And what did we hear when we focused and tuned in on the heart sounds at the upper left sternal edge in our patient? We heard paradoxic splitting of the second heart sound. That means that instead of as in the normal case, when the patient breathed in, the heart sounds split, such as [sounds]. No, in our case, when the patient breathed out, you heard the splitting of the second heart sound. So, in our case, it was [sounds]. Everybody listen together now, focusing on respiration, listening at the upper left sternal edge and timing systole with the movement of the carotid vessel, as reflected in the cotton swab. Listen together. [Cut-away]
Our patient's paradoxic splitting of the second heart sound reflects underlying pathophysiology. In virtually all cases, it is due to delay of the closure of the aortic valve, and the causes could be electrical, such as left bundle branch block, or mechanical, examples include left ventricular systolic dysfunction as well as left ventricular outflow tract obstruction. In any event, what we observed at the bedside is a reflection of the pathophysiology of our patient.
Oscilloscope
By viewing an oscilloscopic image and simultaneously listening, we can further appreciate these auscultatory events.
Paradoxic splitting
Paradoxic splitting of the second heart sound occurs whenever the aortic closure sound is significantly delayed. During inspiration, the sounds fuse, as P2 is also delayed.During expiration, the pulmonary closure sound precedes the delayed A2. Common causes of paradoxic splitting include electrical delay, such as left bundle branch block and mechanical delay, such as left ventricular dysfunction and left ventricular outflow tract obstruction.