Conduction Disorders: The Value of Surface ECG.

PURPOSE OF REVIEW: The purpose of the current mini-review is to describe the importance of surface ECG for the diagnosis of conduction disorder. METHODS: The MEDLINE/PubMed database was used, with the keywords "ECG" and "conduction disorders"; over the past 10 years. Other documents were included because of their relevance. MAIN FINDINGS: Data on the anatomy and function of the cardiac electrical system have been described. Conduction disorders including sinus node dysfunction, atrioventricular blocks, intraventricular conduction disorders are exposed as to their epidemiology, etiology, presentation, anatomical site of impaired conduction of the electrical stimulus. The importance of ECG in patients with a cardiac implantable electronic device was also discussed, in addition to future perspectives. CONCLUSION: Surface ECG allows the diagnosis of atrioventricular and intraventricular conduction disorder and its anatomical block site most of the time, without the need for invasive tests such as electrophysiological study. Dysfunctions of cardiac implantable electronic devices can be diagnosed by ECG, as well as the prediction of response to cardiac resynchronization therapy.

[Radiofrequency ablation in the treatment of focal atrial fibrillation using circumferential mapping and segmentary disconnection of pulmonary veins]. / Ablación por radiofrecuencia para el tratamiento de la fibrilación auricular focal a través de cartografía circunferencial y aislamiento segmentario de las venas pulmonares.

INTRODUCTION: The treatment of paroxysmal atrial fibrillation in patients without structural heart disease using radiofrequency ablation of pulmonary veins is a recently developed procedure with a good clinical success rate, although there have only been a few published series. We analyzed our results with this technique. METHOD: The procedure was performed in 33 highly symptomatic patients with focal atrial fibrillation that had probably originated in the pulmonary veins. The electrophysiological study was carried out with a decapolar catheter inserted by transeptal catheterization. Ablation was performed using a 4-mm catheter and directed to the segments of the ostium of pulmonary veins where venous potentials with greatest precocity were recorded. Subsequent radiofrecuency applications were performed until pulmonary vein disconnection was achieved. RESULTS: Venous electrical activity was recorded in 59 of 115 pulmonary veins that were mapped (58 were disconnected). During a median follow-up of 180 days, 8 patients recurred and only 2 of these continue with repeat episodes. The success rate at short term was 74.2% and at mid-term was 93.5%. Nineteen patients continue to receive antiarrhythmic treatment innefective before the procedure. Two patients showed complications related to catheter manipulation during tansseptal catheterization, probably due to air embolism, that was resolved spontaneously without consequences. No patient showed pulmonary stenosis. CONCLUSIONS: Teatment of focal atrial fibrillation using circumferential mapping and radiofrecuency application in segments of the ostium of pulmonary veins is a highly effective procedure in selected patients and has potentially severe although infrequent complications.

Novel oral anticoagulants in non-valvular atrial fibrillation.

Atrial fibrillation is the most frequent arrhythmia in clinical practice, reaching 2% of the people in the world and is associated with systemic embolism. Thus, the use of anticoagulants is indicated if CHA2DS2-VASc score ≥ 2 or in patients with previous transient ischemic attack or stroke. For decades, warfarin, a vitamin K antagonist, was the only choice for chronic oral anticoagulation. Recently, novel oral anticoagulants (NOACs) have been introduced, offering similar (or better) effectiveness, safety, and convenience to the vitamin K antagonists. Dabigatran was the first NOAC approved and is a direct thrombin inhibitor. Rivaroxaban and apixaban are factor Xa inhibitors. They display rapid onset of action, more predictable of pharmacological profile, less interactions with other drugs, lack of significant effects in the diet, and less risk of intracranial hemorrhage than warfarin. Despite that dose adjustment is necessary for patients with chronic kidney disease or according to body weight, these new drugs do not require regular monitoring. There are recommendations for the start and follow-up therapy with NOACs, planning for cardioversion, ablation and surgical interventions and the management of bleeding. This article is a review of the major studies of the NOACs. The clinical use of these drugs in patients with non-valvular atrial fibrillation is presented.

Syncope: epidemiology, etiology, and prognosis.

