METHOD AND APPARATUS FOR TRENDING A PHYSIOLOGICAL CARDIAC PARAMETER

• US 20070049835A1
• Filed: 09/07/2006
• Published: 03/01/2007
• Est. Priority Date: 06/25/2003
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Goode, Paul
• Granted Patent: US 7,826,891 B2
• Time in Patent Office: Days
• US Class Current: 600/509
• 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 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/4035 Evaluating the autonomic nervous system

Abstract

The present invention relates to an implantable cardioverter-defibrillator or pacemaker whose standard circuitry is used to trend a physiological cardiac parameter using intra-cardiac impedance measurements. The trend information may be used to predict the onset of a sudden cardiac death (SCD) event. By being able to predict the onset of an SCD event, patients and their physicians may be forewarned of a life-threatening event allowing them to respond accordingly. The trend information may also be used to predict the efficacy of cardiac-related medications, monitor progress of congestive heart failure, detect the occurrence of myocardial infarction, or simply track changes in sympathetic tone.

Claims

1. A system for predicting sudden cardiac death episode, comprising:

a measuring device that measures intra-cardiac impedance;

a derivation module that derives a physiologic cardiac parameter from the measured impedance, the derived physiologic cardiac parameter comprising an ejection fraction;

a trending module that trends the derived parameter over spaced time intervals to create trend data; and

an analyzing module that analyzes the trend data to predict the onset of a sudden cardiac death episode.

2. The system of claim 1, comprising comparing trends and detecting a difference between the trends.

3. The system of claim 1, further comprising a reporting module that reports the trend data to an outside source.

4. The system of claim 3, wherein the reporting module reports trend data that predicts onset of a sudden cardiac death episode.

5. The system of claim 1, wherein the derivation module and the trending module are packaged with an implantable measuring device.

6. The system of claim 5, wherein the package is capable of being implanted in a human body.

7. The system of claim 1, further comprising an external device for storing the trend data.

8. The system of claim 1, wherein the physiologic cardiac parameter correlates to sympathetic and parasympathetic activity.

9. The system of claim 1, wherein the system downloads the trend data to a separately located storage device.

10. The system of claim 1, wherein the implanted device measures intracardiac impedance by applying a current between two electrodes and measuring a resulting voltage that is used to calculate the cardiac impedance.

11. The system of claim 10, wherein the electrodes are part of at least one unipolar lead and a remote device.

12. The system of claim 10, wherein the electrodes are part of at least one bipolar lead.

13. The system of claim 10, wherein the electrodes are part of at least one unipolar lead and a bipolar lead.

14. The system of claim 10, wherein the electrodes are part of at least one bipolar lead and a remote device.

15. A device for trending a physiological cardiac parameter, comprising:

an impedance module that measures an intra-cardiac impedance at spaced time intervals;

a parameter module that calculates cardiac parameter values using the measured impedance;

a trending module that generates trend data using the calculated parameter values for monitoring at least one of a drug regimen, a progress of congestive heart failure, and whether a myocardial infarction has occurred.

16. The device of claim 15, wherein the parameter values represent a parameter selected from a group consisting of stroke volume, ejection fraction and pre-ejection period.

17. The device of claim 16, wherein the trending data is used to predict a sudden cardiac death episode and the parameter is an ejection fraction.

18. The device of claim 15, further comprising an analyzing module that analyzes trend data to track one or more predetermined physiological indicators.