Mechanism of tricuspid regurgitation in paramembranous ventricular septal defect.

Literature has been limited in regard to the mechanisms of tricuspid regurgitation (TR) in patients with paramembranous (perimembranous) ventricular septal defect (VSD). Most observations have noted tricuspid valve clefts or dysplasia. We describe another mechanism for production of TR in association with paramembranous VSD. In 8 patients, we found significant TR produced by the VSD jet pushing the tricuspid anterior leaflet forward to open the tricuspid valve orifice. In these patients, a moderate paramembranous VSD extended slightly below the septal tricuspid leaflet with only partial obstruction of the VSD jet. All patients had restrictive VSD with low right ventricular pressure. This mechanism to produce TR was best defined by intraoperative transesophageal echocardiography, but current higher resolution imaging should allow correct diagnosis. We believe that when this mechanism for TR is found in association with a moderate VSD, surgical VSD closure is warranted.