System and method for detecting physiologic states based on intracardiac electrogram signals while distinguishing cardiac rhythm types

• US 8,262,578 B1
• Filed: 11/10/2006
• Issued: 09/11/2012
• Est. Priority Date: 11/24/2004
• Status: Active Grant

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Inventors: Bharmi, Rupinder, Bornzin, Gene A.
• Primary Examiner(s): Natnithithadha, Navin
• Application Number:
  US11/558,787
• Time in Patent Office: 2,132 Days
• Field of Search: 600/481, 600/483, 600/484, 600/529, 600/508, 600/509, 600/513, 600515-518, 600/521
• US Class Current: 600/484
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/08 Detecting, measuring or recording devices for evaluating the respiratory organs A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/0803 Recording apparatus specially adapted therefor
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/11 Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb for measuring pulse A61B5/02 ;A61B5/1038 takes precedence; motion detection to correct for motion artifacts in physiological signals A61B5/721
• CPC Class Codes: A61B 5/145 Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissuemeasuring of blood pressure or blood flow A61B5/02; non-radiation detecting or locating of foreign bodies in blood A61B5/06
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/366 Detecting abnormal QRS complex, e.g. widening
• CPC Class Codes: A61B 5/411 Detecting or monitoring allergy or intolerance reactions to an allergenic agent or substance
• CPC Class Codes: A61B 5/4818 Sleep apnoea
• 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: A61B 5/746 Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms alarms per se G08B
• CPC Class Codes: A61N 1/3601 of respiratory organs
• CPC Class Codes: A61N 1/365 controlled by a physiological parameter, e.g. heart potential evoked response A61N1/371
• CPC Class Codes: A61N 1/37 Monitoring; Protecting
• CPC Class Codes: G16H 40/63 for local operation
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems

Abstract

Techniques are provided for tracking patient respiration or other physiologic states based upon intracardiac electrogram (IEGM) signals. In one example, respiration patterns are detected based upon cycle-to-cycle changes in morphological features associated with individual cardiac cycles while taking into account different cardiac rhythm types within the patient, such as predominantly paced or predominantly intrinsic rhythm types. Once respiration patterns have been identified, episodes of abnormal respiration, such as apnea, hyperpnea, nocturnal asthma, or the like, may be detected and therapy automatically delivered. In addition, techniques for detecting abnormal respiration using a pattern classifier are described, wherein the pattern classifier is trained while distinguishing the different cardiac rhythm types of the patient.

Claims

1. A method for detecting physiologic states within a patient using an implantable medical device, the method comprising:

determining a predominant cardiac rhythm type of the patient;

determining a secondary cardiac rhythm type of the patient, the secondary rhythm type differing from the predominant rhythm type;

sensing cardiac electrical signals via one or more electrodes coupled to a detector incorporated into a housing of the implantable medical device and identifying individual cardiac cycles therein using a predominant cardiac rhythm type determination unit incorporated into a housing of the implantable medical device;

determining whether individual cardiac cycles correspond to the predominant rhythm type; and

detecting a physiologic state within the patient based on changes in morphological parameters associated with the individual cardiac cycles while excluding all cardiac cycles of the secondary rhythm type for the purposes of physiologic state detection.

2. The method of claim 1 wherein determining the predominant rhythm type of the patient is performed to determine whether the cardiac cycles of the patient are predominantly paced or intrinsic.

3. The method of claim 1 wherein determining the predominant rhythm type of the patient is performed to determine whether the cardiac cycles of the patient are predominantly one of the following:

paced atrial beats with intrinsic ventricular beats (AR);

paced atrial beats with paced ventricular beats (AV);

intrinsic atrial beats with intrinsic ventricular beats (PR); and

intrinsic atrial beats with paced ventricular beats (PV).

4. The method of claim 1

wherein identifying individual cardiac cycles includes identifying consecutive cycles of the secondary rhythm type;

and

wherein detecting the physiologic state while distinguishing between cardiac cycles of different rhythm types includes renormalizing cardiac cycles of the secondary rhythm type for the purposes of detecting the physiologic state.

5. The method of claim 1 wherein detecting the physiologic state includes detecting one or more of respiration, apnea, hypopnea, hyperpnea, asthma, Cheyne-Stokes Respiration (CSR), hypoglycemia, hyperglycemia, diabetes, renal failure, hypertension, ischemia, hyperkalemia, hypokalemia, obesity, stroke, chronic obstructive pulmonary disease (COPD), pulmonary edema, edema, anemia, heart failure, exertion induced dyspnea, and tachypnea with hypoglycemia.

