Cardiac Risk Assessment

• US 20090275848A1
• Filed: 04/30/2008
• Published: 11/05/2009
• Est. Priority Date: 04/30/2008
• Status: Abandoned Application

• Current Assignee: Data Sciences U K Limited (International Business Machines Corporation)
• Original Assignee: Transoma Medical, Inc.
• Inventors: Brockway, Marina V., Brockway, Brian P.
• Application Number:
  US12/112,924
• Publication Number:
  US 20090275848A1
• Time in Patent Office: Days
• US Class Current: 600/513
• 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 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/026 Measuring blood flow A61B3/1233, A61B3/1241 take precedence
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/33 specially adapted for cooperation with other devices
• CPC Class Codes: A61B 5/411 Detecting or monitoring allergy or intolerance reactions to an allergenic agent or substance
• 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: A61N 1/3704 Circuits specially adapted therefor, e.g. for sensitivity control
• CPC Class Codes: A61N 1/37258 Alerting the patient
• CPC Class Codes: A61N 1/37282 characterised by communication with experts in remote locations using a network
• CPC Class Codes: G16H 50/30 for calculating health indices; for individual health risk assessment

Abstract

In a system for assessing cardiac risk of a patient, a measuring component measures a cardiac signal comprised of multiple cardiac cycles at multiple periods in time. A processing component calculates sensitivity of cardiac function to sympathetic drive at each of the periods in time from the measured cardiac signal. A risk identification component evaluates a trend of the sensitivity over time as an indicator of a degree of cardiac risk.

Claims

1. A system for assessing cardiac risk of a patient, the system comprising:

a measuring component that measures a cardiac signal comprised of multiple cardiac cycles at multiple periods in time;

a processing component that calculates sensitivity of cardiac function to sympathetic drive at each of the periods in time from the measured cardiac signal; and

a risk identification component that evaluates a trend of the sensitivity over time as an indicator of a degree of cardiac risk.

2. The system of claim 1, wherein the risk identification component evaluates the trend by evaluating a plot of the sensitivity versus time.

3. The system of claim 1, wherein the risk identification component evaluates the trend by comparing the trend with a predetermined threshold.

4. The system of claim 1, wherein the measuring component, the processing component, and the risk identification component reside in an implantable device.

5. The system of claim 1, wherein the measuring component resides in an implantable device, and wherein the processing component and the risk identification component reside in an external device.

6. The system of claim 5, further comprising a first telemetry component that resides in the implantable device and a second telemetry component that resides in the external device, wherein the first telemetry component transmits at least a portion of the cardiac signal for receipt by the second telemetry component.

7. The system of claim 1, wherein the cardiac function is indicated by an altemans burden over a selected period of time, the alternans burden determined from the cardiac signal.

8. The system of claim 7, wherein the alternans burden is a repolarization altemans burden.

9. The system of claim 7, wherein the alternans burden is a mechanical altemans burden.

10. The system of claim 7, wherein the alternans burden is a QRS altemans burden.

11. The system of claim 7, wherein the sensitivity of cardiac function is calculated by computing a ratio of change in the altemans burden to change in a sympathetic tone marker.

12. The system of claim 7, wherein the sensitivity of cardiac function is calculated as an onset value of a sympathetic tone marker at which a sustained elevation in the altemans burden appears.

13. The system of claim 1, wherein the cardiac function is indicated by a hypertension burden over a selected period of time, the hypertension burden determined from the cardiac signal.

14. The system of claim 13 wherein the hypertension burden is elevated diastolic blood pressure.

15. The system of claim 13 wherein the hypertension burden is elevated systolic blood pressure.

16. The system of claim 1, wherein sympathetic drive is estimated from a heart rate variability measurement determined from the cardiac signal.

17. The system of claim 1, wherein sympathetic drive is estimated from a heart rate increase measurement determined from the cardiac signal.

18. The system of claim 1, wherein the cardiac signal is an electrocardiogram signal.

19. The system of claim 1, wherein the cardiac signal is an electrogram signal measured using an intracardiac lead.

20. The system of claim 1, wherein the cardiac signal is a blood pressure signal.

21. The system of claim 1, wherein the cardiac signal is an impedance measurement.

22. The system of claim 1, wherein the processing component further calculates a baroreflex sensitivity value from the measured cardiac signal.

23. The system of claim 22, wherein an indication of heart rate turbulence, determined from the cardiac signal, indicates the baroreflex sensitivity value.

24. The system of claim 23, wherein the indication of heart rate turbulence is a turbulence slope value.

25. The system of claim 23, wherein the indication of heart rate turbulence is a turbulence onset value.

26. The system of claim 1, wherein the risk identification component adjusts the trend based on circadian variability

27. The system of claim 1, wherein the risk identification component filters the trend to remove circadian variability and short term variability.

28. The system of claim 1, wherein the trend of the sensitivity over time indicates a degree of cardiac risk that exceeds an expected degree of cardiac risk because of patient non-compliance with a prescribed therapy.

29. The system of claim 1, wherein the trend of the sensitivity over time indicates a degree of cardiac risk that exceeds an expected degree of cardiac risk because of insufficient therapy effectiveness.

30. A method of monitoring effect of a cardiovascular therapy for a patient;

the method comprising;

receiving physiologic signal data associated with multiple cardiac cycles;

calculating sensitivity of cardiovascular function to sympathetic drive using the received physiologic signal data;

trending the computed sensitivity over time; and

comparing the sensitivity trend to an expected trend, the expected trend based on a previous condition of the patient and a prescribed therapy regimen that specifies the cardiovascular therapy.

31. The method of claim 30, wherein the cardiovascular therapy modulates the effect of the sympathetic tone on cardiac function.

32. The method of claim 30, wherein the cardiovascular therapy modulates vascular tone.