the tubular portion 122 b 122 c though not shown the disk shaped portion 124 b 124 c may be formed to have multiple oblong openings to enable the anchor 120 b 120 c to be secured to the wall 134 of an internal organ such as with sutures or another suitable attachment technique that can be performed during the surgical procedure alternatively the sensing unit 150 c of fig1 is shown as further including a tubular insert 144 that is secured in the incision prior to placement of the remainder of the unit 150 c the insert 144 can be attached to the wall 134 with an interference fit or the use of a biocompatible cement glue or epoxy screws springs nails etc the tubular portion 122 c of the anchor 120 c can then be secured within the bore of the insert 144 a preferred aspect of this embodiment is that the anchor 120 c is not permanently joined to the insert to facilitate exchange of the sensing unit 150 c and or its sensing device 60 and or the use of a different anchor with additional features as evident from fig1 and 11 both the anchors 120 b 120 c and the sensing devices 60 protrude into the internal cavity 136 with the sensing devices 60 protruding farther though any of the configurations discussed in reference to fig5 through 8 could also be present in the embodiments of fig9 through 11 in addition to the above noted features the anchors 120 a 120 c could be modified to provide other features.