US3867949A - Cardiac pacer with voltage doubler output circuit - Google Patents

Cardiac pacer with voltage doubler output circuit Download PDF

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Publication number
US3867949A
US3867949A US355035A US35503573A US3867949A US 3867949 A US3867949 A US 3867949A US 355035 A US355035 A US 355035A US 35503573 A US35503573 A US 35503573A US 3867949 A US3867949 A US 3867949A
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United States
Prior art keywords
transistor
electrode
collector
emitter
terminal
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Expired - Lifetime
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US355035A
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English (en)
Inventor
Arthur W Schwalm
Jon A Anderson
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Cardiac Pacemakers Inc
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Cardiac Pacemakers Inc
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Filing date
Publication date
Application filed by Cardiac Pacemakers Inc filed Critical Cardiac Pacemakers Inc
Priority to US355035A priority Critical patent/US3867949A/en
Priority to AU74727/74A priority patent/AU465024B2/en
Priority to FR7437749A priority patent/FR2290887A1/fr
Priority to BE150574A priority patent/BE822274A/fr
Application granted granted Critical
Publication of US3867949A publication Critical patent/US3867949A/en
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00—Electrotherapy; Circuits therefor
    • A61N1/18—Applying electric currents by contact electrodes
    • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
    • A61N1/362—Heart stimulators

