Murmur of Aortic Stenosis

We’re now going to examine a young man with severe aortic stenosis. He became lightheaded as he went to run and catch a baseball, and his family was quite concerned. He came to you. There had actually been a history of a murmur in the past, and when you examined him, you found his carotid vessel was a bit small, slow rising, with a larger than normal impulse, more sustained in the chest wall. And then you listen at the upper right sternal edge. Again, we’ll time this with the carotid vessel and let’s all listen together.

That is the classic murmur of severe aortic stenosis. Let’s mimic it together. Upper right sternal edge, it’s mid frequency, it’s almost groaning [sounds]. You do it, let’s see how you can groan. [sounds] Now, why do I say severe? Well, to begin with, the murmur was long, that means even during periods of relatively modest flow in late systole, there’s enough stenosis to cause turbulence and generate that audible murmur. In addition, of course, we did more than just auscultation. The carotid pulse was a bit small and there was a sustained apical impulse. All of this tells you that this is significant aortic stenosis. Let’s mimic it again. [sounds] Radiating up from the upper right sternal edge even into the carotid vessel.

Murmur Location and 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.

AS Heart Animation

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. [sounds]

AS 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 grandient and, hence, turbulent flow throughout most of systole. With pulmonary stenosis, analogous events occur on the right side. [sounds]

Aortic Stenosis vs. Aortic Sclerosis

The murmur of aortic stenosis must be differentiated from the murmur of aortic sclerosis. The murmur of aortic sclerosis is commonly heard in older patients and is due to early systolic turbulent flow across a fibrosed aortic valve in the absence of significant obstruction. Like the murmur of aortic stenosis, this murmur is best heard at the upper right sternal edge, is systolic, crescendo-decrescendo and mid frequency. In contrast to the long, late peaking murmur of significant aortic stenosis, it is short and early peaking, as it occurs when the majority of blood is ejected from the ventricle in early systole.