Implantable Device and Method for Monitoring Venous Diameter

• US 20090270729A1
• Filed: 04/25/2008
• Published: 10/29/2009
• Est. Priority Date: 04/25/2008
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Verschelling, Marinus C.J., Van Lembergen, Geert, Van Der Veen, Johannes S., Corbucci, Giorgio, Smit, Josephus P.A.
• Granted Patent: US 8,814,798 B2
• Time in Patent Office: Days
• US Class Current: 600/438
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/02028 Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/02152 specially adapted for venous pressure
• CPC Class Codes: A61B 5/02158 provided with two or more sensor elements
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/1076 for measuring dimensions inside body cavities, e.g. using catheters A61B3/1005 takes precedence
• CPC Class Codes: A61B 5/7275 Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: A61B 5/7282 Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take precedence
• CPC Class Codes: A61B 8/0891 for diagnosis of blood vessels
• CPC Class Codes: A61B 8/12 in body cavities or body tracts, e.g. by using catheters catheters per se A61M25/00

Abstract

An implantable medical device system and associated method receive a signal from an implantable sensor operatively positioned relative to a vein, the signal being responsive to changes in a diameter of the vein. A diameter of the vein is determined in response to the sensor signal and used in estimating central venous pressure (CVP).

Claims

1. A method for use in an implantable medical device, comprising:

receiving a signal from an implantable sensor operatively positioned relative to a vein, the signal being responsive to changes in a diameter of the vein;

determining a diameter of the vein in response to the sensor signal; and

estimating a central venous pressure (CVP) based upon the vein diameter.

2. The method of claim 1 wherein the sensor comprises an electrode and the sensor signal comprises an impedance signal

3. The method of claim 1 wherein the sensor comprises an ultrasound transducer and the signal comprises an ultrasound signal.

4. The method of claim 1 wherein the sensor comprises a first electrode, a second electrode and a third electrode positioned along a preformed portion of a medical lead body, wherein the sensor signal comprises a voltage signal, and wherein determining the vein diameter comprises:

applying an electrical pulse between the first electrode and the second electrode in a driver electrode pair;

measuring the voltage signal between the second electrode and the third electrode in a measurement electrode pair;

computing the vein diameter in response to the measured voltage signal;

the preformed portion changing shape with a change in vein diameter and causing a distance between one of the driver electrode pair and the measuring electrode pair to change in response to the shape change of the preformed portion.

5. The method of claim 4 wherein the first, second and third electrodes being triangulated.

6. The method of claim 1 wherein determining the vein diameter comprises determining a change in vein diameter corresponding to a respiratory cycle.

7. The method of claim 6 further comprising sensing a signal responsive to respiration for detecting the respiratory cycle.

8. The method of claim 6 further comprising detecting congestive heart failure in response to a change in vein diameter corresponding to the respiratory cycle being absent.

9. The method of claim 6 wherein estimating the central venous pressure comprises determining a trend in the change in vein diameter corresponding to a respiratory cycle.

10. The method of claim 9 further comprising determining a respiration rate and wherein the trend in the change in vein diameter corresponding to a respiratory cycle compares the respiration rate to the change in vein diameter.

11. The method of claim 1 further comprising determining a trend in the estimated CVP.

12. The method of claim 11 further comprising detecting a worsening heart failure condition in response to the estimated central venous pressure and the trend in the estimated CVP.

13. An implantable medical device system, comprising:

an implantable sensor adapted to be operatively positioned relative to a vein, the implantable sensor generating a sensor signal responsive to changes in a diameter of the vein;

timing and control circuitry for delivering a driver signal to the sensor to enable the sensor to generate the sensor signal; and

a processor for receiving the sensor signal and configured to determine a diameter of the vein in response to the sensor signal and estimate a central venous pressure (CVP) based upon the vein diameter.

14. The system of claim 13 further comprising an elongated lead body carrying the sensor, the lead body comprises a preformed portion for positioning the sensor relative to a vein wall, the sensor being positioned along the preformed portion.

15. The system of claim 14 wherein the preformed portion having a high compliance relative to the vein wall, the preformed portion changing shape with a change in vein diameter.

16. The system of claim 14 wherein the preformed portion comprises a bifurcation and a branch extending from the bifurcation away from the elongated lead body.

17. The system of claim 14 wherein the sensor comprises an electrode for measuring an electrical signal.

18. The system of claim 13 wherein the sensor comprises an ultrasound transducer and the signal comprises an ultrasound signal.

19. The system of claim 15 wherein the sensor comprises a first electrode, a second electrode and a third electrode positioned along the preformed portion in a triangular relationship to each other;

the driver signal comprises a voltage signal applied between the first electrode and the second electrode in a driver electrode pair;

the sensor signal is a voltage signal measured between the second electrode and the third electrode in a measuring electrode pair;

and the processor is configured to compute the vein diameter in response to the to the measured voltage;

a distance between one of the driver electrode pair and the measuring electrode pair changing in response to a change shape of the preformed portion with a change in vein diameter.

20. The system of claim 13 wherein the processor determining the vein diameter determines a change in vein diameter corresponding to a respiratory cycle.

21. The system of claim 20 further comprising a respiration sensor generating a signal responsive to respiration wherein the processor further configured to detect the respiratory cycle.

22. The system of claim 20 wherein the processor detects congestive heart failure in response to a change in vein diameter corresponding to the respiratory cycle being absent.

23. The system of claim 20 wherein estimating the central venous pressure comprises determining a trend in the change in vein diameter corresponding to a respiratory cycle.

24. The system of claim 23 wherein the processor further configured to determine a respiration rate and wherein the trend in the change in vein diameter corresponding to a respiratory cycle compares the respiration rate to the change in vein diameter.

25. The system of claim 13 wherein the processor further configured to determine a trend in the estimated CVP.

26. The system of claim 25 wherein the processor further configured to detect a worsening heart failure condition in response to the estimated central venous pressure and the trend in the estimated CVP.

27. An implantable medical device system for monitoring central venous pressure (CVP), comprising:

a transvenous lead comprising a preformed portion having a high compliance relative to a vein in which the transvenous lead is positioned, the preformed portion changing shape in response to a physiological change in the diameter of the vein wall;

a first electrode, a second electrode and a third electrode carried by the transvenous lead and positioned along the preformed portion in a triangular relationship;

timing and control circuitry for delivering a driver signal between in a driver electrode pair comprising the first electrode and the second electrode;

a processor configured to measure a response signal between a measurement electrode pair comprising the second electrode and the third electrode and compute a diameter of the vein in response to the measured response signal, estimate CVP in response to the computed vein diameter, and detect a heart failure condition in response to the estimated CVP,

the processor further configured to determine a change in the computed vein diameter due to a respiration cycle;

wherein estimating the CVP comprises determining a trend in vein diameter measurements;

wherein the trend in vein diameter measurements comprises a trend in the change in vein diameter due to respiration;

wherein a shape change of the preformed portion changes a distance between at least one of the driver electrode pair and measuring electrode pair.