The phonocardiogram of children with congenital heart disease.

Summary. The phonocardiography investigations in cases of congenital heart disease have been performed on 90 children, (Table 47). The first heart‐sound shows larger amplitude than normally within the frequency ranges of below 100 cycles per second and 50–175 cycles per second. The mean of the amplitude amounts to 27.8 ± 1.8 millivolts (139.0 ± 9.0 dynes/cm 2 ) in the first‐mentioned frequency range. Apparently, the enlarged amplitude is connected with the higher pulse frequency in these cases. Also the second heart‐sound shows larger amplitude than normally. Significant differences as against the normal cases are noted in the three lowest frequency ranges, relating, principally, to the cases without pronounced cyanosis. The mean of the amplitude is 24.0 ± 1.8 millivolts (120.0 ± 9.0 dynes/cm 2 ) below 100 cycles per second. About 15 per cent of all second sounds possess amplitudes lying outside the normal range of variation in the two lowest frequency ranges. The fact that the second sound (in all probability vibrations from the pulmonary orifice) is accentuated in quite a number of cases of congenital heart disease depends, apparently, on the higher pressure in the pulmonary circulation. The third heart‐sound has been less often registered than in the normal cases. Its amplitude is, on an average, 3.3 ± 0.5 millivolts (16.4 ± 2.5 dynes/cm 2 ) below 100 cycles per second. If 0 figures are excluded the mean is 7.6 ± 0.7 millivolts (37.9 ± 3.5 dynes/ cm 2 ). In the morbus ceruleus cases the mean is 1.2 ± 0.6 millivolts, which is lower than the corresponding value in the normal cases (the difference being significant). The explanation of the smaller amplitude of the third sound may, possibly, be sought in factors connected with the auricular enlargement which occurs, not rarely, in these cases. It should, in such an event, contribute to the decrease in difference of pressure between auricle and ventricle and, in its turn, to the establishment of less favourable conditions of the cause of the third sound. The appearance and amplitude of the auricular sound shows, on an average, no significant differences as against the normal cases. Some cases fall outside the normal range of variation. An instance of such a case has been quoted (case no. 76, Fig. 22), the amplitude within the two lowest frequency ranges disclosing very high values. The post‐mortem case showed on examination auricular enlargement of a high degree. It is of interest to note that the P waves in the electrocardiogram were, in this case, normal. Thus it is evident that auricular enlargement can sometimes be diagnosed electrocardiographically, sometimes phonocardiographically, the two methods supplementing each other in this respect. The systolic murmur shows very considerable deviations from the normal. The amplitude is larger than normally. In the frequency ranges between 50–500 cycles per second the systolic murmur is registered in more than 90 per cent of all cases. Figures 23–26 form instances of systolic murmurs in congenital heart defect. It will be seen from the diagrams belonging to the figures that the amplitude of the murmurs is largest between 50–175 cycles per second and, furthermore, that it is generally recorded as far up as in the frequency range of 500—1,000 cycles per second. From a physical point of view the systolic murmur in congenital heart defects has not been preferably registered in the higher frequency ranges, consisting, as it does, of a mixture of frequencies from about 50—1,000 cycles per second. It is, however, high‐frequent in the sense that it differs, particularly in the higher frequency ranges, from the normal systolic murmur the amplitude of which in frequency ranges higher than 100–250 cycles per second equals 0 in practically every case. In six cases murmurs have either been absent or, when appearing, have not differed from those of the normal cases. In ten cases without pronounced cyanosis continuous murmurs occur (Figures 28–30) which, on account of their significance as pathognomonic symptoms of patent ductus arteriosus, have been the subject of a detailed report. In all these cases the continuous murmur is typical. It begins a while after systole, increasing in strength up towards the second sound, then it decreases until about the middle of diastole, when it disappears. Because of this fact it can easily be differentiated from the systolic as well as the diastolic murmur. Further, the continuous murmur is marked in most cases by a very large amplitude. The second sound discloses larger amplitude than normally in three of the ten cases. Diastolic murmurs do not occur in cases of congenital heart defects, with two exceptions.