US5645065A — Catheter depth, position and orientation location…

Claim 1

Independent Claim 153 words

For externally locating a sensor in tissue, a system comprising: a) an external probe including at least first and second output coils having respective non-parallel first and second output-coil axes; b) an output coil-driver circuit that alternately so energizes the first and second output coils as to generate first and second time-varying magnetic fields that penetrate the tissue; c) a sensor coil that has a sensor-coil axis and develops first and second sensor signals in response to the first and second time-varying magnetic fields, respectively; and d) a distance determinator that determines from the first and second sensor signals, independently of the relative angles between the projection of the sensor-coil axis and the projections of the first and second output-coil axes into a plane parallel to the first and second output-coil axes, the distance between the sensor coil and the output coils and generates a distance signal representative of the distance thus determined.

Claim 2

Dependent Claim 153 words

For externally locating a sensor in tissue, a system comprising: a) an external probe including at least first and second output coils having respective non-parallel first and second output-coil axes; b) an output coil-driver circuit that alternately so energizes the first and second output coils as to generate first and second time-varying magnetic fields that penetrate the tissue; c) a sensor coil that has a sensor-coil axis and develops first and second sensor signals in response to the first and second time-varying magnetic fields, respectively; and d) a distance determinator that determines from the first and second sensor signals, independently of the relative angles between the projection of the sensor-coil axis and the projections of the first and second output-coil axes into a plane parallel to the first and second output-coil axes, the distance between the sensor coil and the output coils and generates a distance signal representative of the distance thus determined.

Claim 3

Dependent Claim 28 words

A system as defined in claim 1 further including a distance indicator that receives the distance signal and generates a humanly perceptible indication of the distance represented thereby.

Claim 4

Dependent Claim 63 words

A system as defined in claim 1 further including: a) a test coil carried by the probe as to develop a test signal in response to at least one of the first and second time-varying magnetic fields; and b) a test circuit that receives the test signal and generates a fault indication if the test signal's magnitude is less than a predetermined minimum.

Claim 5

Dependent Claim 18 words

A system as defined in claim 1 further including a catheter in which the sensor coil is mounted.

Claim 6

Dependent Claim 67 words

A system as defined in claim 1 that further includes a direction determinator that determines from the first and second sensor signals the relative angle between the projection of the sensor-coil axis and that of at least one of the first and second output-coil axes into a plane parallel to the first and second output-coil axes and generates an angle signal representative of the angle thus determined.

Claim 7

Dependent Claim 30 words

A system as defined in claim 5 wherein the direction determinator determines the relative angle by computing a quantity proportional to a ratio of the first and second sensor signals.

Claim 8

Dependent Claim 51 words

A system as defined in claim 6 wherein: a) the output coil-driver circuit drives the first and second coils with time-varying signals with respect to which the first and second sensor signals have relative phases; and b) the direction determinator determines the relative angle additionally in accordance with those relative phases.

Claim 9

Dependent Claim 28 words

A system as defined in claim 5 further including a direction indicator that receives the angle signal and generates a humanly perceptible indication of the angle represented thereby.

Claim 10

Dependent Claim 18 words

A system as defined in claim 5 further including a catheter in which the sensor coil is mounted.

Claim 11

Dependent Claim 120 words

A system as defined in claim 1 wherein: a) the external probe includes a third output coil having a third output-coil axis transverse to a plane parallel to the first and second output-coil axes; b) the output coil-driver circuit further so energizes the third output coil as to generate a third time-varying magnetic field that penetrates the tissue; c) the sensor coil further develops a third sensor signal in response to the third time-varying magnetic fields; and d) the system further includes a sensor-coil-position determinator that determines from the third sensor signal whether the third output coil's axis is proximate a bisecting plane normal to the sensor-coil axis at the sensor coil's midpoint and generates a proximity signal indicative thereof.

Claim 12

Dependent Claim 28 words

A system as defined in claim 10 further including a distance indicator that receives the distance signal and generates a humanly perceptible indication of the distance represented thereby.

Claim 13

Dependent Claim 53 words

A system as defined in claim 10 wherein: a) the output coil-driver circuit drives the third coil with time-varying signals with respect to which the third sensor signal has a relative phase; and b) the sensor-coil-position determinator determines from that relative phase whether the third output coil's axis is proximate the bisecting plane.

Claim 14

Dependent Claim 88 words

A system as defined in claim 12 further including: a) a direction determinator that determines from the first and second sensor signals the relative angle between the projection of the sensor-coil axis and that of at least one of the first and second output-coil axes into a plane parallel to the first and second output-coil axes and generates an angle signal representative of the angle thus determined; and b) a direction indicator that receives the angle signal and generates a humanly perceptible indication of the angle represented thereby.

