llIIlIlllIlIlIIlIIIIll|I|||IIIIIIIIIIIIIIIIIIIIIIIIHIIIIIIIIIIIIIIIIIHIII
`
`USOOS333616A
`
`[11] Patent Number:
`
`5,333,616
`
`[19]
`
`United States Patent
`Mills et a1.
`[45] Date of Patent: Aug. 2, 1994
`
`
`
`4
`’
`-W
`l
`[5 ] WRIST ORN ECG MONITOR
`[75]
`Inventors: GUY N- Mills, Gladstone; Habib
`Homayoun, A101“: bOth 0f Oreg.
`Instromedix, Inc., Hillsboro, Oreg.
`
`[73] Assignee:
`
`1211 Appl- N03 2:151
`e :
`.
`[22] Fil d
`Jan 7 1993
`’
`Related US. Application Data
`.
`.
`.
`153;;15134“ Ser. No' 816’389’ Dec' 26’ 1991’ Pat. No.
`’
`’
`'
`[51]
`Int. 01.5 ............................................ A61B 5/0402
`
`[52] US. Cl. .................................. 128/696; 128/904
`[58] Field of Search ............... 128/696, 670, 710, 903,
`128/904, 690
`
`[62]
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`3,972,320 8/1976 Kalman .
`4,108,166
`8/1978 Schmid .
`4,120,294 10/1978 Wolfe .................................. 128/690
`4,230,127 10/1980 Larson ................. 128/690
`
`4,256,117
`3/1981 Perica et al.
`..... 128/690
`
`4,409,983 10/1983 Albert .................. 128/690
`
`.
`..... 128/690
`4,425,921
`1/1934 Fujisaki et 31.
`
`,,,,, 128/690
`4,450,843
`5/1984 Barney et a1.
`
`. 128/696 X
`.......
`4,791,933 12/1988 Asai et a1.
`
`1/1989 Eckerle ---------------- 128/672
`4,799,491
`
`2/1989 Eckerle ................ 128/672
`4,802,488
`
`4’883’064 ”/1989 015,0“ 5131' """"" 128/696
`
`4’928’690 5/1990 Hglman a a" '
`""" 128/421
`..... 128/690
`7/1990 nghter et a1.
`..
`4,938,228
`
`4,974,607 ”/1990 Miwa ..........
`. 128/904 X
`......... 128/710
`5,191,891
`3/1993 Righter
`...................... 128/696 X
`5,226,431
`7/1993 Bible et a1.
`
`FOREIGN PATENT DOCUMENTS
`
`2753165 11/1978 Fed. Rep. of Germany ...... 128/690
`8119650 10/1981 France .
`
`OTHER PUBLICATIONS
`“Inventors of Heart Monitor Tick Toward Prosperity .
`.
`. ” (Oregon business Journal), Brock, Sep. 17, 1990.
`Primary Examiner—Lee S. Cohen
`Assistant Examiner—Jeffrey R. Jastrzab
`Attorney, Agent, or Firm—Kolisch Hartwell Dickinson
`McCormack & Heuser
`[57]
`ABSTRACT
`A compact, lightweight wrist-worn cardiac data and
`event monitor having dry skin electrodes integral with
`the monitor’s housing is disclosed. Preferably, the skin
`electrodes are made of titanium nitride-plated stainless
`steel and form inner. wrist-contacting, and outer, other
`band’s palm-contaotable regions of the housing. Chro—
`nometric and other multiple functions are provided to
`increase the functional density of the monitor by parti-
`tioning and very-large-scale-integrating the circuitry,
`which includes signal detection; data conversion, stor-
`age, display and telecommunication; and external push-
`button controls operable by the patient’s other hand. In
`accordance with the preferred embodiment, a tele-
`phonic transmitter is integrally included within the
`housing for remote diagnostic purposes without
`the
`.
`”869 for C’Ftemal 80““?“10”? By a pref‘i‘red metho‘j 9f
`the Invemon’ a SlmPhfied digital filter Implemented 1“
`firmware ensures that only ECG and event data are
`recorded at the exclusion of noise and motion artifacts.
`By another preferred method of the invention, a battery
`life prediction method is used to extend the useful life of
`the battery and to indicate to the patient when the bat.
`tery should be replaced. Event data that may be re-
`corded and tele-transmitted along with the ECG data
`.
`.
`.
`include time-ofiday. or elapsed time markers, as well as
`markers or indications of the detect1on of any pulses
`produced, for example, by an implanted pacemaker or
`an
`implanted
`cardio-verter/defibrillator monitor
`(ICDM).
`
`3 Claims, 6 Drawing Sheets
`
`70
`
`ECG AMPLIFIER
`
`
` ECG ELECTRODES
`AND
`
`FILTERS (34)
`
`14.16
`
` MICROCONTROLLER
`
`
`WITH INTERNAL ROM
`
`
`
` POWER.
`SPEED.AND DEVICE
`ACCESS CONTROL
`
`
`
`
`
`|PR2018-01093
`
`Apple Inc. Ex. 1009 Page 1
`
`IPR2018-01093
`Apple Inc. Ex. 1009 Page 1
`
`

