Implantable physiologic monitoring system

• US 20070088214A1
• Filed: 10/14/2005
• Published: 04/19/2007
• Est. Priority Date: 10/14/2005
• Status: Abandoned Application

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Shuros, Allan, Salo, Rodney, Kane, Michael
• Application Number:
  US11/250,928
• Publication Number:
  US 20070088214A1
• Time in Patent Office: Days
• US Class Current: 600/437
• CPC Class Codes: A61B 5/076 Permanent implantations telemetry using implanted circuitry A61B5/0031; implanted stimulators for therapy A61N1/3605, A61N1/362, A61N1/372
• CPC Class Codes: A61B 5/1076 for measuring dimensions inside body cavities, e.g. using catheters A61B3/1005 takes precedence
• CPC Class Codes: A61B 5/6876 Blood vessel
• CPC Class Codes: A61B 5/6884 Clamps or clips
• CPC Class Codes: A61B 8/02 Measuring pulse or heart rate
• 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 8/065 to determine blood output from the heart in general A61B5/029
• 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: A61B 8/4483 characterised by features of the ultrasound transducer

Abstract

An ultrasonic implantable device includes an ultrasonic sensor having a plurality of transducers. The sensor is configured for mounting to a vessel wall. A first of the transducers directs sound waves in a direction at least partially upstream or downstream in the vessel. A second of the transducers directs sound waves in a radial direction through an interior of the vessel against a sidewall of the vessel. The sensor monitors a change in frequency of the sound waves from the first transducer to determine a fluid velocity in the vessel. The sensor also monitors a reflection time of the sound waves from the second transducer that return from the sidewall to determine an internal diameter of the vessel. The determined fluid velocity and vessel diameter can be used to determine a volumetric flow rate of the fluid in the vessel.

Claims

1. An ultrasonic implantable device, comprising:

an ultrasonic sensor having a plurality of transducers, the sensor being mountable to a vessel wall of a vessel, a first of the transducers configured to direct sound waves in a direction at least partially upstream or downstream in the vessel, and a second of the transducers configured to direct sound waves in a transverse direction through an interior of the vessel against a distal portion of the vessel;

wherein the sensor monitors a change in frequency of the sound waves from the first transducer to determine a fluid velocity in the vessel, and the sensor monitors a reflection time of the sound waves from the second transducer that return from the distal portion of the vessel wall to determine an internal diameter of the vessel.

2. The implantable device of claim 1, further comprising an electronic wire lead electronically coupled to the sensor and coupleable to an implanted medical device (IMD).

3. The implantable device of claim 1, wherein the plurality of transducers include piezoelectric crystals arranged as a phased array.

4. The implantable device of claim 1, wherein the sensor includes a first transducer mounting surface facing at least partially upstream or downstream in the vessel, and a second transducer mounting surface facing across the interior of the vessel, wherein at least one of the transducers is positioned on each of the first and second transducer mounting surfaces.

5. The implantable device of claim 1, wherein the determined fluid velocity and the determined internal vessel diameter are used to determine a volumetric flow rate in the vessel.

6. A method of monitoring heart performance, the method comprising:

mounting an ultrasonic sensor having a plurality of transducers to a vessel wall of a first vessel;

directing sound waves from the sensor upstream or downstream in the first vessel to determine a velocity of blood flow in the first vessel;

directing sounds waves from the sensor across the first vessel towards an opposing sidewall of the first vessel to determine a diameter of the first vessel; and

determining blood stroke volume of the heart based on the determined blood flow velocity and the diameter of the first vessel.

7. The method of claim 6, further comprising determining cardiac output by multiplying stroke volume by a heart rate of the heart.

8. The method of claim 6, further comprising determining cardiac output by measuring and combining both the stroke volume and information about a heart rate of the heart.

9. The method of claim 8, wherein the information about a heart rate is obtained from electrogram data that is received from an implanted medical device.

10. The method of claim 8 wherein the information about a heart rate is obtained from electrodes integrated into the sensor.

11. The method of claim 8 wherein the information about a heart rate is obtained from the periodicity of the velocity signal.

12. The method of claim 8 wherein the information about a heart rate is obtained from the periodicity of the diameter signal.

13. The method of claim 6, wherein the sensor is mounted to an interior surface of the vessel wall.

14. The method of claim 6, wherein the sensor is mounted to an exterior surface of the vessel wall.

15. The method of claim 6, wherein determining the blood flow in the vessel includes monitoring a change in frequency of the sound waves directed upstream or downstream in the vessel.

16. The method of claim 6, wherein determining the vessel diameter includes monitoring a reflection time of the sound waves reflected from the opposing sidewall of the vessel.

17. The method of claim 6, further comprising:

directing sound waves from the sensor upstream or downstream in a second vessel located near the first vessel to determine a blood flow velocity in the second vessel;

directing sound waves from the sensor radially across an interior of the second vessel to determine a diameter of the second vessel; and

determining a blood volume flow rate in the second vessel based on the determined blood flow velocity and vessel diameter of the second vessel.

18. The method of claim 17, wherein the first vessel is a vein and the second vessel is an artery.

19. The method of claim 6, further comprising:

directing sound waves from the sensor upstream or downstream in the heart to determine a blood flow velocity of blood in a chamber of the heart, wherein the heart is located near to the first vessel;

directing sound waves from the sensor transversely across an interior of the heart chamber to determine a diameter of the heart chamber; and

determining a blood volume flow rate in the heart chamber based on the determined blood flow velocity and vessel diameter of the heart chamber.

20. The method of claim 6, wherein the first vessel is selected from the group consisting of a coronary artery, a coronary vein, a pulmonary artery, a pulmonary vein, a superior vena cava vein, and the aorta.

21. The method of claim 6, further comprising electrically coupling the sensor to the end of an electric lead.

22. The method of claim 6, further comprising powering the sensor remotely with a wireless connection.

23. The method of claim 6, further comprising conducting wireless communicating between the sensor and a remote device.

24. The method of claim 6, further comprising combining output from one or more additional sensors with output from the ultrasonic sensor to provide greater sensitivity in monitoring a decompensation event, the one or more additional sensors selected from a group comprising a heart rate sensor, a pressure sensor, a temperature sensor, an accelerometer, and an acoustical sensor.

25. The method of claim 6, wherein information provided by the ultrasonic sensor is used in a closed feedback loop system that monitors physiologic performance and is coupled with a therapeutic device to deliver a therapy according to pre-programmed algorithms.

26. The method of claim 6, wherein information from the ultrasonic sensor is used to determine peak flow rate as a cardiac contractility measurement similar to dP/dt assessments and is used for therapeutic optimization purposes.

27. A method of monitoring blood flow in a first vessel, the method comprising:

mounting an ultrasonic sensor having a plurality of transducers to a wall of a second vessel;

directing sound waves from the sensor upstream or downstream in the first vessel to determine a velocity of blood flow in the first vessel;

directing sound waves from the sensor radial across an interior of the first vessel to determine a diameter of the first vessel; and

determining volumetric flow of blood through the first vessel based on the determined blood flow velocity and the determined diameter of the first vessel.

28. The method of claim 27, wherein the first vessel is an artery and the second vessel is a vein, the artery and the vein located adjacent to an intervening vessel.