Methods for adjusting cardiac detection criteria and implantable medical devices using same

• US 6,873,870 B2
• Filed: 04/30/2001
• Issued: 03/29/2005
• Est. Priority Date: 04/30/2001
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Ferek-Petric, Bozidar
• Primary Examiner(s): Sykes, Angela D.
• Assistant Examiner(s): Oropeza, Frances P.
• Application Number:
  US09/843,914
• Publication Number:
  US 20020188215A1
• Time in Patent Office: 1,429 Days
• Field of Search: 600/509, 600/515, 600/516, 600/518, 600/519, 600/521, 607 4- 7, 607/9, 607/11, 607/14, 607/17, 607/18, 607 23- 25
• US Class Current: 600/518
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions
• CPC Class Codes: A61N 1/3956 Implantable devices for applying electric shocks to the heart, e.g. for cardioversion

Abstract

Implantable medical devices and methods of tachycardia detection that provide adjustable detection criteria based upon a hemodynamic parameter. In some embodiments, the apparatus and methods provide for detection and delivery of therapy for hemodynamically stable and hemodynamically unstable tachycardias by varying a number of intervals detected (NID) threshold based on hemodynamic measurements.

Claims

1. A method for distinguishing a hemodynamically stable tachycardia from a hemodynamically unstable tachycardia, comprising:

sensing a heart rate;

comparing the heart rate to a heart rate threshold value;

monitoring a blood pressure sensor upon detecting the heart rate greater than the heart rate threshold value to detect a substantial drop in blood pressure;

invoking a first number of intervals detected (NID) threshold up detecting the heart rate greater than the heart rate threshold value if a substantial drop in blood pressure is not detected;

invoking a second NID threshold that is lower than the first NID threshold upon detecting a substantial drop in blood pressure;

counting a consecutive number at intervals in which the heart rate is greater than the heart rate threshold value;

making a tachycardia detection if the consecutive number of intervals satisfies the invoked NID threshold, the tachycardia detection being a detection of a hemodynamically stable tachycardia if the first NID threshold is invoked and the tachycardia detection being a detection of a hemodynamically unstable tachycardia if the second NID threshold is invoked; and

delivering a first low power tachycardia response therapy upon making a tachycardia detection that the tachycardia is a hemodynamically stable tachycardia and delivering a second high power tachycardia response therapy upon detection that the tachycardia that is a hemodynamically unstable tachycardia.

3. A method according to claim 1, wherein the low power tachycardia response therapy comprises one of an anti-tachycardia pacing regimen and a cardioversion therapy.

4. A method according to claim 1, wherein the high power tachycardia response therapy comprises a defibrillation therapy.

5. A method according to claim 4, wherein the defibrillation therapy comprises at least thirty joules of delivered energy.

6. A method according to claim 4, wherein the defibrillation therapy comprises a ventricular defibrillation therapy.

2. A pacing apparatus, comprising:

sensing and pacing circuitry for sensing cardiac activity and generating pacing pulses;

a blood pressure sensor to detect a substantial drop in blood pressure; and

controller circuitry coupled to the blood pressure sensor, the controller circuitry operable to;

sense a heart rate;

compare the heart rate to a heart rate threshold value;

monitor a blood pressure sensor upon detecting the heart rate greater than the heart rate threshold value to detect a substantial drop in blood pressure;

invoke a first number of intervals detected (NID) threshold upon detecting the heart rate greater than the heart rate threshold value if a substantial drop in blood pressure is not detected;

invoke a second NID threshold that is lower than the first NID threshold upon detecting a substantial drop in blood pressure;

count a consecutive number of intervals in which the heart rate is greater than the heart rate threshold value;

make a tachycardia detection if the consecutive number of intervals satisfies the invoked NID threshold, the tachycardia detection being a detection of a hemodynamically stable tachycardia if the first NID threshold is invoked and the tachycardia detection being detection of a hemodynamically unstable tachycardia if the second NID threshold is invoked; and

deliver a low power tachycardia response therapy upon making a tachycardia detection that the tachycardia is a hemodynamically stable tachycardia and deliverying a high power tachycardia response therapy upon detection that the tachycardia that is a hemodynamically unstable tachycardia.

7. A method according to claim 2, wherein the low power tachycardia response therapy comprises one of an anti-tachycardia pacing regimen and a cardioversion therapy.

8. A method according to claim 2, wherein the high power tachycardia response therapy comprises a defibrillation therapy.

9. A method according to claim 8, wherein the defibrillation therapy comprises at least thirty joules of delivered energy.

10. A method according to claim 8, wherein the defibrillation therapy comprises a ventricular defibrillation therapy.

11. A computer readable medium for storing executable instructions to operate a medical device and cause said medical device to distinguish a hemodynamically stable tachycardia from a hemodynamically unstable tachycardia, comprising:

instructions for sensing a heart rate;

instructions for comparing the heart rate to a heart rate threshold value;

instructions for monitoring a blood pressure sensor upon detecting the heart rate greater than the heart rate threshold value to detect a substantial drop in blood pressure;

instructions for invoking a first number of intervals detected (NID) threshold upon detecting the heart rate greater than the heart rate threshold value if a substantial drop in blood pressure is not detected;

instructions for invoking a second NID threshold that is lower than the first NID threshold upon detecting a substantial drop in blood pressure;

instructions for counting a consecutive number of intervals in which the heart rate is greater than the heart rate threshold value;

instructions for making a tachycardia detection if the consecutive number of intervals satisfies the invoked NID threshold the tachycardia detecting being a detection of a hemodynamically stable tachycardia if the first NID threshold is invoked and the tachycardia detection being a detection of a hemodynamically unstable tachycardia if the second NID threshold is invoked; and

instructions for delivering a first low power tachycardia response therapy upon making a tachycardia detection that the tachycardia is a hemodynamically stable tachycardia and delivering a second high power tachycardia response therapy upon detection that the tachycardia that is a hemodynamically unstable tachycardia.

12. A medium according to claim 11, wherein the low power tachycardia response therapy comprises one of an anti-tachycardia pacing regimen and a cardioversion therapy.

13. A medium to claim 11, wherein the high power tachycardia response therapy comprises a defibrillation therapy.

14. A medium according to claim 13, wherein the defibrillation therapy comprises at least thirty joules of delivered energy.

15. A medium according to claim 13, wherein the defibrillation therapy comprises a ventricular defibrillation therapy.