Nemec J et al. - A patient with a sporadic heart-hand syndrome, which includes thumb hypoplasia, septum primum atrial septal defect, and cleft mitral valve is described. During attempted placement of a pacemaker lead, persistence of left superior and inferior vena cava was found in addition to the right-sided caval veins. This corresponds to persistence of left-sided supracardinal vein present during fetal development.