`

`US. Patent
`
`29m.
`
`4.99l
`
`6f0
`
`616a333,5
`
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`
`1.4.m4|1/
`
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`
`AB
`
`3
`
`Fw.
`
`4.!
`
`|PR2018—01093
`
`Apple Inc. Ex. 1009 Page 2
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`IPR2018-01093
`Apple Inc. Ex. 1009 Page 2
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`

`

`US. Patent
`
`Aug. 2, 1994
`
`Sheet 2 of 6
`
`5,333,616
`
`
`
`|PR2018—01093
`
`Apple Inc. Ex. 1009 Page 3
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`IPR2018-01093
`Apple Inc. Ex. 1009 Page 3
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`

`

`US. Patent
`
`Aug. 2, 1994
`
`Sheet 3 of 6
`
`5,333,616
`
`
`
`|PR2018—01093
`
`Apple Inc. Ex. 1009 Page 4
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`IPR2018-01093
`Apple Inc. Ex. 1009 Page 4
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`

`

`US. Patent
`
`Aug. 2, 1994
`
`Sheet 4 of 6
`
`5,333,616
`
`on
`
`
`
`m2:SEEM.52mm
`
`3690
`
`$352805:mo5:238m
`28#255.1:;mEm$20o2oz<
`
`mzoEaImosmaozémwaa.$558<5
`
`..l6528$82
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`
`|PR2018—01093
`
`Apple Inc. Ex. 1009 Page 5
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`IPR2018-01093
`Apple Inc. Ex. 1009 Page 5
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`
`
`
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`
`

`

`US. Patent
`
`Aug. 2, 1994
`
`Sheet 5 of 6
`
`5,333,616
`
`®
`
`2°°
`
`FIG. 5
`
`POWER = BATTERY CAPACITY,
`BATTERY SYMBOL = OFF, V = GOOD
`
`202
`
`POWER = 0
`
`
`
`
`OR V = DEAD
`
`
`
`
` POWER < OR = 5% BATTERY CAPACITY
`
`OR V = LOW
`9
`
`BLINK BATTERY SYMBOL
`
`
`
`NO
`
`222
`
`POWER = POWER - LOW POWER,
`SHOW TIME
`
`
`
`
`ANY BUTTON pUSHED
`
`.
`
`
`
`
`DATE BumN
`?
`
`POWER = POWER - MEDIUM POWER,
`SHOW DATE
`
`
`
`
`PROCESS RECORD, TRANSMIT, SET TIME,
`
`POWER=POWER-[{V(B)-V(R)}/RXV(R)]
`ABORT RECORD, TRANSMIT IF POWER = 0
`OR v = DEAD
`
`
`
`
`
`MEASURE BATTERY VOLTAGE V = GOOD.
`LOW OR DEAD
`
`|PR2018—01093
`
`Apple Inc. Ex. 1009 Page 6
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`IPR2018-01093
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`

