# US 5,978,705 A · Method and apparatus for treating cardiac arrhythmia using auxiliary pulse > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,978,705 A - Document ID: US5978705A - Status: Granted - Kind: A - Application number: 09/039,143 - Filed: 1998-03-13 - Granted: 1999-11-02 - Earliest claimed: 1997-03-14 - Assignees: The UAB Research Foundation - Inventors: Bruce H. KenKnight; Raymond E. Ideker; Robert S. Booker, III; Stephen J. Hahn - Web page: https://patentgrep.com/patent/US5978705A ## CPC - A61N 1/3937: {Monitoring output parameters} - A61N 1/3918: {characterised by shock pathway, e.g. by electrode configuration} - A61N 1/3943: {for threshold determination} - A61N: ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY (measurement of bioelectric currents A61B; surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body A61B18/00; anaesthetic apparatus in general A61M; incandescent lamps H01K; infrared radiators for heating H05B) ## Abstract An implantable system for the defibrillation or cardioversion of the heart of a patient in need of such treatment comprises a plurality of primary electrodes, a power supply, and a control circuit. Preferably, at least one auxiliary electrode is also included. The plurality of primary electrodes are configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of the heart, the current pathway defining a weak field area in a second portion of the heart. The at least one auxiliary electrode is configured for delivering an auxiliary pulse to the a portion of the heart where the primary shock field intensity is at or near a minimum. The control circuit is operatively associated with the primary electrodes, the auxiliary electrode, and the power supply, with the control circuit configured for delivering a cardioversion sequence comprising an auxiliary pulse sufficient to induce a cessation of propagation in the weak field area through the auxiliary electrode, followed by a defibrillation pulse through the primary electrodes delivered during the cessation of propagation in the weak field area. ## Claims ### Claim 1 An implantable system for the defibrillation or cardioversion of the heart of a patient in need of such treatment, said system comprising: a primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart; at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area; a power supply; and a control circuit operatively associated with said primary electrodes, said auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising an auxiliary pulse sufficient to induce a cessation of propagation in said weak field area through said auxiliary electrode, followed by a defibrillation pulse through said primary electrodes delivered during said cessation of propagation in said weak field area; wherein said control circuit is configured to deliver a biphasic auxiliary pulse and a biphasic defibrillation pulse, with the first phase of said defibrillation pulse in opposite polarity to said auxiliary pulse. ### Claim 2 (depends on 1) A system according to claim 1, wherein said control circuit is configured so that a trailing edge voltage of said auxiliary pulse is equal to a leading edge voltage of said defibrillation pulse. ### Claim 3 (depends on 1) A system according to claim 1, wherein said control circuit is configured to deliver a monophasic auxiliary pulse of from 0.5 to 10 milliseconds in duration. ### Claim 4 (depends on 1) A system according to claim 1, wherein said control circuit is configured to deliver said defibrillation pulse within 20 milliseconds after said auxiliary pulse. ### Claim 5 (depends on 1) A system according to claim 1, wherein said at least one auxiliary electrode is configured for positioning through the coronary sinus and in either the apical third of the posterior cardiac vein or the apical half of the great cardiac vein. ### Claim 6 (depends on 1) A system according to claim 1, wherein each of said at least one auxiliary electrode is carried by a transvenous lead. ### Claim 7 (depends on 1) A system according to claim 1, wherein said power supply includes a capacitor. ### Claim 8 (depends on 1) A system according to claim 1, wherein said power supply includes a single capacitor, and wherein said control circuit is configured so that both said auxiliary pulse and said defibrillation pulse are generated by the discharge of said single capacitor. ### Claim 9 (depends on 1) A system according to claim 1, wherein said power supply includes a first and second capacitor, and wherein said control circuit is configured so that said auxiliary pulse is generated by the discharge of said first capacitor and said defibrillation pulse is generated by the discharge of said second capacitor. ### Claim 10 (depends on 1) A system according to claim 1, wherein said power supply includes a first and second capacitor, and wherein said control circuit is configured so that said auxiliary pulse is generated by the discharge of said first and second capacitors, and said defibrillation pulse is generated by the discharge of said first and second capacitors. ### Claim 11 (depends on 1) A system according to claim 1, wherein said control circuit is configured so that said auxiliary pulse is not more than 50% of the peak current and not more than 30% of the delivered energy of said defibrillation pulse. ### Claim 12 An implantable system for the defibrillation of the ventricles of the heart of a patient in need of such treatment, said system comprising: a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart; at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area, with