Method for adapting charge initiation for an implantable cardioverter-defibrillator

• US 8,160,697 B2
• Filed: 01/25/2005
• Issued: 04/17/2012
• Est. Priority Date: 01/25/2005
• Status: Active Grant

• Current Assignee: Cameron Health Inc (Boston Scientific Corporation)
• Original Assignee: Cameron Health Inc (Boston Scientific Corporation)
• Inventors: Warren, Jay A., Bardy, Gust H.
• Primary Examiner(s): Layno, Carl H
• Assistant Examiner(s): OROPEZA, FRANCES P
• Application Number:
  US11/042,911
• Publication Number:
  US 20060167503A1
• Time in Patent Office: 2,639 Days
• Field of Search: 600/373, 600/374, 600/377, 600/393, 600/509, 600/515, 600/516, 600/518, 600/519, 600/521, 607/4, 607/5, 607/7, 607/9, 607/11, 607/14, 607/15, 607/25, 607/27, 607/28, 607/34, 607/116, 607/119, 607/122, 607/123
• US Class Current: 607/5
• CPC Class Codes: A61N 1/3621 for treating or preventing abnormally high heart rate
• CPC Class Codes: A61N 1/3943 for threshold determination
• CPC Class Codes: A61N 1/3956 Implantable devices for applying electric shocks to the heart, e.g. for cardioversion

Abstract

Adaptive methods for initiating charging of the high power capacitors of an implantable medical device for therapy delivery after the patient experiences a non-sustained arrhythmia. The adaptive methods adjust persistence criteria used to analyze an arrhythmia prior to initiating a charging sequence to deliver therapy.

Claims

1. A method of cardiac treatment using an implantable medical device system having implanted electrodes and an energy storage system for storing charge for performing cardiac electrical stimulus, the method comprising:

capturing a first predetermined number of selected cardiac events using the implanted electrodes;

determining whether a threshold proportion of the first predetermined number of selected cardiac events are abnormal;

determining treatment is indicated if the threshold proportion of the first predetermined number of selected cardiac events are abnormal for a second predetermined number of consecutive iterations,

and, if treatment is indicated;

initiating a charging operation for the energy storage system; and

determining whether cardiac rhythm has returned to normal before stimulus is delivered and, if so, increasing the threshold proportion;

wherein;

the first predetermined number has an initial value of 24 and the threshold proportion has an initial value of 18/24, and the step of increasing the threshold proportion comprises increasing the first predetermined number to 27 and the threshold proportion to 21/27.

2. The method of claim 1, further comprising determining if treatment is indicated if:

at least the threshold proportion of the first predetermined number of selected events are abnormal; and

at least the threshold proportion of the predetermined number of selected events is abnormal for at least a threshold number of events out of a preselected number of events.

3. A method of cardiac treatment using an implantable medical device system having implanted electrodes and an energy storage system for storing charge for performing cardiac electrical stimulus, the method comprising:

capturing a predetermined number of selected cardiac events using the implanted electrodes;

observing whether a malignant cardiac condition exists for at least one of the selected cardiac events;

determining whether the malignant cardiac condition persists for at least a threshold duration or threshold number of cardiac events, and, if so;

initiating a charging operation for the energy storage system;

determining whether the malignant cardiac condition has terminated prior to delivery of cardiac stimulus and, if so, extending the threshold duration or increasing the threshold number; and

if the malignant cardiac condition has not terminated, delivering cardiac stimulus;

wherein;

the step of determining whether the malignant cardiac condition persists includes determining that a threshold percentage of selected cardiac events appear malignant from among a predetermined set of cardiac events for at least a threshold number of consecutive events and determining that a most recently detected cardiac event indicates a malignant cardiac event, and wherein the step of extending the threshold duration or increasing the threshold number includes increasing the threshold number of consecutive events.