Medical Mystery of the Week

      You are presented with a recording of the heart sounds of a 62-year-old man who is being seen for his annual physical examination.
      What is your diagnosis, what test(s) would you order to confirm you suspicions, and what treatment, if any, do you recommend?
      DIAGNOSIS: Paradoxical split of the second heart sound over the pulmonic area (left 2nd intercostal space) due to a left bundle branch block (LBBB).

This figure demonstrates the effects of inspiration and expiration on the timing of heart sounds over the aortic area (A, right second intercostal space), pulmonic area (P, left second intercostal space) and cardiac apex. Because inspiration increases right heart return and therefore delays right heart emptying, S2A occurs before S2P in the pulmonic area.  S1, first heart sound; S2, second heart sound; S3 and S4, gallop sounds.

The video demonstrates a paradoxical split of S2P - the splitting of S2 occurs during expiration rather than during inspiration. In this case the abnormal splitting was due to a left bundle branch block (LBBB). LBBB delays left ventricular emptying, hence the paradoxical splitting of S2.

Bonus Question Diagnosis: Lische's nodules (hamartomas) in the iris of a patient with neurofibromatosis type I.