A estimulação direta do sistema de condução foi idealizada na década de 70, porém, o procedimento só se tornou factível e reprodutível com o desenvolvimento de ferra-mentas específicas. A qualidade da estimulação obtida depende de fatores como: nível anatômico do sistema His-Purkinje alcançado; captura muscular concomitante ou não e resposta eletrocardiográfica obtida. A estimulação do sistema de condução envolve a captura do feixe de His ou do ramo esquerdo e seus fascículos, podendo ser seletiva (S) ou não seletiva (NS), na dependência de ausência ou presença, respectivamente, de captura simultânea do miocárdio ventricular adjacente. Diante das atuais evidências, a estimulação direta do sistema de condução pode ser considerada uma alternativa aos pacientes com bradicardia e indicação para implante de marcapasso, evitando-se os efeitos indesejáveis do dissincronismo ventricular causado pela estimulação tradicional de ventrículo direito (VD) como, também, uma alternativa à estimulação biventricular para terapia de ressincronização cardíaca (TRC). Apesar de promover ativação ventricular fisiológica, a estimulação do feixe de His apresenta algumas limitações anatômicas e funcionais além da incapacidade de corrigir a doença distal do sistema de condução, enquanto a estimulação do ramo esquerdo fornece limiares mais baixos e estáveis, além de corrigir as doenças de condução, sendo capaz de promover sincronismo intraventricular equivalente à estimulação direta do feixe de His e, por esses motivos, sua aplicação vem se ampliando largamente. Embora os dados ainda sejam limitados e grandes estudos prospectivos para avaliação de segurança e eficácia a longo prazo sejam necessários, os resultados são favoráveis à essa modalidade de estimulação.
Up to 30-40% of patients undergoing cardiac resynchronization therapy (CRT) are described as nonresponders since the initial studies. This paradigm has inspired several modifi cations of the devices, electrodes and surgical technique in the implant. The defi nition of CRT response should be rethought, standardized, and ratings based on structural and/or clinical response should be proposed. The authors discuss a series of cases in which sustained clinical improvement was achieved despite structural worsening. Objective: To assess the profi le of clinical responders to CRT who have worsened structurally. Method: It is a retrospective cohort of patients in outpatient follow-up from January 2012 to March 2017. We included 13 patients (2.7%) out of a total of 476 submitted to CRT. Inclusion criteria were to present an improvement in functional class according to the New York Heart Association criteria (FC-NYHA) ≥ 1 sustained for at least one year and absence of improvement or worsening of the structural parameters evaluated by transthoracic echocardiogram [ejection fraction (EF), diastolic diameter (LVDD) and systolic diameter (LVSD)]. The variables analyzed were age, gender, FC-NYHA, cardiopathy, echocardiographic and electrocardiographic parameters, medications in use, location of implanted electrodes, device programming, cardiary defi brillator therapies, and mortality. Statistical analysis was performed using non-parametric Wilcoxon and McNemar tests. Results: There were 13 patients, 92% male, mean age 60.9 ± 9.2 years and mean follow-up of 3.3 ± 1.1 years, 76% of CRT associated with implantable cardioverter defi brillator (CRT-D). In pre-implantation, 84.6% were in FC-NYHA III and then 61.5% were in FC-NYHA I (p = 0.001). The mean pre-implantation EF was 31.3 ± 7.6% and 26.6 ± 7.3 (p = 0.002) in the last evaluation. The predominant heart disease was non-ischemic in 92.5%, most of which were chagasic cardiomyopathy (CCM) (66%). In the TRC-D group, no shock therapy was recorded in the period; there was one death in a patient with ischemic cardiomyopathy (IC) for the septic shock of pulmonary focus after 2.2 years of follow-up. The mean QRS was 189.9 ± 23.1 ms to 157.9 ± 35.2 after CRT (p = 0.032). There was no signifi cant change in pre-and postimplant medications during follow-up. Conclusion: The absence of structural improvement should not be considered therapeutic failure, since CRT seeks to modify the electrical activation, and may be related to better performance and decrease of symptoms, even in evolutionary heart diseases.
