PHONOCARDIOGRAPHY 



717 



Consider next systolic murmurs that arise out of 

 insufficiency of the atrioventricular valves. In this 

 circumstance there is regurgitation of blood from the 

 ventricle back into the atrium during \entricular 

 systole. The atrial pressure, which normally declines 

 earlv in systole and rises gradually in late systole up 

 to the point of opening of the atrioventricular valve, 

 shows instead a progressive rise up to the peak of the 

 V wave. This contour is variable, howe\er, and in 

 certain cases atrial pressure may rise sharply early in 

 systole mimicking the ventricular pressure. This has 

 been called \entricularization of the atrial pressure 

 curve. The level and contour of the atrial pressure 

 bear no strict relationship to the severity of the re- 

 gurgitation, due undoubtedly to the fact that other 

 parameters such as atrial volume and distensibility 

 play an unquantifiable role. In any case, there is a 

 gradient of pressure from ventricle to atrium all the 

 time between the upward and downward crossings of 

 the pressure curves. From the acoustic standpoint, 

 then, the murmur can begin immediately with the 

 atrioventricular closure component of the first sound 

 (if it is present) and can continue to the time of 

 opening of the atrioventricular valve which occurs 

 later than the second sound component. The time- 

 course of the murmur between these two points 

 varies. In the case of the ejection murmur a first 

 approximation attempt has been inade to correlate 

 murmur intensity with pressure gradient and found 

 not to be unreasonable (35). Such a correlation 

 appears to be not as good for atrio\entricular regurgi- 

 tation. It is possible that this difference between the 

 two tvpes of murmurs is due to a better correlation 

 between pressure gradient and flow in the former 

 case than in the latter. .Such an explanation implies a 

 relatively constant resistance during systole on the 

 part of the semilunar valve with stenosis and a varying 

 resistance on the part of the atrioventricular valve 

 with regurgitation. It is hoped that techniques will 

 become available to investigate this question more 

 thoroughly. With well-developed cases of atrioven- 

 tricular valve insufficiency the most common finding 

 is a murmur that shows little or no variation in 

 intensity from the beginning to the end. Other cases 

 show increasing intensity from onset to end. Still 

 others show maximum intensity early with declining 

 intensity with time, and in some cases there appear 

 to be fluctuations in murmur intensity throughout its 

 course. A detailed correlation between murmur con- 

 tour and the exact nature of any given lesion awaits 

 further investigation. In any e\ent, regardless of the 

 type of en\elope, that of crescendo-decrescendo is not 



seen. This murmur therefore has three attributes, 

 which are: /) it begins with the first sound, 2) it is 

 not crescendo-decrescendo but is usually unchanged 

 in intensity throughout systole, and j) it continues up 

 into and perhaps beyond the .second sound compo- 

 nent. This type of murmur, which is different in all 

 three characteristics from the ejection type, Leatham 

 has called the regurgitant type (fig. 7). Again, because 

 of the physiological circumstances surrounding its 

 origin, this valvular murmur, regardless of location on 

 the thorax, comes from an atrioventricular valve. 



For systolic murmurs of valvular origin, those from 

 the semilunar valve can be recognized by the fact 

 that they are of the ejection type, whereas murmurs 

 from the atrioventricular \al\e are of the regurgitant 

 type. Such a division, although it undoubtedly has 

 exceptions (92), is well based on hemodynamics and 

 represents a notable contribution. One problem for 

 the future is a more precise correlation between the 

 variations within each type and the specific hemo- 

 dynamic and anatomical variations of the pathology. 



In the same way that the hemodynamic events 

 control the nature of the production of systolic 

 murmurs, just so do they control diastolic murmurs. 

 Consider first diastolic murmurs that arise out of 

 insufficiency of the .semilunar valve. Here again the 

 relationship between ventricular and great vessel 

 pressure is altered. In the well-established case there 

 is a more rapid decline of the great vessel pressure in 

 diastole with a lower end-diastolic level. The ven- 

 tricular pressure in diastole is either unaltered or 

 shows a gradually increasing level up to end-diastolic 

 pressure. Indeed, in the severe case these two pressures 

 may be virtually identical at the start of v'entricular 

 systole. There is therefore a gradient of pressure from 

 the time that the ventricular pressure falls below 

 great vessel pressure to the end of the next phase of 

 isometric contraction, and this gradient shows a steady 

 decline throughout the course of diastole. From the 

 point of view of the acoustics, then, the murmur will 

 begin with the closure of the semilunar valve, the 

 second sound component if it occurs, and then show a 

 gradually decreasing intensity (decrescendo). Note 

 that as in atrioventricular insufficiency a strict corre- 

 lation between murmur and pressure gradient is not 

 present, and no final answer can be expected until 

 the time-course of regurgitant flow is measured. It is 

 due to this and other factors that an assessment of 

 the severity of semilunar insufficiency on the basis of 

 the murmur may be hazardous. The other important 

 characteristics of semilunar insufficiency murmurs is 

 that they are almost all uniformly high-pitched in 



