A case is reported in which is described a modification of staged septation for univentricular atrioventricular connection with double-inlet left ventricle and left-sided rudimentary outlet chamber beneath the aorta. This modification diminishes the risk of atrioventricular conduction disturbances by gluing the perforated septation patch on the myocardium in the area overlying the central conduction system. Fixation of the patch was facilitated by exact fitting of the patch in this area, by ample contact of the patch and the myocardium in this area, and by immobilization of the patch because of equal pressures on both sides because of the perforation of the patch. In addition, this modification facilitates evenly drawing in of the ventricular free wall because already, in the first stage, the complete circumference of the patch is fixed, defining the maximal contribution of prosthetic material to the newly created septum.