[The double-chambered right ventricle (author's transl)]

Report on two girls with an obstruction within the right ventricle beneath the infundibulum. A muscular band - probabaly the abnormally situated moderator band - emerges at right angles from the ventricular septum, crosses the lumen and ends at the anterior wall of the right ventricle, thus separating a high-pressure inflow chamber from a low-pressure out-flow chamber. The latter compartment is distinctly larger than the infundibular chamber in Fallot's tetralogy. In bt connecting the left ventricle with the hig-pressure compartment. In one patient an increase of severity of the obstruction could be documented; this child showed a subvalvular membranous aortic stenosis. The diagnosis has to be established by meticulous pressure recording between pulmonary and tricuspid valve and by dye injection into the right ventricle. Ventricular septum defect (in 80%), subvalvular aortic stenosis (in about 10%), pulmonary valvular and peripheric stenosis and open Ductus Botalli are the most important accompanying lesions. The malformation - not diagnosed prior to surgery - causes serious trouble during operation. The investigator thus has to be aware of this condition in every pulmonary valvular ahd subvalvular stenosis especially when accompanied by a ventricular septum defect.