This device (1) comprises at least one inflatable balloon (2), an implantable chamber and a conduit (3) intended to connect the balloon (2) and the implantable chamber in a sealed manner, this balloon (2), this chamber and this conduit (3) being filled with fluid； the pressure of this fluid is such that the balloon (2) is normally inflated but can be compressed, temporarily putting said implantable chamber under overpressure, by circulation of the fluid in said conduit (3). According to the invention, the device (1) further comprises: a catheter (5) in which the balloon (2) is capable of being placed in the deflated state and in which the balloon and said duct (3) are capable of slide； at least one anchoring member (6) at the pulmonary artery or a wall of the heart, connected to an actuating wire (7) sliding in the catheter (5), this anchoring member (6) being mobile, independently of the balloon (2), between a retracting position in the catheter (5) and an anchoring position in which it has exited the catheter (5) and performs an anchoring, and - means (15-18) connecting said conduit (3) and said actuating wire (7) to the catheter (5), allowing, in an active position, to block the sliding of this conduit (3) and this wire relative to the catheter (5) , and in an inactive position, to release this slide. Ce dispositif (1) comprend au moins un ballon (2) gonflable, une chambre implantable et un conduit (3) destiné à relier le ballon (2) et la chambre implantable de manière étanche, ce ballon (2), cette chambre et ce conduit (3) étant remplis de fluide ； la pression de ce fluide est telle que le ballon (2) est normalement gonflé mais qu'il peut être comprimé, mettant temporairement ladite chambre implantable en surpression, par circulation du fluide dans ledit conduit (3). Selon l'invention, le dispositif (1) comprend en outre : - un cathéter (5) dans lequel le ballon (2) est apte à être placé à l'état dégonflé et dans lequel ce ballon et le
