Survey of the literature

Abstract

SummaryThe extra sounds in healthy individuals are of two different kinds, viz., a third heart sound and an auricular sound. The third sound is due to vibratiolns in the ventricularwall probably owing to the rapid inrush of blood into the ventricle at the beginning of diastole. The auricular sound occurs in connection with aurkular systole, lseveral factorsin all likelihood cooperating in this case. Both are frequently registered phonocardiographically, above all in children and young individluals. However, the auricular sound is practically inaudible under normal conditions while the third sound has been perceived by different authors to a varyiing degree.Extra sounds are also observed in certain cardiac diseases, and the term gallop rhythm is then generally used. There are two different kinds of gallop rhythm, viz., the thirdsound gallop (or rapid filling gallop) and the auricular sound gallop. The extra sounds at gallop rhythm are identical in several respects with the normal third sound and auricular sound, respectively, and are considered to be an accentuation of thelse sounds. The third sound gallop is believed to originate from a pathologically reduced tone of the ventricular wall, although experimental proof of this is lacking. The auricular sound gallop is probably also due in part. to such a decrease in tone to which may perhaps he added an increased auricular contraction.The gallop slounds have been submitted to detailed analysis in elderly persons, among whom they seem to appear chiefly in hypertensive‐arteriosclerotic and coronary dilseases, and have been attributed to failing cardiac funotion. Since extra sounds are practically non‐existent in healthy individuals in the corresponding age‐groups, there is reason to assume that they are pathological in this connection.The gallop rhythm is also said to occur among children and young people and, above all, in acute myocarditiis. However, the extra sounds in these cases cannot be regarded as definitely pathological, since they are a normal occurrence in the age‐groups concerned here. It is conceivable that the extra sounds are more common in cardiac disease and the sounds may, possibly, have a different quality. Still, no investigations have been performed proving this. As a rule, the pathological and physiological extra sounds are considered to be indistinguishable from one another whether a t auscultation or by means of the phonocardiographic registration methods hitherto employed. According to the majority of authors, the only criterion of a pathological extra sound is the fact that other signs of cardiac disease are present simultaneously. On the other hand, when the cardiac function is normal, the extra sound is regarded as physiological.However, by the use of the forementioned definition, we are deprived of the l'ossibility of utilizing the gallop rhythm as a diagnostic aid. It is, therefore, necessary to try to arrive a, definition of the gallop rhythm which is based on a objective method. This has been rendered possible by means of calibrated phonocardiography, as demonstrated earlier by Mscannheimer (1940).Thanks to this method, the absolute amplitude of the heart sounds can be measured in dynes per cm2 within the various frequency ranges (cp. the chapter on Methods). By determining the normal variation range of the third heart sound and the auricular sound, an upper limit can be established with regard to the amplitude which may not he exceelded if the sound in question is to be regarded as physiological.The purpose of the preslent work is in the first place to offer a phonocardiographic definition of the gallop rhythm, based on calculations made on a normal material of children.By means of a clinical investigation, attempts will then be made to derive information regarding the significance of the gallop rhythm in childhood.An experimental study of the gallop rhythm has been made, with a view to shedding further light on the problem.