Intensity Of Heart Sounds Research Articles

Digital spectrum analysis of the first and second heart sounds

With the advent of the fast Fourier transform and the development of hybrid computing, the digital analysis of various biologic signals in the frequency domain has become a realistic objective. the application of spectrum analysis to biomedical problems is no longer restricted by either hardware or software limitations, and consequently one is now confronted with what is best described as a problem in data analysis. In this paper an application of spectrum analysis in phonocardiography is described. We propose that separate spectra be computed for the first and second heart sounds and suggest how the spectra can be used in both experimental and clinical investigations. The computational procedure is described, an example is presented, and a FORTRAN subroutine is provided that can be used to compute the spectrum estimates. The results presented here represent a first step in the data analytic process and provide a method of exposing and summarizing the “information” in the data. The method has potential application in both the diagnosis of cardiovascular disease and the monitoring of critically ill patients. To illustrate the latter point, we propose that the heart sound spectra could be used to construct an index of relative heart sound intensity that has potential application in monitoring the depth of anesthesia during surgery.

Computer mapping for the equal intensity distribution of heart sounds and murmurs on the chest surface

The present study was undertaken to develope a practical method for displaying quantitatively the intensity distribution of heart sounds on the chest surface as the basic research for analyzing the mechanism of production and propagation of these sounds and murmurs. This report presents: (1) a digital computer method for drawing the equal intensity surface maps; (2) the apparatus for measuring the intensity of heart sounds and murmurs; (3) a clinincal application for normal subjects and patients with heart murmurs. Materials and methods The study was made in normal subjects and patients with typical heart murmurs, ranging in age from 20 to 30 years. The recording system consisted of micro-phone, preamplifier, high-pass filters, cathode-ray oscilloscope and photographic recorder. To explore the entire chest, a grid system was marked over the anterior thorax to record from 98 to 140 points. All measurements were made in only beats which occurred during resting expiration and the individual records include five or more cardiac cycles at a paper speed of 50 mm/sec.. A reference electrocardiogram (usually the standard limb lead 2) was simultaneously recorded. The gain setting of amplification was kept constant in all the phonocardiograms. All subjects were placed in the supine position and in a soundproof room. The oscillographic data were reviewed and the proper beats chosen for analysis. The maximum amplitudes of the first, the second heart sounds and murmurs were measured at the 98 or 140 points on the chest surface. In the second step, the values between the points at which the amplitudes were measured were estimated by linear interpolation. Finally, the equal intensity contour lines were automatically drawn on the chest maps with a drafting machine and displayed simultaneously on the cathode-ray oscilloscope. The programs developed herein consisted of about 420 FORTRAN steps. These procedures were executed by using a NEAC 22001500 computer and on-line TSS terminal.

Alterations in intensity of heart sounds after myocardial infarction.

A reduction in the intensity of the heart sounds is a familiar sequel to myocardial infarction. Sounds are sometimes described as muffled, weakened, or distant, and when the first sound alone is affected so that both sounds become of equal loudness a characteristic sometimes known as ticktack rhythm, is produced. This change in intensity of the heart sounds has been attributed to alterations in heart rate, lengthening of the P-R interval, or to a lowering of systemic blood pressure, but it may be the only physical sign detectable, and not infrequently it is observed for the first time several days after the acute episode when the patient is making an otherwise uneventful recovery. In this paper the results of measurement of intensity of the sounds after myocardial infarction are described, and an attempt is made to relate them to other effects of myocardial infarction.

The calibration of heart sound intensity.

There is no standardized method for the calibration of total energy conducted to the surface of the chest caused by the cardiac sounds. Loudness is a subjective term which is dependent upon total energy, frequency of the main components and the specific sensitivity of the human hearing mechanism. A method is described in which the amplitude of the chief component of the heart sounds is compared to that produced by a standard sound signal at 80 decibels at 500 cycles per second and an intensity ratio calculated. The method has been applied to normal individuals of different ages and to those with mitral valve disease and those with pulmonary hypertension. The findings confirm the clinical observation that mitral stenosis with persisting mobility of the valve leaflets is associated with a loud first heart sound. However, the measurement of intensity of the second heart sound did not show so reliable a correlation between the loudness of the sound and the pulmonary blood pressure. The relationship is somewhat obscured by the wide range of normal values in the intensity of the second heart sound.

Chronic constrictive pericarditis and rheumatic heart disease

1. 1. In a series of eighteen cases of chronic constrictive pericarditis, five had coexisting rheumatic valvular disease and are reported in detail. 2. 2. If constrictive pericarditis is suspected in patients with heart disease who have an atypical course, more cases will be discovered. 3. 3. Cardiac enlargement, normal intensity of heart sounds, and normal cardiac pulsations are not rare in patients with constrictive pericarditis. 4. 4. The presence of definite rheumatic heart disease does not exclude the existence of associated chronic constrictive pericarditis although there is no evidence that the two conditions are causally related. 5. 5. It is of significance that in three of the five cases in which constrictive pericarditis was associated with rheumatic heart disease, there was a history of another etiologic factor which may have played a role in the development of the disease.

The intensity of the first heart sound in auricular fibrillation with mitral stenosis

Simultaneous phonocardiographic and electrocardiographic tracings were taken on ten patients with auricular fibrillation and mitral stenosis and two patients with auricular fibrillation without mitral stenosis. In each instance the intensity of the first heart sound, as gauged by totalling the amplitude of the three largest vibrations of the first sound, was plotted against the duration of the preceding ventricular diastole. In six of the patients with mitral stenosis there was no definite relationship between the intensity of the first sound and the duration of the preceding ventricular diastole. In four patients with mitral stenosis there was a clear-cut and striking relationship: The intensity of the first sound varied, within limits, inversely as the duration of ventricular diastole. The first sounds were loud when diastole was short and became less intense as diastole lengthened, until a low intensity was reached and maintained. The type of variation of the first heart sound seen in these four patients differs from the variation that occurs in patients with auricular fibrillation without mitral stenosis. Possible explanations for the variation in the first heart sound intensity are discussed.

Difference of Intensity of Heart Sounds Expressed Numerically. Preliminary Report

It was proposed to express the difference of intensity of heart sounds numerically (though only comparatively) by the combined use of the magnoscope and an attenuator connected to it. As already explained in the 1st Report, the magnoscope was invented and constructed not so much for the heart sounds as for the breath sounds. So the present paper is rather a by-work.