Let us continue the chest wall examination by seeking other areas of precordial movement, and we do have additional movement at the lower left sternal edge. Again, the cotton swab surely helps us evaluate this in terms of the contour of that movement and its timing and in contrasting it to the apical impulse. So we shall place the cotton swab at that lower left sternal edge movement, another one at the apical impulse and analyze the lower left sternal edge precordial movement.
Precordial impulses are not normally palpable at the left sternal edge. When present, they may occur in two areas. The most common impulse is felt at the mid to lower left sternal edge. It reflects movement of the right ventricle. And is almost always due to hypertrophy and/or dilatation of this anteriorly located chamber. More rarely, a dilated pulmonary artery can be felt at the upper left sternal edge. This movement only occurs during systolic expansion of the vessel.
Let us evaluate the significance of the movement at the lower left sternal edge. I have my trusty cotton swabs and we put one at the lower left sternal edge and we feel that impulse quite clearly and exaggerated a bit with the cotton swab… [cut-away] …and then we also use the cotton swab at the apex for timing purposes. And what we observe is rather interesting, that the impulse at the lower left sternal edge is systolic but it is late systolic, and that is a bit unusual. The usual impulse at the parasternal edge reflects dilatation and/or hypertrophy of the right ventricle and that sort of impulse comes up early in systole, and yet again, this is late in systole. Is this a clue to a possible diagnosis in this patient?