Claim 15

Dependent Claim 37 words

A system as defined in claim 13 wherein the direction indicator generates the humanly perceptible indication of the angle only when the proximity signal has indicated that the third output coil's axis is proximate the bisecting plane.

Claim 16

Dependent Claim 66 words

A system as defined in claim 12 further including a direction determinator that determines from the first and second sensor signals the relative angle between the projection of the sensor-coil axis and that of at least one of the first and second output-coil axes into a plane parallel to the first and second output-coil axes and generates an angle signal representative of the angle thus determined.

Claim 17

Dependent Claim 33 words

A system as defined in claim 15 wherein the direction determinator determines the relative angle only when the proximity signal has indicated that the third output coil's axis is proximate the bisecting plane.

Claim 18

Dependent Claim 24 words

A system as defined in claim 12 further including a proximity indicator that receives the proximity signal and generates a humanly perceptible indication thereof.

Claim 19

Dependent Claim 21 words

A system as defined in claim 17 wherein the humanly perceptible indication that the proximity indicator generates is an audible indication.

Claim 20

Dependent Claim 18 words

A system as defined in claim 10 further including a catheter in which the sensor coil is mounted.

Claim 21

Dependent Claim 39 words

A system as defined in claim 10 wherein the sensor-coil-position determinator determines that the third output coil's axis is proximate the bisecting plane by determining that a relative null has occurred in the magnitude of the third sensor signal.

Claim 22

Dependent Claim 50 words

A system as defined in claim 20 wherein the sensor-coil-position determinator establishes a first threshold equal to a predetermined fraction of a peak value of the third sensor signal's magnitude and determines that the relative null has occurred only if the third sensor signal's magnitude falls below the first threshold.

Claim 23

Dependent Claim 46 words

A system as defined in claim 21 wherein the sensor-coil-position determinator establishes a second threshold greater than the first threshold and determines that the relative null has occurred only if the third sensor signal's magnitude rises above the second threshold after falling below the first threshold.

Claim 24

Dependent Claim 41 words

A system as defined in claim 22 wherein the sensor-coil-position determinator determines that the relative null has occurred only if the third sensor signal's magnitude rises above the second threshold within a predetermined time interval after falling below the first threshold.

Claim 25

Dependent Claim 16 words

A system as defined in claim 23 further including means for adjusting the predetermined time interval.

Claim 26

Dependent Claim 17 words

A system as defined in claim 21 wherein the sensor-coil-position determinator reduces the first threshold over time.

Claim 27

Dependent Claim 24 words

A system as defined in claim 20 further including a proximity indicator that receives the proximity signal and generates a humanly perceptible indication thereof.

Claim 28

Dependent Claim 21 words

A system as defined in claim 26 wherein the humanly perceptible indication that the proximity indicator generates is an audible indication.

Claim 29

Dependent Claim 18 words

A system as defined in claim 20 further including a catheter in which the sensor coil is mounted.

Claim 30

Dependent Claim 88 words

A system as defined in claim 20 further including: a) a direction determinator that determines from the first and second sensor signals the relative angle between the projection of the sensor-coil axis and that of at least one of the first and second output-coil axes into a plane parallel to the first and second output-coil axes and generates an angle signal representative of the angle thus determined; and b) a direction indicator that receives the angle signal and generates a humanly perceptible indication of the angle represented thereby.

Claim 31

Dependent Claim 37 words

A system as defined in claim 29 wherein the direction indicator generates the humanly perceptible indication of the angle only when the proximity signal has indicated that the third output coil's axis is proximate the bisecting plane.

Claim 32

Dependent Claim 66 words

A system as defined in claim 20 further including a direction determinator that determines from the first and second sensor signals the relative angle between the projection of the sensor-coil axis and that of at least one of the first and second output-coil axes into a plane parallel to the first and second output-coil axes and generates an angle signal representative of the angle thus determined.

Claim 33

Dependent Claim 31 words

A system as defined in claim 31 wherein the direction determinator determines the relative angle when the proximity signal indicates that the third output coil's axis is proximate the bisecting plane.

Claim 34

Dependent Claim 154 words

For externally locating a sensor in tissue, a system comprising: a) an external probe including an output coil; b) an output coil-driver circuit that so energizes the output coil as to generate a time-varying magnetic field that penetrates the tissue; c) a sensor coil that has a sensor-coil axis and develops a sensor signal in response to the time-varying magnetic field; and d) a sensor-coil-position determinator that establishes a first threshold equal to a predetermined fraction of a peak value of the sensor signal's magnitude, makes a determination from the sensor signal of whether the output coil's axis is proximate a plane normal to the sensor-coil axis at the sensor coil's midpoint by determining whether a relative null has occurred in the sensor signal, and generates a proximity signal indicative of that determination, the proximity signal indicating that the relative null has occurred only if the sensor signal's magnitude falls below the first threshold.