Definitions

  • the invention comprises a long life, direct cur- I I 128/419 2 307/110, rent energy source which is connected to an astable /2 331/113 R multivibrator which produces output pulses of a pre- Il'rtdetermined duration at a prescribed frequency Con.
  • Field of Search 128/419 419 421, nected to the output of the multivibrator is a voltage multiplying circuit which serves to increase the ampli- 320/39; 323/4, 81; 331/113 R tude of the output pulses from the multivibrator.
  • This invention relates generally to electronic heart pacing apparatus, and more specifically to the novel design of a semi-conductor pulse generator circuit which is efficient in terms of energy source drain, yet extremely stable in terms of frequency and amplitude of the output heart stimulating pulses.
  • a device of the type described herein is usually implanted within the body of the patient and electrodes are coupled from the implanted circuit to the heart muscle so that artificially generated pulses may be applied to the ventricle as if they were originated at the atrium. Because the circuit is implanted surgically within the body of the patient, it is most desirable that the pacer operate reliably over extended periods of time.
  • the electronic design of the pulse generator must be such that the circuits operate with low current drain.
  • the circuit is particularly adapted for use with lithiumiodide power sources, which source provides for delivery of power over extended periods of time without requiring venting for any gases which may be generated as a result of power generation.
  • the pulse generating circuit of the present invention through the use of a novel constant current source which feeds the astable multivibrator pulse generator.
  • the output from the pulse generator is supplied to a voltage multiplier network of unique design which produces at the cardiac electrodes impulses of an amplitude approximately twice that of the potential supplied by the implanted lithium-iodide battery power source.
  • Another object of the invention is to provide an improved pulse generator network which efficiently utilizes power from the battery source utilized therein.
  • Still another object of the invention is to provide an improved pulse generating circuit having voltage multiplier meansat the output thereof which operates extremely efficiently.
  • FIG. 1 is a circuit schematic of the preferred embodiment of the invention
  • FIG. 2 illustrates the waveform of the signal existing at the output from the constant current source in the circuit of FIG. 1;
  • FIG. 3 illustrates the waveform of the signal appearing at the output of the multi-vibrator stage in the circuit of FIG. I;
  • FIG. 4 illustrates the waveshape of the output signal appearing at the cardiac electrodes.
  • the pulse generator of the present invention is seen to consist of three main sections, namely, the power supply section including a constant current source enclosed by dashed line box 10, an astable multivibrator contained within dashed line box I2, and a voltage multiplier output circuit shown enclosed by dashed line box 14.
  • a lithium-iodide battery I6 Contained within the power supply section 10 is a lithium-iodide battery I6 which provides energiz'ation for the remainderof the circuit.
  • a lithium-iodide cell is most desirable as the energy source because of its long life, the absence of gas generation during discharge, and the absence of a highly corrosive liquid electrolyte.
  • Such a battery may be hermetically sealed and implanted in the body of a patient along with the electronic circuits which it serves.
  • a capacitor 22 Connected in parallel with battery 16 between terminals 18 and 20 is a capacitor 22. Also connected in parallel with battery 16 is a constant current network which includes a resistor 23, transistor 24, 26 and 28, and a voltage divider including resistors 30 and 32. More specifically, a conductor 34 connects junction 18 to a junction 36 to which is connected one terminal of the resistor 23. The other terminal of resistor 23 is connected by a conductor 38 to a junction 40 to which is connected the emitter electrode of the PNP transistor 24. The junction 40 is also connected by a conductor 42 to junction 44. A resistor 46 of relatively small ohmic value is disposed between junction 44 and the emitter electrode of PNP transistor 28. The base electrodes of transistors 24 and 28 are connected to one another.
  • the collector electrode of transistor 24 connects to he emitter electrode of PNP transistor 26 and to the base of transistor 24.
  • the base and collector electrodes of transistor 26 are connected together and to a terminal point 47 by means of a conductor 48.
  • the resistors 30 and 32 are serially connected between the collector electrode of transistor 26 and a return conductor 50.
  • Completing the constant current circuit 10 is a capacitor 49 which is connected between the junction 40 and the return conductor 50.
  • the multivibrator section of the circuit enclosed by box 12 includes a timing network which comprises a capacitor 52 and a resistance voltage divider including resistors 54 and 56. Also included in the multivibrator are the semi-conductor switches 58, 60 and 62. Specifically, the output from the constant current source is obtained at the collector electrode of transistor 28 which is tied to junction 64.
  • the timing capacitor 52 has one terminal thereof connected to junction 64 and the remaining terminal connected by conductor 66 to junction 68. Connected between junction 68 and the return conductor 50 are the series resistors 54 and S6.
  • the base electrode of transistor 62 is coupled through a resistor 70 to junction 68 by conductor 72.
  • the collector electrode of transistor 62 is coupled by means of a diode 74, a resistor 76, and a conductor to junction point 64.
  • the emitter electrode of transistor 62 is directly connected to the return conductor 50.
  • Transistor 60 here shown as being of the NPN type, has its base electrode connected to junction 64 by means of a resistor 78 and conductor 80.
  • the emitter electrode of transistor 60 is connected by conductor 82 to the junction point 84 between timing circuit voltage divider resistors 54 and 56.
  • the collector electrode of transistor 60 is connected to the base electrode of tran-' sistor S8.
  • the collector electrode of transistor 58 is connected to junction 68 by the conductor 86.
  • the emitter electrode of transistor 58 is connected to the emitter electrode of transistor 28 by conductor 42 and resistor 46.
  • the voltage multiplier portion of the circuit enclosed in box 14 includes a capacitor 90 and first and second semi-conductor switches, here shown as NPN transistor 92 and PNP transistor 94.
  • Transistor 92 has its base electrode coupled through a resistor 96 to the junction point 68 at which the output from the multivibrator appears.
  • the emitter electrode is connected by conductor 98 to the return conductor 50.
  • the collector electrode of transistor 92 is coupled through a resistor 100 to a junction 102 on conductor 34.
  • the base electrode of PNP transistor 94 is coupled through resistor 104 to the collector electrode of transistor 92.
  • the emitter electrode of transistor 94 is also connected to the junction point 102 on conductor 34.
  • the collector electrode of transistor 94 is coupled through a resistor 106 to the return conductor 50.
  • a first terminal of capacitor 90 is connected to the junction point 108 between the collector electrode of transistor 94 and the resistor 106. its other terminal is connected to the positive output terminal 110.
  • the negative output terminal 112 is connected by a conductor 114 to the collector electrode of transistor 92.
  • a diode 116 is connected directly across the output terminals 110 and 112.
  • the load 118 which in the present application, is the heart muscle to be stimulated, is connected across the output terminals 110 and 112.
  • the circuit shown enclosed by box 12 is an astable multivibrato r, i. e., it is a freejrunning multivibrator having two astable states. In one state, the transistors 58, 60 and 62 are non-conducting, and in the other state, these transistors are all simultaneously conducting. The operation of the circuit can best be understood by considering the voltage appearing at the junction 64. The waveform of thisvoltage is illustrated in FIG.'2.
  • transistors 58, 60 and 62 eachnon-conducting and with the voltage appearing at junction 64 at its zero value.
