a extrasístoles ventriculares bigeminadas, que originó una secuencia de trigeminia sobre la bigeminia, evidenciando la existencia de dos circuitos reentrantes (reentrada de la reentrada); después de una dupla de la extrasístole bigeminada se genera un aleteo ventricular.

The process that follows an acute myocardial infarction generates an appropriate substrate for the formation of reentry circuits, considered to be the most frequent mechanism of ventricular extrasystoles and tachyarrhythmias. We present the case of a patient with an acute myocardial infarction unusually concurring with ventricular trigeminy coupled to ventricular bigeminated extrasystoles giving rise to a trigeminy sequence over the bigeminy, which indicates the existence of two reentry circuits (reentry of reentry) that trigger ventricular flutter.

Síncope em pacientes com extra-sístoles de via de saída de ventrículo direito e sem cardiopatia estrutural aparente / Syncope in patients with right ventricle outflow tract premature beats and no apparent structural cardiopathy

OBJETIVO: Estudar a prevalência de síncope neurocardiogênica em pacientes com síncope inexplicada e extra-sístoles ventriculares (EV), com morfologia de via de saída de ventrículo direito (VSVD) sem cardiopatia estrutural aparente. MÉTODOS: Noventa pacientes (66 mulheres, idade média de 40,2 ± 16,95 anos) com EV monomórficas com origem na VSVD foram avaliados prospectivamente. Cinqüenta e quatro pacientes apresentavam síncopes ou pré-síncopes associadas ou não a palpitações; 27 apresentavam palpitações sem pré-síncope ou síncope, e 9 eram assintomáticos. Todos foram submetidos a ecocardiograma, ECG de alta resolução, ressonância magnética cardíaca e teste de esforço para afastar cardiopatia estrutural e taquicardia ventricular adrenérgico-dependente, e a monitorização com Holter e monitor de eventos sintomáticos para correlacionar os sintomas com a arritmia. A investigação de suscetibilidade a síncope neurocardiogênica foi avaliada pelo teste de inclinação (TI). Os grupos foram comparados quanto a sexo, idade, freqüência e complexidade das extra-sístoles, com e sem esforço físico, resultado do TI e evolução clínica. RESULTADOS: No grupo com síncope e pré-síncope, o TI foi positivo em 38 por cento dos casos e nos grupos com palpitações e assintomáticos, em 11 por cento (p = 0,0257). Após orientação e tratamento da síncope neurocardiogênica, 85 por cento dos pacientes com síncope e pré-sincope e TI positivo permaneceram assintomáticos durante seguimento médio de 40 meses. Dois pacientes com síncope e TI negativos apresentaram taquicardia ventricular sustentada espontânea durante a evolução clínica. CONCLUSÃO: A prevalência de síncope neurocardiogênica em pacientes com EV idiopáticas de VSVD é alta. Pacientes com síncope recorrente inexplicada e EV idiopáticas devem ser mantidos sob investigação.

OBJECTIVE: Study the prevalence of neurocardiogenic etiology in patients with unexplained syncope and ventricular premature beats, with right ventricle outflow tract morphology (RVOT) and no apparent structural cardiopathy. METHODS: Ninety patients (66 women, mean age 40.2±16.95 years of age) with monomorphic premature beats originated at RVOT were evaluated prospectively. Fifty-four patients reported syncopes or near-syncopes associated to palpitations or not; twenty-seven presented palpitations with no pre-syncope or syncope, and nine were asymptomatic. All patients were submitted to echocardiogram, high resolution ECG and cardiac MRI to rule out structural cardiopathy, to exertion test to rule out adrenergic dependent ventricular tachycardia, and ECG prolonged outpatient monitoring (Holter and symptomatic events monitor) to correlate symptoms and ventricular arrhythmias. Investigation on the susceptibility to neurocardiogenic syncope was evaluated by Tilt Table Test (TTT). Groups were compared regarding gender, age, premature beats frequency and complexity, at exertion or not, TTT results and clinical course. RESULTS: In the syncope and pre-syncope groups, TTT was positive for 38 percent of cases, and in groups with palpitations and assymptomatics, it was positive for 11 percent (p = 0.0257). After recommendations and treatment of neurocardiogenic syncope, 85 percent of syncope and pre-syncope patients and positive TTT was asymptomatic along the 40-month follow-up. Two patients with syncope and negative TTT presented spontaneous, sustained ventricular tachycardia during clinic course. CONCLUSION: The prevalence of neurocardiogenic syncope in patients with idiopathic RVOT premature beats is high. Patients with recurrent, unexplained syncope and idiopathic VE must be kept under investigation.

