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Recording provided by Jules Constant, MD.

Split 2nd Heart Sound in Right Bundle Branch Block
Sound is that of wide splitting, ie, S 1 -A 2 -P 2 at rest (“out”) with an even wider A 2 -P 2 interval with inspiration (“in”). Right bundle branch block delays pulmonic valve closure so that S 2 splitting becomes audible at rest. Inspiration decreases intrathoracic pressure, drawing more blood into the right ventricle and postponing pulmonic valve closure even more, so that the normal split becomes wider.