A medical fixation system for temporary fixation of an implantable medical device such as a short lead pacemaker outside of the heart in a larger blood vessel such as the superior or inferior vena cava. The fixation mechanism or element is temporary in nature in that the fixation holds the implantable medical device in place until the implantable medical device is grown in to the wall of the vessel and the short lead attached to the implantable medical device and implanted in the heart is grown in. The cell tissue surrounding the implantable medical device and the short lead then keeps the implantable medical device in place without the temporary fixation element.