Mechanisms underlying the genesis of post-extrasystolic potentiation in rat cardiac muscle

Changes of contractility resulting from changes in stimulation pattern (post-extrasystolic potentiation - PESP) were investigated in right ventricular papillary muscles from female albino rats (EPM strain, 160-200 g). The preparations were superfused with bicarbonate buffered solution at 24 + or - 0.5§C, and stimulated at 0.5 Hz. Maintaned paired stimulation was performed at several coupling intervals (360, 500, 660, 770 and 920 ms) with normal Krebs for 30 s. After treatment with ryanodine (1 µM), used as an inhibitor of the release of sarcoplasmic reticulum Ca2+ activity, the same protocol was repeated in the presence of normal Krebs, low Na+ (80 mM, LiCl used as substitute) and low K+ concentrations to change the level of activity of the Na+/Ca2+ exchange mechanism. With normal Krebs, paired pulse stimulation produced a maintained potentiation of the post-extrasystolic beat and an extrasystole and the normal beat was increased the potentiation of the post-extrasystolic beat was reduced and the force of the extrasystole was increased. Rynodine treatment reduced the force of contraction and increased its duration, and the pattern of the PESP...

Variabilidade espontânea da extra-sistolia ventricular na cardiopatia chagásica crônica / Spontaneous variabitity of ventricular extrasystole in chronic Chagas cardiopathy

Purpose - To study the spontaneous variability of single (VPCs) and coupled (CVPCs) in patients with chronic Chagas' disease (CCD). Patients and Methods - Twenty patients with CCD, 14 male, in class I and III NYHA, with frequent VPCs and VCPCs, free of drug therapy were studied.21 hour Holter monitoring was done for 4 subsequent days. The data analysis assessed the variation in the frequency of VPCs and CVPCs between patients, seven hour periods one hour periods in a hierarchical model by a Poisson process. Results - a) the frequency of VPCs follows a circadian rhythm, closely related to the hourly variations of the mean heart rate; b) disregarding the heart rate influence on the variability of the ventricular arrhythmia, its behavior was at random and unpredictable; c) the minimal percentual reduction in VPCs/h that discriminated between antiarrhythmic effect and spontaneous between antiarrhythmic effect and spontaneous variability was 121.86% for sevenhour, 58.42% for 21-hour and 38.45% for 42-hour electrocardiographic monitoring periods; d) the same approch for the VCPCs revealed values of 133,8%, 63.21% and 41.3% respectively

Arritmias infantiles: transtornos sinusales. Estrasístoles / Disrhythmian in children: sinusal disorders. Extrasystoles

Los autores hacen una revisión de las arritmias propias de la infancia, en cuanto a etiología, patogenia, interpretación de ECG, manifestaciones clínicas, bases del tratamiento y prevención

Extrasistolia supraventricular con intervalo post-extrasistólico prolongado: su importancia para el diagnóstico de la enfermedad del nódulo sinusal / Supraventricular extrasystole with prolonged post-extrasystolic interval: its importance for the diagnostic of sick sinus

Se presentan 5 (cinco) pacientes estudiados mediante monitoreo electrocardiográfico contínuo (sistema Holter), se mostraron en sus respectivos registros extrasístoles supraventriculares con pausas post-extrasistólicas de más de 2.000 milisegundos (Ms) y PRs normal. Se correlaciona este dato con aumento significativo del Tiempo de recuperación del Nódulo Sinusal corregido (TRNSo), determinado por medio de estudios electrofisiológicos. De la relación directa y permanente observada entre ambos datos, siempre coincidentes, se infiere la importancia que adquiere la medición de la pausa post-extrasistólica auricular en el ECG de Holter para el diagnóstico de la Enfermedad del Nódulo Sinusal (ENS)

Determinación del tiempo de condución senoauricular

El aumento del tiempo de conducción senoauricular (TCSA) es uno de los signos electrofisiológicos del síndrome del seno enfermo. Para medirlo en forma indirecta Strauss y cols desarrolaron una técnica basada en la introducción prematura de estímulos auriculares artificales. Se revisan los fundamentos teoricos del método de dicho autor y se propone el uso de extrasístoles auriculares en vez de extraestímulos artificiales para la medida del TCSA

Retrograde atrial conduction and reciprocal beating

Esta comunicación se refiere a la conducción atrial retrograda y la pulsación recíproca, particularmente su relación con los marcapasos cardíacos. Se ilustran cuatro de estos casos. Se enfatiza el rol patogénico de la conducción atrial retrógrada, la sensibilidad atrial al desatar el movimiento en círculo. Se discuten las taquicardias mediadas por marcapasos en pacientes con marcapasos DDD y VDD, asi como el manejo de estos pacientes

Extra-sístole sinusal. Fato ou ficçäo? Relato de caso / Sinus extrasystole. Factor of fiction? Report of a case

Um caso de extra-sístole sinusal foi estudado e os aspectos de diagnóstico, os diagnósticos diferenciais, os mecanismos eletrofisiológicos e as possíveis implicaçöes clínicas säo discutidos. Conclui-se que 1) o diagnóstico é feito pela presença de ondas P prematuras idênticas às sinusais em todos os aspectos e derivaçöes; acoplamento fixo e pausa pós-extra-sistólica incompleta; 2) a reentrada é seu provável mecanismo eletrofisilógico básico; 3) o principal diagnóstico diferencial é com o bloqueio sino-atrial 3:2 com fenômeno de Wenckebach; 4) a implicaçäo clínica, provavelmente, é a mesma das extra-sístole atriais