The electrocardiogram of children with congenital heart disease.

Summary. The electrocardiographic investigations of congenital heart disease have been performed on 135 individuals between 0 years of age and 17. In Group A, embracing 43 cases of congenital heart defects with pronounced cyanosis (the cases of morbus ceruleus) the electrocardiogram is almost invariably pathological. Only 2 cases, = 4.6 ± 3.2 per cent, show but insignificant changes. Within this group the following changes are most frequent. Heart rapidity is considerably higher than normally. In common with earlier investigations it has been proved that the P wave has a larger amplitude than normally. Close on half of the morbus ceruleus cases (46.5 ± 7.6 per cent) have P waves, amounting to, or exceeding, 0.30 millivolt, i. e. a value outside normal range of variation. The QRS complexes within Group A are often atypical. Large Q waves occur in 11.6 ± 4.9 per cent, enlarged R waves, on the other hand, only in 7.0 ± 3.9 per cent. The S waves are larger than normally in leads I and II which, in all probability, is due to an often pronounced right axis deviation in these cases. Among the morbus ceruleus cases changed S–T segments are frequently found. Depression of S–T segment occurs in 32.6 ± 7.2 per cent, elevation in 18.6 ± 5.9 per cent. Prolonged conduction time is found but exceptionally. Systolic duration shows normal values. In accordance with earlier findings right axis deviation, often pronounced, is one of the most important electrocardiographic characteristics in morbus ceruleus. In a good half of the cases (53.5 ± 7.6 per cent) right axis deviation has been regarded as definitely pathological. This value is, however, smaller than is usually stated. The explanation is, apparently, that normal range of variation, disclosing a certain tendency to the right in childhood, has not been sufficiently taken into consideration earlier. In some cases with pronounced cyanosis, on the other hand, left axis deviation occurs, as mentioned earlier by LEECH (1935), among others. In 6 cases belonging to this group, and in 2 cases belonging to Group B, the angle of the electrical axis lies between – 90° and 180°. In accordance with COMEAU and WHITE (1939) defective intraventricular conductivity is supposed to be at hand in these cases. Thus, the most important changes in morbus ceruleus are enlarged P waves, pronounced right axis deviation and changed QES complexes , (Figs. 33, 34, 39, 41, 43, 44 and 49, p. 213 etc.,). In Group B, consisting of 92 cases without pronounced cyanosis, an inquiry has given the following results. 20 cases, = 21.7 ± 4.3 per cent, show normal electrocardiograms, 48 cases, = 52.2 ± 5.2 per cent, show changes such as to justify the classification of the electrocardiograms as pathological. The remainder, 24 cases, =– 26.1 ± 4.6 per cent, have shown probable pathological electrocardiograms. The pathological characteristics are as follows: Pulse frequency is, also within this group, higher than normally. Enlarged P waves are found only in 10.0 ± 3.1 per cent. The QRS complex is often the centre of characteristic changes with atypically shaped, diphasic QRS complexes as its most prominent mark. Enlarged Q waves in lead III occur in 7.6 ± 2.8 per cent. The R waves display “high voltage” in 12.0 ± 3.4 per cent. Also occasional cases with R waves showing “low voltage” have been noticed in this group. The S waves are in all leads larger than normally. It is worth noting, that, in common with the large R waves, the atypical, diphasic QRS complexes occur, just as often, it would seem, in cases without pronounced cyanosis, a fact of practical importance since, for natural reasons, they are less easy to diagnose than the morbus ceruleus cases. Depression of S–T occurs in Group B in 17.4 ± 3.9 per cent, elevation equally often. Conduction time is but exceptionally prolonged. Systolic duration is, as in Group A, normal. Within Group B normal direction of the electrical axis prevails in a good two thirds of the cases. Right axis deviation, apart from 2 cases of situs inversus in which it occurs owing to change of position of the heart, is to be found approximately as often in this group as left axis deviation, i. e. in over 10 per cent, which accords with the result of LEECH'S (1935). Group B 2 shows, generally speaking, the same changes as the other cases without pronounced cyanosis. However, diphasic QRS complexes are not so frequent. The electrocardiogram in congenital heart disease without pronounced cyanosis is, thus, not rarely, perfectly normal. Atypical, diphasic QRS complexes are the most important pathological characteristic. In addition, enlarged R waves and axis deviation to the right, as well as to the left, are noticed in certain cases , (Figs. 35 –38, 40 and 42, p. 218 etc.,). Four cases of congenital arrhythmias, comprising 1 case of auricular flutter and 3 cases of complete heart block, have formed the subject of a report, (Figs. 45–48, p. 234 etc.,). In 10 cases of patent ductus Botalli the electrocardiogram shows, on the whole, comparatively insignificant changes. In 2 cases right axis deviation and in 3 cases more or less pronounced signs of secondary myocardial damage, were noted, (Fig. 42, p. 227). Two cases of situs inversus in a brother and a sister with electrocardiograms typical of this anomaly have been described. In one case of coarctation of the aorta normal electrocardiogram has been recorded. The electrocardiograms relating to the 25 post‐mortem cases, have been examined with a view to the possibility of special diagnosis. Almost all the post‐mortem cases display combinations of malformations and most cases divulge, at post‐mortem, individually distinctive pathological‐anatomical pictures (see Table 14, page 66). The electrocardiograms are also very variable in these cases. With two exceptions, all electrocardiograms are pathological with changes typical of the collective diagnosis, congenital heart disease, but special diagnosis cannot, in the individual case, be based on the electrocardiogram. It is, moreover, of interest that, as stated by SEHAM (1924), among others, conformity is not always to be found between the electrocardiogram and the result of the pathological‐anatomical investigation of a case. The majority of cases of congenital heart disease have formed the subject of repeated electrocardiographic investigations. Generally speaking they show fair agreement, a fact of certain differential‐diagnostic value as against the acquired heart defects the electrocardiograms of which are often changed in the course of the disease. During infancy the electrocardiograms, however, show certain changes at re‐examinations because of which they should, at that period, be judged with particular care, (Figs. 50 –53, p. 245 etc.,).