Até 30-40% dos pacientes submetidos à terapia de ressincronização cardíaca (TRC) são descritos como não respondedores desde os trabalhos iniciais. Esse paradigma tem inspirado diversas modificações dos dispositivos, eletrodos e técnica cirúrgica no implante. A definição de resposta à TRC deverá ser repensada, padronizada, e classificações pautadas na resposta estrutural e/ou clínica devem ser propostas. Os autores discutem uma série de casos em que se obteve melhora clínica sustentada a despeito da piora estrutural. Objetivo: Avaliar o perfi l dos pacientes respondedores clínicos à TRC que pioraram estruturalmente. Método: Trata-se de coorte retrospectiva de pacientes em seguimento ambulatorial de janeiro de 2012 a março de 2017. Foram incluídos 13 pacientes (2,7%) de um total de 476 submetidos à TRC. Os critérios de inclusão foram apresentar melhora da classe funcional pelos critérios da New York Heart Association (CF-NYHA) ≥ 1 sustentada por pelo menos um ano e ausência de melhora ou com piora dos parâmetros estruturais avaliados pelo ecocardiograma transtorácico [fração de ejeção (FE), diâmetro diastólico (DDVE) e diâmetro sistólico (DSVE)]. As variáveis analisadas foram idade, gênero, CF-NYHA, cardiopatia, parâmetros ecocardiográficos e eletrocardiográficos, medicações em uso, localização do implante dos eletrodos, programação do dispositivo, terapias do cardiodesfibrilador e mortalidade. A análise estatística foi realizada por meio dos testes não paramétricos de Wilcoxon e McNemar. Resultado: Foram 13 pacientes, sendo 92% do sexo masculino, idade média de 60,9 ± 9,2 anos e seguimento médio de 3,3 ± 1,1 anos, 76% de TRC associada a cardiodesfibrilador implantável (TRC-D). No pré-implante, 84,6% encontravam-se em CF-NYHA III e, em seguida, 61,5% estavam em CF-NYHA I (p = 0,001). A FE média pré-implante foi de 31,3 ± 7,6% e 26,6 ± 7,3 (p = 0,002) na última avaliação. A cardiopatia predominante foi a não isquêmica em 92,5%, sendo a maioria cardiomiopatia chagásica (CMC) (66%). No grupo TRC-D, não foi registrada terapia de choque no período; houve um óbito em um paciente com cardiomiopatia isquêmica (CMI) por choque séptico de foco pulmonar após 2,2 anos de seguimento. O QRS médio foi de 189,9 ± 23,1 ms para 157,9 ± 35,2 após TRC (p = 0,032). Não houve mudança significativa nas medicações administradas pré- e pós-implante durante o seguimento. Conclusão: A ausência de melhora estrutural não deve ser considerada falha terapêutica, pois a TRC procura modificar a ativação elétrica, podendo estar relacionada a melhor desempenho e diminuição dos sintomas, mesmo em cardiopatias evolutivas.
BACKGROUND Patients (pts) with atrioventricular nodal reentrant tachycardia (AVNRT) have a higher incidence of atrial fibrillation (AF) during follow-up. Conventional risk factors can play a role in AF development, however atrial electrical conduction properties may be implicated in AF pathogenesis. AIMS to evaluate atrial conduction times and assess its effect on AF development during follow-up. METHODS We studied AVNRT pts who performed EPS and catheter ablation of the slow pathway between 2013 and 2016 in a single center. Pts with AF or valvular disease were excluded. We evaluated duration of symptoms due to AVNRT, conventional risk factors for AF (age, gender, obesity, hypertension, diabetes and structural heart disease (SHD)), left atrium (LA) enlargement and electrophysiologic study (EPS) time intervals related with atrial electrical conduction properties. We measured the time interval between: (1) the beginning of the P wave on the ECG to the A deflection in His-bundle electrogram (P-AHis); (2) the beginning of the P wave to the mid-distal coronary sinus (CS) atrial electrogram (P-CS) and (3) the beginning of the P wave to the H deflection in His-bundle electrogram (P-HHis). RESULTS Fifty-two pts were evaluated during a median follow-up of 63 months (IQR 51-69): 22% male, median age 55 years (IQR 42-67). AF occurred in 9 patients (17%) (39 cases per 1000 person-years). Patients with AF were older (67 vs 53 years, p= 0.005) and had more frequently LA enlargement (33% vs 7%, p= 0.024) but they did not differ in hypertension, obesity, diabetes, SHD and duration of symptoms. EPS measured intervals P-AHis and P-HHis interval were not different between the groups (26.0 vs 22.8 ms, p = 0.89 and 151 vs 106 ms, p= 0.56, respectively) but P-CS were prolonged in patients with AF (70 vs 55 ms, p = 0.02) (figure 1). Univariate logistic analysis for AF is presented in table 1. There was no interaction between P-CS and LA enlargement (p = 0.87). In multiavariate analysis, only P-CS was independently associated with AF (table). CONCLUSIONS In this group of patients with AVNRT, P-CS, but not other atrial conduction intervals, was independently associated with AF development. The possible role of LA electrical conduction impairment in AVNRT pts for AF development needs further studies. Univariate and multivariate analysis Univariate analysis Multivariate analysis OR 95% CI p-value OR 95% CI p-value Age (years) 1.10 1.02-1.19 0.016 1.10 1.00-1.21 0.051 LA enlargement 7.00 1.10-44.71 0.040 3.42 0.41-28.03 0.255 P-CS 1.07 1.021.14 0.013 1.06 1.01-1.12 0.044 OR Odds ratio. CI: confidence interval Abstract Figure. Box-plot for the studied intervals
Introduction: BCG vaccine (bacillus Calmette–Guérin) has been developed against tuberculosis and proven to be used for other purposes by activating and/or training innate immunity. The protective effect against the new coronavirus should be investigated and tested while a specific vaccine is not available. Objective: To compare the acceleration rates of incidence and lethality of COVID-19 according to the vaccination program for BCG of the main countries affected by the pandemic. Methods: Part one of three of the data survey from official sources on the number of cases and number of deaths by COVID-19 between December 31, 2019 and April 11, 2020, being calculated the incidence, mortality and lethality acceleration rates, and compared among predefined groups according to their BCG vaccination programs. Results: Countries without a vaccination program in place or that never had one for BCG had incidence and mortality acceleration rates of 21.36 and 53.21 times higher (p < 0.001), respectively, than the same rates in countries with a universal vaccination program. In addition, patients with an expanded vaccination program had a 43% lower mortality rate (p < 0.001) compared to countries with a vaccination program at birth only. Conclusion: There is a correlation between the coverage of BCG vaccination programs and the acceleration in the number of new cases and deaths in countries, showing a possible protective factor in places with existing BCG vaccination programs.
