Pressure-sensing stent

• US 6,053,873 A
• Filed: 04/09/1998
• Issued: 04/25/2000
• Est. Priority Date: 01/03/1997
• Status: Expired due to Term

• Current Assignee: Biosense, Inc. (Cardinal Health, Inc.)
• Original Assignee: Biosense, Inc. (Cardinal Health, Inc.)
• Inventors: Govari, Assaf, Fenster, Maier
• Primary Examiner(s): Hindenburg, Max
• Assistant Examiner(s): Natnithithadha, Navin
• Application Number:
  US09/057,634
• Time in Patent Office: 747 Days
• Field of Search: 600/505, 600/462, 600/465, 600/468, 600/479, 600/480, 623/1, 623/12, 623/11, 606/191, 606/194, 606/198
• US Class Current: 600/505
• CPC Class Codes: A61B 2562/028 Microscale sensors, e.g. electromechanical sensors [MEMS]
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/02158 provided with two or more sensor elements
• CPC Class Codes: A61B 5/027 using catheters
• CPC Class Codes: A61B 5/6862 Stents
• CPC Class Codes: A61B 5/6876 Blood vessel
• CPC Class Codes: A61B 8/06 Measuring blood flow measuring volume flow in general G01F, e.g. G01F1/66, G01F1/72; measuring speed of fluids in general G01P5/00
• CPC Class Codes: A61B 8/12 in body cavities or body tracts, e.g. by using catheters catheters per se A61M25/00
• CPC Class Codes: A61F 2/82 Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents stent-grafts for tubular structures of the body other than blood vessels A61F2/04; stent-grafts for blood vessels A61F2/07; instruments specially adapted for placement or removal of stents or stent-grafts A61F2/95; for closing wounds, or holding wounds closed A61B17/04 - A61B17/115; dilators A61M29/00
• CPC Class Codes: A61F 2250/0001 Means for transferring electromagnetic energy to implants
• CPC Class Codes: A61M 2005/16863 Occlusion detection

Abstract

Implantable apparatus for measuring a fluid flow in the body of a subject, including a stent, having a generally cylindrical radial outer wall and a central lumen. A flow parameter sensor is fixed to the stent, and measures a parameter relating to a rate of blood flow through the stent. A transmitter transmits signals responsive to the measured parameter to a receiver outside the body.

Claims

1. Implantable apparatus for measuring a fluid flow in the body of a subject, comprising:

a stent, having a generally cylindrical radial outer wall and a central lumen;

a flow parameter sensor fixed to the stent, which measures a parameter relating to a rate of blood flow through the stent; and

a transmitter, which transmits signals responsive to the measured parameter to a receiver outside the body; and

wherein the transmitter comprises a coil fixed to the stent.

2. Apparatus according to claim 1, wherein the flow parameter sensor comprises a pair of electrodes, in communication with the lumen.

3. Apparatus according to claim 1, wherein the flow parameter sensor measures a magnetohydrodynamic potential across the lumen.

4. Apparatus according to claim 1, wherein the flow parameter sensor measures an electrical impedance across the lumen.

5. Apparatus according to claim 1, wherein the flow parameter sensor comprises at least one pressure sensor.

6. Apparatus according to claim 5, wherein the pressure sensor comprises a pressure-to-frequency transducer.

7. Apparatus according to claim 1, wherein the flow parameter sensor comprises at least one ultrasound-responsive device.

8. Apparatus according to claim 1, wherein the coil is helically-disposed within the outer wall of the stent, along the length thereof.

9. Implantable apparatus for measuring a fluid flow in the body of a subject, comprising:

a stent, having a generally cylindrical radial outer wall and a central lumen;

a flow parameter sensor fixed to the stent, which measures a parameter relating to a rate of blood flow through the stent;

a transmitter, which transmits signals responsive to the measured parameter to a receiver outside the body; and

wherein the flow parameter sensor comprises;

a flexible diaphragm, fixed within the outer wall of the stent so as to expand radially outward in response to a pressure increase in the lumen; and

a deflection sensor, which generates signals responsive to expansion of the diaphragm.

10. Apparatus according to claim 9, wherein the deflection sensor comprises:

a magnetic core fixed to the diaphragm; and

an electrical coil, circumferentially surrounding the diaphragm and the coil, so that movement of the core due to expansion of the diaphragm causes a change in the inductance of the coil, responsive to the pressure increase.

