Although vascular plugs allow the interventional closure of medium-sized to large abnormal vessels, their application is limited by the need for long sheaths or large guiding catheters. The authors report their experience with the new Amplatzer vascular plug 4 (AVP 4), a self-expanding spindle-shaped occluder made of Nitinol wire mash, which can be placed through 4-Fr catheters with an internal diameter of 0.038 in. or larger. From October 2009 until June 2012, 14 AVP 4 devices were deployed in 12 patients (ages, 0.3–48.8 years). Nine patients had venovenous or arteriovenous collaterals in functional univentricular hearts. One patient had pulmonary atresia with a ventricular septal defect and major aortopulmonary collateral arteries, and one patient had a pulmonary arteriovenous fistula. One child had a large coronary artery fistula to the right atrium. The authors used AVP 4 devices with diameters of 4–8 mm. In all the patients, the AVP 4 was implanted successfully. No occluder dislocations and no complications related to the procedure occurred. Complete vessel occlusion was achieved in seven cases. In seven additional cases, a residual shunt was present at the end of the procedure while the patients were still fully heparinized. In 2 of 14 vessels, the decision was made to place additional devices to abolish residual shunting. According to the authors’ experience, the AVP 4 allows safe and effective occlusion of medium-size and large abnormal vessels. It is also well suited for tortuous high-flow vessels such as coronary or pulmonary arteriovenous fistulas. In case of a suboptimal position, it is possible to reposition the occluder with ease. Further studies are needed to determine whether initial residual shunting in heparinized patients disappears during follow-up care. The AVP 4 represents a valuable new device for the interventional treatment of complex congenital vessel malformations.