OOppeerraattoorr TTrraaiinniinngg GGuuiiddeeffoorr

CCaarrddiiooffaaxx EECCGG--99002200KK

FFrroomm NNiihhoonn KKoohhddeenn

ECG Recording for Most Mammalsand

Interpretive ECG Analysisfor Dogs and Cats

Veterinary ECG Software Kit QP-992E

AA nnoottee aabboouutt tthhiiss gguuiiddee:: It is intended to be used as a brief overview of the instruments operation andto familiarize you with the basic operations you are likely to require. It is not intended to replace theaccompanying Operators Manual. The Operators Manual should be read in its entirety and referredto for further explanation of the instruments operation.

QQuuiicckk RReeffeerreennccee IInnddeexx

I. Getting Started - An Instrument Overview 1

II. Keypad Overlay 6

III. System Setup Menu 7

IV. Using System Test Menu for Simulated ECG Recordings 10

a. Exercise One: ECG Analysis on Medium Size Dog 11 - 12

b. Exercise Two: ECG Analysis on a Cat 11 - 13

c. Exercise Three: Rhythm Strip Recording 11 - 14

d. Manually Recording ECG Waveforms 15 - 16

e. Manual Mode - Rhythm Strip Recording 15 - 17

f. Lead II (Rhythm Strip) Surgical Monitoring 15 - 18

V. Attaching Electrodes and Performing an ECG Recording 19

VI. Troubleshooting 22

VII. Reference Articles 24

1GGEETTTTIINNGG SSTTAARRTTEEDD Install Battery Charge Battery - (an installed, charged battery is required for AC Power Operation) Install Printer Paper

AC Operation and Battery Operation

AACC PPoowweerr OOppeerraattiioonn::When AC power is supplied, the cardiograph operates on AC power and the ACpower lamp is lit.

CCAAUUTTIIOONNAAllwwaayyss iinnssttaallll tthhee bbaatttteerryy wwhheenn tthhee ccaarrddiiooggrraapphh ooppeerraatteess oonn AACC ppoowweerr.. OOtthheerrwwiissee

ssuuddddeenn ppoowweerr ddoowwnn ooccccuurrss wwhheenn aann eelleeccttrrooddee iiss ddeettaacchheedd dduurriinngg rreeccoorrddiinngg..

BBaatttteerryy PPoowweerr OOppeerraattiioonn::When AC power is not supplied, the cardiograph automatically switches to to bat-tery power operation and the battery operation lamp is lit to indicate the reminingbattery power.The cardiograph can operate at least 60 minutes with a new fullycharged battery.

NNOOTTEE WWhheenn tthhee bbaatttteerryy iiss aallmmoosstt ddiisscchhaarrggeedd aanndd tthhee ppoowweerr iiss ttuurrnneedd oonn,, tthhee CChhaarrggee BBaatttteerryy mmeessssaaggee aappppeeaarrss,, tthhee bbaatttteerryy ooppeerraattiioonn llaammpp bblliinnkkss iinn oorraannggee,, aann aallaarrmm ssoouunnddss aanndd tthhee ccaarrddiiooggrraapphh iimmmmeeddiiaatteellyy ttuurrnnss tthhee ppoowweerr ooffff..

AAuuttoommaattiicc PPoowweerr OOffffOn battery operation, to prevent unwanted battery consumption in battery operation,the cardiograph automatically turns the power off when the Fail message (no electrode is attached to the animal) is displayed on the screen and there is no keyoperation for approximately three minutes. In this case, temporarily changed settingsare lost. If this happens, turn the power back on to use the cardiograph continuously.In AC operation, the backlight turns off.To light the backlight, press any key.

BBaatttteerryy OOppeerraattiioonn TTiimmee

NNOOTTEERReemmaaiinniinngg bbaatttteerryy ppoowweerr cchhaannggeess ddeeppeennddiinngg oonn tthhee ssuurrrroouunnddiinngg

tteemmppeerraattuurree aanndd qquuaalliittyy ooff rreeccoorrddiinngg wwaavveeffoorrmm..

