The Amplatzer vascular plugs (AVPs), including AVP 4, have excellent occlusion; however, insufficient embolization or recanalization may occasionally occur. This study aimed to evaluate the feasibility and effectiveness of internal coil packing method to insert microcoils into the AVP 4 using an experimental vascular model. The insertion of a 1.7 F microcatheter through the nitinol mesh of the AVP 4 was not possible. Only 0.010-inch electrolytic detachable microcoils could be inserted through catheter tips in contact with nitinol mesh. The internal coil packing of the AVP 4 may be accomplished by inserting 0.010-inch microcoils into the AVP 4 in cases of continued perfusion or recanalization with required short-segment embolization.,