Implantable atrial defibrillator apparatus

• US 6,405,084 B2
• Filed: 04/25/2001
• Issued: 06/11/2002
• Est. Priority Date: 01/28/1999
• Status: Expired due to Fees

• Current Assignee: Sorin Biomedica Cardio Srl (LivaNova Plc)
• Original Assignee: Sorin Biomedica Cardio Srl (LivaNova Plc)
• Inventors: Marcelli, Emanuela, Gaggini, Guido, Plicchi, Gianni, Garberoglio, Bruno
• Primary Examiner(s): EVANISKO, GEORGE ROBERT
• Application Number:
  US09/843,511
• Publication Number:
  US 20010016758A1
• Time in Patent Office: 412 Days
• Field of Search: 607/4, 607/5, 607/6, 607/9, 607/14
• US Class Current: 607/5
• CPC Class Codes: A61N 1/3918 characterised by shock pathway, e.g. by electrode configuration
• CPC Class Codes: A61N 1/395 for treating atrial fibrillation
• CPC Class Codes: A61N 1/3956 Implantable devices for applying electric shocks to the heart, e.g. for cardioversion

Abstract

An implantable defibrillator apparatus having a plurality of defibrillation electrodes which can be applied to the heart muscle in order to apply electric defibrillation shocks thereto, and a defibrillation-controller for selectively applying respective electric defibrillation shocks to the electrodes preferably sequentially in time and in synchronism with the QRS.

Claims

1. An implantable atrial defibrillator apparatus comprising:

a plurality of defibrillation electrodes adapted to be applied to the heart muscle of at least one atrium and to deliver electric defibrillation shocks thereto,

first sensor means for detecting an occurrence of atrial fibrillation and for generating a first signal indicative thereof;

second sensor means for detecting a ventricular electrogram and an absolute refractory period of the ventricular myocardium and generating a second signal indicative thereof;

control means connected to receive the first and second signals for selectively supplying a defibrillation pulse sequence to the electrodes in response to the occurrence of atrial fibrillation, the defibrillation pulse sequence including a plurality of voltage pulses separated in time by a pulse interval, the pulse sequence being configured by the control means to have a time of duration no greater than the absolute refractory period of the ventricular myocardium as detected by the second sensor means, the control means being connected to supply the pulse sequence to the electrodes so that the pulses are applied to the heart muscle only during the absolute refractory period of the ventricular myocardium, the control means being adapted to selectively vary at least one characteristic of the voltage pulses, the at least one characteristic selected from the group of waveform of the voltage pulses, the duration of the voltage pulses, the interval between successive voltage pulses, and the electrodes to which a voltage pulse is applied at any particular time such that application of the defibrillation pulse sequence to the heart muscle creates an electric defibrillation field of variable geometry dependent on the selective variations of the at least one characteristic of the voltage pulses.

2. An apparatus according to claim 1, wherein the first and second sensor means comprise respective sensing lines that connect the plurality of electrodes to the control means to enable the plurality of electrodes to act both as defibrillation electrodes and as sensing electrodes.

3. An apparatus according to claim 1 wherein the plurality of defibrillation electrodes comprises three to five electrodes.

4. An implantable atrial defibrillator apparatus comprising:

a plurality of defibrillation electrodes adapted to be applied to the heart muscle of at least one atrium and to deliver electric defibrillation shocks thereto;

a first sensor configured to detect an occurrence of atrial fibrillation and to generate a first signal indicative thereof;

a second sensor configured to detect a ventricular electrogram and an absolute refractory period of the ventricular myocardium and to generate a second signal indicative thereof;

a control unit connected to receive the first and second signals, the control unit being configured to selectively supply a defibrillation pulse sequence to the electrodes in response to the occurrence of atrial fibrillation, the defibrillation pulse sequence including a plurality of voltage pulses separated in time by a pulse interval, the pulse sequence being configured by the control means to have a time of duration no greater than the absolute refractory period of the ventricular myocardium as detected by the second sensor means, the control means being connected to supply the pulse sequence to the electrodes so that the pulses are applied to the heart muscle only during the absolute refractory period of the ventricular myocardium, the control unit being configured to selectively vary at least one characteristic of the voltage pulses, the at least one characteristic selected from the group of waveform of the voltage pulses, the duration of the voltage pulses, the interval between successive voltage pulses, and the electrodes to which a voltage pulse is applied at any particular time such that application of the defibrillation pulse sequence to the heart muscle creates an electric defibrillation field of variable geometry dependent on the selective variations of the at least one characteristic of the voltage pulses.

5. An apparatus according to claim 4, wherein the voltage pulse interval is about 100 microseconds.

6. An apparatus according to claim 4, wherein an electrode of the plurality of electrodes has a surface area ranging from about 50 mm² to about 100 mm².

7. An apparatus according to claim 4, wherein the time of duration of the pulse sequence is no greater than 50 milliseconds.

8. An apparatus according to claim 4, wherein the first and second sensors comprise respective sensing lines that connect the plurality of electrodes to the control unit to enable the electrodes to act both as defibrillation electrodes and as sensing electrodes.

9. An apparatus according to claim 4 wherein the plurality of defibrillation electrodes comprises three to five electrodes.

10. A method of treating atrial fibrillation comprising:

supplying a stimulating device having a control unit, a plurality of defibrillation electrodes, a first sensor configured to detect an occurrence of atrial fibrillation and a second sensor configured to detect a ventricular electrogram;

implanting the stimulating device so that the plurality of electrodes are applied to the heart muscle of at least one atrium, the first sensor is positioned to detect an occurrence of atrial fibrillation and the second sensor is positioned to detect a ventricular electrogram;

detecting at the first electrode an occurrence of atrial fibrillation;

detecting at the second electrode a ventricular electrogram and an absolute refractory period of the ventricular myocardium;

supplying to the control unit first and second signals indicative of the occurrence of atrial fibrillation and of the ventricular electrogram, respectively;

generating, in response to the first and second signals, a defibrillation pulse sequence comprising a plurality of voltage pulses separated in time by a pulse interval, the pulse sequence being configured by the control unit to have a time of duration no greater than the absolute refractory period of the ventricular myocardium as detected by the second sensor; and

applying the pulse sequence to the plurality of electrodes so that the voltage pulses are applied to the heart muscle only during the absolute refractory period of the ventricular myocardium, such that the control unit selectively varies at least one characteristic of the voltage pulses, the at least one characteristic selected from the group of the waveform, the duration, the interval between voltage pulses, and the sequence of activating voltage pulses to various electrodes and such that application of the defibrillation pulse sequence to the heart muscle creates an electric defibrillation field of variable geometry dependent on the selective variations of the at least one characteristic of the voltage pulses.