Q. Can you explain Non-restrictive ventricular septal defect?
In non-restrictive VSD PA pressures are elevated hence VSD gradient is low. Non-restrictive VSD is larger in size and has laminar flow in colour Doppler study. Serial echocardiographic studies are done in infants with VSD to assess the VSD size, VSD jet velocity, LV dimension (indirect assessment of level of shunt) and surrounding structures to decide the exact time of intervention. Smaller VSDs are hemodynamically insignificant but they are more prone for bacterial endocarditis due to turbulence created by VSD jet. Associated conditions in a case of VSD makes the major shift in clinical course and management like association of severe RVOT obstruction (TOF). RVOT obstruction changes the direction of flow across the VSD and patient needs early intervention. VSD may be only outlet for LV when both great vessels align with RV. In that case finding of restrictive VSD is an ominous sign and requires urgent intervention. VSD in inlet area may be associated with abnormal attachment of tricuspid valve i.e. chordae to opposite side of septum. Shunt calculation across the VSD can be done utilizing the RVOT and LVOT dimensions and RVOT VTI but such a calculation are not very correct and they are not done routinely. Best echocardiographic parameter of increased shunt is LVIDd (LV end diastolic dimension) Z-Score.