Reconfirmation prior to shock for implantable defibrillation

An apparatus for treating a tachyarrhythmia of the heart comprising:

• detection means for detecting a tachyarrhythmia;
• shock means for delivering a shock to the heart;
• and
• reconfirmation means for confirming a presence of the tachyarrhythmia subsequent to detection by said detection means and for reconfirming the presence of the tachyarrhythmia immediately prior to delivery of a shock by said shock means, said reconfirmation means controlling said shock means so that only if the presence of said tachyarrhythmia is both confirmed and reconfirmed does said shock means deliver said shock to the heart,
• said detection means comprising:
• means for defining a tachycardia detection window for sensed events;
• means for determining whether at least a predetermined portion of said sensed events fall within said window;
• and
• means for providing an output signal to said reconfirmation means when at least said predetermined portion of sensed events fall within said window.

A method for treating tachyarrhythmias of the heart comprising the steps of:

• a) detecting a tachyarrhythmia;
• b) reconfirming whether said tachyarrhythmia exists at at least one time after detecting said tachyarrhythmia;
• and
• c) delivering a shock to the heart only if at said step of reconfirming whether said tachyarrhythmia exists, a presence of said tachyarrhythmia is reconfirmed, one of said at least one times being immediately prior to delivering said shock,
• said method further comprising the steps of:
• commencing charging of a capacitor when said tachyarrhythmia is detected;
• reconfirming the presence of said tachyarrhythmia at a first predetermined time;
• and
• discharging the charge on said capacitor to a load other than the heart if said presence of said tachyarrhythmia is not confirmed at said first time,
• said method still further comprising the steps of:
• again reconfirming the presence of said tachyarrhythmia at a second time, said second time being a shorter of a second predetermined time or the time required for said capacitor to charge to a predetermined energy level, and
• supplying a shock to the patient by discharging said capacitor into the heart if said tachyarrhythmia is present at said first time and at said second time.

A method for treating tachyarrhythmias of the heart comprising the steps of:

• a) detecting a tachyarrhythmia;
• b) reconfirming whether said tachyarrhythmia exists at at least one time after detecting said tachyarrhythmia;
• and
• c) delivering a shock to the heart only if at said step of reconfirming whether said tachyarrhythmia exists, a presence of said tachyarrhythmia is confirmed, one of said at least one times being immediately prior to delivering said shock,
• said step of confirming whether a tachyarrhythmia exists comprising:
• sensing a series of events of the heart;
• defining a tachycardia window during which a number of sensed events of the heart occurs;
• and
• recognizing the presence of a tachyarrhythmia if a predetermined portion of said sensed evens occur within said tachycardia window.

An apparatus for treating a tachyarrhythmia of the heart comprising:

• detection means for detecting a tachyarrhythmia;
• shock means for delivering a shock to the heart;
• reconfirmation means for confirming a presence of the tachyarrhythmia subsequent to detection by said detection means and for reconfirming the presence of the tachyarrhythmia immediately prior to delivery of said shock means, said reconfirmation means controlling said shock means so that only if the presence of said tachyarrhythmia is both confirmed and reconfirmed does said shock means deliver said shock to the heart,
• said shock means including:
• an energy storage means;
• a discharge means for discharging to the heart energy stored in said storage means;
• and
• means for supplying energy to said energy storage means;
• said apparatus further comprising:
• monitoring means for monitoring a value of energy supplied to said energy storage means;
• and
• comparison means for comparing said value to a predetermined value, said comparison means being for controlling said reconfirmation means to reconfirm the presence of the tachyarrhythmia when said value of energy supplied to said energy storage means reaches said predetermined value.

An apparatus for treating a tachyarrhythmia of the heart comprising:

• detection means for detecting a tachyarrhythmia;
• shock means for delivering a shock to the heart;
• and
• reconfirmation means for confirming a presence of the tachyarrhythmia subsequent to detection by said detection means and for reconfirming the presence of the tachyarrhythmia immediately prior to delivery of a shock by said shock means, said reconfirmation means controlling said shock means so that only if the presence of the tachyarrhythmia is both confirmed and reconfirmed does said shock means deliver said shock to the heart,
• said detection means continuously detecting for said tachyarrhythmia and continuously providing an output indicative of detection thereof, and said reconfirmation means being responsive to said continuously provided output to determine whether a tachyarrhythmia is still present.