The heart in myotonic dystrophy

Steinert's disease (myotonic dystrophy) is a hereditary degeneration transmitted as an autosomal dominant trait recognized by clinical history, physical examination, electromyography and muscle biopsy. In a prospective study of Steinert's disease, thirty-one patients underwent physical examination, standard ECG, exercise ECG, Holter electrocardiography, chest X-ray, M-mode and two-dimensional echocardiography, phonocardiography and radionuclide angiocardiography with the intent to study the involvement of cardiac muscle. Owing to the frequent complaint of dyspnea (l4 patients - 45.16 per cent) and the evidence of peripheral cyanosis (8 patients - 25.80 per cent), spirometry was carried out in order to evaluate the cardiorespiratory involvement. Twenty-one patients (67.7 per cent) presented symptoms and 30 patients (96.71 per cent) clinical signs at the examination. Standard ECG disclosed 27 patients (90 per cent) with some abnormality. Conduction defects were shown in 14 patients (46.66 per cent), arrhythmias in 9 cases (30 per cent) and low voltage of the P wave in 8 cases (26.66 per cent). Conduction defects not disclosed by standard ECG were shown by Holter electrocardiographic recordings. Echocardiography disclosed a high incidence of mitral valve prolapse (39.13 per cent). Phonocardiographic systolic time intervals were abnormal in all patients, even through with normal PEP/LVET ratio. Ejection fraction and segmental contractility were normal as measured at rest by radionuclide angiocardiography in 20 cases (64.51 per cent). Fourteen patients were subjected to spirometry. This study showed 9 patients (64.28 per cent) with respiratory disturbances. The major ventilatory dysfunction was the restrictive component, present in 7 cases (77.77 per cent). These data suggest respiratory involvement in myotonic dystrophy.

Nova apresentação das derivações do plano frontal no eletrocardiograma / New presentation of frontal plane derivations in electrocardiogram

Foram realizados 77 eletrocardiogramas de individuos normais e com diversas cardiopatias. Utilizou-se um eletrocardiografo que permite a inversao da polaridade das derivacoes do plano frontal e selecionaram-se seis delas que foram ordenadas conforme a medida angular: DIII (+ 120 graus) aVF (+ 90 graus), DII (+ 60 graus), -aVR (+ 30 graus), DI (0 graus) e aVL (- 30 graus), o que permite a visibilizacao da morfologia das deflexoes, de maneira ordenada e progressiva, como a das derivacoes precordiais. Analisou-se aVR com polaridade invertida e valorizou-se sua morfologia predominantemente positiva e sua integracao na sequencia das derivacoes. Ficou assim, facilitada a determinacao do eixo eletrico, do diagnostico de bloqueio de ramo direito e esquerdo, do infarto inferior, do hemibloqueio anterior e das hipertrofias ventriculares. Com esta nova apresentacao o ensino da eletrocardiografia torna-se mais logico e simples, dispensando a memorizacao das morfologias das derivacoes, como no modelo classico