We shall now listen together at the lower left sternal edge. We shall be using the diaphragm of the stethoscope and, again, we shall be using the cotton swab, so that we can recognize systole, by the reflection on the cotton swab of the carotid impulse. Let us listen together at the lower left sternal edge.
Murmur
The murmur at the lower left sternal edge is diastolic, early in onset, long in duration, decrescendo in contour, and high in frequency.
LLSE auscultation remedial
What is the murmur well heard at the lower left sternal edge? Let’s listen again. Let’s analyze the murmur. Let’s time it with systole by virtue of assessing the carotid impulse at the same time, and all listen together. Lower left sternal edge.
Now, that murmur is impressive – “lub-koooo,” “lub-koooo,” “lub-koooo.” That murmur is also typical. It is diastolic. It begins with S2. It is high in frequency. It trails off in diastole and lasts a long time in diastole. This is typical of semilunar valve regurgitation. That is, aortic or pulmonary regurgitation. It was so readily heard here, but don’t be fooled, sometimes it’s rather subtle. So remember bedside technique. Remember it’s gonna be full hard pressure on the diaphragm to bring out that high frequency murmur. Remember also, you can enhance it if the patient breathes out, expires and holds their breath, you’ll hear it just a bit better. And thirdly, body position – sit them up, have them lean forward – press hard, deep expiration, hold their breath – leaning forward again. You listen carefully and you hear that subtle murmur – not the “lub-koooo,” “lub-koooo.” But subtle, “lub-whew,” “lub-whew.” You’ll pick up the subtle bedside regurgitant murmurs of the semilunar valve.
Murmur descriptors
Murmurs may be characterized by descriptors that include, location, timing, contour, and frequency.
Murmur location/radiation
The murmur is best heard at the lower left sternal edge and this location is related to the underlying lesion. Note the position of the aortic valve in relationship to chest wall landmarks. Regurgitation from this valve results in turbulent diastolic flow in the direction of the mid-to-lower left sternal edge.
Moving heart
This is a graphic example of the heart in a patient with aortic regurgitation. In the animation that follows, we can appreciate that the murmur is generated across the regurgitant aortic valve during left ventricular diastole.
Pressure curves
These simultaneous aortic and left ventricular pressure curves illustrate the relationship of the hemodynamic events to the timing, contour, and frequency of the murmur.
The murmur begins with the aortic sound because the aortic root diastolic pressure exceeds left ventricular pressure immediately after the onset of diastole. The murmur then diminishes as aortic root pressure falls and left ventricular pressure rises in diastole.
Because the pressure difference does not disappear, the murmur is long. The murmur is high frequency primarily because blood is flowing from the high pressure aortic root to the low pressure left ventricle. When pulmonary regurgitation is due to pulmonary hypertension, analogous events occur on the right side.