said at least one auxiliary electrode configured for positioning through the coronary sinus and in a vein on the surface of the left ventricle of said heart; a power supply; and a control circuit operatively associated with said primary electrodes, said at least one auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising a biphasic auxiliary pulse through said auxiliary electrode, followed by a biphasic defibrillation pulse through said primary electrodes, with said defibrillation pulse delivered within 20 milliseconds after said auxiliary pulse, and with the first phase of said defibrillation pulse in opposite polarity to said auxiliary pulse. ### Claim 13 (depends on 12) A system according to claim 12, wherein said control circuit is configured so that a trailing edge voltage of said auxiliary pulse is equal to a leading edge voltage of said defibrillation pulse. ### Claim 14 (depends on 12) A system according to claim 12, comprising: a first primary electrode configured for positioning in the superior vena cava or innominate vein; and a second primary electrode configured for positioning in the right ventricle. ### Claim 15 (depends on 14) A system according to claim 14, wherein said first and second primary electrodes are carried by a common transvenous lead. ### Claim 16 (depends on 12) A system according to claim 12, comprising: a first primary electrode configured for positioning in the superior vena cava or innominate vein; a second primary electrode configured for positioning in the right ventricle; and a second auxiliary electrode positioned near the right ventricular conus; with said control circuit configured for delivering said monophasic auxiliary pulse through said first and second auxiliary electrodes. ### Claim 17 (depends on 16) A system according to claim 16, with said second auxiliary electrode configured for positioning in the anterior portion of the right atrial appendage or in the right ventricular outflow track. ### Claim 18 (depends on 16) A system according to claim 16, wherein said second auxiliary electrode is carried by a transvenous lead, and wherein said second auxiliary electrode is positioned on the distal end of said transvenous lead. ### Claim 19 (depends on 16) A system according to claim 16, wherein said first and second primary electrodes are carried by a common transvenous lead. ### Claim 20 (depends on 12) A system according to claim 12, wherein said power supply includes a single capacitor, and wherein said control circuit is configured so that both said auxiliary pulse and said defibrillation pulse are generated by the discharge of said single capacitor. ### Claim 21 (depends on 12) A system according to claim 12, wherein said power supply includes a first and second capacitor, and wherein said control circuit is configured so that said auxiliary pulse is generated by the discharge of said first capacitor and said defibrillation pulse is generated by the discharge of said second capacitor. ### Claim 22 (depends on 12) A system according to claim 12, wherein said power supply includes a first and second capacitor, and wherein said control circuit is configured so that said auxiliary pulse is generated by the discharge of said first and second capacitors, and said defibrillation pulse is generated by the discharge of said first and second capacitors. ### Claim 23 An implantable system for the defibrillation or cardioversion of the heart of a patient in need of such treatment, said system comprising: a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart; at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area; a power supply; and a control circuit operatively associated with said primary electrodes, said auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising a defibrillation pulse through said primary electrodes, followed by an auxiliary pulse sufficient to induce a cessation of propagation in said weak field area through said auxiliary electrode; wherein said control circuit is configured to deliver a biphasic auxiliary pulse and a biphasic defrillation pulse; and wherein said control circuit is configured so that a leading edge voltage of said auxiliary pulse is equal to a trailing edge voltage of said defibrillation pulse. ### Claim 24 (depends on 23) A system according to claim 23, wherein said control circuit is configured to deliver a monophasic auxiliary pulse of from 0.5 to 10 milliseconds in duration. ### Claim 25 (depends on 23) A system according to claim 23, wherein said control circuit is configured to deliver said defibrillation pulse within 20 milliseconds after said auxiliary pulse. ### Claim 26 (depends on 23) A system according to claim 23, wherein said at least one auxiliary electrode is configured for positioning through the coronary sinus and in a vein on the surface of the left ventricle of said heart. ### Claim 27 (depends on 23) A system according to claim 23, wherein said at least one auxiliary electrode is configured for positioning through the coronary sinus and in either the apical third of the posterior cardiac vein or the apical half of the great cardiac vein. ### Claim 28 (depends on 23) A system according to claim 23, wherein each of said plurality of primary electrodes is carried by a transvenous lead. ### Claim 29 (depends on 23) A system according to claim 23, wherein each of said at least one auxiliary electrode is carried by a transvenous lead. ### Claim 30 (depends on 23) A system according to claim 23, wherein said power supply includes a capacitor. ### Claim 31 (depends on 23) A