Method and apparatus for detection and treatment of tachycardia and fibrillation

• US 5,464,430 A
• Filed: 01/13/1995
• Issued: 11/07/1995
• Est. Priority Date: 11/23/1993
• Status: Expired due to Term

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Rossing, Martin A.
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): SCHAETZLE, KENNEDY
• Application Number:
  US08/372,622
• Time in Patent Office: 298 Days
• Field of Search: 607/5, 607/4, 607/9, 607/14, 607/25, 128/702, 128/703, 128/705
• US Class Current: 607/4
• CPC Class Codes: A61N 1/3702 Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371
• CPC Class Codes: A61N 1/3962 in combination with another heart therapy
• CPC Class Codes: A61N 1/39622 Pacing therapy

Abstract

An automatic implantable device for detecting and differentiating between tachyarrhythmias in order to therapeutically stimulate the heart in response thereto, particularly for distinguishing fibrillation from tachycardia and to provide appropriate therapies for each condition. The event intervals between successive heart depolarizations are measured, stored and classified as within fibrillation or tachycardia interval ranges. The numbers of intervals falling within the fibrillation and tachycardia interval ranges are employed to distinguish fibrillation from tachycardia. The number of intervals required to detect and discriminate between tachycardia and fibrillation in situations where the tachyarrhythmia includes intervals in both interval ranges is reduced by adjusting the interval ranges as a function of the relative distribution of measured intervals within the interval ranges.

Claims

1. An apparatus for detection and treatment of tachyarrhythmias, comprising:

means for sensing depolarizations of a patient'"'"'s heart;

means for measuring intervals separating successive depolarizations of said patient'"'"'s heart;

means for defining a first interval range extending between a first interval duration and a second interval duration less than said first interval duration and a second interval range including interval durations less than said second interval duration;

means for determining whether said measured intervals fall within said first or second interval ranges;

first diagnosing means for diagnosing occurrence of a first type of arrhythmia in response to said measured intervals falling within said first interval range;

second diagnosing means for diagnosing occurrence of a second type of arrhythmia in response to said measured intervals falling within said second interval range;

interval range adjustment means responsive to said determining means for adjusting said second interval duration, for subsequent use by said determining means, as a function of the durations of said measured intervals preceding a diagnosis of said first or second type of arrhythmia;

means for delivering a first anti-arrhythmia therapy in response to detection of said first type of arrhythmia; and

means for delivering a second anti-arrhythmia therapy in response to detection of said second type of arrhythmia.

2. An apparatus according to claim 1 wherein said adjustment means comprises means for determining numbers of said measured intervals falling within said first and second interval ranges.

3. An apparatus according to claim 2 wherein said adjusting means comprises means for increasing said second interval duration in response to the number of said measured intervals falling within said second interval range equalling or exceeding a predetermined first value.

4. An apparatus according to claim 2 wherein said adjusting means comprises means for decreasing said second interval duration in response to the number of said measured intervals falling within said first interval range equalling or exceeding a predetermined second value.

5. An apparatus according to claim 3 or claim 4 wherein said first and second predetermined values comprise predetermined numbers of said measured intervals falling within said first and second interval ranges, respectively.

6. An apparatus according to claim 1 or claim 2 wherein said first diagnosing means comprises means for diagnosing the occurrence of a tachycardia and wherein said second diagnosing means comprises means for diagnosing the occurrence of fibrillation.

7. An apparatus according to claim 1 or claim 2 wherein said means for sensing depolarizations comprises means for sensing depolarizations of said patient'"'"'s ventricle.

8. A method of detection and treatment of tachyarrhythmias, comprising:

sensing depolarizations of a patient'"'"'s heart;

measuring intervals separating successive depolarizations of said patient'"'"'s heart;

defining a first interval range extending between a first interval duration and a second interval duration less than said first interval duration and a second interval range including interval durations less than said second interval duration;

determining whether said measured intervals fall within said first or second interval ranges;

diagnosing occurrence of a first type of arrhythmia in response to said measured intervals falling within said first interval range;

diagnosing occurrence of a second type of arrhythmia in response to said measured intervals falling within said second interval range;

adjusting said second interval duration as a function of the durations of said measured intervals preceding diagnosis of said first or second type of arrhythmia;

delivering a first anti-arrhythmia therapy in response to detection of said first type of arrhythmia;

delivering a second anti-arrhythmia therapy in response to detection of said second type of arrhythmia; and

subsequently employing said adjusted second interval duration in determining whether said measured intervals fall within said first or second interval ranges.

9. A method according to claim 8 wherein said adjusting step comprises determining numbers of said measured intervals falling within said first and second interval ranges.

10. A method according to claim 9 wherein said adjusting step comprises increasing said second interval duration in response to the number of said measured intervals falling within said second interval range equalling or exceeding a predetermined first value.

11. A method according to claim 9 wherein said adjusting step comprises decreasing said second interval duration in response to the number of said measured intervals falling within said first interval range equalling or exceeding a predetermined second value.

12. A method according to claim 10 or claim 11 wherein said step of sensing depolarizations comprises sensing depolarizations of said patient'"'"'s ventricle.

13. A method according to claim 8 or claim 9 wherein step of diagnosing said first type of arrhythmia comprises diagnosing the occurrence of a tachycardia and wherein said step of diagnosing said second type of tachyrhythrnia comprises diagnosing the occurrence of fibrillation.