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Publication numberUS3566876 A
Publication typeGrant
Publication dateMar 2, 1971
Filing dateDec 14, 1967
Priority dateDec 14, 1967
Publication numberUS 3566876 A, US 3566876A, US-A-3566876, US3566876 A, US3566876A
InventorsShaw Robert F, Stoft Paul E
Original AssigneeHewlett Packard Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Defibrillator
US 3566876 A
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Description  (OCR text may contain errors)

United States Patent Paul E. Stoft LINE SYNCHRONIZER [56] References Cited UNITED STATES PATENTS 3,481,341 12/1969 Siedband 128/421 FOREIGN PATENTS 864,362 4/1961 Great Britain 128/419D OTHER REFERENCES Leeds, Journal of Arnerican Medical Association, Vol. 152,N0. 15,Aug. 8, 1953,pp. 1411-1413 (128-419D) Primary ExaminerWilliam E. Kamm Attorney-A. C. Smith ABSTRACT: A monopolar cardiac defibrillator obviates the need for bulky storage capacitors by operating directly from line signal to supply a high power-defibrillating pulse substantially as a half-wave portion of the line signal the defibrillating pulse is generated in timed relationship to a patients electrocardiogram by activating a signal-controlled switch to apply a half wave of line signal to the defibrillator circuitry.

PULSER PATENTEU MAR 2197i SYNCHRONIZER PULSER INVENTORS PAUL. E. STOFT ROBERT F. SHAW ATTORNEY DEFIBRILLATOR BACKGROUND OF THE INVENTION Conventional cardiac defibrillators commonly include a storage capacitor for storing a sufficient quantity of charge to supply to a patient a defibrillating pulse of about 2000 volts and 20 amperes for about 5 milliseconds. The physical size and weight of the'storage capacitor is typically of the order of 1 cubic foot and several pounds and thus is not readily conductive to miniaturized packaging and convenient portability. Defibrillator. apparatus of this type is described in the literature (See U.S. Pat. No. 3,236,239 issued on Feb. 22, 1966 to B. V. Berkovits). Also, the time required between defibrillating pulses to charge the storage capacitor of such conventional defibrillator apparatus prevents the delivery of several defibrillating pulses in rapid succession.

SUMMARY OF THE INVENTION DESCRIPTION OF THE DRAWING The drawing shows a schematic diagram and selected signal waveforms present in the defibrillator circuit'of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, there is shown a line input 9 which may be connected to receive an alternating signal 11 from the power lines. The power line signal at input 9 is applied to the primary winding 13 of a step-up transformer 15 through a controlled rectifier 17 or other suitable signal-controlled switch. The voltage step-up ratio from the primary 13 to the secondary winding 19 of the transformer 15 may be as high as 30 to provide a secondary voltage as high as 2000 volts, even under conditions where the voltage applied to the primary may be as low as 60 volts at the peak of the half sine wave supplied to the primary winding 13. The pulse 20 of voltage produced on the secondary winding 19 when controlled rectifier 117 is conductive is applied to the patient 23 through diode 21, connecting cables 24 and the contact electrodes 25 suitably positioned on the chest of the patient 23. Typical peak values of the wave 20 applied to the patient 23 are about 2000 volts and 20 amps for about 5 to 10 milliseconds. The secondary winding 19 may include a plurality of taps to alter the turns ratio and provide selected values of secondary voltages and currents.

For power line frequency of 60 cycles, the pulse width of a half-wave is about 8 milliseconds. The portion of the line signal applied to the primary winding through the controlled rectifier 17 may be regulated simply by adjusting the electrical angle 22 at which the controlled rectifier 17 is rendered conductive. The inductance and resistance in the circuitry which supplies the defibrillating pulse 20 to the electrodes 25 smooths out transients upon turn-on of controlled rectifier 17 and causes a small amount of undershoot 26 in the defibrillating pulse 20. This undershoot portion of the waveform produces a reversal of pulse polarity which causes diode 21 to become nonconductive and which renders diode 27 conductive. The undershoot portion 26 is not applied to the patient but rather is dissipated in the resistor 29 which is serially con nected with diode 27 across the secondary winding 19 of transformer 15.

it should be noted that the peak secondary current of about 20 amperes requires a peak primary current of several hundred amperes which must be supplied from the applied power line signal. However, since the primary current of such high value flows from the power lines only during a portion of a half-wave period, and since the response time of fuses is typically equal to the period of a few cycles of line signal, the average power supplied to the circuit of the present invention during such response time is sufficiently low so that fuses in the supply lines are not blown. Thus, the transformer 15 may be relatively small in size with typically core dimensions of about 21 X 21 centimeters with a 7 .X 7 centimeter cross section. The primary winding comprises wire of sufficiently large cross section to carry the high peak current and the number of primary turns with reference to the number of secondary turns is selected with due consideration for the fact that such high primary currents produce high line drops and thus that only about 60-70 volts may be available across the inputs 9 at the time peak current flows in the primary winding 13.

