abnormal interventricular septum membranous part morphology ventricular septal defect perimembraneous ventricular septal defect abnormal communications between the two lower chambers of the heart, occurring in the membranous septum with defects in the adjacent muscular portion of the septum; it is generally located in the LV outflow tract just below the aortic valve, associated with pouches or aneurysms of the septal leaflet of the tricuspid valve, which may partially or completely close the defect; an LV-to-RA shunt may also be associated with this defect infracristal ventricular septal defect conoventricular ventricular septal defect perimembranous muscular ventricular septal defect VSD, Type 2 high ventricular septal defect ventricular septal defect, membranous csmith perimembranous outlet ventricular septal defect membraneous ventricular septal defect MP:0010418 MPheno.ontology 2010-09-27T04:12:45Z pmVSD Fyler:1310 perimembranous inlet ventricular septal defect paramembranous ventricular septal defect