system according to claim 23, wherein said power supply includes a single capacitor, and wherein said control circuit is configured so that both said auxiliary pulse and said defibrillation pulse are generated by the discharge of said single capacitor. ### Claim 32 (depends on 23) A system according to claim 23, wherein said power supply includes a first and second capacitor, and wherein said control circuit is configured so that said auxiliary pulse is generated by the discharge of said first capacitor and said defibrillation pulse is generated by the discharge of said second capacitor. ### Claim 33 (depends on 23) A system according to claim 23, wherein said power supply includes a first and second capacitor, and wherein said control circuit is configured so that said auxiliary pulse is generated by the discharge of said first and second capacitors, and said defibrillation pulse is generated by the discharge of said first and second capacitors. ### Claim 34 An implantable system for the defibrillation of the ventricles of the heart of a patient in need of such treatment, said system comprising: a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart; at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area, with said at least one auxiliary electrode configured for positioning through the coronary sinus and in a vein on the surface of the left ventricle of said heart; a power supply; and a control circuit operatively associated with said primary electrodes, said at least one auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising a biphasic defibrillation pulse through said primary electrodes followed by a biphasic auxiliary pulse through said auxiliary electrode, with said auxiliary pulse delivered within 20 milliseconds after said auxiliary pulse, and with the first phase of said defibrillation pulse in opposite polarity to said auxiliary pulse; wherein said system further comprises a first primary electrode configured for positioning in the superior vena cava or innominate vein; a second primary electrode configured for positioning in the right ventricle; and a second auxiliary electroden positioning near the right ventricular conus; with said control circuit configured for delivering said monophasic auxiliary pulse through said first and second auxiliary electrode. ### Claim 35 (depends on 34) A system according to claim 34, wherein said control circuit is configured so that a leading edge voltage of said auxiliary pulse is equal to a trailing edge voltage of said defibrillation pulse. ### Claim 36 (depends on 34) A system according to claim 34, with said second auxiliary electrode configured for positioning in the anterior portion of the right atrial appendage or in the right ventricular outflow track. ### Claim 37 (depends on 34) A system according to claim 34, wherein said second auxiliary electrode is carried by a transvenous lead, and wherein said second auxiliary electrode is positioned on the distal end of said transvenous lead. ### Claim 38 (depends on 34) A system according to claim 34, wherein said first and second primary electrodes are carried by a common transvenous lead. ### Claim 39 (depends on 34) A system according to claim 34, wherein said power supply includes a single capacitor, and wherein said control circuit is configured so that both said auxiliary pulse and said defibrillation pulse are generated by the discharge of said single capacitor. ### Claim 40 (depends on 34) A system according to claim 34, wherein said power supply includes a first and second capacitor, and wherein said control circuit is configured so that said auxiliary pulse is generated by the discharge of said first capacitor and said defibrillation pulse is generated by the discharge of said second capacitor. ### Claim 41 (depends on 34) A system according to claim 34, wherein said power supply includes a first and second capacitor, and wherein said control circuit is configured so that said auxiliary pulse is generated by the discharge of said first and second capacitors, and said defibrillation pulse is generated by the discharge of said first and second capacitors. ### Claim 42 An electrode lead useful for the cardioversion or defibrillation of a patient's heart, comprising: an elongate transvencous electrode lead having a distal end portion, with said lead configured for positioning said distal end portion within the right atrial appendage; and a primary electrode connected to said electrode lead and positioned on said distal end portion; further comprising a secondary pace/sense electrode connected to said electrode lead at said distal end portion; wherein said secondary pace/sense electrode is connected to said electrode lead in a position proximal to said electrode. ### Claim 43 (depends on 42) An electrode lead according to claim 42, wherein said secondary pace/sense electrode comprises a pair of ring electrodes. ### Claim 44 An implantable system for the defibrillation of the ventricles of the heart of a patient in need of such treatment, said system comprising: a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart, said plurality of primary electrodes including an electrode configured for positioning in the right ventricle; at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area, with said at least one auxiliary electrode configured for positioning through the coronary sinus and in a vein on the surface of the left ventricle of said heart; a power supply; and a control circuit operatively associated with said primary electrodes, said at least one auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising a biphasic defibrillation pulse through said primary electrodes followed by a biphasic auxiliary pulse through said auxiliary electrode, with said auxiliary pulse delivered within 20 milliseconds after said defibrillation pulse, and with the first phase of said defibrillation pulse in opposite polarity to said auxiliary pulse. ### Claim 45 (depends on 44) A system according to claim 44, further comprising a housing configured for being implanted in the left thoracic region of said patient, said housing containing said power supply and said control circuit, and with said housing having an active external portion serving as a second primary electrode. ### Claim 46 (depends on 45) A system according to claim 45, wherein said auxiliary pulse is delivered between said auxiliary electrode and said second primary electrode. ### Claim 47 (depends on 44) A system according to claim 44, further comprising a second primary electrode configured for positioning in the superior vena cava or innominate vein. ### Claim 48 (depends on 47) A system according to claim 47, wherein said auxiliary pulse is delivered between said auxiliary electrode and said second primary electrode. ### Claim 49 (depends on 44) A system according to claim 44, further comprising: a housing configured for being implanted in the left thoracic region of said patient, said housing containing said power supply and said control circuit, and with said housing having an active external portion serving as a second primary electrode; and a third primary electrode configured for positioning in the superior vena cava or innominate vein; wherein said second and third primary electrodes are electrically common. ### Claim 50 (depends on 49) A system according to claim 49, wherein said auxiliary pulse is delivered between said auxiliary electrode, and said second and third electrically common primary electrodes. ### Claim 51 (depends on 44) A system according to claim 44, wherein said control circuit is configured so that a leading edge voltage of said auxiliary pulse is equal to a trailing edge voltage of said defibrillation pulse. ### Claim 52 An implantable system for the defibrillation of the ventricles of the heart of a patient in need of such treatment, said system comprising: a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart, said plurality of primary electrodes including an electrode configured for positioning in the right ventricle; at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area, with said at least one auxiliary electrode configured for positioning through the coronary sinus and in a vein on the surface of the left ventricle of said heart; a power supply; and a control circuit operatively associated with said primary electrodes, said at least one auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising an auxiliary pulse through said auxiliary electrode followed by a biphasic defibrillation pulse through said primary electrodes, with said defibrillation pulse delivered within 20 milliseconds after said auxiliary pulse, and with the first phase of said defibrillation pulse in opposite polarity to said auxiliary pulse; further comprising a housing configured for being implanted in the left thoracic region of said patient, said housing containing said power supply and said control circuit and with said housing having an active external portion serving as a second primary electrode. ### Claim 53 (depends on 52) A system according to claim 52, wherein said auxiliary pulse is delivered between said auxiliary electrode and said second primary electrode. ### Claim 54 (depends on 52) A system according to claim 52, wherein said control circuit is configured so that a leading edge voltage of said auxiliary pulse is equal to a trailing edge voltage of said defibrillation pulse. ### Claim 55 An implantable defibrillator, comprising: a housing; a power supply contained within said housing, with said power supply including a storage capacitor; and a control circuit contained within said housing and operatively associated with said power supply, said control circuit configured for delivering a cardioversion sequence comprising an auxiliary pulse and a defibrillation pulse; said housing having a volume less than 35 cubic centimeters. ### Claim 56 (depends on 55) An implantable defibrillator according to claim 55, said power supply further comprising a battery. ### Claim 57 (depends on 55) An implantable defibrillator according to claim 55, wherein said control circuit is configured so that said defibrillation pulse follows said auxiliary pulse, and so that a trailing edge voltage of said auxiliary pulse is equal to a leading edge voltage of said defibrillation pulse. ### Claim 58 (depends on 55) An implantable defibrillator according to claim 55, wherein said control circuit is configured so tat said auxiliary pulse follows said defibrillation pulse, and so that a trailing edge voltage of said defibrillation pulse is equal to a leading edge voltage of said auxiliary pulse. ### Claim 59 (depends on 55) An implantable defibrillator according to claim 55, said housing having a volume of at least 5 cubic centimeters. ### Claim 60 An implantable system for the defibrillation or cardioversion of the heart of a patient in need of such treatment, said system comprising: a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart; at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area; a power supply; and a control circuit operatively associated with said primary electrodes, said auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising an auxiliary pulse sufficient to induce a cessation of propagation in said weak field area through said auxiliary electrode, followed by a defibrillation pulse through said primary electrodes delivered during said cessation of propagation in said weak field area; wherein said at least one auxiliary electrode is configured for positioning through the coronary sinus and in a vein on the surface of the left ventricle of said heart. ### Claim 61 An implantable system for the defibrillation or cardioversion of the heart of a patient in need of such treatment, said system comprising: a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart; at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area; a power supply; and a control circuit operatively associated with said primary electrodes, said auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising an auxiliary pulse sufficient to induce a cessation of propagation in said weak field area through said auxiliary electrode, followed by a defibrillation pulse through said primary electrodes delivered during said cessation of propagation in said weak field area; wherein said at least one auxiliary electrode is configured for positioning through the coronary sinus and in a vein on the postero-lateral surface of the left ventricle of said heart. ### Claim 62 An implantable system for the defibrillation or cardioversion of the heart of a patient in need of such treatment, said system comprising; a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart; at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area; a power supply; and a control circuit operatively associated with said primary electrodes, said auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising an auxiliary pulse sufficient to induce a cessation of propagation in said weak field area through said auxiliary electrode, followed by a defibrillation pulse through said primary electrodes delivered during said cessation of propagation in said weak field area; wherein each of said plurality of primary electrodes is carried by a transvenous lead. ### Claim 63 An implantable system for the defibrillation or cardioversion of the heart of a patient in need of such treatment, said system comprising: a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart; at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area; a power supply; and a control circuit operatively associated with said primary electrodes, said auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising an auxiliary pulse sufficient to induce a cessation of propagation in said weak field area through said auxiliary electrode, followed by a defibrillation pulse through said primary electrodes delivered during said cessation of propagation in said weak field area; wherein said power supply includes a 20 to 400 microfarad capacitor. ### Claim 64 An implantable system for the defibrillation or cardioversion of the heart of a patient in need of such treatment, said system comprising: a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart; at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area; a power supply; and a control circuit operatively associated with said primary electrodes, said auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising a defibrillation pulse through said primary electrodes, followed by an auxiliary pulse sufficient to induce a cessation of propagation in said weak field area through said auxiliary electrode; wherein said control circuit is configured to deliver a monophasic auxiliary pulse of from 0.5 to 10 milliseconds in duration. ### Claim 65 An implantable system for the defibrillation or cardioversion of the heart of a patient in need of such treatment, said system comprising: a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart; at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area; a power supply; and a control circuit operatively associated with said primary electrodes, said auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising a defibrillation pulse through said primary electrodes, followed by an auxiliary pulse sufficient to induce a cessation of propagation in said weak field area through said auxiliary electrode; wherein said at least one auxiliary electrode is configured for positioning through the coronary sinus and in a vein on the postero lateral surface of the left ventricle of said heart. ### Claim 66 An implantable system for the defibrillation or cardioversion of the heart of a patient in need of such treatment, said system comprising: a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart; at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area; a power supply; and a control circuit operatively associated with said primary electrodes, said auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising a defibrillation pulse through said primary electrodes, followed by an auxiliary pulse sufficient to induce a cessation of propagation in said weak field area through said auxiliary electrode; wherein said power supply includes a 20 to 400 microfarad capacitor. ### Claim 67 An implantable system for the defibrillation or cardioversion of the heart of a patient in need of such treatment, said system comprising: a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart; at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area; a power supply; and a control circuit operatively associated with said primary electrodes, said auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising a defibrillation pulse through said