BBaatttteerryy OOppeerraattiioonn LLaammpp AAvvaaiillaabbllee RReeccoorrddiinngg TTiimmeeLit in GREEN Approximately 60 minutesLit in GREEN and ORANGE Approximately 40 minutesLit in ORANGE Approximately 20 minutesBlinking in ORANGE Power will be lost in approximately one minute.

Recharge the battery immediately or operate on AC power.

AC power lamp on

Battery operation lamp on

2IINNSSTTRRUUMMEENNTT OOVVEERRVVIIEEWW

TToopp VViieeww

NNAAMMEE FFUUNNCCTTIIOONN1. Operation Panel Refer to the next page.2. Magazine (recording paper container) Contains the recording paper.3. Magazine Release Button Press this button to open the magazine

when loading the recording paper.4. LCD Screen Displays ECG waveforms, animal information,

marks and messages.

OOppeerraattiioonn PPaanneell

NNAAMMEE FFUUNNCCTTIIOONN5. Battery Charge Lamp Indicates the battery charge status

LIT - The battery is being chargedBLINKING - The battery is almost fully chargedOFF - The battery is fully chargedNNOOTTEEAAfftteerr cchhaarrggiinngg iiss ccoommpplleettee,, tthhee bbaatttteerryy cchhaarrggee llaammpp wwiillll bblliinnkk.. TThhiiss iiss bbeeccaauussee aa ssmmaallll ccuurrrreennttiiss ssuupppplliieedd ttoo tthhee bbaatttteerryy ((ssuupppplleemmeennttaarryy rreecchhaarrggiinngg)) iinn oorrddeerr ttoo pprreevveenntt sseellff--ddiisscchhaarrggiinnggooff tthhee bbaatttteerryy.. KKeeeepp tthhee ppoowweerr ccoorrdd pplluuggggeedd iinnttoo tthhee AACC oouuttlleett..

6. Battery Operation Lamp During battery operation, indicates the remaining battery power with the color and lighting state. Blinking in orange indicates the battery is almost discharged.

Panel Descriptions

37. AC Power Lamp Lit when AC power is supplied.

8. POWER Key/Lamp Turns the cardiograph on/off.

The cardiograph is turned on.

The cardiograph is turned off.

9. MODE Key Calls up the Main Menu screen.

10. RHYTHM Key/Lamp Starts the rhythm recording in ECG examination.The lamp is lit while waveforms are acquired and recorded.

11. FEED/MARK Key Paper Feeding:Paper with a paper mark (black rectangle) at the bottom of the paper: Feeds the paper until the paper mark is detected.Paper without the mark:Feeds the paper continuously while this key is pressed.Event Mark:In the manual recording mode, you can annotate the ECG waveform by pressing this key. An event mark is recorded.

12. FILTER Key/Lamp Turns the EMG filter on/off.The lamp is lit when the EMG filter is turned on.NOTE:The EMG filter reduces the amplitude of high frequency components which may distort the waveform. Automatic ECG analysis is performed on this possibly distorted waveform.

Refer to section 11 ECAPS 12V ANI-MAL ECG INTERPRETATION PROGRAM.

13. COPY/CAL Key/Lamp Automatic recording mode and rhythm recording mode:Prints any number of copies of the recording results. When copy is available and during printing, the lamp is lit.Manual Recording Mode:Records the calibration waveforms. For external input signals, this key is not operative.

14. START/STOP Key/Lamp Starts or stops recording. During recording, thelamp is lit.

15. POSITION Key/Lamp Selects animal position during examination.Right L (Lying on right side), Sitting, Steral (lying flat on stomach with front paws forward),Standing.

