Sensors for detecting substances indicative of stroke, ischemia, or myocardial infarction

• US 20060079740A1
• Filed: 11/16/2005
• Published: 04/13/2006
• Est. Priority Date: 05/15/2000
• Status: Active Grant

• Current Assignee: Darius F. Mostowfi, James H. Silver
• Original Assignee: Darius F. Mostowfi, James H. Silver
• Inventors: Mostowfi, Darius F., Silver, James H.
• Granted Patent: US 7,769,420 B2
• Time in Patent Office: Days
• US Class Current: 600/309
• CPC Class Codes: A61B 2560/0219 of externally powered implanted units
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/14528 invasively
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/14865 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors
• CPC Class Codes: A61B 5/6862 Stents
• CPC Class Codes: A61B 5/6876 Blood vessel
• CPC Class Codes: A61B 5/6882 Anchoring means

Abstract

A sensor is disclosed, for implantation within a blood vessel to monitor a substance in or property of blood. In one embodiment, the sensor detects nitric oxide or a nitric oxide metabolite. In another embodiment, other substances such as glutamate, aspartate, arginine, citrulline, acetylcholine, calcium, potassium, or dopamine are monitored. The sensor may be attached to a support structure such as a stent, guidewire, or catheter. In a further embodiment, a catheter is disclosed that extracts patient fluid to a sensor outside the body for monitoring a substance or property of the patient fluid. Methods are also disclosed.

Claims

1. A sensor for insertion within a blood vessel comprising:

a support structure;

a sensor housing carried by the support structure; and

a sensing surface exposed to the exterior of the housing;

wherein the sensor is configured to detect a concentration of a substance indicative of stroke or the onset of stroke and wherein the sensor housing has a streamlined configuration.

2. A sensor as in claim 1, wherein the substance is from the group consisting of NO, a metabolite of NO, glutamate, aspartate, calcium, potassium, arginine, citrulline, acetylcholine, and dopamine.

3. A sensor of claim 1, wherein the sensor detects the concentrations of at least two substances from the group consisting of glutamate, NO, a NO metabolite, dopamine, potassium, calcium, acetylcholine, citrulline, arginine, and aspartate.

4. A system for monitoring a substance within bodily fluid, comprising:

a catheter,

a membrane on the surface of the catheter that allows a substance to diffuse across the membrane, wherein the membrane has a streamlined configuration;

a lumen within the catheter, wherein the lumen is in fluid communication with the membrane;

a sensor in fluid communication with the lumen, wherein the sensor determines the concentration of the substance.

5. The system of claim 4, wherein the substance is from the group consisting of glutamate, NO, a NO metabolite, dopamine, potassium, calcium, acetylcholine, citrulline, arginine, and aspartate.

6. The system claim 4, wherein the sensor determines the concentrations of at least two substances from the group consisting of glutamate, NO, a NO metabolite, dopamine, potassium, calcium, acetylcholine, citrulline, arginine, and aspartate.

7. The system of claim 4, wherein the lumen circulates a physiologically compatible fluid past the membrane.

8. A retrievable sensor, comprising:

a support, having a first side for contacting the wall of the vessel and a second side for facing radically inwardly toward the center of the vessel;

a sensor carried by the support and having a sensing surface thereon;

a retrieval means connected to the sensor or the support, wherein the retrieval means is configured to move from a first position to a second position.

9. The retrievable sensor of claim 8, wherein the first position is within the sensor and the second position is outside the sensor.

10. A method of assessing cerebral vasculature status in a patient, comprising the steps of:

positioning a sensor in communication with a body fluid;

determining a baseline concentration of an indicator of the presence of NO or an NO metabolite;

monitoring changes from the baseline; and

activating a signal in response to a change from the baseline by more than a predetermined limit.

11. A method as in claim 10, wherein the positioning step comprises positioning a sensor in communication with blood.

12. A method as in claim 10, wherein the positioning step comprises positioning a sensor in communication with cerebral spinal fluid.

13. A method as in claim 10, wherein the activating a signal step comprises activating an alarm.

14. A method as in claim 13, wherein the activating an alarm step comprises activating an audio alarm.

15. A method as in claim 13, wherein the activating an alarm step comprises activating a visual alarm.

16. A method as in claim 13, wherein the activating an alarm step comprises activating a tactile feedback alarm.

17. A method as in claim 13, wherein the activating a signal step comprises activating a transmission of information to a remote location.

18. A method as in claim 10, wherein the activating a signal step comprises activating a signal to commence a responsive therapy to the patient.

19. A method as in claim 10, wherein the activating a signal step is accomplished in response to a change from the baseline by about 0.01% to about 100% per second.

20. A method as in claim 10, wherein the activating a signal step is accomplished in response to a change from the baseline by more than about 10% to about 100,000%.

21. A sensor for insertion within a blood vessel comprising:

a guidewire;

a sensor housing attached to the guidewire; and

a sensing surface exposed to the exterior of the housing;

wherein the sensor is configured to detect a concentration of a substance indicative of stroke or the onset of stroke and wherein the sensing surface has a streamlined configuration.

22. A sensor of claim 21, wherein the sensor is located at the tip of the guidewire.

23. A sensor of claim 21, wherein the sensor is located proximal to the distal tip of the guidewire.

24. A sensor of claim 21, wherein the sensor is positioned coaxially within the body of the guidewire.

25. A sensor of claim 21, wherein the substance is NO or an NO metabolite.