EP0359697B1
Expired / Lapsed
EP
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Method and apparatus for catheter location determination
Assignee: Smiths Medical ASD Inc
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Filing: 1989-09-13
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Granted: 1994-11-02
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Expires: 2009-09-13
Abstract
Abstract A method and apparatus (10) for determining accurately the location of the tip (14) of a catheter (16) inside biological tissue is disclosed including a locator (34) having a coil (38) wound axially on a core (36) and a detector (12) in the form of a coil (28) wound on a core (24) removably positionable within catheter (16) adjacent the tip (14). A controller (20) generates AC current to coil (38) to produce an electromagnetic field and compares it with the output voltage developed in coil (28) when the locator (34) comes within close physical proximity to detector (12). Locator (34) includes an amber LED indicator (42) which is energized when the locator (34) is behind the detector (12) and the monitored output voltage is in phase with the generated alternating current and includes a red LED indicator (44) which is energized when the locator (34) is beyond the detector (12) and the monitored output voltage is 180 DEG out of phase with the generated alternating current. The controller (20) includes a beeper (48) which provides an audible indicator when energization changes between the indicators (42, 44).
Inventors
- 👤 Clair L. Strohl, Jr.
- 👤 Michael C. Ferragamo
- 👤 Donald A. Kay
- 👤 Alan R. Shapiro
- 👤 Gary R. Whipple
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 08:52
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/06; A61B5/061; A61B5/062
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
272 words
An apparatus (10) for use with a catheter (16), said catheter (16) having a tip (14) and a lumen, and the apparatus (10) being suitable for determining the location of the tip (14) of the catheter (16) inside biological tissue, comprising: energy source means (18) for generation of an alternating current magnetic field, the current having a first phase, which means is adapted to be positionable outside the biological tissue according to external anatomical landmarks consistent with the approximate location of the tip (14) of the catheter (16) and is adapted to cause the flux lines of the field to be essentially perpendicular to the plane of the tissue surface, detecting means (12) for development of an alternating output voltage having a second phase in reaction to the alternating current magnetic field, and electronic means for connection with the energy source means (18), and the detecting means (12), characterised in the detecting means (12) being adapted to be removably positioned within the catheter lumen at the catheter tip (14), comparing means being provided for comparing the first phase and the second phase, the electronic means being also adapted for connection with the comparing means and for indication of the region of the alternating current magnetic field which develops zero net alternating output voltage in the detecting means (12) and for indication of a predetermined phase transition sequence in the output voltage compared to the first phase when the energy source means (18) is moved in close proximity and in a relative perpendicular arrangement past the detecting means (12), said indication providing a single coordinate of the location of the catheter tip (14).
Claim 2
Dependent Claim
68 words
An apparatus according to claim 1 wherein the electronic means is adapted for determination of a phase transition sequence of in-phase and out-of-phase as well as an opposite phase transition sequence between the alternating current of the energy source means (18) and the alternating output voltage when the energy source means (18) is moved in close proximity and in a relative perpendicular arrangement past the detecting means (12).
Claim 3
Dependent Claim
28 words
The catheter location determining apparatus (10) of claim 1 wherein the electronic means includes at least a first visual indicator (42) positionable with the energy source means (18).
Claim 4
Dependent Claim
71 words
The catheter location determining apparatus (10) of claim 2 wherein the electronic means includes a second visual indicator (44) positionable with the energy source means (18), with the first visual indicator (42) providing a visual indication when the alternating output voltage is in phase with the alternating current and the second visual indicator (44) providing a visual indication when the alternating output voltage is out of phase with the alternating current.
Claim 5
Dependent Claim
27 words
The catheter location determining apparatus (10) of claim 2 wherein the electronic means includes means for producing an audible signal (48) when the phase transition sequence occurs.
Claim 6
Dependent Claim
79 words
The catheter location determining apparatus (10) of claim 1 wherein the energy source means (18) comprises a core (36) of magnetically permeable material and encircling coil (38) and wherein the detecting means (12) comprises a core (24) of magnetically permeable material and an encircling coil (28), with the core (36) of the energy source means (18) being positionable generally perpendicular to the core (24) of the detecting means (12) removably positionable adjacent the tip (14) of the catheter (16).
Claim 7
Dependent Claim
57 words
The catheter location determining apparatus (10) of claim 6 wherein the electronic means includes first (U1) and second amplifiers (U2) for amplifying any electrical signal detected by the coil (28), and switch means (U3) for by-passing one of said amplifiers to provide a different operational mode when said one amplifier is by-passed by said switch means (U3).
Claim 8
Dependent Claim
40 words
The catheter location determining apparatus (10) of claim 1 further including a guidewire (22) removably insertable in the catheter lumen, with the detecting means (12) secured to the guidewire (22) and positionable adjacent the tip (14) of the catheter (16).
Claim 9
Dependent Claim
61 words
The catheter location determining apparatus (10) of claim 1 including a battery (66), means for converting direct current supplied by said battery (66) to alternating current for energizing the energy source means (18), and means for preventing the supply of direct current to said converting means when said battery (66) is being charged so as to render the apparatus (10) inoperable.
Claim 10
Independent Claim
279 words
A method for use with a catheter (16) having a tip (14) and a lumen, the method determining the location of the tip (14) of the catheter (16) inside biological tissue, comprising: providing within the tip portion (14) of the catheter (16) lumen a detecting means (12) for development of an alternating output voltage in reaction to an alternating current magnetic field in close proximity to the detecting means (12), passing an energy source means (18) over the outside of the biological tissue according to anatomical landmarks consistent with the approximate location of the catheter (16) tip (14), the energy source means (18) generating the alternating current magnetic field, the current having a first phase and with flux lines essentially perpendicular to the plane of the tissue surface and developing the alternating output voltage having a second phase in the detecting means (12) when the energy source means (18) and the detecting means (12) are in close proximity and in perpendicular relation, characterised by providing a comparing means connected to the energy source means (18) and the detecting means (12) for comparing the second phase of the alternating output voltage with the first phase of the alternating current magnetic field, and determining a single coordinate of the location of the catheter (16) tip (14) by measuring a planar region within which the alternating current magnetic field develops zero net output voltage in the detecting means (12) and within which the comparing means produces a predetermined phase transition sequence in the output voltage compared to the first phase as the energy source means (18) is moved in close proximity and in a relative perpendicular arrangement past the detecting means (12).
Claim 11
Dependent Claim
42 words
A method according to claim 10 which further comprises determining the location of the catheter (16) tip (14) by combining the single coordinate of the determining step with the anatomical landmarks indicating the biological tissue in which the catheter (16) is located.
Claim 12
Dependent Claim
49 words
The method according to claim 10 wherein the determining step includes providing a first visual indication (42) when the alternating output voltage is in phase with the alternating current; and providing a second visual indication (44) when the alternating output voltage is out of phase with the alternating current.
Claim 13
Dependent Claim
24 words
The method of claim 12 wherein the determining step further includes providing an audible signal (48) upon the occurrence of the phase transition sequence.
Claim 14
Dependent Claim
45 words
The method of claim 10 wherein the providing step includes: (a) providing a guidewire (22), with the detecting means being secured to the guidewire (22); and (b) positioning the guidewire (22) within the catheter (16) for entry into the biological tissue with the catheter (16).
References Cited (Backward Citations)
US4173728A
Cited
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