`

`US. Patent
`
`Aug. 2, 1994
`
`Sheet 6 of 6
`
`5,333,616
`
`FIG. 6 @ 300
`
`302
`
`SHIFT PREVIOUS 3 ECG SAMPLES
`x (-2) <--X(-1 <_x (0
`AND TAKE NEw EC SAMPL x (0)
`
`304
`
`HANNING FILTER: A(O) = 1/4[X(0) + 2x (-1) + X(-2)]
`
`305
`
`FIRST ORDER HIGH PASS IIR FILTER:
`HIGH PASS = SIGNAL— LOW PASS
`0 (0): A (0)——B (0)/m WHERE
`—4 AND 3(0): A(-4)-— A(0)— B (-1)
`mFILTER FREQUENCY = 3 db @ 9 Hz.
`
`HANNING FILTER: D(0) = 1/4 [0(0) + 20 (-1) + C (-2)]
`
` FIRST ORDER HIGH PASS IIR FILTER:
`
` 308
`
`
`
`
`HIGH PASS = SIGNAL— LOW PASS
`F(O)= DO()-— E(0)/m WHERE
`m = 4 AND E O)=D(--4)D(0)-E(-1)
`FILTER FRE UENCY = 3 db @ 9 Hz.
`310
`
`
`
`
`
`FIRST ORDER LOW PASS_IIR FILTER:
`G (0>= F?—
`G-(1)
`WHE GAI0
`FILTER FREQUENCY = 3 db @ 14 Hz.
`
`312
`
`QRS DETECTOR
`
`314
`
`|PR2018—01093
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`

`

`1
`
`5,333,616
`
`2
`
`WRIST-WORN ECG MONITOR
`
`This is a continuation of application Ser. No.
`07/816,389 filed Dec. 26, 1991 now US. Pat. No.
`5,289,824.
`
`5
`
`face to contact an upper skin electrode. Custom very-
`large-scale integrated (VLSI) circuit components con-
`tained within the housing include ECG signal and ab-
`normal event detection circuitry,
`analog—to-digital
`(AD) and digital-to-analog (DA) conversion circuitry,
`memory and processor circuitry for scanning the push-
`buttons and displaying selected chronometric, cardiac
`and status information. Circuitry is also provided to
`drive an integral speaker for the telecommunication of
`ECG signal or cardiac event data via telephone lines to
`a remote site for so-called “over-read”, diagnosis and
`archival recording.
`integral dry
`The monitor’s housing includes dual,
`skin electrodes located on a wrist-contacting, inner or
`rear base plate and on an outer or front surface contact-
`able by the palm of the patient’s other hand. The elec-
`trodes preferably are formed by plating a region of a
`stainless steel or other base metal expanse with a thin
`layer of titanium nitride (TIN), titanium carbide (TIC)
`or titanium carbo-nitride (TiCN). The microprocessor
`and associated electronics, including firmware executed
`thereby, employs a digital bandpass filter reliably to
`detect ECG signals characterized by QRS complexes or
`pacer and defibrillator pulses but to ignore noise and
`motion artifacts. A current draw measuring method
`implemented by the microprocessor and associated
`electronics monitors usage and predicts the end of life
`of the integral battery beyond which monitoring is
`halted, thereby to maximize long-term monitoring ca-
`pacity, to avoid potentially inaccurate ECG data re-
`cording and to inform the patient when the battery
`should be replaced.
`These and other objects and advantages of the inven-
`tion will be more clearly understood from a consider-
`ation of the accompanying drawings and the following
`description of the preferred embodiment.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is an isometric view of the wrist-worn ECG
`monitor made in accordance with the preferred embodi-
`ment of the invention.
`FIG. 2 is an exploded frontal isometric view of the
`ECG monitor corresponding with that of FIG. 1, with
`the wrist band removed for clarity.
`FIG. 3A is an exploded isometric view of the ECG
`monitor corresponding with that of FIG. 2, but show-
`ing it generally from the rear instead of the front.
`FIG. 3B is an enlarged, fragmentary cross-sectional
`view of the lower electrode shown in FIG. 3.
`FIG. 4 is a schematic block diagram of the monitor
`show in FIG. 1.
`
`FIG. 5 is a flowchart illustrating the battery life pre-
`diction method of the invention.
`
`BACKGROUND AND SUMMARY OF THE
`INVENTION
`
`The invention generally relates to wrist-worn cardiac
`monitors. More particularly, the invention concerns a