416. F1, F2, F3 Function Keys Correspond to the functions displayed at the bottom of the screen.

17. AGE/SEX Key Selects the animal age zone and sex.

18. CLASSIFICATION Key Selects the animal classification. Large (Dog),Medium (Dog), Small (Dog), Mini (Dog), and Cat.

RRIIGGHHTT SSIIDDEE PPAANNEELL

CCAAUUTTIIOONN

WWhheenn ccoonnnneeccttiinngg tthhee eexxtteerrnnaall iinnssttrruummeenntt ttoo tthhee ccoonnnneeccttoorrss mmaarrkkeedd wwiitthh U,, eennssuurree tthhee eexxtteerrnnaall iinnssttrruummeenntt ccoommpplliieess wwiitthh tthhee IIEECC6600660011--11 ssaaffeettyy ssttaannddaarrdd ffoorr mmeeddiiccaall eeqquuiippmmeenntt oorr CCIISSPPRR 1111 SSeeccoonnddEEddiittiioonn 11999900--0099,, GGrroouupp 11 aanndd CCllaassss BB SSttaannddaarrdd.. WWhheenn eexxtteerrnnaall iinnssttrruummeenntt ddooeess nnoott ccoommppllyy wwiitthheeiitthheerr ooff tthheessee ssttaannddaarrddss,, uussee aa llooccaallllyy aavvaaiillaabbllee mmeeddiiccaall uussee iissoollaattiioonn ttrraannssffoorrmmeerr uunniitt bbeettwweeeenn tthheeeexxtteerrnnaall iinnssttrruummeenntt aanndd tthhee AACC oouuttlleett.. DDoo nnoott uussee tthhee oouuttppuutt ssiiggnnaall ffrroomm tthhee oouuttppuutt ccoonnnneeccttoorr ffoorr aa ssyynncchhrroonniizzaattiioonn ssiiggnnaall ssuucchh aass tthhee ssyynncchhrroonniizzeedd ccaarrddiioovveerrssiioonn ssiiggnnaall.. TThheerree iiss aa ttiimmee ddeellaayy bbeettwweeeenn tthhee iinnppuutt EECCGG ssiiggnnaall aanndd tthhee oouuttppuutt ssiiggnnaall..

NNaammee FFuunnccttiioonn

19. Patient input connector Connects the patient cable.

20. EXT-IN Connector Inputs an analog signal from an external instrument.

21. CRO-OUT Outputs the rhythm lead (lead II) to an external instrument.

22. SIO Connector Connects to other cardiographs and personal computer for RS-232C digital communication.

23. AC Power Cord Socket Connects the power cord to supply AC power to the cardiograph.

24. Battery Compartment Contains the battery.

CCAAUUTTIIOONNAAllwwaayyss iinnssttaallll tthhee bbaatttteerryy wwhheenn tthhee ccaarrddiiooggrraapphh ooppeerraatteess oonn AACC ppoowweerr.. OOtthheerrwwiissee ssuuddddeenn ppoowweerr ddoowwnnooccccuurrss wwhheenn aann eelleeccttrrooddee iiss ddeettaacchheedd dduurriinngg rreeccoorrddiinngg..

25. Equipotential Ground Terminal When the equipotential grounding is required to ensure electrical safety, connect this terminal to the equipotential ground terminal with the ground lead.

!

5EEXXPPLLAANNAATTIIOONN OOFF TTHHEE EECCGG SSCCRREEEENN

1. Selected mode in the Main Menu screen.

2. Animal information display areaAnimal age zone/sex, classification and examination position are displayed. For the default settings, refer to section 3 Changing settings before measurement.

3. Heart RateUpdated every two seconds.

4. QRS Sync MarkBlinks in synchronization with the QRS wave.

5. Electrode Status Display AreaDisplays the error message for electrode detachment and noise.

6. Waveform Display Area

7. Message and Key Function Display AreaDisplays the function of the function keys F1 to F3 and screen message.

6KKEEYYPPAADD OOVVEERRLLAAYY

Purpose: Keys have an assigned numerical value and action/function.F1, F2, F3 keys have their assigned numerical value and the function displayed above them on the display screen.

1. Use the following keys on the operation panel to enter the numbers of the desired setting.Refer to the printed setting list for the current status of all settings. Every setting has a 3 digit number to change the setting.

NNuummeerriicc KKeeyy NNuummeerriicc KKeeyy0 COPY/CAL Key 5 CLASSIFICATION Key1 F1 Function Key 6 MODE Key2 F2 Function Key 7 RHYTHM Key3 F3 Function Key 8 FEED/MARK Key4 AGE/SEX Key 9 FILTER Key

For easy reference, place the provided 9020 program sheet on the operation panel.

To delete the entered number, press the POSITION key.

