Study of the value of phono cardiography in clinical medicine
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The work presented here was originally undertaken with three main objects in view - firstly, to master the technique of phonocardiography; secondly, to decide whether accurate visual records of the heart sounds could be made with reasonable ease; and, finally, to decide what actual value such recordings might have for the practising physician.It is already clear that, in the past, phonocardiographic analysis of the various heart sounds and murmurs occurring in health and disease has been of great interest to the physiologist and the enquiring physician. As a research instrument the phonocardiograph is of proved value; as an adjunct to the teaching of cardiology its value is also obvious; but whether or not it can take its place beside the electrocardiograph as an apparatus of practical value to the clinician is still undecided.Experience was sought in the study of all varieties of cardiovascular disease and the work was not confined to one particular type of sound, murmur or condition. In this way recordings were made week by week, at first of a fairly simple nature; and thus, in the early months there was a tendency for recordings to be made of gallop rhythms rather than cardiac murmurs, the reason for this being that the low frequency of the heart sounds make them relatively easy to record when compared with the high frequency of heart murmurs. Later, as techniques improved and as more satisfactory phonocardiograph machines became available, all types of heart sounds and murmurs were recorded as they were encountered in the daily routine.The only factors that influenced the selection of cases were,therefore, firstly, the fitness of patients and their ability to co-operate without undue fatigue or distress, and, secondly, the desire by the clinician to obtain graphic information of a doubtful auscultatory sign which was felt to be of diagnostic importance or of medical interest.In this way, third heart sounds were recorded in normal hearts and abnormal auscultatory phenomena such as gallop rhythms accompanying hypertension, congestive cardiac failure, congenital heart disease, myocardial infarction and bundle-branch block and other conditions were studied. The systolic and diastolic murmurs occurring in apparently normal hearts and in the presence of aortic and mitral valvular disease were also recorded as they were encountered and when precise diagnosis was in doubt. In the case of mitral stenosis a particularly extensive study was made as surgical operations for relief of mitfal stenosis were being developed at this time. A wide variety of recordings was also made in other conditions such as congenital heart disease, pericarditis, and other cardiovascular abnormalities. In particular, specific information was sought on the following points by studying the literature and making a series of recordings from normal subjects and from patients with cardiovascular disease.1) The mechanism of the normal and abnormal heart sounds and murmurs,*their physical and auscultatory characteristics, and their appearance when recorded graphically. 2) Whether or not any additional diagnostic information with regard to these sounds and murmurs could be obtained from such recordings. 3) Whether the auscultatory findings could always be correlated with the appearance of the phonocardiographic tracing. 4) The frequency of occurrence and significance of splitting of the first and second heart sounds. 5) The frequency of occurrence and significance of the physiological auricular and rapid filling sounds, and their relationship to the extra sounds responsible for clinical gallop rhythm. 6) The prognostic significance of rapid filling, auricular,indeterminate, and systolic gallop rhythms, their correct classification and relation to the different types of heart disease. 7) The recognition and differentiation between right- and left sided gallop as originally described by Potain, and since,by others. 8) The heart sounds in bundle-branch block and the possibility of diagnosing right- and left bundle-branch block by auscultation and palpation. 9) The differentiation between innocent or unexplained systolic murmur and those due to clear cut organic disease. 10) The analysis of the auscultatory signs of mitral stenosis and incompetence and their value in the assessment of the severity and degree of the mitral lesion present. Also the separate identification and importance of splitting of the second heart sound, the opening snap of mitral stenosis, and the rapid filling gallop, and their relation to other events in the cardiac cycle. 11) The particular significance of the opening snap as a sign of mitral stenosis and its occurrence in mitral incompetence. 12) The practical value of recording auscultatory phenomena in miscellaneous cardiovascular abnormalities, either for diagnostic or teaching purposes.All the 151 patients reported here were examined, carefully auscultated, phonocardiograms made, and the photographic recordings processed and analysed by the author himself.Only in the section dealing with mitral disease has information been used which was not obtained from the author'sown recordings. In this section some of the final analytical data includes information obtained from a further series of recordings which were subsequently made, after instruction, by the senior electrocardiograph technician. The 66 recordings of 46 patients with mitral disease which are presented in this section, however, were all taken from the author's own series.The clinical and phonocardiographic observations a represented in Volume I of this thesis and are set out in separate sections. Each section deals with a particular aspect of the problem and is preceded by a survey of the literature and concluded by a sectional summary of the observations. Finally,there is a summary of all the observations presented and the conclusions drawn therefrom. The phonocardiographic tracings which illustrate this thesis are presented together in Volume II.