A device for the transvascular implantation and fixation of prosthetic heart valves having a self-expanding heart valve stent (10) with a prosthetic heart valve (11) at its proximal end is introducible into a patient's main artery. With the objective of optimizing such a device to the extent that the prosthetic heart valve (11) can be implanted into a patient in a minimally-invasive procedure, to ensure optimal positioning accuracy of the prosthesis (11) in the patient's ventricle, the device includes a self-expanding positioning stent (20) introducible into an aortic valve positioned within a patient. The positioning stent is configured separately from the heart valve stent (10) so that the two stents respectively interact in their expanded states such that the heart valve stent (10) is held by the positioning stent (20) in a position in the patient's aorta relative the heart valve predefinable by the positioning stent (20).