When we initially evaluated the precordium, we found movement in two areas: the apex and the mid to lower left sternal edge. We have fully evaluated and timed the impulses at the apex, now let's evaluate the impulse at the lower left sternal edge. We'll use the apical movement as a reference, since we already know the timing of those three impulses. Let's everybody look together and evaluate the movement at the lower to mid left sternal edge. [Cut-away]
The movement at the parasternal edge is clearly systolic and it is sustained. And what does that mean? It means this patient likely has significant right ventricular hypertrophy, and that is consistent with what we observed in the jugular venous pulse. Recall that giant "a" wave that also suggested the association of right heart disease in this patient. A parasternal impulse prolonged in systole, right ventricular hypertrophy.
Parasternal impulses graphic
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; tt 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.