Septum port locator system and method for an implantable therapeutic substance delivery device
An implantable medical device system includes an implantable device and an external locator device for percutaneously locating detecting port opening of the implantable device. The implantable device includes a port chamber forming the port opening, a septum sealing the port chamber relative to an exterior of the device, and a coil positioned at a known location relative to the port opening. The locator device includes a controller, at least one X-loop electrically coupled to the controller and oriented along a first major axis, and at least one Y-loop electrically coupled to the controller and oriented along a second major axis differing from the first major axis. The system is configured such that when the locator is spatially proximate the coil, an induced voltage in at least the Y-loop(s) is read by the controller to indicate a location of the coil relative to the locator device.
1. A locator device for externally detecting a coil carried by a substance delivery device implanted within a patient, the locator device comprising:
a controller; and
a locator grid including:
a plurality of interleaved X-loops electrically coupled to the controller, each of the X-loops defining a major axis that is oriented parallel to a first major axis,
at least one Y-loop electrically coupled to the controller and oriented along a second major axis differing from the first major axis;
wherein the locator device is configured such that when the locator device is spatially proximate the coil, energization of the coil induces a voltage in the at least one Y-loop that is read by the controller, and further wherein the controller is adapted to determine a location of the coil relative to the locator grid based upon the read voltage.
2. The locator device of claim 1 , wherein the plurality of X-loops includes a central X-loop oriented along a first central axis and the at least one Y-loop comprises a central Y-loop oriented along a second central axis, and further wherein the locator device defines a needle opening extending through a housing of the locator device at a location where the first central axis intersects the second central axis.
3. The locator device of claim 1 , wherein the second central axis is orthogonal to the first central axis.
4. The locator device claim 1 , wherein each of the X-loop is staggered relative to, and overlaps, a neighboring X-loop.
5. The locator device of claim 1 , wherein the locator grid includes a plurality of Y-loops, each Y-loop including a major axis that is parallel to the second major axis such that each Y-loop is staggered relative to a neighboring Y-loop.
6. The locator device of claim 5 , wherein the plurality of Y-loops are interleaved.
7. The locator device of claim 6 , wherein the plurality of X-loops are electrically decoupled from the plurality of Y-loops.
8. The locator device of claim 1 , wherein at least one of the plurality of X-loops comprises a rectangular loop defining a first side opposite a second side and opposing ends, the first and second sides being parallel to the first major axis and the opposing ends being parallel to a minor axis of the at least X-loop, the minor axis being orthogonal to the first major axis.
9. The locator device of claim 1 , wherein the locator device further includes a power source.
10. The locator device of claim 9 , wherein the locator device is adapted such that when the locator grid is positioned proximate the coil and a current is applied to one of the plurality of X-loops, the coil is energized and a voltage is induced in the at least one Y-loop.
11. The locator device of claim 10 , wherein at least one Y-loop includes a plurality of Y-loops, and further wherein the controller is adapted to iteratively sample and compare signals generated at each of the Y-loops in at least partially determining a location of the coil relative to the locator grid.
12. The locator device of claim 11 , wherein the coil is passively energized by the X-loop, and further wherein the controller is adapted to sequentially power respective ones of the plurality of X-loops and iteratively compare signals generated at a selected one of the Y-loops in at least partially determining a location of the coil relative to the locator grid.
13. The locator device of claim 11 , wherein the controller is adapted to output amplitude and phase information of signals that are induced in at least one of the plurality of Y-loops.
14. The locator device of claim 1 , wherein the plurality of X-loops includes a central loop and adjacent loops positioned at opposite sides, respectively, of the central loop, and further wherein the controller is adapted to estimate a tilt of an implantable substance delivery device relative to the locator grid based upon evaluation of symmetry of induced voltages at the central loop and the adjacent loops.