`wrist-worn ECG monitor having integral electrodes for
`recording and teletransmitting ECG data to a remote
`site for analysis by a diagnostician.
`Known wrist-wom cardiac monitors are extremely
`limited in functionality. For example, some conven-
`tional monitors simply monitor and display pulse rate
`and thus provide no ECG data recording capability at
`all. Others record ECG data and provide only for the
`local playback of recorded data and thus provide no
`remote diagnostic capability. Still others require exter-
`nal electrodes on the ends of a cable for detection of an
`ECG signal near the heart of the cardiac patient—often
`necessitating the use of messy conductive gels-and thus
`are difficult to hook up and use, especially for long-term
`monitoring of a relatively active patient. Problems
`abound in producing small, lightweight ECG monitors
`that provide for long-term cardiac event recording and
`remote professional diagnostic and prescriptive patient
`care.
`
`Accordingly, it is a principal object of the present
`invention to provide a self-contained, wrist-worn ECG
`monitor that provides at least single event recording
`and telecommunication of ECG data to a remote site for
`professional diagnosis.
`It is another important object of the invention to
`provide such a monitor with the greatest possible func-
`tionality in an extremely compact, integral housing.
`Yet another object is to provide such a monitor that
`reliably detects and records ECG signals without the
`use of external electrodes or messy gels or other skin
`preparation.
`It is also an object of the invention to provide an
`improved dry skin electrode system that is an integral
`part of the housing of such a monitor.
`Another object is to render such a wrist-worn moni-
`tor that easily and conveniently can be used by a cardiac
`patient without assistance by another, for long-term
`ambulatory patient care.
`Still another object is to make such a wrist-worn
`ECG monitor the multiple functions of which readily
`can be operated with the patient’s other hand.
`One equally important object is to provide such func-
`tionality in a lightweight, compact, wrist-worn monitor
`that yet has the capacity to record multiple events that
`may occur over a long period of time, e.g. days.
`One other object of the invention is to make such a
`monitor easily manufactured and maintained, and cost
`effective.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`Briefly summarizing the invention in its preferred
`embodiment, a wrist-worn monitor is provided that,
`without external connections of any kind, enables local,
`multiple event ECG data recording and telecommuni-
`cation to a remote site, as well as providing the time and
`date functions normally provided by a wristwatch. The
`monitor is housed in an extremely compact and light—
`weight housing and is operable by the patient‘s simply
`placing the other palm over a portion of the monitor’s
`
`65
`
`55
`
`FIG. 6 is a flowchart illustrating the digital filtering
`method of the invention.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENT
`
`Referring first and briefly to FIG. 1, the apparatus of
`the invention made in accordance with its preferred
`embodiment is indicated in isometric view at 10. It may
`be seen from FIG. 1 that apparatus 10, which is drawn
`generally in enlarged but otherwise accurate scale, is am
`extremely compact and lightweight, extremely full
`function cardiac monitor that conveniently and com-
`fortably can be wrist-worn by a cardiac patient, because
`the form factor and size of the monitor’s housing rela-
`tive to the conventional wrist band is only slightly
`
`|PR2018-01093
`
`Apple Inc. Ex. 1009 Page 8
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`

