An occluder device for occluding a cardiovascular defect or a gap between a medical device and adjacent body tissue, the occluder device comprising: a compliant balloon defining a balloon chamber; a tip element disposed at a distal side (B1) of the compliant balloon , a base element disposed at a proximal side (B2) of the compliant balloon , and connecting means comprising at least one connecting strut attached to the tip element and to the base element; elongated actuating means, releasably connectable to the tip element , and longitudinally slidable with respect to the base element ; locking means for maintaining a predetermined distance between the tip element and the base element ; and proximal connector means for releasably connecting the occluder device to correspondingly configured distal connector means of a catheter device , characterised in that : the balloon chamber is fluid-tight; the compliant balloon is provided with a balloon channel forming a longitudinal passage from the proximal side (B2) to the distal side (B1) of the compliant balloon ; the tip element and the base element each have a guide opening substantially coaxial to the balloon channel for slidingly receiving therein a guidewire for the device; the elongated actuating means are disposed longitudinally slidable in the balloon channel ; and the compliant balloon comprises a fluid port for filling and unfilling a fluid into and from the balloon chamber. a compliant balloon defining a balloon chamber; a tip element disposed at a distal side (B1) of the compliant balloon , a base element disposed at a proximal side (B2) of the compliant balloon , and connecting means comprising at least one connecting strut attached to the tip element and to the base element; elongated actuating means, releasably connectable to the tip element , and longitudinally slidable with respect to the base element ; locking means for maintaining a predetermined distance between the tip element and the base element ; and proximal connector means for releasably connecting the occluder device to correspondingly configured distal connector means of a catheter device , characterised in that : the balloon chamber is fluid-tight; the compliant balloon is provided with a balloon channel forming a longitudinal passage from the proximal side (B2) to the distal side (B1) of the compliant balloon ; the tip element and the base element each have a guide opening substantially coaxial to the balloon channel for slidingly receiving therein a guidewire for the device; the elongated actuating means are disposed longitudinally slidable in the balloon channel ; and the compliant balloon comprises a fluid port for filling and unfilling a fluid into and from the balloon chamber. the balloon chamber is fluid-tight; the compliant balloon is provided with a balloon channel forming a longitudinal passage from the proximal side (B2) to the distal side (B1) of the compliant balloon ; the tip element and the base element each have a guide opening substantially coaxial to the balloon channel for slidingly receiving therein a guidewire for the device; the elongated actuating means are disposed longitudinally slidable in the balloon channel ; and the compliant balloon comprises a fluid port for filling and unfilling a fluid into and from the balloon chamber. <EOS>