Análise do bloqueio do ramo esquerdo pelo mapeamento eletrocardiográfico de superfície. Comparação com os achados eletro-vetorcardiográficos / Left bundle branch block analysis by body surface mapping. Comparison with electrocardiographic and vectocardiographic findings

PURPOSE: To compare the correlation between the departure areas (DA), negative or positive, in patients whose electrocardiogram showed left bundle branch block (LBBB) and association with left ventricular hipertrophy (LVH) and myocardial infarction (MI), to the electrocardiographic (ECG) and vectocardiographic (VCG) classic criteria. METHODS: The study was carried out with 46 patients (27 males) with LBBB. These patients had hypertension (19.5), coronary heart disease (34.7) and 21 patients with no heart disease (45.8). RESULTS: The statistic analysis using the Cluster method divided the patients in two groups. Group I (22 patients) showed an average rate for the DA (-2 SD) of 1091 for QRS and of 640 for ST-T. For the DA (+2 SD), the average rate was 618 for QRS and 881 for ST-T; group II (24 patients) showed an averaged for the DA (-2 SD) of 1063 for QRS and of 225 for ST-T. For the DA (+2 SD), the averaged rate was 428 for QRS and 600 for ST-T. CONCLUSION: In general the current ECG/VCG findings, can not differentiate the presence of the association of LBBB to LVH and MI. The DA of ST-T, mainly negative was the most efficient to separate the two groups and help in the differential diagnosis.

Estudo da etiologia do bloqueio do Ramo Esquerdo em Porto Alegre / Etiologic Evaluation of Left Bundle Branch Block in

PURPOSE--To determine the type of cardiac disease causing left bundle branch block (LBBB) in Porto Alegre, Brazil, and to assess the role of associated left axis deviation (-30 degrees or more in the frontal plane) in order to identify a specific etiology of LBBB. METHODS--Through reports from the assistant physicians or through examination of the patients, the underlying heart disease in 264 cases of LBBB was assessed. The chi-square test was used to determine a possible association between left anterior hemiblock LBBB and one or more specific type of underlying heart disease. RESULTS--Systemic arterial hypertension (30.7), ischemic heart disease (30.3), valvar heart disease (8.7), cardiomyopathies (7.5), idiopathic degenerative disease of the conduction system (1.6) and miscellaneous heart diseases (1.2) were the underlying heart diseases. The presence of LBBB did not indicate any specific type of cardiac disease. CONCLUSION--The causes of LBBB in Porto Alegre are the same as reported in the international medical literature. Upward and leftward deviation (> or = -30 degrees) of QRS axis in the frontal plane did not show statistical significant association with any type of underlying cardiac disease.

Objetivo - Estudar a doença cardíaca subjacente ao bloqueio de ramo esquerdo (BRE) na Grande Porto Alegre e avaliar se o desvio do eixo de QRS ao plano frontal para cima e para a esquerda está associado a determinada etiologia do BRE. Métodos - Foram estudados 264 casos de BRE com diagnóstico cardiológico determinado através de informação do médico assistente ou de entrevista com o próprio paciente. Casos com eixo SÂS de-30º no plano frontal receberam também o diagnóstico de hemibloqueio anterior esquerdo (HBAE). Utilizou-se o teste do qui-quadrado para o estudo de associação. Resultados - Hipertensão arterial sistêmica (50,7%), cardiopatia isquêmica (30,7%), valvopatias (8,7%), miocardiopatias (7,5%), doença degenerativa do sistema de condução (1,6%) e cardiopatias diversas (1,2%) foram as causas. Presença de HBAE não permitiu prever o tipo de cardiopatia. Conclusão - As causas de BRE na área de Porto Alegre são semelhantes às observadas na literatura internacional. O desvio do eixo do QRS para a esquerda não mostrou associação estatisticamente significante com o tipo de cardiopatia subjacente