  • the current flowing out of the constant current source which includes transistors 24, 26 and 28 and the high impedance resistors 30 and 32, serves to charge the timing capacitor 52 until such time as the base-emitter threshold of transistor 60 is reached. At this point, conduction is initiated in transistors 58 and 62. As the collector of transistor 58 assumes a more positive value, so does the emitter of transistor 60 and the junction 64.
  • transistor 62 With transistor 62 fully conducting, a discharge path through conductor 80, diode 74, resistor 76 and the collector to emitter path of transistor 62 is established. Because of the relative values of the various resistors and resulting circuit parameters, the rate of discharge of the capacitor 52 through this last-mentioned path is greater than the rate at which charge is being added to the capacitor 52 by way of the constant current source connected to junction 64, conductor 66 and the resistors 54 and 56. Thus, the voltage at junction 64 now decreases until the'point is reached'that there is insufficient base current to hold transistor 58 in its saturated condition. As a result, transistors 62 60 and 58 revert to their non-conducting state in a regenerative manner.
  • junction 64 The voltage appearing at junction 64 is thereby decreased to a negative value. With transistor 62 nonconducting, the capacitor 52 again begins to charge in a positive direction from the constant current source connected to junction 64 through conductor 66 and resistors 54 and 56, thus repeating the cycle.
  • transistors 24 and 28 are selected to have matched characteristics, thereby ensuring that the collector currents of these two transistors will be approximately equal or at least proportional to one another. ,If, in practice, it is found that the parameters of transistors 24 and 28 vary, stabilization in circuit operation can be obtained by interposing the small resistor 46 in the emitter circuit of the transistor
  • the constant current source 10 is designed to provide a stable oscillator drive current, yet one which will yield an external indication of the condition of the battery 16. More specifically, the resistors 30 and 32 are trimmed during manufacture to provide av six-beat per minute decrease in output pulse rate when the output voltage across the load 118 drops to approximately 3.5 volts. This change in rate becomes noticeable to the patient and allowshim toseek medical attention prior to the time that the battery fails completely.
  • FIG. 2 there is shown the waveform' of the voltage observed at junction 64.
  • the voltage swings were ,as illustrated in FIG. 2. No attempt has been made to calibrate the abscissa and accordingly this parameter is not to scale.
  • transistors 58, 60 and 62 nonconducting and the voltage at junction 64 at the zero level
  • current from the constant current source comprised of transistors, 24,26 and 28 flows through capacitor 52 and resistors 54 and 56 causing a voltage to build up on the capacitor 52.
  • base current flows through resistor 78 and the base to emitter path of transistor 60 and through the resistor 56 causing transistor 60 to begin conducting.
  • transistors 58 and 62 are rapidly switched from their non-conducting to their saturated state in a regenerative manner, thereby causing the voltage appearing at junction 64 to swing to a positive value of 2.9 volts. With transistor 62 fully conducting, a low impedance path is presented to the charge on capacitor 52 and the capacitor begins to discharge through conductor 80,
  • the waveform of FIG. 3 represents the voltage appearing at junction 68, the output terminal of the multivibrator. It can be seen from this waveform that the voltage at this point remains fairly constant in spite of the partial discharge of capacitor 52 through diode 74, resistor 76 and transistor 62. This is due to the fact that the voltage across capacitor 49 is applied to this junction by way of the low impedance emitter to collector path of transistor 58. However, when transistor 58 (along with transistors 60 and 62) is turned off, the voltage at junction 68 approaches zero volt as a reference.
  • capacitor 90 will be charged by way of a current flowing from terminal 18 of the battery 16, through conductor 34, through resistor 100, conductor 114, diode 116, resistor andconductor 50 back to the terminal of battery 16.
  • the charging current for capacitor 90 passes through diode 116 only when the voltage drop across the heart load 118 exceeds the diode threshold voltage.
  • the diode Y 116 is included primarily to prevent erosion of the cardiac electrodes in the event a non-nobel metal -is used in forming the electrodes.
  • the multivibrator parameters are such that it remains in its of "condition sufficiently long for the full battery potential to be stored on capacitor 90.
  • transistors 92 and 94 are simultaneously rendered fully conductive and capacitor 90 discharges through the load connected between terminals 110 and 112 (the heart), through conductor 114, from the collector to emitter path of transistor 92, through conductors 98 and 50, through the low impedance of the battery 16 and capacitor 22, through conductor 34 and the emitter to collector path of transistor 94.
  • the voltage across the load will be approximately equal to the sum of the voltage across capacitor 90 and the potential of the battery 16 which is also stored in capacitor 22. Since, when the output pulse is applied to the heart muscle, the only impedance (other than the low impedance of the heart itself) is the forward impedance of the transistor 94, substantially twice the battery voltage is initially impressed. 7
  • circuit parameters may be used in the embodiment of the cardiac pacer circuit shown in FIG. 1:
  • resistors 30 and 32 should be approximately 3 megohms, but are normally adjusted to a value such that the multi-vibrator circuit produces 72 pulses per minute. However, with resistor 30 shorted, the circuit will oscillate at pulses per minute if resistors 30 and 32 are properly trimmed. I
  • a cardiac pacer circuit comprising in combination:
  • a constant current source including (l) a source of direct current potential of a predetermined voltage value having first and second terminals,
  • first and second terminals including first and second resistors and first and second transistors, each having an emitter electrode, a collector electrode and a base electrode, the emitter electrode of said first transistor being connected to the collector and base electrode of said second transistor, the base and collector electrodes of said first transistor being coupled through said first resistor of said first terminal of said source and the emitter electrode of said second transistor being coupled through said second resistorto said second terminal of said source,
  • a third transistor having an emitter, a collector and a base electrode, the base electrode of said third transistor being connected to the emitter electrode of said first transistor and the emitter electrode of said third transistor being coupled to the emitter electrode of said second transistor,
  • an astable multivibrator including:
  • fourth, fifth and sixth transistors each having a base, emitter and collector electrodes, the emitter electrode of said fourth transistor being connected to the emitter electrode of said second transistor, the collector electrode of said fourth transistor being connected to the junction between saidvthird resistor and first capacitor and coupled to the base electrode of said fifth transistor, the emitter electrode of said fifth transistor being connected to the first terminal of said source and the collector electrode of said fifth transistor being coupled through fourth resistor means to the collector electrode of said third transistor and the base electrode of said sixth transistor, said collector electrode of said sixth transistor being connected to the base electrode of said fourth transistor, said emitter electrode of said sixth transistor being coupled to said first terminal of said source,
  • a voltage doubler circuit including:
  • said base electrode of ,said seventh transistor being coupled to said junction, the emitter electrode of said seventh transistor being connected to said first terminal of said source, said collector electrode of said seventh transistor being coupled to said second terminal of said source by means of a fifth resistor and coupled to d.
  • a pair of output electrodes 1. a first of said pair of electrodes being connected to the collector electrode of said seventh transistor, 2. the second of said pair of output electrodes being connected in series with second capacitor means of said collector electrode of said eighth transistor.