6. The method of claim 5 wherein detecting respiration includes detecting one or more of a respiration rate, an inter-breath interval, a depth of respiration, a standard deviation of the depth of respiration, and a median of the depth of respiration.

7. The method of claim 5 wherein abnormal respiration is detected based on detected respiration.

8. The method of claim 7 further including evaluating a severity of abnormal respiration.

9. The method of claim 5 wherein detecting apnea is performed only while the patient is asleep.

10. The method of claim 1 further including delivering therapy based on the physiologic state.

11. A method for detecting physiologic states within a patient using an implantable medical device, the method comprising:

determining a predominant cardiac rhythm type of the patient;

determining a secondary cardiac rhythm type of the patient, the secondary rhythm type differing from the predominant rhythm type;

detecting spurious cardiac cycles of the secondary rhythm type;

sensing cardiac electrical signals via one or more electrodes coupled to a detector incorporated into a housing of the implantable medical device and identifying individual cardiac cycles therein using a predominant cardiac rhythm type determination unit incorporated into a housing of the implantable medical device;

determining whether individual cardiac cycles correspond to the predominant rhythm type; and

detecting a physiologic state within the patient based on changes in morphological parameters associated with the individual cardiac cycles while excluding spurious cardiac cycles of the secondary rhythm type for the purposes of respiration detection.

12. A method for detecting physiologic states within a patient using an implantable medical device, the method comprising:

determining a predominant cardiac rhythm type of the patient;

sensing cardiac electrical signals via one or more electrodes coupled to a detector incorporated into a housing of the implantable medical device and identifying individual cardiac cycles therein using a predominant cardiac rhythm type determination unit incorporated into a housing of the implantable medical device;

determining whether individual cardiac cycles correspond to the predominant rhythm type;

detecting abnormal patient respiration based on cycle-to-cycle changes in parameters associated with individual cardiac cycles; and

training the device to discriminate between normal and abnormal respiration within the patient based on individual cardiac cycles within the patient, the training step distinguishing between cardiac cycles of the predominant rhythm type and cardiac cycles of other rhythm types.

13. The method of claim 12 wherein training the device includes excluding all cardiac cycles not corresponding to the predominant rhythm of the patient during training.

14. The method of claim 12 wherein the trained device is a component of the implanted device and wherein detecting abnormal respiration using the trained device is performed by the implanted device.

15. The method of claim 12 wherein the trained device is a component of a system external to the patient and wherein detecting abnormal respiration using the trained device is performed by the external system based on cardiac signals originally sensed by the implanted device and transmitted to the external system.

16. A system for detecting physiologic states within a patient using an implantable medical device, the system comprising:

a predominant cardiac rhythm type determination unit operative to determine a predominant cardiac rhythm type of the patient;

a secondary cardiac rhythm type determination unit operative to determine a secondary cardiac rhythm type of the patient the secondary rhythm type differing from the predominant rhythm type;

a cardiac cycle detection unit operative to sense cardiac electrical signals and identify individual cardiac cycles therein;

a cardiac cycle discrimination unit operative to determine whether individual cardiac cycles correspond to the predominant rhythm type; and

a predominant rhythm-based detector operative to detect a physiologic state within the patient based on morphological parameters associated with the individual cardiac cycles while excluding all cardiac cycles of the secondary rhythm type for the purposes of physiologic state detection.

17. The system of claim 16 wherein the predominant rhythm-based detector includes a respiration detector operative to detect respiration based on cycle-to-cycle changes in morphological parameters associated with the individual cardiac cycles while distinguishing between cardiac cycles of the predominant rhythm type and cardiac cycles of other rhythm types.

18. A system for detecting physiologic states within a patient using an implantable medical device, the system comprising:

means for sensing cardiac electrical signals and identifying individual cardiac cycles therein;

means for determining whether individual cardiac cycles correspond to a predetermined predominant rhythm type within the patient;

means for determining whether individual cardiac cycles correspond to a secondary cardiac rhythm type within the patient, the secondary rhythm type differing from the predominant rhythm type; and

means for detecting a physiologic state within the patient based on morphological parameters associated with the individual cardiac cycles while excluding all cardiac cycles of the secondary rhythm type for the purposes of physiologic state detection.