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`'
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`3
`larger than a traditional digital watch. The full function-
`ality of apparatus 10, which provides unprecedented
`functional density and convenience due to its fully inte-
`grated dry skin electrodes, will be described in detail by
`reference to FIGS. 2—6.
`Referring now to FIG. 2, apparatus 10 is shown in
`exploded isometric view. Wrist-worn ECG, or cardiac
`data, monitoring apparatus 10 comprises a housing 12
`including first and second dry skin electrodes 14, 16
`unitarily connected therewith and forming an integral
`part thereof for making conductive contact with a car-
`diac patient’s skin surface and a bezel 18 (with associ-
`ated gasket 18:: ) also forming an integral part thereof;
`plural pushbutton switches 20, 22, 24, 26 (with associ-
`ated O-ring gaskets 20a, 2017, 220, 22b, 24a, 24b, 26a,
`26b); a conventional watchband 28 of any suitable size
`and structure (see FIG. 1); and, entirely contained
`within housing 12, electronics indicated generally at 30.
`Turning briefly to FIG. 4, electronics 30 include an
`ECG signal amplifier 32 including hardware filters 34
`coupled with electrodes 14, 16 for producing an analog
`signal representative of the electrical field on the sur~
`face of the patient’s skin and between electrodes l4, 16.
`Electronics 30 also include analog-to-digital signal con-
`version means, or analog-to-digital converter (ADC),
`36 connected with amplifier 32 for producing digital
`data representing the patient’s ECG waveform over a
`predefined interval of time. Electronics 30'preferably
`include 32-kilobytes (32-kb) of static read-and-write
`memory (SRAM) 38 that operates as means for record-
`ing digital data produced by ADC 36. Electronics 30
`also include means 40 (preferably including a microcon-
`troller with 8-kb of read-only memory (ROM) 42, a
`digital-to-analog converter (DAC) 44, a voltage-con-
`trolled oscillator (VCO) 46 and a speaker 48) for wire-
`lessly, and preferably audibly, communicating data re-
`corded in SRAM 38 to a remote site for verification or
`so-called “over-read”, real-time diagnosis and/or archi-
`val recording.
`Because in its preferred embodiment wrist-wom car-
`diac data monitor 10 comprises electronics 30 providing
`at
`least all of the functions described immediately
`above, an extremely high level of functional density is
`achieved by the invention. By functional density is
`meant a measure of the functionality per unit volume,
`whether the volume is that contained within housing 12
`or is that contained within and including housing 12 (of
`which electrodes 14, 16 form an integral part: electrode
`14 integrally molded therein and electrode 16 by the use
`of screws S turned into corresponding tapped holes
`formed therein). In accordance with the preferred em-
`bodiment of the invention, and as measured by conven-
`tional water displacement means, the interior, or con-
`tained, predetermined volume within housing 12 does
`not exceed approximately 0.75-inches3, and is prefera-
`bly equal to or less than approximately 0.625-inches3.
`Similarly measured, the exterior predetermined volume
`within and including housing 12 (and integral electrodes
`l4, l6 and bezel 18) does not exceed approximately
`1.5-inches3, and is preferably equal to or less than ap-
`proximately 1.25-inches3.
`Dry skin electrodes 14, 16 are designed for use with
`equipment capable of producing or monitoring chang-
`ing electrical conditions (indicative of changing cardio-
`graphic conditions) at the surface of a patient’s skin, and
`are particularly suitable in cardiac monitoring, e.g. by
`apparatus 10. As illustrated in Detail A, an electrode
`such as electrode 14 preferably comprises an expanse
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`6O
`
`65
`
`5,333,616
`
`4
`14a formed of a base metal such as stainless steel, with
`expanse 14a being electrically connectable with such
`monitoring equipment, as illustrated in FIGS. 1 and 2.
`Plating an outer, skin-contactable region or surface 140’
`of expanse 14a is a composition 14b (shown in greatly
`enlarged thickness in Detail A relative to that of ex-
`panse 14a) including a first component of a preferably
`bio-compatible, conductive (e.g. metallic) element such
`as titanium, and at least a second component chosen
`from a group including nitrogen and carbon. It will be
`understood that electrode 16 of apparatus 10 is of identi-
`cal material content and cross-sectional structure as
`electrode 14, but is of much greater surface area.
`Those of skill in the arts will appreciate that such
`electrode 14 might be connectable with stimulus/re-
`sponse equipment by any suitable means including an
`electrical conductor or wire, e.g. the coil spring used in
`connection with apparatus 10 having such electrode 14
`integrally housed therewith. Those skilled also will
`appreciate that such electrode 14 comprising such
`plated expanse obviates use of a messy, conductive gel,
`and even the so-called “residue-free”, self-adhesive
`gelatinous pads that often are used to enhance conduc-
`tivity between an electrode and a patient’s skin. Finally,
`those of skill in the arts will appreciate that stimulus/re-
`sponse equipment with which such invented electrode
`14 is believed to be useful includes not only electrical
`conditions change-monitoring, or response, equipment
`but also electrical conditions change-producing, or
`stimulus, equipment such as neural, muscular or other
`anatomical electrostimulation equipment.
`Preferably base metal-plating composition 14b is in
`order of preference a titanium nitride (TIN), titanium
`carbide (TIC) or titanium carbo-nitride (TiCN) layer
`approximately 3-microns (0.003-inch) thick. Such com-
`position can be plated by known chemical or physical
`vapor deposition techniques, and preferably the plating
`composition is polished to a smooth finish primarily for
`aesthetic reasons. Such plating of base metal expanse
`14a has been found to protect, and thus to greatly ex-
`tend the life, of a dry skin electrode such as electrode 14
`by producing an extremely hard, exterior, skin-contact-
`able surface. Such plating also has been found to pro-
`vide high conductivity and thus to produce a high qual-
`ity electrical interface between an electrode such as
`electrode 14 and the patient’s skin surface, which may
`be very dry.
`Referring now briefly to FIGS. 2 and 3, necessary
`details of the structure of apparatus 10 made in accor-
`dance with its preferred embodiment will be described.
`Electronics 30 may be seen to be implemented prefera-
`bly in various discrete and integrated circuits surface-
`mounted or ultrasonic wire bonded onto a multi-layer
`printed circuit board (PCB) 50 supported within hous-
`ing 12 by a perimeter support member 52. Thus, PCB
`50, which preferably comprises plural adhered, copper-
`clad epoxy layers, may be seen physically to mount and
`interconnect the various circuitry shown schematically
`in FIG. 4, including on its bottom side a microcontroller
`(with integral ROM) chip 42,
`interconnecting and
`mounting support members 54a, 54b for connection
`with one terminal of battery B, a double-leaf spring
`member 56 for connection with the other terminal of
`battery B and a “land” or circuit pad, 58 for connecting
`lower electrode 16 via a coil spring 60 to one signal
`input terminal of ECG amplifier 32.
`Upper electrode 14 is connected to the other signal
`input
`terminal of ECG amplifier 32 via a generally
`
`|PR2018—01093
`
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`