7SSYYSSTTEEMM SSEETTUUPP MMEENNUUThe system setup menu allows the operator to configure functions and operations to fit particularneeds and situations it is to be used in. A list of options will be printed out bye the instrument at thebeginning of this exercise. Asterisks(*) indicate the current setting in the instrument. All listed functionscan be selections/changes have been completed, the instrument must be turned off and restarted toactivate new settings/changes.Printer operation can be terminated at any point by depressing the Start/Stop key.

SSEETTTTIINNGG UUPP TTHHEE SSYYSSTTEEMM SSEETTUUPP SSCCRREEEENN1. If the power is on, turn it off.

2. Press the POWER key and COPY/CAL key together. Hold the COPY/CAL key until the cardiograph begins to print the list ofsettings.The System Setup screen is displayed.

To stop printing, press the START/STOP key.

NNOOTTEE::IIff yyoouu ccoonnttiinnuuee ttoo hhoolldd tthhee CCOOPPYY//CCAALL kkeeyy wwhhiillee tthhee lliisstt ooff sseettttiinnggss iiss pprriinntteedd,, tthhee ssyysstteemm iinnffoorrmmaattiioonnEErrrroorr 0055 iiss pprriinntteedd aatt tthhee eenndd ooff pprriinnttiinngg.. TThhiiss mmeeaannss tthhaatt tthhee CCOOPPYY//CCAALL kkeeyy wwaass pprreesssseedd ffoorr ttoooo lloonngg..

EEXXEERRCCIISSEE -- CCHHAANNGGIINNGG SSEETTTTIINNGGSS IINN TTHHEE SSYYSSTTEEMM SSEETTUUPP MMEENNUU

1. Change manual recording channels. Select 3 ch + RHYTHM (502). On the displayed System Setup screen, enter setting number and press START/STOP key.

2. From the printed system list, select setting number for turning the QRS SYNC SOUND on (301). On the displayed System Setup screen, enter setting number and press START/STOP key.

3. Verify AC Filter setting is 60 HZ. Active selections are indicated by asterisk (*).

4.Turn Power off. At next power-up, the cardiofax will start with new settings.

502

8System Setup T shold printout : (0000)Recorder setting :Grid recording : On (207)*

To change configuration, press : Off (208)system set number. then press Slow paper speed : 12.5 mm/s (211)START/STOP key. 10 mm/s (212)*Key Explanation0: COPY/CAL Baseline drift suppression : On (214)*1: F1 Off (215)2: F2 High cut filter : 75 Hz (217)3: F3 100 Hz (218)*4: Age/Sex 150 Hz (219)5: Classification EMG suppression : 25 Hz (220)6: MODE 30 Hz (221)*7: RHYTHM AC filter : 50 Hz (222)8: FEED/MARK 60 Hz (223)*9: FILTER Off (224)

Lead selection mode : Limb leads (226)*Cabera leads (227)

Machine Settings Date display format : yyyy/mm/dd (325)QRS sync/pen sound selection :QRS sync sound (301 ) yyyy/mm/dd (326)

Pen sound (302 ) mmm-dd-yyyy (327)*Off (303 )* dd-mmm-yyyy (328)

QRS sync sound volume :1 (min) (304 )* Time display format: 12 hour day (329)*2 (305 ) 24 hour day (330)3 (306 ) Display language : English (334)*4 (max) (307 ) Local language(335)

Alarm sound volume :0 (off) (308 )*Communication settings *1 (min) (309 ) Modem initialize command (401)2 (310 ) ATV1Q0X4S)=ODT3 (311 ) Telephone number : (402)4 (max) (312 )

Time sound volume :0 (off) (313 )* Direct/modem connection:Direct (403)*1 (min) (314 ) Modem (404)2 (315 )3 (316 )4 (max) (317 )

Date and Time :Year (318yyyy)Month and Date (319mmdd)Hour and Minute (320hhmm)Set (322 )

Baud rate (bps) :2400 (405) Power on4800 (406) EMG Suppression :On (901)*9600 (407)* Off (902)19200 (408) Sex :M (903)*38400 (409) F (904)57600 (410) Space (905)115200 (411) Age :0 (916)

