Pansystolic murmurs are heard from beginning of S1 and up to S2, where as ejection systolic murmurs are heard from midsystole and end well before S2.
Duration (intensity not always) of ejection murmurs can increase with increasing severity of stenosis. Ejection systolic murmurs have crescendo and decrescendo character, peaking occurs more later with increasing severity of murmurs. Usually ESM tend decrease in intensity at the end of systole because ejection tend reduce.
Pansystolic murmur classically have same intensity throughout systole, they tend not decrease towards later part of systole sometimes they may increase in intensity towards end of systole. .
Although pansystolic murmurs began with S1 due to dampening effect of S1, initial part of murmurs may not be heard, although is recorded phonocardiographically. So clinical differentiation of Pansystolic from ejection systolic murmur, is by concentrating on end of systole; is murmur well heard before S2, or there is definite gap between murmur and S2, if gap is present than it is sign of ejection systolic murmur
Late systolic murmurs like pansystolic murmurs are also heard well up to S2.
Early systolic murmurs occur early in systole and end well before S2
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