Physiologically Split 2nd Heart Sound


This record will help you to recognize the presence of a physiologically split second heart sound. In this case the difference between the first and second component of the second heart sound varies with respiration. At peak inspiration the distance between the first and second heart sound is at a maximum and at peak expiration it is at a minimum. The second heart sound (S2) is created by the closing of the aortic valve and the closing of the pulmonic valve. The difference in timing between the closure of the aortic and pulmonic valves creates a split second heart sound.  Careful analysis of the splitting and intensity of the second heart sound can indicate the presence of many cardiac abnormalities.  In this example splitting varies between zero and eighty milliseconds depending on the phase of the respiratory cycle.  In physiologic splitting the maximum separation between aortic and pulmonic components of the second heart sound occurs at peak inspiration.  In paradoxical splitting the maximum separation occurs at peak expiration.  Paradoxical splitting can occur with left bundle-branch block (LBBB) and aortic stenosis both of which cause the aortic valve closure to be delayed until after the pulmonic valve closure, reversing the normal sequence of events. 
Physiologic Split 2nd HS
Fixed Split Second HS

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