Conventional electrocardiographic apparatus 28 may be attached to the patient 23 using pickup electrodes 30, 32 suitably positioned on the patient to receive the electrocardial signals 34. The apparatus 28 may include a monitor 36 such as an oscilloscope or strip chart recorder which is connected to provide a continuous display of the patients electrocardial signals 34.

In operation, it is desirable that defibrillating pulses be applied to the patients with nonfibrillating hearts during the period of the electrocardial signal waveform designated 1,, to t,, and avoided during the period t,, to t,. During the period t to t several cycles of the line signal occur and thus the controlled rectifier 17 may be rendered conductive during any one of these cycles occurring during this desirable period t to t,,. A synchronized pulser 39 responsive to the predominant QRS portion of the electrocardial signal may thus include a conventional monostable multivibrator or other suitable circuit for generating the conduction-initiating gate pulse 41 and may include transformer coupling to the gate electrode of controlled rectifier 17 so that true isolation of the patient 23 from line signal is preserved. The synchronized pulser 39 may also include conventional lockout circuitry for preventing gate pulses 41 from being generated during the undesirable period to t It should be apparent that the present circuit may also be operated with a controlled rectifier in place of diode 21 where it is desirable to switch lower currents. However, the high secondary voltage presents some problems in biasing and insulating a trigger circuit for a controlled rectifier so connected, and also may require that another controlled rectifier connected in place of diode 27 be rendered conductive in the following half cycle to dissipate the undershoot portion 26 of the defibrillating pulse 20.

Therefore, the defibrillator circuit of the present invention obviates the need for a large and heavy storage capacitor by supplying to a patient a high power-defibrillating pulse derived directly from the power lines. The present circuit thus eliminates the requirement of charging time between defibrillating pulses and therefore permits several such pulses to be supplied to a patient in rapid succession.

We claim:

1. Monopolar defibrillator apparatus for applying an electrical signal to a mammalian subject, the apparatus comprising:

an input for receiving alternating signal from a source;

output means for applying an electrical signal to a subject;

a transformer having primary and secondary windings;

signal controllable switch means connecting the primary winding of said transformer to said input for applying a selected portion of a half cycle of alternating signal appearing at said input to said transformer in response to a control signal applied to said switch means;

circuit means connecting said secondary winding to said output means and including a first diode connected to conduct current in one direction to said output means from said secondary winding for signal therefrom of one polarity, and including a second diode and impedance means in series therewith for conducting current through said second diode and impedance means from said secondary winding for signal therefrom of the opposite polarity; and

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3481341 *Sep 6, 1968Dec 2, 1969Westinghouse Electric CorpPortable defibrillator having saturable core output transformer
GB864362A * Title not available
Non-Patent Citations
Reference
1 *Leeds, Journal of American Medical Association, Vol. 152, No. 15, Aug. 8, 1953, pp. 1411 1413 (128-419D)
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4453547 *Apr 6, 1981Jun 12, 1984Physio Technology, Inc.T-Wave inhibiting system
US4517976 *Sep 27, 1982May 21, 1985Fuji Photo Film Co., Ltd.High frequency scalpel and endoscope system and method of operating same
US4685461 *Aug 11, 1986Aug 11, 1987Dornier System GmbhApparatus and method for triggering shock waves in lithotripsy
US4745920 *Aug 10, 1987May 24, 1988Dornier System GmbhApparatus and method for triggering therapeutic shock waves
US4834100 *May 12, 1986May 30, 1989Charms Bernard LApparatus and method of defibrillation
US5074301 *Jul 16, 1990Dec 24, 1991Telectronics Pacing Systems, Inc.Apparatus and method for atrial pace before ventricular shock in dual chamber arrhythmia control system
US5188105 *Nov 14, 1990Feb 23, 1993Medtronic, Inc.Apparatus and method for treating a tachyarrhythmia
US5514165 *Dec 23, 1993May 7, 1996Jace Systems, Inc.Combined high voltage pulsed current and neuromuscular stimulation electrotherapy device
US5591209 *May 19, 1994Jan 7, 1997Angeion CorporationImplantable defibrillator system for generating an active biphasic waveform
US6885562Dec 28, 2001Apr 26, 2005Medtronic Physio-Control Manufacturing CorporationCircuit package and method for making the same
US7282040Dec 24, 2002Oct 16, 2007Vygon Us, LlcGravitational pressure regulating mechanism
US7340301Jun 30, 2002Mar 4, 2008Hadasit Medical Research Services & Development Ltd.Defibrillator system
DE4225893A1 *Aug 5, 1992Feb 10, 1994Siemens AgDefibrillator with diode protection for capacitor-charging circuit - incorporates diode string on secondary side of transformer for rectification of AC and dissipation of negative portion of pulse
EP0409591A1 *Jul 18, 1990Jan 23, 1991Rey S ReyesInterface cable for connecting bedside electrocardiograph monitor to portable defibrillator/electrocardiograph machine
WO2003004094A1 *Jun 30, 2002Jan 16, 2003Shraga GornyDefibrillator system
Classifications
U.S. Classification607/5, 607/72
International ClassificationA61N1/39, A61B5/0452, A61B5/0456
Cooperative ClassificationA61B5/0456, A61N1/39
European ClassificationA61B5/0456, A61N1/39