11. Implantable apparatus for measuring a fluid flow in the body of a subject, comprising:

a stent, having a generally cylindrical radial outer wall and a central lumen;

a flow parameter sensor fixed to the stent, which measures a parameter relating to a rate of blood flow through the stent;

a transmitter, which transmits signals responsive to the measured parameter to a receiver outside the body; and

wherein the transmitter comprises;

the electrical coil; and

circuitry coupled to the coil, having a resonant frequency dependent on the inductance of the coil,

circuitry coupled to the coil, having a resonant frequency dependent on the inductance of the coil,

wherein the coil receives energy from an electromagnetic field and radiates energy substantially at the resonant frequency.

12. Implantable apparatus for measuring a fluid flow in the body of a subject, comprising:

a stent, having a generally cylindrical radial outer wall and a central lumen;

a flow parameter sensor fixed to the stent, which measures a parameter relating to a rate of blood flow through the stent; and

a transmitter, which transmits signals responsive to the measured parameter to a receiver outside the body; and

comprising an implantable capsule, which supplies energy to the flow parameter sensor.

13. A method for measuring blood flow in the body of a subject, comprising:

implanting a stent, to which a transmitter is coupled, in a blood vessel in the body;

receiving signals from the transmitter, responsive to blood flow through the stent; and

comprising irradiating the body with an electromagnetic field, to provide energy to the stent.

14. A method for measuring blood flow in the body of a subject, comprising:

implanting a stent, to which a transmitter is coupled, in a blood vessel in the body;

receiving signals from the transmitter, responsive to blood flow through the stent; and

comprising receiving an ECG signal from the subject, and using the ECG signal in analyzing the blood flow signals received from the transmitter.

15. A method for measuring blood flow in the body of a subject, comprising:

implanting a stent, to which a transmitter is coupled, in a blood vessel in the body;

receiving signals from the transmitter, responsive to blood flow through the stent; and

comprising;

applying a magnetic field to the body in a vicinity of the stent, in a direction generally transverse to the flow of blood through the stent; and

measuring an electrical potential across the stent, along a transverse axis thereof generally perpendicular to the direction of the magnetic field,

wherein receiving signals from the transmitter comprises receiving signals responsive to the electrical potential.

16. A method for measuring blood flow in the body of a subject, comprising:

implanting a stent, to which a transmitter is coupled, in a blood vessel in the body;

receiving signals from the transmitter, responsive to blood flow through the stent; and

comprising measuring a bioimpedance across the stent, wherein receiving signals from the transmitter comprises receiving signals responsive to the bioimpedance.

17. A method for measuring blood flow in the body of a subject, comprising:

implanting a stent, to which a transmitter is coupled, in a blood vessel in the body;

receiving signals from the transmitter, responsive to blood flow through the stent; and

comprising measuring a pressure in the stent, wherein receiving signals from the transmitter comprises receiving signals responsive to the pressure.

18. A method for measuring blood flow in the body of a subject, comprising:

implanting a stent, to which a transmitter is coupled, in a blood vessel in the body;

receiving signals from the transmitter, responsive to blood flow through the stent; and

comprising detecting ultrasonic signals from blood flowing in the stent, wherein receiving signals from the transmitter comprises receiving signals responsive to the detected ultrasonic signals.

19. A method for measuring blood flow in a stent implanted in a blood vessel in the body of a subject, comprising:

implanting two ultrasound markers along the blood vessel, each marker in a known spatial relation to a respective end of the stent;

determining respective positions of the markers relative to an ultrasound probe;

aligning the probe with a long axis of the stent using the determined positions of the markers; and

receiving and analyzing Doppler ultrasound signals from blood flowing in the stent.

20. A method according to any of claims 19, wherein determining the positions of the markers comprises forming an ultrasound image of a portion of the body that contains the stent.

21. A method for fabricating a stent, comprising:

forming at least a portion of the stent from non-conducting material;

fixing electronic components to the portion; and

printing strips of conducting material on a surface of the portion to interconnect the components.

22. A method according to claim 21, wherein forming the device from non-conducting material comprises forming the device from polyimide plastic.

23. A method according to claim 21, wherein printing the strips on the surface comprises transferring an image of the strips to the surface by photolithography.

24. A stent, at least a portion of which comprises non-conducting material, and comprising:

a plurality of electronic components fixed to the portion; and

one or more strips of conducting material printed on a surface of the portion to interconnect the components.