Medical devices for closing anatomical apertures, such as atrial or ventricular septal defects, are disclosed. The medical devices can include a plug body having a proximal end, a distal end, and a longitudinal axis. The plug body can include an exterior surface, an interior surface defining an interior lumen, and a seal which can be located within the interior lumen. The medical devices can also include at least one arm member extending through the plug body between the exterior surface and the interior surface of the plug body. In certain embodiments, the medical device can include a distal loop and a proximal loop extending through the plug body. In certain embodiments, the proximal loop can be smaller than the distal loop, such that a top end and a bottom end of the proximal loop can fit within a top end and a bottom end of the distal loop.