Apparatus for detection of and discrimination between tachycardia and fibrillation and for treatment of both

• US 5,257,621 A
• Filed: 01/29/1993
• Issued: 11/02/1993
• Est. Priority Date: 08/27/1991
• Status: Expired due to Term

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Bardy, Gust H., Olson, Walter H., Taepke, Robert T., Peterson, David K.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US08/010,926
• Time in Patent Office: 277 Days
• Field of Search: 128/419 PG, 128/419 D, 128/705
• US Class Current: 607/5
• CPC Class Codes: A61N 1/3621 for treating or preventing abnormally high heart rate
• CPC Class Codes: A61N 1/365 controlled by a physiological parameter, e.g. heart potential 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 implantable cardioverter/defibrillator provided with method and apparatus for discrimination between ventricular tachycardia and ventricular fibrillation. The device is provided with two pairs of electrodes, each pair of electrodes coupled to processing circuitry for identifying a predetermined fiducal point in the electrical signal associated with a ventricular depolarization. The cumulative beat to beat variability of the intervals separating the two identified fiducal points, over a series of detected depolarizations is analyzed. The result of this analysis is used to distinguish between ventricular tachycardia and ventricular fibrillation.

Claims

1. A cardioverter/defibrillator, comprising:

treatment means for delivering a first therapy to a patient'"'"'s heart to treat tachycardia and a second therapy to said patient'"'"'s heart to treat fibrillation;

first means for sensing electrical signals from said patient'"'"'s heart indicative of the depolarization of said patient'"'"'s heart;

second means for sensing electrical signals from said patient'"'"'s heart indicative of the depolarization of said patient'"'"'s heart;

means for defining a first criterion indicative of a depolarization of said patient'"'"'s heart;

means for defining a second criterion indicative of a depolarization of said patient'"'"'s heart;

first fiducial point detection means, coupled to said first sensing means for determining the time at which the electrical signal sensed by said first sensing means meets said first criterion and for issuing a first fiducial point signal indicative thereof;

second fiducial point detection means, coupled to said second sensing means for determining the time at which the electrical signal sensed by said second sensing means meets said second criterion and for issuing a second fiducial point signal indicative thereof; and

tachycardia/fibrillation discriminator means responsive to said first and second fiducial point signals comprising means for defining time intervals based on the times of occurrence of said first fiducal point signals, means for detecting failures of said second fiducal point signals to occur within said defined time intervals, and means responsive to said detected failures for selecting between said first and second therapies.

3. A cardioverter/defibrillator according to claim 1 or claim 2 wherein said variability measuring means comprises means responsive to said first and second fiducial point signals for measuring time intervals separating said first and second fiducal point signals.

4. A cardioverter/defibrillator according to claim 3 wherein said variability measuring means comprises means for measuring the variability of said measured time intervals over a series of depolarizations of said patient'"'"'s heart.

5. A cardioverter/defibrillator according to claim 4 wherein said tachycardia/fibrillation discriminator means comprises means for defining a time value in response to a said failure of a second fiducal point signal to occur within a said defined time interval, and wherein said variability measuring means comprises means responsive to said time value for measuring said variability.

2. A cardioverter/defibrillator, comprising:

treatment means for delivering a first therapy to a patient'"'"'s heart to treat tachycardia and a second therapy to said patient'"'"'s heart to treat fibrillation;

first means for sensing electrical signals from said patient'"'"'s heart indicative of the depolarization of said patient'"'"'s heart and for issuing a first fiducial point signal indicative of a depolarization of said patient'"'"'s heart, said first sensing means comprising a first electrode pair;

second means for sensing electrical signals from said patient'"'"'s heart indicative of the depolarization of said patient'"'"'s heart and for issuing a second fiducial point signal indicative of a depolarization of said patient'"'"'s heart, said second sensing means comprising a second electrode pair including at least one electrode not included in said first electrode pair;

tachycardia/fibrillation discriminator means responsive to said first and second fiducal point signals for cumulatively measuring the variability of the depolarization wavefront within said patient'"'"'s heart over a series of depolarizations of said patient'"'"'s heart and means for selecting between said first and second therapies as a function of said measured variability, said discriminator means comprising means for defining time intervals based on the times of occurrence of said first fiducal point signals, means for detecting failures of said second fiducal point signals to occur within said defined time intervals, and means responsive to said detected failures for selecting between said first and second therapies.

6. A defibrillator, comprising:

treatment means for delivering a defibrillation therapy to a patient'"'"'s heart to treat to treat fibrillation;

first means for sensing electrical signals from said patient'"'"'s heart indicative of the depolarization of said patient'"'"'s heart and for providing a first fiducal point signal indicative thereof, said first sensing means comprising a first electrode pair;

second means for sensing electrical signals from said patient'"'"'s heart indicative of the depolarization of said patient'"'"'s heart and for providing a second fiducal point signal indicative thereof, said second sensing means comprising a second electrode pair including at least one electrode not included in said first electrode pair;

fibrillation detection means responsive to said first and second fiducal point signals for measuring the variability of wavefront propagation within said patient'"'"'s heart over a series of depolarizations of said patient'"'"'s heart, said variability measuring means comprising means for defining time intervals based on times of occurrence of said first fiducal point signals, means for detecting failures of said second fiducal point signals to occur within said defined time intervals, and means responsive to said detected failures for initiating said defibrillation therapy.

7. A cardioverter, comprising:

treatment means for delivering an anti-tachycardia therapy to a patient'"'"'s heart to treat to treat tachycardia;

first means for sensing electrical signals from said patient'"'"'s heart indicative of the depolarization of said patient'"'"'s heart and for providing a first fiducal point signal indicative thereof, said first sensing means comprising a first electrode pair;

second means for sensing electrical signals from said patient'"'"'s heart indicative of the depolarization of said patient'"'"'s heart and for providing a second fiducal point signal indicative thereof, said second sensing means comprising a second electrode pair including at least one electrode not included in said first electrode pair;

tachycardia detection means responsive to said first and second fiducal point signals comprising means for measuring the variability of wavefront propagation within said patient'"'"'s heart over a series of depolarizations of said patient'"'"'s heart, said variability measuring means comprising means for defining time intervals based on times of occurrence of said first fiducal point signals, means for detecting failures of said second fiducal point signals to occur within said defined time intervals, and means responsive to said detected failures for initiating said anti-tachycardia therapy.

8. Apparatus for detecting fibrillation, comprising:

means for defining a first criterion indicative of a depolarization of said patient'"'"'s heart;

means for defining a second criterion, different from said first criterion, indicative of a depolarization of said patient'"'"'s heart;

first means for sensing electrical signals from said patient'"'"'s heart indicative of the depolarization of said patient'"'"'s heart and for providing a first fiducal point signal indicative thereof in response to said electrical signals meeting said first criterion;

second means for sensing electrical signals from said patient'"'"'s heart indicative of the depolarization of said patient'"'"'s heart and for providing a second fiducal point signal indicative thereof in response to said electrical signals meeting said second criterion;

fibrillation identification means responsive to said first and second fiducial point signals comprising means for defining time intervals based on times of occurrence of said first fiducal point signals, means for detecting failures of said second fiducal point signals to occur within said defined time intervals, and means responsive to said detected failures for identifying the occurrence of fibrillation.