Frequency analysis of the first heart sound for patients on chronic hemodialysis

According to Adolph et al., valuable information on the nature of myocardium can be obtained through frequency analysis of first heart sounds (S1) during the isometric contraction phase (ICP). We compared dominant frequencies (DF), which were defined as the frequency of maximum sound voltage, of S1 among 37 outpatients undergoing chronic hemodialysis (HD group) and 28 outpatients with neurosis (control group). Heart sounds, which were obtained at apex by a sound microphone and polygraph, were analyzed into frequency spectra by the maximum entropy method through a computer. Left ventricular dimensions and wall thickness were measured by echocardiography. Histories of hemodialysis ranged from 4 to 164 months, with an average of 54 months. Age and body weight of patients before each hemodialysis were comparable with control subjects. Although systolic blood pressure, left ventricular mass (LVM), and combined left ventricular mass (CLVM), which means LVM and the blood it contains, showed higher values in the HD group, the ratio of LVM and CLVM and ejection fraction were almost equal in both groups. Therefore, if elastic tissue of myocardium of HD patients is less, lower DF is expected. However, DFs were 22.6 +/- 7.8 Hz in the HD group and 22.6 +/- 9.6 Hz in the control group. It was concluded that (1) hypertension and overhydration were not primary causes of uremic cardiomyopathy, and (2) myocardium of HD patients received no significant damage if cardiac function remained intact, even through left ventricular hypertrophy and dilatation were induced.