CARDIOVASCULAR SOUND 



69. 



OS 



* DM 



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OS 



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TIME (sec) 



FIG. 10. Spectral phonocardiogram, apex, in patient with classical mitral stenosis. The loud ring- 

 ing first heart sound (/), mitral opening snap (OS), mid-diastolic murmur (DM), and crescendo 

 presystolic murmur {PS) are well demonstrated. 



PHYSIOLOGIC D.'^TA FOR CORRELATION 



The electrocardiogram is a minimal requirement 

 for physiologic correlative data in phonocardiography. 

 As an additional timing device, the arterial pulse, 

 usually the carotid pulse, has had favor because it 

 provides an indication of the time of closure of the 

 aortic valve. The jugular \enous pulse, sponsored by 

 earlier workers as a useful indicator of diastolic 

 events such as opening of the tricuspid valve, has 

 fallen into disfavor with appreciation of the consider- 

 able and not easily quantifiable delay between cardiac 

 events and their reflection in the venous pulse. 

 Respirations represent, next to the electrocardiogram, 

 perhaps the most useful phenomenon for correlative 

 purposes because of the potent influence of respiration 

 in splitting of the second heart sound and on some 

 murmurs, such as those of tricuspid valve disease. In 

 patients it is possible to follow respirations visually 

 and mark them appropriately in the recording. 

 Devices which automatically pick up respiration, 

 such as a strap around the chest or a detector of air 

 movement at the mouth or nose, incur practical 

 difficulties particularly in ill patients, and may be 

 limited in the faithfulness with which thev follow the 

 respiratory phase. Intracardiac pressure recordings 

 are, of course, useful for correlative purpose. '^ In 



' Eldridge & Hultgren (4) point out the production of 

 spurious heart sounds by cardiac catheters, especially when the 

 tip is located at or near a valve orifice. Such artifacts must be 

 guarded against when doing correlative studies involving intra- 



general, the t\pe of correlative recordings made in 

 phonocardiography are dictated by the nature of the 

 study, i.e., the questions to which answers are sought. 

 Transducers for use in recording various pressure 

 pulses are discussed elsewhere. 



Techniques for recording low-frequency physiologic 

 data on magnetic tape (using frequency modulation) 

 along with cardiovascular sound have increased the 

 flexibility of methods for studying cardiovascular 

 sound. The recording of electrocardiogram, respira- 

 tory mark, or pressure pulse can be demodulated for 

 oscillographic display. If they are to be used in con- 

 junction with the spectral phonocardiogram demodu- 

 lation is not required, since the write-out is in terms 

 of frequency and the correlative phvsiologic trace is 

 inscribed directly on the spectral record. If the sound 

 recordings are to be used for teaching purposes, 

 separate tape channels can be used for the correlative 

 recordings, or the correlative recordings applied at a 

 higher frequency level, e.g., 3.0 kc, can be filtered ofT. 



SOME PR.^CTICAL .^SPECTS OF RECORDING, WITH 

 A DISCUSSION OF .'ARTIFACTS 



As in the other parts of this discussion, the com- 

 ments made here concern mainly recording in man 

 but are pertinent also to work in animals. 



cardiac catheterization (and must also be kept in mind in 

 intracardiac phonocardiography). 



