Relation of intensity of cardiac sounds to age

Beat-to-beat alterations of acoustic intensity and frequency at the maximum power of heart sounds are associated with NT-proBNP levels

Background

Auscultatory features of heart sounds (HS) in patients with heart failure (HF) have been studied intensively. Recent developments in digital and electrical devices for auscultation provided easy listening chances to recognize peculiar sounds related to diastolic HS such as S3 or S4. This study aimed to quantitatively assess HS by acoustic measures of intensity (dB) and audio frequency (Hz).

Methods

Forty consecutive patients aged between 46 and 87 years (mean age, 74 years) with chronic cardiovascular disease (CVD) were enrolled in the present study after providing written informed consent during their visits to the Kitasato University Outpatient Clinic. HS were recorded at the fourth intercostal space along the left sternal border using a highly sensitive digital device. Two consecutive heartbeats were quantified on sound intensity (dB) and audio frequency (Hz) at the peak power of each spectrogram of S1-S4 using audio editing and recording application software. The participants were classified into three groups, namely, the absence of HF (n = 27), HF (n = 8), and high-risk HF (n = 5), based on the levels of NT-proBNP < 300, ≥300, and ≥900 pg/ml, respectively, and also the levels of ejection fraction (EF), such as preserved EF (n = 22), mildly reduced EF (n = 12), and reduced EF (n = 6).

Results

The intensities of four components of HS (S1-S4) decreased linearly (p < 0.02-0.001) with levels of body mass index (BMI) (range, 16.2-33.0 kg/m2). Differences in S1 intensity (ΔS1) and its frequency (ΔfS1) between two consecutive beats were non-audible level and were larger in patients with HF than those in patients without HF (ΔS1, r = 0.356, p = 0.024; ΔfS1, r = 0.356, p = 0.024). The cutoff values of ΔS1 and ΔfS1 for discriminating the presence of high-risk HF were 4.0 dB and 5.0 Hz, respectively.

Conclusions

Despite significant attenuations of all four components of HS by BMI, beat-to-beat alterations of both intensity and frequency of S1 were associated with the severity of HF. Acoustic quantification of HS enabled analyses of sounds below the audible level, suggesting that sound analysis might provide an early sign of HF.

Dyspnoea of cardiac origin in 67 year old men: (2). Relation to diastolic left ventricular function and mass. The study of men born in 1913

The relation of cardiac dyspnoea to diastolic left ventricular dysfunction was examined in a sample of 67 year old men from the general population of Gothenburg, Sweden. Forty two men with cardiac dyspnoea and 45 controls were selected from the screened cohort of 644 men. M mode echocardiography, apexcardiography, and phonocardiography were used to evaluate heart sounds, diastolic time intervals, aortic root motion (atrial emptying index); peak rate of change in left ventricular dimension, left atrial and ventricular size; and left ventricular mass. There was a significant relation between dyspnoea grade and left ventricular mass and posterior wall thickness. Dyspnoea grade also correlated significantly with the amplitude of the rapid filling wave and the third heart sound, atrial emptying index and left atrial size, the pulmonary component of the second heart sound, and the dimension of the right ventricle. In mild to moderate dyspnoea fractional shortening was normal, but posterior wall thickness and left atrial dimension were increased. The time from the second heart sound to the O point of the apexcardiogram, adjusted for heart rate, was significantly prolonged in mild to moderate dyspnoea, but not in severe dyspnoea. There was a significant decrease of rate adjusted isovolumic relaxation time, probably secondary to altered loading conditions, in severe dyspnoea, but not in mild to moderate dyspnoea. When the effect of systolic function was excluded multivariate analyses showed that the relation between dyspnoea grade and left atrial dimension persisted. The finding that diastolic abnormalities of the heart contributed to the generation of cardiac dyspnoea may have implications for treatment.