Syncope is a common medical problem, with a frequency between 15% and 39%. In the general population, the annual number episodes are 18.1-39.7 per 1000 patients, with similar incidence between genders. The first report of the incidence of syncope is 6.2 per 1000 person-years. However, there is a significant increase in the incidence of syncope after 70 years of age with rate annual 19.5 per thousand individuals after 80 years. It presents a recurrence rate of 35% and 29% of physical injury. Among the causes of syncope, the mediated neural reflex, known as neurocardiogenic or vasovagal syncope, is the most frequent. The others are of cardiac origin, orthostatic hypotension, carotid sinus hypersensitivity, neurological and endocrinological causes and psychiatric disorders. The diagnosis of syncope can be made by clinical method associated with the electrocardiogram in up 50% of patients. Its prognosis is determined by the underlying etiology specifically the presence and severity of cardiac disease. The annual mortality can reach between 18 and 33% if cardiac cause, and between 0 and 12% if the non-cardiac cause. Thus, it is imperative to identify its cause and risk stratification for positive impact in reducing morbidity and mortality.

Electrical interference from an abdominal muscle stimulator unit on an implantable cardioverter defibrillator: report of two consecutive cases.

Two consecutive cases are presented of patients with ICDs in whom the use of commercial units for muscle stimulation for abdominal training caused interference with the device, mimicked cardiac signals, and resulted in inappropriate treatment shock delivery.

Radiofrequency catheter ablation for arrhythmic storm in patients with an implantable cardioverter defibrillator.

The aim of the study was to analyze the usefulness of RFA in controlling arrhythmic storm due to hemodynamically stable VT in a cohort of patients with an ICD and to evaluate the incidence of arrhythmic storm among patients with an ICD. A group of 13 (3%) of 403 consecutive ICD recipients were submitted to RFA of VT during an arrhythmic storm. Two additional patients were referred from other institutions. Standard criteria were used for VT endocardial ablation. A transcatheter epicardial approach was required in three patients. A total of 18 procedures were performed in 15 patients. A mean of 13.2 +/- 9.7 pulses of RF were delivered. Clinical tachycardia was successfully ablated in 12 (80%) patients. One patient died in incessant VT, 1 patient underwent heart transplant, and 1 was treated with direct current ablation. During a mean follow-up of 12 +/- 17 months, only two patients suffered a single episode of VT. Arrhythmic storm requiring VT ablation was uncommon among patients with an ICD and occurred late after ICD implantation. The arrhythmic episode was successfully controlled in the majority of patients with endocardial or epicardial RFA.

Short head-up tilt test potentiated with oral nitroglycerine: comparison with a conventional test using isoproterenol.

Conventional tilt test protocols are time consuming and there is no consensus regarding the optimal duration of the test and the provocative drug to be used. This study evaluated the diagnostic power of a short nitroglycerine test against a conventional isoproterenol protocol. A cohort of 128 patients with unexplained syncope was studied. A group of 64 consecutive patients were tilted with a short nitroglycerine test consisting of a passive phase of 15 minutes and if this proved negative, 400 microg of sublingual nitroglycerin spray for a further 15 minutes. The control group consisted of 64 patients tilted with a conventional isoproterenol protocol with a passive phase of 30 minutes and a drug-challenge phase of 20 minutes. In the nitroglycerine protocol 39 (60.9%) patients showed a positive response versus 27(42.2%) in the isoproterenol group (P = 0.034). The duration of the protocol was 23.2 +/- 7.2 minutes in the nitroglycerine group versus 41.1 +/- 15.5 minutes with isoproterenol (P = 0.001). The time until syncope was 18.87 +/- 6.1 versus 29 +/- 18, respectively (P = 0.002). For evaluating unexplained syncope the short tilt test protocol with nitroglycerine is less time consuming, easier to perform, and has a higher rate of positive response than a conventional isoproterenol protocol.