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  • Health & Medical Sciences (AREA)
  • Cardiology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Radiology & Medical Imaging (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Electrotherapy Devices (AREA)
US355035A 1973-04-27 1973-04-27 Cardiac pacer with voltage doubler output circuit Expired - Lifetime US3867949A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US355035A US3867949A (en) 1973-04-27 1973-04-27 Cardiac pacer with voltage doubler output circuit
AU74727/74A AU465024B2 (en) 1973-04-27 1974-10-25 Cardiac pacer with voltage doubler output circuit
FR7437749A FR2290887A1 (fr) 1973-04-27 1974-11-15 Stimulateur cardiaque a circuit doubleur de tension
BE150574A BE822274A (fr) 1973-04-27 1974-11-18 Stimulateur cardiaque a circuit doubleur de tension

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US355035A US3867949A (en) 1973-04-27 1973-04-27 Cardiac pacer with voltage doubler output circuit
AU74727/74A AU465024B2 (en) 1973-04-27 1974-10-25 Cardiac pacer with voltage doubler output circuit
FR7437749A FR2290887A1 (fr) 1973-04-27 1974-11-15 Stimulateur cardiaque a circuit doubleur de tension

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US3867949A true US3867949A (en) 1975-02-25

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US355035A Expired - Lifetime US3867949A (en) 1973-04-27 1973-04-27 Cardiac pacer with voltage doubler output circuit

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US (1) US3867949A (fr)
AU (1) AU465024B2 (fr)
BE (1) BE822274A (fr)
FR (1) FR2290887A1 (fr)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4065807A (en) * 1977-02-07 1977-12-27 Gte Automatic Electric Laboratories Incorporated DC-to-DC voltage converter employing a common transistor in both switching and multivibrator functions
US4203448A (en) * 1977-08-19 1980-05-20 Biotronik Mess- Und Therapiegerate Gmbh & Co. Programmably variable voltage multiplier for implanted stimulator
US4312355A (en) * 1977-01-12 1982-01-26 Medtronic B.V. Heart pacemaker
US4471784A (en) * 1981-04-06 1984-09-18 Tesla Koncernovy Podnik Source of pulses for electronic suppression of pain
US4610408A (en) * 1980-03-13 1986-09-09 Coiled Investments, Inc. Strip feed mechanism
US4792886A (en) * 1987-02-19 1988-12-20 Em Microelectronic Marin Sa Device comprising an electronic circuit for processing an analog signal
US5800461A (en) * 1992-11-19 1998-09-01 Cardiac Pacemakers, Inc. Constant charge time of defibrillation capacitor
US5986361A (en) * 1997-04-22 1999-11-16 Board Of Trustees Operating Michigan State University Automated electronically controlled microsprayer
US6871090B1 (en) * 2000-10-13 2005-03-22 Advanced Bionics Corporation Switching regulator for implantable spinal cord stimulation
US20080281368A1 (en) * 2007-05-09 2008-11-13 Cherik Bulkes Implantable digital device for tissue stimulation
US20120200297A1 (en) * 2009-10-19 2012-08-09 Commissariat A L'energle Atomique Et Aux Energies Alternatives Device for measuring battery voltage and related monitoring device

