Mondo Description Heart-hand syndrome type 3 is a very rare heart-hand syndrome, described in three members of a Spanish family to date, which is characterized by a cardiac conduction defect (sick sinus, bundle-branch block) and brachydactyly, resembling brachydactyly type C of the hands, affecting principally the middle phalanges in conjunction with an extra ossicle on the proximal phalanx of both index fingers. Feet abnormalities are more subtle.