We describe the simultaneous occurrence of a temporal complete atrioventricular block and a persistent disappearance of preexcitation, in a patient with rheumatic mitral stenosis and a ventricular preexcitation, after an effective percutaneous mitral valvuloplasty. These conduction disturbances were attributed to atrioventricular node and paraseptal atrioventricular pathway trauma, due to transseptal manipulation during the mitral valvuloplasty.