SYSTEM AND METHOD FOR EXPLOITING ATRIAL EELCTROCARDIAC PARAMETERS IN ASSESSING LEFT ATRIAL PRESSURE USING AN IMPLANTABLE MEDICAL DEVICE

• US 20110208077A1
• Filed: 02/25/2010
• Published: 08/25/2011
• Est. Priority Date: 02/25/2010
• Status: Active Grant

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: Bornzin, Gene A., Soriano, Alex
• Granted Patent: US 8,600,487 B2
• Time in Patent Office: Days
• 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); and

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

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. The method of claim 1 further including detecting physiological signals representative left ventricular (LV) overload within the patient and wherein the detection of changes in LAP is confirmed based on LV overload.

9. The method of claim 1 further including:

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.

10. The method of claim 1 wherein further including:

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 R-wave duration.

11. The method of claim 1 further including:

detecting ventricular QRS complexes within the electrocardiac signals;

detecting impedance (Z);

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

measuring an interval between the QRS complex and a minimum value of dZ/dt; and

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

12. The method of claim 1 wherein impedance is detected between a supraventricular (SVC) coil and a device housing electrode.

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

an atrial parameter detector operative to detect atrial parameters affected by left atrial pressure (LAP) within electrocardiac signals sensed within the patient; and

an atrial parameter-based LAP detector operative to detect changes in LAP within the patient based on the atrial parameters.

14. The system of claim 13 wherein the atrial parameter-based detector is operative to detect one or more of an intra-atrial conduction delay (IACD) and an atrial depolarization (P-wave) duration within the electrocardiac signals.

15. The system of claim 13 wherein the device includes one or more of a pacemaker, implantable cardioverter-defibrillator (ICD), implantable loop recorder (ILR), cardiac resynchronization therapy (CRT) device, and a subcutaneous (sub-Q) device.

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

sensing impedance (Z) signals within the patient and estimating left atrial pressure (LAP) based on impedance (zLAP);

sensing electrocardiac signals within the patient and detecting atrial parameters within the electrocardiac signals affected by LAP;

detecting changes in LAP within the patient based on zLAP; and

confirming the detection of changes in LAP based on the atrial parameters.