Claim 35

Dependent Claim 154 words

For externally locating a sensor in tissue, a system comprising: a) an external probe including an output coil; b) an output coil-driver circuit that so energizes the output coil as to generate a time-varying magnetic field that penetrates the tissue; c) a sensor coil that has a sensor-coil axis and develops a sensor signal in response to the time-varying magnetic field; and d) a sensor-coil-position determinator that establishes a first threshold equal to a predetermined fraction of a peak value of the sensor signal's magnitude, makes a determination from the sensor signal of whether the output coil's axis is proximate a plane normal to the sensor-coil axis at the sensor coil's midpoint by determining whether a relative null has occurred in the sensor signal, and generates a proximity signal indicative of that determination, the proximity signal indicating that the relative null has occurred only if the sensor signal's magnitude falls below the first threshold.

Claim 36

Dependent Claim 45 words

A system as defined in claim 33 wherein the sensor-coil-position determinator establishes a second threshold greater than the first threshold and determines that the relative null has occurred only if the sensor signal's magnitude rises above the second threshold after falling below the first threshold.

Claim 37

Dependent Claim 40 words

A system as defined in claim 34 wherein the sensor-coil-position determinator determines that the relative null has occurred only if the sensor signal's magnitude rises above the second threshold within a predetermined time interval after falling below the first threshold.

Claim 38

Dependent Claim 16 words

A system as defined in claim 35 further including means for adjusting the predetermined time interval.

Claim 39

Dependent Claim 17 words

A system as defined in claim 33 wherein the sensor-coil-position determinator reduces the first threshold over time.

Claim 40

Dependent Claim 18 words

A system as defined in claim 33 further including a catheter in which the sensor coil is mounted.

Claim 41

Dependent Claim 256 words

For externally locating a sensor in tissue, a system comprising: a) an external probe including at least first and second output coils having respective non-parallel first and second output-coil axes; b) an output coil-driver circuit that alternately so energizes the first and second output coils as to generate first and second time-varying magnetic fields that penetrate the tissue; c) a sensor coil that has a sensor-coil axis and develops first and second sensor signals in response to the first and second time-varying magnetic fields, respectively; d) an analog-to-digital converter that responds to the sensor signals by generating digital signals representative thereof; e) a microprocessor that controls the output of the coil-driver circuit, that determines from the digital signals (1) the relative angle between the projection of the sensor-coil axis and that of at least one of the first and second output-coil axes into a plane parallel to the first and second output coil axes and, (2) independently of the relative angles between the projection of the sensor-coil axis and the projections of the first and second output-coil axes into a plane parallel to the first and second output-coil axes, the distance between the sensor coil and the output coils, and that generates angle and distance signals respectively indicative of the angle and distance thereby determined; f) a direction indicator that receives the angle signal and generates a humanly perceptible indication of the angle represented thereby; and g) a distance indicator that receives the distance signal and generates a humanly perceptible indication of the distance represented thereby.

Claim 42

Dependent Claim 256 words

For externally locating a sensor in tissue, a system comprising: a) an external probe including at least first and second output coils having respective non-parallel first and second output-coil axes; b) an output coil-driver circuit that alternately so energizes the first and second output coils as to generate first and second time-varying magnetic fields that penetrate the tissue; c) a sensor coil that has a sensor-coil axis and develops first and second sensor signals in response to the first and second time-varying magnetic fields, respectively; d) an analog-to-digital converter that responds to the sensor signals by generating digital signals representative thereof; e) a microprocessor that controls the output of the coil-driver circuit, that determines from the digital signals (1) the relative angle between the projection of the sensor-coil axis and that of at least one of the first and second output-coil axes into a plane parallel to the first and second output coil axes and, (2) independently of the relative angles between the projection of the sensor-coil axis and the projections of the first and second output-coil axes into a plane parallel to the first and second output-coil axes, the distance between the sensor coil and the output coils, and that generates angle and distance signals respectively indicative of the angle and distance thereby determined; f) a direction indicator that receives the angle signal and generates a humanly perceptible indication of the angle represented thereby; and g) a distance indicator that receives the distance signal and generates a humanly perceptible indication of the distance represented thereby.

Claim 43

Dependent Claim 18 words

A system as defined in claim 39 further including a catheter in which the sensor coil is mounted.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2000-07-07	2001-01-06	2001-07-08	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2004-07-07	2005-01-06	2005-07-08	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2008-07-07	2009-01-06	2009-07-08	$7700.00	Window Closed / Lapsed

Catheter depth, position and orientation location system

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