`5,333,616
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`5
`trapezoid-shaped, split and thus slidably yielding, leaf
`spring 62 connected to a circuit pad formed on the top
`side of PCB 50. In the preferred embodiment of the
`invention, ECG amplifier 32, including associated hard-
`ware input signal filters 34, are implemented in a custom
`analog chip-on-board (e.g. a so-called application-
`specific integrated circuit, or ASIC) 64, which is
`mounted on PCB 50 by known ultrasonic wiretbonding
`techniques. A custom digital (ASIC) chip-on-board 66
`implements ADC 36, DAC 44, VCO 46, pushBUT-
`TONS logic 68, an elapsed-time clock 70 and POWER,
`SPEED and DEVICE ACCESS CONTROL logic 72
`(refer briefly to FIG. 4). Custom analog and digital
`chips 64, 66 may be formed on conventional substrates,
`may have any desired layout as determined by speed/-
`power requirements and conventional VLSI chip de-
`sign rules and tools.
`Yet another VLSI chip, which is surface-mounted on
`the top side of PCB 50, is SRAM chip 38. Preferably
`connected to the top side of PCB 50 via a so-called
`“Zebra” elastomeric strip (or other flexible connector
`means) 74 is a custom-masked liquid crystal display
`(LCD) chip 76, which upon assembly of apparatus 10
`lies above neighboring digital chip 66 and SRAM 38
`and directly below bezel 18. As will be seen by refer-
`ence to the operational description provided herein,
`conventional chronometric, as well as cardiac monitor-
`ing and other status information, are provided by selec-
`tively activating masked segments of LCD 76 to pro-
`vide visible alphanumeric, graphic and symbolic indicia
`of the operation of apparatus 10.
`The remaining circuitry of electronics 30 preferably
`is mounted, as better shown in FIG. 2, to the top side of
`PCB 50. Such circuitry includes speaker 48, relatively
`smaller decoupling capacitors C1, C2, relatively larger
`decoupling capacitors C3, C4 and resistors R1, R2,.R3,
`R4. It will be understood by those skilled in the arts that
`external capacitors C1 and C2 are too large to be inte-
`grated into the VSLI chips, and that external resistors
`R1, R2, R3, R4 (one of which is the physical embodi-
`ment of current sense resistor R shown in FIG. 4) are
`either precision resistors that cannot be so integrated or
`resistors the values of which are application or opera-
`tional mode specific in the use of apparatus 10. For
`example, certain of the external resistors are used to 45
`establish voltage or frequency response thresholds of
`ECG amplifier 32 and filters 34, and advantageously are
`provided external to the VSLI chips so that such opera—
`tional parameters easily may be changed.
`Importantly enabling the achievement of unprece-
`dentedly high functional density in a wrist-worn cardiac
`monitor, along with the electrical and physical parti-
`tioning and packaging design described above, is the
`design of speaker 48. Speaker 48 generally is of the type
`used in hearing aids and pagers, but is customized for its
`application in means 40 for audibly communicating
`ECG data to a remote site preferably over a voice chan-
`nel, e.g. telephone lines, without the need for external
`connection or transmitter. Speaker 48 is characterized
`in that it provides preferably approximately 83-decibels
`(83-db) sound pressure at approximately l-inch, and a
`relatively flat response preferably between approxi-
`mately l-kHz and 3-khz.
`These attributes enable speaker 48 to deliver to a
`conventional
`telephone microphone or equivalent
`transducer for transmission over telephone lines the
`required audio tones, which preferably are a frequency-
`shift keyed (FSK) signal at frequencies of approxi-
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`6
`mately 1.5-kHz and 2.5-kHz for the pulse, date and time
`markers, and a frequency modulated (FM) carrier for
`the digitized ECG data representing the patient’s cardi-
`ography. Such a speaker, or what is referred to as a
`“hearing aid receiver” is available, for example, from
`Knowles, Inc. of Franklin Park, 111., but of course other
`sources may be suitable. Preferably, apparatus 10 is
`rendered water-resistant, despite the provision in hous—
`ing 12 adjacent speaker 48 of three slotted speaker
`holes, or speaker grill, 12a, by affixing a small patch of
`water-impermeable but air-permeable material such as