Introduction: the necessity for a temporary pacemaker (TP) goes through several scenarios. Some patients require the device to complete an infection treatment, regain the pace after myocardial infarction, or while awaiting the release of the definitive device by the health care provider. Regardless of the TP passage technique, good electrode fixation is essential, avoiding dislocation and the necessity for repositioning, among other complications. Objective: to compare two forms of TP fixation, one under direct fixation to the skin and the other keeping the venous introducer connected to the plastic protection through the pacemaker electrode lead. Methods: Forty patients were randomized, 20 in each group. Data regarding the procedure time, electrode lead position, command thresholds, sensitivity, and complications were recorded. The primary outcome considered was the necessity for repositioning or exchange of transvenous TP and secondary any complication without the necessity to reposition it. Results: There were no significant differences in the total duration of the procedure between the groups in the initial position of the electrode and the access route used. The group with plastic protection had a higher primary outcome (60%) than the direct fixation group (20%; p = 0.0098). There were no differences regarding the secondary outcome (p = 1.0). The group with plastic protection also had more total complications compared to the other group (p = 0.0262). Conclusion: Direct fixation of the pacemaker electrode lead was safer concerning the fixation with plastic protection, reducing complications such as electrode dislocation requiring repositioning or replacement without increasing the procedure time.
The correlation between atrial fibrillation (AF) and thromboembolism is well known. In 1951, Raymond Daley et al. associated the occurrence of this arrhythmia to systemic embolic events with consistent information in patients with chronic rheumatic heart disease1. In this study involving 194 patients with rheumatic heart disease who were victims of thromboembolism, with autopsy information in 39 patients, the presence of AF was demonstrated in about 90% of cases. The classic Framingham study, published in 1978, was the first large study that established this same correlation in nonrheumatic individuals, showing that individuals with AF are nearly six times more likely to have a stroke than the AF-free individuals with characteristics adjusted for sex, age and blood pressure2. The inclusion of rheumatic individuals has raised this risk to approximately 18 times. Since this important publication, several studies have corroborated these findings.
A relação entre fibrilação atrial (FA) e tromboembolismo é conhecida de longa data. Em 1951, Raymond Daley et al. associaram com informações consistentes a ocorrência dessa arritmia a eventos embólicos sistêmicos em pacientes portadores de cardiopatia reumática crônica 1 . Nesse estudo envolvendo 194 portadores de cardiopatia reumática vítimas de tromboembolismo, contando com informações de autópsia em 39 pacientes, ficou demonstrada a presença de FA em cerca de 90% dos casos. O clássico estudo de Framingham, publicado em 1978, foi o primeiro grande estudo que estabeleceu essa mesma relação em indivíduos não reumáticos, demonstrando que os portadores de FA têm perto de seis vezes mais chances de apresentar um acidente vascular cerebral do que aqueles indivíduos livres de FA com características ajustadas para sexo, idade e pressão arterial 2 . A inclusão de indivíduos reumáticos elevou esse risco para algo em torno de 18 vezes. Desde essa importante publicação, diversos estudos corroboraram esses achados 3-7 .Na Tabela 1 são apresentados os resultados de cinco estudos envolvendo mais de 100 mil pacientes, que situam a prevalência de FA em pacientes vítimas de um acidente vascular cerebral isquêmico (AVCi) em torno de 15 a 40%. É bastante razoável contudo deduzir que, mesmo nos 60 a 85% dos pacientes que apresentam um AVCi sem o diagnóstico pregresso de FA, a prevalência da arritmia seja maior, considerando a possibilidade de arritmia assintomática não diagnosticada. Em revisão sistemática e metanálise de 32 estudos envolvendo cerca de 5.000 pacientes sem antecedentes de FA que sofreram um AVCi submetidos a monitoramento agressivo do ritmo cardíaco, por Holter de 24 h, Holter de 7 dias ou monitor de eventos implantável, demonstrou-se o diagnóstico de FA em cerca de 11% dos pacientes 8 . Portanto, a partir das informações obtidas nesses grandes estudos ao longo das últimas seis décadas, com resultados incorporados de significativa força e consistência de associação, o seguinte paradigma foi construído: "fibrilação atrial causa AVCi tromboembólico".
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