And what did we learn together by listening with the diaphragm of the stethoscope at the upper right sternal edge? Well, to begin with, we needed a timing mechanism, so we are going to observe the carotid impulse by virtue of looking at the systolic movement of the tip of the cotton swab. Let’s listen together.
What have we heard by listening at the upper right sternal edge? Well, we want to evaluate two things: heart sounds and if there are any murmurs present and, in this case, the murmur was the most impressive finding. That systolic murmur must now be characterized by several things that describe it and help us with the diagnosis.
Number one, it was systolic. That was clear, it occurred with the carotid impulse, as reflected by the movement of the tip of the cotton swab. The second thing that was important was that the murmur went up and down in systole, that it was crescendo-decrescendo. That means something also. Another important factor was that it was a long murmur. It was not short, but rather it was long. So, how do we interpret that?
Well, heard in this area, at the upper right sternal edge, one must think of lesions associated with the aortic valve. One must always think of that. Secondly, the crescendo-decrescendo nature suggests some sort of outflow tract obstruction, and the fact that that murmur was long, that suggests if there is obstruction, that the obstruction is severe, because even in late systole, there is enough gradient and turbulence, even when flow is low, to make that noise that we interpret as a murmur. We have been told an awful lot by listening at the upper right sternal edge and focusing in on the murmur.
Murmur oscilloscope
By viewing an oscilloscopic imaging and simultaneously listening, we can further appreciate these auscultatory events.
Murmur descriptors
Murmurs may be characterized by descriptors that include: location, timing, contour, and frequency.
Location/radiation
The murmur is best heard at the upper right sternal edge, or aortic area, and this location is related to the underlying lesion. Note the position of the aortic valve in relation to chest wall landmarks. Stenosis of this valve results in turbulent systolic flow in the direction of the upper right sternal edge. In many cases, systolic vibrations may be palpated as a thrill in this area.
Moving heart
This is a graphic example of the heart in a patient with aortic stenosis. In the animation that follows, we can appreciate that the murmur is generated across the stenosed aortic valve during left ventricular systole.
Pressure curves
These simultaneous aortic and left ventricular pressure curves illustrate the relationship of the hemodynamic events to the timing and contour of the murmur.
The murmur begins with the opening of the aortic valve, as left ventricular pressure exceeds aortic root pressure early in systole.
The crescendo-decrescendo configuration of the murmur is related to the changing pressure gradient between the left ventricle and the aortic root in systole. The long length of the murmur reflects significant obstruction, as there is a gradient and hence turbulent flow throughout most of systole.
With pulmonary stenosis, analogous events occur on the right side.
Graphic example
This is a graphic example of a systolic, long, late-peaking, crescendo-decrescendo murmur.
Note that the murmur is mid-frequency.