`Gortex ® fabric to the inside surface of housing 12 (not
`shown in FIGS. 2 and 3, for the sake of clarity).
`In accordance with the preferred embodiment of the
`invention, analog chip 66 includes not only ECG ampli-
`fier 32 and associated hardware filters 32, but also digi-
`tal logic circuitry that permits microcontroller 42 pro-
`grammably to select various operational parameters.
`For example, analog chip 66 includes gating circuitry
`for controlling the gain, common-mode rejection ratio
`(CMMR) and DC offset/zeroing of amplifier 32, as by
`digital potentiometer design techniques used in various
`applications. e.g. cathode ray tube (CRT) monitors.
`Analog chip 66 also includes gating circuitry for con-
`trolling the upper and lower bandpass frequencies of
`filters 34, as by selectively switching capacitors into and
`out of the filter circuit. Those of skill in the arts will
`appreciate that, because it includes both analog and
`digital circuitry, analog chip 66 is preferably partitioned
`internally to protect the relatively noise-sensitive digital
`circuitry from the relatively noise-productive analog
`circuitry.
`Those skilled, in the arts will appreciate that the illus-
`trated and described partitioning and physical packag-
`ing of apparatus 10, and particularly of electronics 30,
`achieves the extremely high functional density ac-
`claimed herein, although it is possible that alternative
`device selection and circuit topology, partitioning and-
`/or packaging schemes might be used within the spirit
`of the invention. Those of skill also will appreciate that
`in accordance with the preferred embodiment, housing
`12 and support member 52 are molded plastic such as
`acrylonitrile-butadiene-styrene (ABS), which renders
`apparatus 10 extremely rigid and durable, but also light-
`weight and relatively inexpensive to manufacture.
`Returning to FIG. 4, a schematic block diagram of
`the invention is shown that illustrates means by which
`the various power management, chronometric, ECG
`signal conditioning and digitizing, demand data record-
`ing and trans-telephonic communication functions are
`performed. Those skilled in the art will appreciate that
`the illustrated circuit structure, by the preferred em-
`bodiment of the invention, is contained entirely within
`housing 12 of apparatus 10, with the exception of course
`of electrodes 14, 16, which it may be seen from FIG. 1
`form an integral, unitary part of housing 12.
`In operation, apparatus 10 is worn on the wrist of the
`cardiac patient much like a conventional wrist watch.
`In the embodiment of the invention shown in FIG. 1,
`wrist-wom cardiac monitor 10 would be worn on the
`left wrist, yielding access by the patient to pushbuttons
`20, 22, 24, 26 by the right hand and visibility to the
`patient of LCD 76. With apparatus 10 thus positioned
`on the leftwrist, the palm of the right hand easily can be
`placed into contact with upper electrode 14, thus im-
`pressing between upper electrode 14 and lower elec-
`trode 16 a signal representative of the patient’s cardiog—
`raphy (as indicated by a varying electrical potential at
`
`|PR2018-01093
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`5,333,616
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`7
`the patient’s skin surface). When the recording of a
`cardiac waveform is desired,
`the patient merely de-
`presses pushbutton 26, effecting so-called “demand”
`recording of what may prove to be an arrhythmic car-
`diac waveform representing an abnormal cardiac
`“event.”
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`Continuously, microcontroller 42 monitors pushbut-
`tons 20, 22, 24, 26 for even momentary closure, via
`pushbuttons logic 68 and power, speed and device ac-
`cess control 72. Upon the depression of pushbutton 26,
`microcontroller 42 supplies power to ECG amplifier 32
`and to ADC 36 and then delays a few, e.g. approxi-
`mately five, seconds. This timeout provides time for the
`user to position his or her palm on upper electrode 14
`and for the ECG signal to stabilize.
`After the delay, microcontroller 42 stores, or cap-
`tures, ECG data input via ECG electrodes 14, 16, ECG
`amplifier 32 and ADC 36 in SRAM 38 as a cardiac data
`record. Such a stored ECG data record is available for
`immediate or delayed playout, e.g. trans-telephonic or
`other telecommunication, to a remote site. Importantly,
