GgO HANDBOOK OF PHYSIOLOGY -^^ CIRCULATION I 



"LOW FREQUENCY' 



SI 



SM ^^ DM 





LLSB 



'HIGH FREQUENCY* 



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INSP 



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 2-0S»0.07 SEC 



SI 



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FIG. 8. A modern oscillographic phonocardiogram revealing more faithful representation of the 

 sound vibrations. The patient has mitral stenosis. The low-frequency recording at the apex reveals 

 a loud first sound (Si) and a diastolic murmur (DM). The recording from the LLSB with high- 

 frequency emphasis shows an opening snap (OS). The second sound becomes split at the height of 

 inspiration. 



/) Quality, or timbre, is represented olDJectively and 

 given physical definition in terms of frequency, time, 

 and intensity. 2) Resolution in the dimension of time 

 is improved. For example, two elements of the second 

 heart sound, which are indistinguishable in the 

 o.scillogram and at some levels of frequency in the 

 spectrogram, may be distinguished at other levels of 

 frequency in the spectrogram, j) A more accurate 

 display of the wide dynamic (i.e., intensity) range 

 of cardiovascular sound is attained. For example, a 

 very loud systolic murmur of aortic stenosis and a 

 very faint diastolic murmur of aortic regurgitation 



FIG. 9. Oscillographic record- 

 ing of musical murmur. The 

 patient had a retroserted aortic 

 cusp due to syphilis. Ballisto- 

 cardiogram and electrocardio- 

 gram are also shown. The regular 

 vibrations of the diastolic mur- 

 mur indicate its musical quality. 

 Only the fundamental is demon- 

 strated. Overtone harmonics can- 

 not be identified. 



can be displayed at nearly their true relati\c intensity 

 proportions in a single spectral phonocardiogram. 



Rushmer and colleagues (15) have developed a 

 method for producing what they call "sonvelograms." 

 In essence, these are the intensit\ envelope of the 

 sound. The method involves, first, half-wave rectifica- 

 tion of the oscillographic phonocardiogram, and, 

 second, electrical integration. The resulting curves 

 can be used for timing purposes, and possibly the 

 shape of murmurs will have some uscfiil hemo- 

 dynamic correlations. 