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0090467A3 (fr) * 1982-03-25 1987-03-04 Walter Spaa Stimulateur cardiaque

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3433228A (en) * 1966-05-06 1969-03-18 Cordis Corp Multimode cardiac pacer
US3534245A (en) * 1967-12-08 1970-10-13 Rca Corp Electrical circuit for providing substantially constant current
US3547127A (en) * 1968-04-29 1970-12-15 Medtronic Inc Cardiac pacemaker with regulated power supply
US3571694A (en) * 1968-08-08 1971-03-23 Honeywell Inc Dc voltage regulator employing an fet constant current source and current flow indicator
US3726285A (en) * 1971-04-26 1973-04-10 Gen Electric Body organ stimulus pulse generator with decoupled timing circuit and voltage multiplier
US3743850A (en) * 1972-06-12 1973-07-03 Motorola Inc Integrated current supply circuit

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1813040A1 (de) * 1968-12-06 1970-07-02 Siemens Ag Herzschrittmacher mit einem elektrischen Taktgeber
US3759266A (en) * 1970-10-07 1973-09-18 Medcor Inc Ng reset and voltage increasing circuits cardiac autopacer with variable refractory non linear feedback latchi
US3857085A (en) * 1972-05-24 1974-12-24 Medtronic Inc Pulse generator output regulator
IL42784A (en) * 1972-08-09 1975-12-31 Greatbatch W Ltd Constant energy pulse generator

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3433228A (en) * 1966-05-06 1969-03-18 Cordis Corp Multimode cardiac pacer
US3534245A (en) * 1967-12-08 1970-10-13 Rca Corp Electrical circuit for providing substantially constant current
US3547127A (en) * 1968-04-29 1970-12-15 Medtronic Inc Cardiac pacemaker with regulated power supply
US3571694A (en) * 1968-08-08 1971-03-23 Honeywell Inc Dc voltage regulator employing an fet constant current source and current flow indicator
US3726285A (en) * 1971-04-26 1973-04-10 Gen Electric Body organ stimulus pulse generator with decoupled timing circuit and voltage multiplier
US3743850A (en) * 1972-06-12 1973-07-03 Motorola Inc Integrated current supply circuit

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4312355A (en) * 1977-01-12 1982-01-26 Medtronic B.V. Heart pacemaker
US4065807A (en) * 1977-02-07 1977-12-27 Gte Automatic Electric Laboratories Incorporated DC-to-DC voltage converter employing a common transistor in both switching and multivibrator functions
US4203448A (en) * 1977-08-19 1980-05-20 Biotronik Mess- Und Therapiegerate Gmbh & Co. Programmably variable voltage multiplier for implanted stimulator
US4610408A (en) * 1980-03-13 1986-09-09 Coiled Investments, Inc. Strip feed mechanism
US4471784A (en) * 1981-04-06 1984-09-18 Tesla Koncernovy Podnik Source of pulses for electronic suppression of pain
US4792886A (en) * 1987-02-19 1988-12-20 Em Microelectronic Marin Sa Device comprising an electronic circuit for processing an analog signal
US5800461A (en) * 1992-11-19 1998-09-01 Cardiac Pacemakers, Inc. Constant charge time of defibrillation capacitor
US5986361A (en) * 1997-04-22 1999-11-16 Board Of Trustees Operating Michigan State University Automated electronically controlled microsprayer
US6871090B1 (en) * 2000-10-13 2005-03-22 Advanced Bionics Corporation Switching regulator for implantable spinal cord stimulation
US20080281368A1 (en) * 2007-05-09 2008-11-13 Cherik Bulkes Implantable digital device for tissue stimulation
US20120200297A1 (en) * 2009-10-19 2012-08-09 Commissariat A L'energle Atomique Et Aux Energies Alternatives Device for measuring battery voltage and related monitoring device
US8922216B2 (en) * 2009-10-19 2014-12-30 Commissariat A L'energie Atomique Et Aux Energies Alternatives Device for measuring battery voltage and related monitoring device

Also Published As

Publication number Publication date
AU465024B2 (en) 1975-08-26
AU7472774A (en) 1975-09-18
BE822274A (fr) 1975-03-14
FR2290887B1 (fr) 1978-09-22
FR2290887A1 (fr) 1976-06-11

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