`pushbutton 26 is monitored to begin such ECG data
`recording at all times, even if the patient is in the pro-
`cess of initializing chronometric functions, e.g. setting
`the date, day or time. This “override” feature of appara-
`tus 10 assures no loss of ECG data even when there is a
`cardiac event worthy of recording that happens to coin-
`cide with the patient’s other uses of apparatus 10.
`Those skilled in the arts will appreciate that apparatus
`of the invention made in accordance with its preferred
`embodiment described above provides unprecedented
`functional density in an integral, wholly self-contained,
`compact and lightweight, wrist-wom package,
`the
`functionality including the ability to produce ECG data
`records on demand and to play the same back to a re-
`mote site with the use only of a touch tone telephone or
`other suitable audio communication channel. It further
`will be appreciated that, with the addition to apparatus
`10 of one or more input signal jacks, one or more pairs
`of external electrodes also or instead may be monitored
`to produce ECG data independent upon the detection
`of a cardiac event, i.e. based not upon patient demand
`but upon continuous or periodic monitoring of the pa-
`tient’s cardiography and comparing the same to prede-
`termined ECG signal criteria.
`As described and illustrated in U.S. Pat. No.
`4,958,641 entitled “Heart Monitoring Method and Ap-
`paratus” issued Sep. 25, 1990 and having a common
`assignee with the present invention, event determina-
`tion and automatic windowed data recording means
`may be included within apparatus 10. Similarly, as de-
`scribed and illustrated in our US. Pat. No. 5,012,814
`entitled “Implantable-Defibrillator Pulse Detection-
`Triggered ECG Monitoring Method and Apparatus”,
`issued May 7, 1991, pacemaker or implantable cardi-
`overter/defibrillator monitor (ICDM) pulse detection
`means may be included within apparatus 10. The teach-
`ings of these patents are incorporated herein by this
`reference, and the provision in apparatus 10 of what will
`be referred to generally as pulse monitoring capability is
`described below in general terms that assume familiarity
`with such patent teachings.
`Generally, such inclusion requires simply providing
`supporting firmware in the integral ROM of microcon-
`troller 42, designed in accordance with the teachings of 65
`the patents mentioned above and also designed properly
`to program the programmable hardware filter and am-
`plifier operational parameters discussed herein. For
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`example, for pacemaker or ICDM pulse detection, the
`hardware filter through which the patient’s skin poten-
`tial- or cardiography-representative analog input signal
`is passed typically might have a 0.5-Hz lower cutoff
`frequency and a lOO-Hz upper cutoff frequency, rather
`than the typically 0.5-Hz lower and 30-Hz upper cutoff
`frequencies of the filters as they are programmed in
`accordance with the preferred embodiment in which
`apparatus utilizes integral electrodes 14, 16 and is opti-
`mized for monitoring ECG signals for a patient having
`neither pacemaker nor ICDM (e.g. the required cardi-
`ography bandwidth for a cardiac patient with a pace-
`maker is somewhat wider than for one without because
`finer ECG data resolution is desired).
`For detection of the relatively fast pacemaker-pro-
`duced and/or ICDM-produced pulses, the hardware
`and digital filters might be bypassed, e.g. by a jumper
`wire or programmable gate, and a hardware pacer or
`ICDM pulse detector circuit (similar to that described
`in our US. Pat. No. 5,012,814) used to produce a trigger
`signal the duration of which is analyzed by microcon-
`troller 42 of apparatus 10 for “marking” the time-
`associated ECG data record. In both of these alterna-
`tive embodiments, the pulse detection circuitry is inte-
`grated preferably within analog chip 64 and there is
`provided in connection with housing 12 a miniature
`external jack to accommodate external electrodes (e.g.
`for a two conductor miniature phono plug). Such even
`further increases the functional density of apparatus 10.
`It will be appreciated that, in the case of pacemaker-
`produced pulse detection,
`typically the input signal
`would need to be amplified, e.g. by preferably approxi-
`mately lOOX, prior to being characterized in accor-
`dance with th