After receiving :Save (412)* 1+ (917)*Print (413) System set printing (999)Save and Print(414)

**********System Information**********Manual recording

Recording channels :3 ch (501)*3 ch + rhythm (502)6 ch (503) Error number: 05

COPY/CALAuto recording

Auto feed after recording :On (529)*Off (530)

Auto file save :On (531)Off (532)* Date: Jul 18, 2001 7:23 PM

Include reason :On (607)Off (608)* Program: 9020KV

Measurement Table :On (612)Off (613)* Version: 01-04 01-02 01-02

**********Error History**********

No. 1 Error number: 27

9UUSSIINNGG TTHHEE SSYYSSTTEEMM TTEESSTT MMEENNUU FFOORR SSIIMMUULLAATTEEDD EECCGG RREECCOORRDDIINNGGSS

By accessing the System Test Menu you can use the Demonstration Mode of operation to familiarizeyourself with the instruments many features.The resulting simulated canine tracing enables user tofamiliarize oneself with basic operation without involving use of an animal. All instrument functionsare active.

To access the System Test Mode:1. With the power off, PRESS BOTH POWER key and #8 (PAPER FEED) keys simultaneously.

Hold down until printer starts to print, then release both.2. From printed menu, select Demonstration Code (00) and enter setting number.3. Press START/STOP key.4. Review screen-recorder should be in AUTO MODE (Upper left corner)

System TestTest Level 1 Input unit test result

1: Demonstration (00)To check system, press system Recorder (01) RF (RL) Normaltest number. then press Key (02) R (RA) NormalSTART/STOP key. Memory (03) L (LA) Normal

2: LCD/LED (04) F (LL) NormalTo quit the test, press Reccumb. Input unit (05) C1 Error key Calibration (06) C2 Error

Communication (07) C3 ErrorKey Explanation CRO/EXT1 (08) C4 Error0: COPY/CAL System Setup Initialization (10) C5 Error1: F1 ECG Findings List Recording (11) C6 Error2: F23: F34: Age/Sex5: Classification6: MODE7: RHYTHM8: FEED/MARK9: FILTER

10

CCAALLLLIINNGG UUPP TTHHEE TTEESSTT LLEEVVEELL 221.If the power is on, turn it off

NNOOTTEERReelleeaassee tthhee FFEEEEDD//MMAARRKK kkeeyy iimmmmeeddiiaatteellyy aafftteerr tthhee iinnssttrruummeenntt ssttaarrttss pprriinnttiinngg.. IIff yyoouu ccoonnttiinnuuee ttoo hhoolldd tthhee FFEEEEDD//MMAARRKK kkeeyy ffoorr mmoorree tthhaann 1155 sseeccoonnddss,, tthhee iinnssttrruummeenntt rreeccooggnniizzeess tthhaatt tthhee FFEEEEDD//MMAARRKK kkeeyy iiss sshhoorrtt--cciirrccuuiitteedd aanndd pprriinnttss tthhee ssyysstteemm iinnffoorrmmaattiioonn EErrrroorr 0055 aatt tthhee eenndd ooff pprriinnttiinngg..

2. Press the POWER key while pressing the FEED/MARK and EXAMPOSITION keys together. Hold the FEED/MARK and EXAM POSITIONkeys until the instrument begins to print the system test procedure,relationship between the input number and its corresponding key nameon the operation panel and system test number list as shown below.The Test Level 2 is called up and the instrument is in standby mode for entering the system test number (The System Test screen appears for the ECG-9020K only as shown below.)

To cancel printing the following information, press the START/STOP key.

The only difference between the ECG-9010K and ECG-9020K printoutsis the description of the key explanation.

