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HANDBOOK OF PHYSIOLOGY ^^ CIRCULATION I 



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FIG. II. Intracardiac phonocardiogram, illustrating one aspect of acoustic localization with this 

 technique. The recordings were taken from a 5g-year-old male with tricuspid insufficiency secondary 

 to right heart failure. The upper recording shows from the top down : chest phonocardiogram from 

 the fifth intercostal space at the left sternal border (sics LSB) ; ne.xt, the intracardiac phonocardio- 

 gram from the main pulmonary artery; and below this, lead II of the electrocardiogram. The lower 

 recording is the same with the exception that the intracardiac phonocardiogram is recorded from 

 the ascending aorta just above the aortic valve. In each recording the beginning was taken near 

 the end of the phase of expiration, and inspiration begins about in the middle of the record. Note 

 that in each recording the tracing taken from the chest shows the increase in the intensity of the 

 murmur with inspiration. In the intracardiac recordings this is well shown in the pulmonary artery 

 but not in the aorta, pointing toward localization of the murmur to the right heart. The demon- 

 stration of an increase in the intensity of this murmur with inspiration confirms the thesis ol Rivero 

 Carvallo (84) that the change in intensity of the murmur on the chest is due to a change in dynamics. 

 It cannot be considered as being due to a change in the position of the heart or in its relation to the 

 chest wall. In addition, note that both components of the second sound are present in the pulmonary 

 artery tracing, whereas only the aortic valve closure component is seen in the tracing taken in the 

 aorta. 



septal defect is regurgitant in type and decreases 

 on inspiration. These two criteria are tliose of tlie 

 murmur of mitral insufiiciency. It must be remem- 

 bered, therefore, that on these two acoustic criteria 

 alone one cannot confidently make the differential 

 diagnosis between mitral insufficiency and ventricular 

 septal defect. 



For diastolic murmurs of valvular origin, the major 

 differentiating feature besides the frequency charac- 

 teristics is again the form of the murmur. Murmurs 

 from the semilunar valve begin with the second 

 sound component and arc dccrcscendo in character. 

 Murmurs from the atrioventricular valve begin shortly 

 after the second sound component with the opening 

 of the atrioventricular valve. They are decrescendo in 

 character with presystolic accentuation, the latter 



occurring in the presence of atrial contractions. For 

 the group that originate at the atrioventricular vahe 

 a murmur that increases in intensit)' with inspiration 

 identifies the site of origin as the tricuspid vahe. 

 A decrease with inspiration or an increase witli 

 expiration identifies the murmur as mitral in origin. 

 The eflfect of normal respiration on semilunar diastolic 

 murmurs, although theoretically following the pattern 

 establislied, is less well brought out than the others, 

 and care must be used in reaching conclusions. Of 

 help here should be a properly performed \'alsalva 

 maneuver or the proper pharmacological agent. 



For continuous imnmurs which arise at abnormal 

 communications of one sort or another, respiration 

 can be used to provide a partial differentiation. An 

 increase in intensity witii inspiration identifies the 



