Phonocardiograms of auricular murmurs from a case with mitral stenosis and heart block.

It is well known that an auricular sound can sometimes be recognized by means of the stethoscope or phonocardiogram. In some instances it can be shown that the so-called first heart sound consists of a fusion of an auricular sound with a ventricular sound, and this may be evident in cases with prolongation of the P-R interval. This, however, is generally not easily recognized; otherwise there should be a presystolic sound or a double first heart sound in all cases of partial A-V block. In their monograph, Orias and Braun-Menendez (1939) state that three different acoustic phenomena contribute to the auricular first heart sound, namely-and in the following ordervibrations in the contracting auricles, the dilatation of the ventricles during their filling with blood, and vibrations in the mitral and tricuspid valves at the closure of the corresponding orifices at the end of the auricular systole. The first mentioned can only be studied from the cesophagus; the other two from the precordium also. It is stressed by different authors (Orias and Braun-Menendez, 1939; Bramwell, 1935; and Cossio and Fongi, 1936) that the auricular first heart sound will be increased during conditions, when the blood stream through the auriculo-ventricular orifices is increased or hastened (thyrotoxicosis, hypertension, and mitral stenosis with left auricular hypertrophy). It is also easy to understand that the rigidity of the valves in mitral stenosis might change the auricular sound to a murmur. If the statement of Levine (1941) is true, that seven-eighths of the blood stream from auricles to ventricles passes the orifice only on account of pressureequalization, whereas the last eighth is caused by auricular contraction, it will be clear that only the presystolic murmur in mitral stenosis is caused by auricular systole. This is also evident from the fact that the presystolic part of the diastolic murmur disappears when auricular fibrillation starts and there is no regular auricular systole. We have recently studied a case of mitral stenosis with complete heart block, where the auricular murmur is very beautifully demonstrated on the phonocardiogram. As such cases are rare, according to Lewis (1944), and also from our own experiences, it might be of interest to report one instance. The physical and phonocardiographic quality of the sound places it in the class of murmurs.