Printout (ECG-9020K)System Test Test Level 21: Recorder (00) Cue mark adjustment (-4.0 mm) (13)To check system, press system Thermal head (01) Cue mark adjustment (-3.5 mm) (14)test number, then press Recording resolution setting (02) Cue mark adjustment (-3.0 mm) (15)START/STOP key. Key (03) Cue mark adjustment (-2.5 mm) (16)

2: Memory (single) (04) Cue mark adjustment (-2.0 mm) (17)To quit the test, press Memory (continuous) (05) Cue mark adjustment (-1.5 mm) (18)AUTO/MANUAL key. LCD/LED (06) Cue mark adjustment (-1.0 mm) (19)

Input unit (07) Cue mark adjustment (-0.5 mm) (20)Key Explanation Calibration (08) Cue mark adjustment ( 0 mm) (21)0: COPY/CAL Communication (09) Cue mark adjustment (-0.5 mm) (22)1: F1 CRO/EXT1 (10) Cue mark adjustment (-1.0 mm) (232: F2 System Setup Initialization (12) Cue mark adjustment (-1.5 mm) (24)3: F3 Cue mark adjustment (-2.0 mm) (25)4: AGE Cue mark adjustment (-2.5 mm) (26)5: SEX Cue mark adjustment (-3.0 mm) (27)6: MODE Cue mark adjustment (-3.5 mm) (28)7: RHYTHM System Setup transfer (29)8: FEED/MARK System Setup receiver (30)9: FILTER Reset elapsed time (31)

Download font (32)

System Test Screen (ECG-9020K)

11

EXERCISE ONE

1. Select MMeeddiiuumm DDoogg using the AANNIIMMAALL CCLLAASSSSIIFFIICCAATTIIOONN key2. Select 11 yyeeaarr oolldd, MMaallee using the AAGGEE//SSEEXX key3. Select SSttaannddiinngg PPoossiittiioon using the EEXXAAMM PPOOSSIITTIIOONN key4. Change SSeennssiittiivviittyy setting to 2200 mmmm//mmvv ((FF22 kkeeyy))

(NNOOTTEE:: DDeeffaauulltt sseettttiinngg iiss 1100 mmmm//mmvv)5. Press FF11 key for printout (RReeaall TTiimmee PPrriinnttiinngg Mode)6. Review printout. Note input setting made by operator

(See sample printout on page 12)

EEXXEERRCCIISSEE TTWWOO

1. Select CCaatt using the AANNIIMMAALL CCLLAASSSSIIFFIICCAATTIIOONN key2. Select LLeessss tthhaann 11 yyeeaarr,, ffeemmaallee using the AAGGEE//SSEEXX key3. Select RRiigghhtt LLaatteerraall examination position using EEXXAAMM PPOOSSIITTIIOONN key4. Change SSeennssiittiivviittyy to 2200 mmmm//mmvv using the FF22 key

(NNOOTTEE:: DDeeffaauulltt sseettttiinngg iiss 1100 mmmm//mmvv)5. Turn on the EEMMGG FFIIlltteerr using FFIILLTTEERR ((##99)) key6. Press SSTTAARRTT//SSTTOOPP key to print (RReevviieeww RReeccoorrdd PPrriinnttiinngg Mode)7. Press CCOOPPYY key to make a copy

(See sample printout on page 13)

EEXXEERRCCIISSEE TTHHRREEEE (DVM requests rhythm strip [Lead II])

1. Depress RRHHYYTTHHMM key2. Acquire 3300 sseeccoonnddss elapsed time (waveform acquisition)3. WWaattcchh eellaappsseedd ttiimmee ddiissppllaayyeedd oonn ssccrreeeenn4. AAtt 3300 sseeccoonnddss eellaappsseedd ttiimmee, press RRHHYYTTHHMM key. Acquisition will stop and printout begins. AAnnyy

ttiimmee uupp ttoo 6600 sseeccoonnddss ccaann bbee aaccqquuiirreedd. If left to acquire 60 seconds of elapsed time, printout will occur automatically at 60 seconds.

5. Review recorded rhythm strip. NNOOTTEE:: TTrraaccee ssppeeeedd iiss ffiixxeedd aatt 2255 mmmm//sseecc

(See sample printout on page 14)

12

EEXXEERRCCIISSEE OONNEE(See instructions on page 11)

13

EEXXEERRCCIISSEE TTWWOO(See instructions on page 11)

14

EEXXEERRCCIISSEE TTHHRREEEE(See instructions on page 11)

15

EEXXEERRCCIISSEE FFOOUURR -- MMAANNUUAALL RREECCOORRDDIINNGG

You can manually record the ECG waveform. During recording you can annotate the ECG wave-forms when there is a change in animal condition or artifact. In the manual recording mode, thebaseline is automatically adjusted every time a recording is started, a lead group is selected or asensitivity change is made.The paper trace speed [Slow Paper Speed, 10 mm/sec or 12.5 mm/sec(see System Set-up)] can be selected.