primary electrodes, followed by an auxiliary pulse sufficient to induce a cessation of propagation in said weak field area through said auxiliary electrode; wherein said control circuit is configured so that said auxiliary pulse is not more than 50% of the peak current and not more than 30% of the delivered energy of said defibrillation pulse. ### Claim 68 An implantable system for the defibrillation of the ventricles of the heart of a patient in need of such treatment, said system comprising: a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart; at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area, with said at least one auxiliary electrode configured for positioning through the coronary sinus and in a vein on the surface of the left ventricle of said heart; a power supply; and a control circuit operatively associated with said primary electrodes, said at least one auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising a biphasic defibrillation pulse through said primary electrodes followed by a biphasic auxiliary pulse through said auxiliary electrode, with said auxiliary pulse delivered within 20 milliseconds after said auxiliary pulse, and with the first phase of said defibrillation pulse in opposite polarity to said auxiliary pulse; said system comprising a first primary electrode configured for positioning in the superior vena cava or innominate vein; and a second primary electrode configured for positioning in the right ventricle. ### Claim 69 An implantable system for the defibrillation of the ventricles of the heart of a patient in need of such treatment, said system comprising: a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart; at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area, with said at least one auxiliary electrode configured for positioning through the coronary sinus and in a vein on the surface of the left ventricle of said heart; a power supply; and a control circuit operatively associated with said primary electrodes, said at least one auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising a biphasic defibrillation pulse through said primary electrodes followed by a biphasic auxiliary pulse through said auxiliary electrode, with said auxiliary pulse delivered within 20 milliseconds after said auxiliary pulse, and with the first phase of said defibrillation pulse in opposite polarity to said auxiliary pulse. ### Claim 70 (depends on 69) An implantable system according to claim 69, wherein said first and second primary electrodes are carried by a common transvenous lead. ### Claim 71 An implantable system for the defibrillation of the ventricles of the heart of a patient in need of such treatment, said system comprising: a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart, said plurality of primary electrodes including an electrode configured for positioning in the right ventricle; at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area, with said at least one auxiliary electrode configured for positioning through the coronary sinus and in a vein on the surface of the left ventricle of said heart; a power supply; and a control circuit operatively associated with said primary electrodes, said at least one auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising an auxiliary pulse through said auxiliary electrode followed by a biphasic defibrillation pulse through said primary electrodes, with said defibrillation pulse delivered within 20 milliseconds after said auxiliary pulse, and with the first phase of said defibrillation pulse in opposite polarity to said auxiliary pulse; further comprising a second primary electrode configured for positioning in the superior vena cava or innominate vein. ### Claim 72 (depends on 71) A system according to claim 71, wherein said auxiliary pulse is delivered between said auxiliary electrode and said second primary electrode. ### Claim 73 An implantable system for the defibrillation of the ventricles of the heart of a patient in need of such treatment, said system comprising: a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart, said plurality of primary electrodes including an electrode configured for positioning in the right ventricle; at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area, with said at least one auxiliary electrode configured for positioning through the coronary sinus and in a vein on the surface of the left ventricle of said heart; a power supply; and a control circuit operatively associated with said primary electrodes, said at least one auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising an auxiliary pulse through said auxiliary electrode followed by a biphasic defibrillation pulse through said primary electrodes, with said defibrillation pulse delivered within 20 milliseconds after said auxiliary pulse, and with the first phase of said defibrillation pulse in opposite polarity to said auxiliary pulse, said system further comprising: a housing configured for being implanted in the left thoracic region of said patient, said housing containing said power supply and said control circuit, and with said housing having an active external portion serving as a second primary electrode; and a third primary electrode configured for positioning in the superior vena cava or innominate vein; wherein said second and third primary electrodes are electrically common. ### Claim 74 (depends on 73) A system according to claim 73, wherein said auxiliary pulse is delivered between said auxiliary electrode, and said second and third electrically common primary electrodes.