System and method for estimating cardiac pressure based on cardiac electrical conduction delays using an implantable medical device

• US 9,066,662 B2
• Filed: 07/16/2013
• Issued: 06/30/2015
• Est. Priority Date: 04/04/2007
• Status: Active Grant

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: Wenzel, Brian J., Gutfinger, Dan E., Naware, Mihir, Min, Xiaoyi, Siou, Jeffery, Bjorling, Anders, Panescu, Dorin
• Primary Examiner(s): DIETRICH, JOSEPH M
• Application Number:
  US13/943,680
• Publication Number:
  US 20150025397A1
• Time in Patent Office: 714 Days
• Field of Search: 607/23, 600513-516
• US Class Current: 1/1
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61B 5/02156 Calibration means
• CPC Class Codes: A61B 5/72 Signal processing specially adapted for physiological signals or for diagnostic purposes character recognition, recognising digital ink, document-oriented image-based pattern recognition G06V30/00; recognition or understanding of postal images G06V30/424
• CPC Class Codes: A61N 1/365 controlled by a physiological parameter, e.g. heart potential evoked response A61N1/371
• CPC Class Codes: A61N 1/36564 controlled by blood pressure
• CPC Class Codes: A61N 1/36578 controlled by mechanical motion of the heart wall, e.g. measured by an accelerometer or microphone
• CPC Class Codes: A61N 1/3682 with a variable atrioventricular delay
• CPC Class Codes: A61N 1/3684 for stimulating the heart at multiple sites of the ventricle or the atrium
• CPC Class Codes: A61N 1/36842 Multi-site stimulation in the same chamber
• CPC Class Codes: A61N 1/36843 Bi-ventricular stimulation
• CPC Class Codes: A61N 1/37258 Alerting the patient

Abstract

Techniques are provided for estimating left atrial pressure (LAP) or other cardiac performance parameters based on measured conduction delays. In particular, LAP is estimated based interventricular conduction delays. Predetermined conversion factors stored within the device are used to convert the various the conduction delays into LAP values or other appropriate cardiac performance parameters. The conversion factors may be, for example, slope and baseline values derived during an initial calibration procedure performed by an external system, such as an external programmer. In some examples, the slope and baseline values may be periodically re-calibrated by the implantable device itself. Techniques are also described for adaptively adjusting pacing parameters based on estimated LAP or other cardiac performance parameters. Still further, techniques are described for estimating conduction delays based on impedance or admittance values and for tracking heart failure therefrom.

Claims

1. A method for calibrating a cardiac pressure estimation system of an implantable medical device for implant within a patient, the method comprising:

detecting a first cardiac pressure value (Pressure₁) and a first calibration value (D₁) while the patient is at rest, the first calibration value being a detected conduction delay within the heart of the patient;

detecting a second cardiac pressure value (Pressure₂) and a second calibration value (D₂) while the patient is subject to a condition significantly affecting cardiac pressure within the patient, the second calibration value also being a detected conduction delay within the heart of the patient;

determining conversion factors for converting additional detected conduction delays into cardiac pressure estimates based on the first and second cardiac pressure values (Pressure₁, Pressure₂) and the first and second calibration values (D₁, D₂); and

transmitting the conversion factors to the implantable medical device for use therein.

2. The method of claim 1 wherein a slope conversion factor is calculated by:

Slope=(Pressure₂−

Pressure₁)/(D₂−

D₁).

3. The method of claim 2 wherein determining a baseline conversion factor is calculated by:

Baseline=Pressure₂−

Slope*D₁.

4. The method of claim 1 wherein:

detecting the first cardiac pressure value (Pressure₁) comprises detecting a first left atrial pressure (LAP₁);

detecting the first calibration value (D₁) comprises detecting a first conduction delay between the LV and the RV (D_LV-RV/1);

detecting the second cardiac pressure value (Pressure₂) comprises detecting a second left atrial pressure (LAP₂);

detecting the second calibration value (D₂) comprises detecting a second conduction delay between the LV and the RV (D_LV-RV/2); and

determining conversion factors comprises determining conversion factors for converting additional detected conduction delays between the LV and the RV into left atrial pressure estimates based on the first and second left atrial pressure values (LAP₁, LAP₂) and the first and second calibration values (D_LV-RV/1, D_LV-RV/2).

5. The method of claim 4, wherein the conversion factors comprise

a Slope_LAP/LV-RV calculated by

Slope_LAP/LV-RV(LAP₂−

LAP₁)/(D_LV-RV/2−

D_LV-RV/1).

6. The method of claim 5, wherein the conversion factors comprise

a Baseline_LAP/LV-RV calculated by:

Baseline_LAP/LV-RV=LAP₂−

Slope_LAP/LV-RV*D_LV-RV/1.

7. The method of claim 6 further comprising:

inputting into a memory of the implantable medical device the conversion factors;

detecting an additional detected conduction delays between the LV and the RV (D_LV-RV/N); and

estimating left atrial pressure (qLAP_LV-RV) within the patient from the electrical conduction delay by applying the conversion factors to the conduction delay (D_LV-RV/N).

8. The method of claim 7, wherein the left atrial pressure value (qLAP_LV-RV) is estimated by calculating:

qLAP_LV-RV=D_LV-RV*Slope_LAP/LV-RV+Baseline_LAP/LV-RV.

9. The method of claim 7 further comprising updating Baseline_LAP/LV-RV by:

detecting an additional measured conduction delay between the LV and the RV (D_LV-RV/N); and

calculating;

Baseline_LAP/LV-RV=−

Slope_LAP/LV-RV*D_LV-RV/N.

10. The method of claim 3 further comprising:

inputting into a memory of the implantable medical device the conversion factors;

measuring an electrical conduction delay in the heart of the patient using the implantable medical device; and

estimating cardiac pressure within the patient from the electrical conduction delay by applying the conversion factors to the conduction delay.

11. The method of claim 10 wherein estimating cardiac pressure includes calculating:

Cardiac Pressure=Delay*Slope+Baseline.

12. The method of claim 10 further comprising:

detecting an additional conduction delay value (D_N) using the implantable device; and

re-calibrating the baseline value by calculating;

Baseline=−

Slope*D_N.

13. The method of claim 10 further comprising:

detecting an additional conduction delay value (D_N) using the implantable device; and

re-calibrating the slope and baseline values based on D_N and on a first effective cardiac pressure value (Pressure₁) by calculating

Slope=Pressure₁/(D_N−

D₁) and

Baseline=−

Slope*D_N.

14. The method of claim 10 further comprising reprogramming the implantable medical device based on the estimated cardiac pressure.

15. The method of claim 14, wherein the estimated cardiac pressure is an estimated left atrial pressure (qLAP) and the implantable medical device is reprogrammed based on the qLAP.

16. The method of claim 15, wherein the implantable medical device is reprogrammed to change the pacing timing parameters based on the qLAP.

17. The method of claim 16, wherein the pacing timing parameters include at least one of an atrioventricular (AV) pacing delay, an interventricular (LV-RV) pacing delay, an intraventricular (LV₁-LV₂) pacing delay, or an intra-atrial (LA₁-LA₂) pacing delay.

18. The method of claim 15, wherein the implantable medical device is reprogrammed to switch to a different pacing configuration or use different pacing electrodes based on the qLAP.

19. The method of claim 15, wherein the implantable medical device is adaptively reprogrammed so that the adjustments are performed in a closed-loop so as to adapt the reprogramming to changes in qLAP.

20. The method of claim 19, further comprising detecting cardiogenic impedance signals, and wherein the implantable medical device is further adaptively reprogrammed using the impedance signals.