it means there is a defect either in the membranous part of the IV septum or the muscular part of it.

Membranous part is due to endocardial cushion defect; muscular's could occur in multiple small one - swiss cheese VSD

blood would flow from LV to RV causing the overload in RV in long term and Eisenmenger complex results.

Features of Eisenmenger complex is due to the pulmonary hypertension that developed as a result of P.arteriolar hypertension, destruction of

pulmonary bed, causing the blood to flow back from RV to LV. Ended up cyanosis

typically for eisenmenger, RV hypertrophy, cyanosis, reversal of shunt