System and method for exploiting atrial electrocardiac parameters in assessing left atrial pressure using an implantable medical device

• US 8,600,487 B2
• Filed: 02/25/2010
• Issued: 12/03/2013
• Est. Priority Date: 02/25/2010
• Status: Active Grant

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Inventors: Soriano, Alex, Bornzin, Gene A.
• Primary Examiner(s): Layno, Carl H
• Assistant Examiner(s): Stice, Paula J
• Application Number:
  US12/713,019
• Publication Number:
  US 20110208077A1
• Time in Patent Office: 1,377 Days
• Field of Search: 600/509, 600/516, 600/513
• US Class Current: 600/513
• CPC Class Codes: A61B 2562/0204 Acoustic sensors
• CPC Class Codes: A61B 5/002 Monitoring the patient using a local or closed circuit, e.g. in a room or building A61B5/0017 takes precedence
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• 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 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/4839 combined with drug delivery
• CPC Class Codes: A61B 7/00 Instruments for auscultation
• CPC Class Codes: A61B 7/006 Detecting skeletal, cartilage or muscle noise A61B7/003 and A61B7/008 take precedence
• CPC Class Codes: A61N 1/36507 controlled by gradient or slope of the heart potential
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/36564 controlled by blood pressure
• CPC Class Codes: A61N 1/3682 with a variable atrioventricular delay
• CPC Class Codes: A61N 1/3962 in combination with another heart therapy
• CPC Class Codes: A61N 1/39622 Pacing therapy

Abstract

Techniques are provided for assessing left atrial pressure (LAP) based on atrial electrocardiac signal parameters, particularly intra-atrial conduction delay (IACD) and P-wave duration. In one example, a pacemaker or other implantable device senses an intracardiac electrogram (IEGM) or a subcutaneous electrocardiogram (ECG), from which IACD and P-wave duration are derived. The device tracks changes, if any, in the parameters. A significant increase in either IACD or P-wave duration is associated with an increase in LAP. In some examples, conversion factors are calibrated for use with a particular patient to relate IACD and/or P-wave duration values to LAP values to provide an estimate of actual LAP. The conversion factors are pre-calibrated using LAP measurements obtained using a wedge pressure sensor. In other examples, IACD and P-wave duration are instead used to confirm the detection of an elevation in LAP initially made using impedance signals. Other confirmation parameters are described as well.

Claims

1. A method for use with an implantable medical device for implant within a patient, the method comprising:

sensing electrocardiac signals within the patient;

detecting atrial parameters within the electrocardiac signals that are affected by left atrial pressure (LAP);

detecting changes in LAP within the patient based on the atrial parameters;

detecting physiological signals representative of left ventricular (LV) overload within the patient; and

wherein the detection of changes in LAP is confirmed based on the detected LV overload.

2. The method of claim 1 wherein detecting atrial parameters affected by LAP includes detecting one or more of:

an intra-atrial conduction delay (IACD) and an atrial depolarization event (P-wave) duration.

3. The method of claim 2 wherein detecting changes in LAP within the patient based on the atrial parameters includes associating an increase in IACD with an increase in LAP.

4. The method of claim 2 wherein detecting changes in LAP within the patient based on the atrial parameters includes associating an increase in P-wave duration with an increase in LAP.

5. The method of claim 2 further including calibrating changes in one or both of IACD and P-wave duration to changes in LAP.

6. The method of claim 2 further including:

detecting impedance (Z) signals within the patient;

estimating left atrial pressure (LAP) based on impedance (zLAP); and

detecting changes in LAP within the patient based on zLAP.

7. The method of claim 6 further including using the atrial parameters to confirm a detection of changes in LAP initially made based on zLAP.

8. A method for use with an implantable medical device for implant within a patient, the method comprising:

sensing electrocardiac signals within the patient;

detecting atrial parameters within the electrocardiac signals that are affected by left atrial pressure (LAP);

detecting changes in LAP within the patient based on the atrial parameters;

detecting changes in one or more of heart contractility, systolic time intervals and stroke volumes; and

confirming the detection of changes in LAP based on one or more of heart contractility, systolic time intervals and stroke volumes.

9. A method for use with an implantable medical device for implant within a patient, the method comprising:

sensing electrocardiac signals within the patient;

detecting atrial parameters within the electrocardiac signals that are affected by left atrial pressure (LAP);

detecting changes in LAP within the patient based on the atrial parameters;

detecting ventricular depolarization events (R-waves) within the electrocardiac signals;

detecting impedance (Z);

detecting a time rate of change in impedance (dZ/dt);

measuring an interval between the R-wave and a minimum value of dZ/dt; and

confirming the detection of changes in LAP based on changes in the interval.

10. The method of claim 9 wherein impedance is detected between a supraventricular (SVC) coil and a device housing electrode.

11. A method for use with an implantable medical device for implant within a patient, the method comprising:

sensing electrocardiac signals within the patient;

detecting atrial parameters within the electrocardiac signals that are affected by left atrial pressure (LAP);

detecting changes in LAP within the patient based on the atrial parameters;

detecting ventricular depolarization events (R-waves) within the electrocardiac signals;

detecting changes in R-wave duration; and

confirming the detection of changes in LAP based on changes in R-wave duration.