Características e identificaçäo dos sítios de taquicardia ventricular de etiologia chagásica por mapeamento endocárdico / Charcteristics and identification of sites of chagasic ventricular tachycardia by endocardial mapping

Objetivo - Estudar as características eletrofisiológicas que possibilitem identificar e realizar a ablação dos sítios de taquicardia ventricular de etiologia chagásica. Métodos - Trinta e um portadores de cardiopatia chagásica crônica e taquicardia ventricular sustentada (TVS), foram submetidos a estudo eletrofisiológico para tentativa de mapeamento e ablação dessa arritmia, sendo 15 pacientes cuja TVS reprodutível por estimulação ventricular programada e tolerável hemodinamicamente, 9 homens e 6 mulheres com idade variando de 37 a 67 anos e fração de ejeção de 0,17 a 0,64. O mapeamento endocárdico foi realizado durante a TVS em todos os pacientes. A energia de radiofreqüência (RF) foi aplicada nos sítios de atividade pré-sistólica de pelo menos 30ms. Utilizou-se a técnica de entrainment para identificar os circuitos reentrantes. Tanto nos sítios de sucesso como nos de insucesso da aplicação de RF em interromper a taquicardia foram analisadas as características dos eletrogramas doentrainment. Resultados - Entrainmente foi obtido durante todas as TVS mapeadas. Em 70,5 por cento dos sítios, ve-se entrainment oculto e interrupção da taquicardia nos primeiros 15s da aplicação de RF. Nos sítios de insucesso observou-se atividade elétrica significantemente mais precoce do que nos de sucesso. Observou-se nos sítios estimulados uma associação significante entre a obtenção de entrainment oculto com o sucesso da aplicação de RF. Não foram observadas regiões de bystander. Conclusão - O mecanismo reentrante foi o responsável pela gênese de todas as taquicardias. Em 70,5 por cento dos sítios demonstrou-se participação endocárdica da zona de condução lenta dos circuitos reentrantes. Entrainment oculto foi o principal parâmetro eletrofisiológico associado com o sucesso da RF. Não houve evidências eletrofisiológicas de regiões de bystander nos circuitos de TVS.

Ablaçäo por cateter de taquicardia de via de saída de ventrículo direito utilizando radiofrequência como fonte de energia / Catheter ablation of tachycardia of the outlet right ventricle using radiofrequency as power source

Two female patients, 54 and 38 years-old with refractory ventricular tachycardia were undertaken to electrophysiologic study for diagnosis and radiofrequency ablation of their arrhythmias. The tachycardias were only inducible with intravenous isoproterenol infusion. The site of the origin of ventricular tachycardia was localized in the right ventricular outflow tract in both cases. Radiofrequency current was delivered at 40V (40-60s) in each patient and was followed by complete abolition of ventricular arrhythmias

Ablação por cateter de foco de taquicardia atrial ectópica incessante utilizando radiofrequência: reversäo de taquicardiomiopatia / Catheter ablation of ectopic incessant atrial tachycardia using radiofrequency: reversion of tachycardiomyopathy

A 8-year-old female patient with refractory incessant atrial tachycardia, very symptomatic and with left ventricular ejection fraction of 0.25. Electrophysiological study and endocardial mapping localized the site of the origin of atrial tachycardia in the superior right atrium. In this site 2 applications of radiofrequency current (25V, 20 and 50 seconds) resulted in termination of the atrial tachycardia. She was discharged off antiarrhythmic drugs and after 2 months ejection fraction was 0.52. She was completely asymptomatic 6 months after ablation procedure

Paciente de 8 anos com história de taquicardia atrial ectópica incessante e refratária a drogas antiarrítmicas, muito sintomática e tendo grande comprometimento da função ventricular, com fração de ejeção de 0,25. A paciente foi submetida a estudo eletrofisiológico e ao mapeamento endocárdico que localizou o foco da taquicardia na regino superior do átrio direito, observando-se precocidade de 40ms do eletrograma nesse local em relação à onda P do eletrocardiograma de superfície. Nesta região foram feitas 2 aplicações de radiofreqüência de 25V com 20 e 50s de duração, com desaparecimento da taquicardia. A paciente evoluiu sem arritmia e após 2 meses a fração de ejeção era de 0,52. Atualmente, encontra-se assintomática após 6 meses de acompanhamento ambulatorial