PHONOCARDIOGRAPHY 



727 



GREAT 

 VESSEL 



MURMURS 

 S-L 



>-D- 



FIG. 10. Effect of premature ventricular contraction on 

 systolic murmurs of vaKnilar origin. The pressures are from the 

 great vessel, \entricle, and atrium of a subject with both 

 semilunar valvular stenosis and atrio\entricular vaKular 

 insufficiency. The acoustics below show only the envelopes of 

 the respective murmurs from the semilunar valve iS-h) and 

 from the atrioventricular valve (A-V). The first beat is normal, 

 followed by a premature ventricular contraction, and the last a 

 normal beat after a compensatory pause. Note the relatively 

 greater effect of the premature contraction on the systolic 

 pressure gradient across the semilunar valve and its murmur 

 than on the systolic pressure gradient across the atrioventricular 

 valve and its murmur. 



cordings with other parameters on the surface, as 

 discussed above, the timing of various events can be 

 implemented. 



Method of Identification of Site of 

 Origin of a Murmur 



With the physiological basis for murmur produc- 

 tion described, one can now set down certain methods 

 of approach and criteria that will allow for identifica- 

 tion of the site of murmur production. Where the 

 physiological circumstances surrounding murmur pro- 

 duction are unique, a characteristic or pathognomonic 

 murmur may result which leads iinmediately to 

 identification. However, more often similar phys- 

 iological circumstances coexist for more than one 

 lesion and the best that can be done on purely 

 acoustic grounds is a differential diagnosis. Again, 

 this discussion will be limited to physiological prin- 

 ciples and no attempt will be made to catalogue in 

 detail all lesions and their variations. 



The first step, as mentioned previously, is to identity 

 the phase of the cardiac cycle in which the murmur 

 occurs. When a murmur or combination of murmurs 

 occurs in both systole and diastole, a distinction 



should be made as to whether the murmur has a 

 systolic and a diastolic component, or whether it is 

 truly a continuous murmur. Next, one should de- 

 termine the region on the thorax over which the 

 murmur is heard. Although this criterion is not 

 withoiu exceptions, in the vast majority of cases 

 there is good uniformity with expected localization. 

 The next step should be the determination of the 

 internal characteristics of the murmur, this is, the 

 form. This may not always be readily discernible 

 by auscultation, and, if important, should be de- 

 termined by phonocardiography. For systolic mur- 

 murs, this allows separation of murmurs from the 

 semilunar valve from those originating at tlie atrio- 

 ventricular valve. The former group yield ejection- 

 type murmurs and the latter group yield regurgitant- 

 type miumurs. To this latter group must be added 

 the murmur of ventricular septal defect. The next 

 step should be to note tlie effect of respiration, in- 

 cluding the \'alsalva maneus'er if necessary, on the 

 intensitv of the murmur. This allows for a separation 

 into two different groups; one that originates and is 

 limited to the right heart (increase with inspiration) 

 and the other that originates in the left heart or 

 from left-to-right shunts (decrease with inspiration). 



Therefore for systolic murmurs of valvular origin, a 

 murmur may be pinpointed to the tricuspid vah'e if it 

 is regurgitant in type and increases on inspiration. 

 Murmurs from the pulmonic valve also increase with 

 inspiration but are ejection in type. A murmur is 

 identified as coming from the mitral valve if it is 

 regurgitant in type and either decreases on inspira- 

 tion or increases on expiration. This same response to 

 respiration occurs if the murmur originates at the 

 aortic valve but it is ejection in type rather than 

 regurgitant (table i). 



It should be noted that tlie miu'tnur of \entricular 



TABLE I. Systolic Murmurs of Valvular Origin, 

 Criteria for Identification of Site of Origin 

 (Other Than Localization on Thorax) 



Internal Effect of 



Characteristics Inspiration* 



R D 



R I 



E D 



E I 



Mitral insufficiency (MI)t 

 Tricuspid insufficiency (TI) 

 Aortic stenosis (AS) 

 Pulmonic stenosis (PS) 



E=ejection type; R= regurgitant type; I=increased inten- 

 sity; D= decreased intensity. * The effect of expiration is 

 just the opposite. f The murmur of ventricular septal de- 

 fect with left-to-right shunt (VSD, L-R) has the same charac- 

 teristics. 



