THE MERCK MANUAL: The Merck Manual of Diagnosis and Therapymultimedia

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  • Cardiovascular Examination
  • Split 2nd Heart Sound in Right Bundle Branch Block

    Sound is that of wide splitting, ie, S1-A2-P2 at rest (“out”) with an even wider A2-P2 interval with inspiration (“in”). Right bundle branch block delays pulmonic valve closure so that S2 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.

    Recording provided by Jules Constant, MD.