1. Change recorder settings if necessary. (Refer to System Set-up menu)2. Press PPOOWWEERR and ##88 ((PPAAPPEERR FFEEEEDD)) keys simultaneously.3. Enter DDEEMMOONNSSTTRRAATTIIOONN MMOODDEE (00)4. Change mode by depressing MMOODDEE ((##66)) key. From the resulting MAIN MENU screen, select

MMAANNUUAALL RREECCOORRDD using the F2 (NEXT) key followed by the F3 (OK) key. Note change on main menu screen (Upper left corner).

5. Press FF11 key to select first lead Group (I, II, III)6. Select PPAAPPEERR ((TTRRAACCEE)) SSPPEEEEDD using FF33 key. Set to 50 mm/sec. Note: Either 10 mm/sec or

12.5 mm/sec available with the slow paper speed. See System Set-up menu for selection.7. Change SSEENNSSIITTIIVVIITTYY to 20 mm/mv using FF22 key.8. Enter patient parameters if appropriate for later reference. Reminder; interpretation of

waveform will not be made in manual mode.9. Press SSTTAARRTT//SSTTOOPP key to start printout.10. Press SSTTAARRTT//SSTTOOPP key to end printout.

(See sample printout on page 16)

EEXXEERRCCIISSEE FFIIVVEE

AA -- RRHHYYTTHHMM SSTTRRIIPP RREECCOORRDDIINNGG IINN MMAANNUUAALL MMOODDEE

1. Select EExxtteerrnnaall IInn ( Rhythm [II] lead) group using the FF11 key (I, II, III) (AVR, AVL, AVF) p Rhythm [II]

2. Acquire 3300 sseeccoonnddss of (Lead II) Rhythm lead by:a. Press ((##77)) RRHHYYTTHHMM key.b. At elapsed time of 30 seconds, press ((##77)) RRHHYYTTHHMM key again. Note: Will automatically

print 60 seconds of acquired time if no action is taken.c. Review printout. Note heart rate, elapsed time and trace speed (25 mm/sec)

(See sample printout on page 17)

BB -- PPRRIINNTTIINNGG RRHHYYTTHHMM SSTTRRIIPP ((LLEEAADD IIII)) DDUURRIINNGG LLEEAADD IIII MMOONNIITTOORRIINNGG ((SSUURRGGEERRYY))

1. Using the recorder setting from Exercise Four. Press the SSTTAARRTT//SSTTOOPP key. Note: Printer starts printing lead II as seen on recorder screen. Printout is continuous in real time. Recorderdoes not acquire waveform nor show elapsed time.

2. Press SSTTAARRTT//SSTTOOPP key to end printing.3. Review printout. Note that trace speed is as selected on Main Menu screen - NOT as fixed 25

mm/sec.

(See sample printout on page 18)

16

EEXXEERRCCIISSEE FFOOUURR(See instructions on page 15)

17

EEXXEERRCCIISSEE FFIIVVEE ((AA))(See instructions on page 15)

18

EEXXEERRCCIISSEE FFIIVVEE ((BB))(See instructions on page 15)

19

AATTTTAACCHHIINNGG TTHHEE EELLEECCTTRROODDEESS AANNDD PPEERRFFOORRMMIINNGG AANN EECCGG

LLeeaavvee tthhee iinnssttrruummeenntt ttuurrnneedd ooffff uunnttiill tthhee lleeaaddss aarree aattttaacchheedd aanndd tthhee aanniimmaall iiss ccaallmm..

Right lateral recumbency is the standard body position for recording the ECG in the dog and cat. If respiratory distress is evident, the ECG should be recorded with the animal standing or in sternal position.

To obtain the most accurate assessment of the ECG tracing, care needs to be taken toavoid undo stress, and minimize the white coat effect.The animal should be allowed toacclimate to the area. Establishing contact with the animal is important, especially for the person that will be administering the ECG.The area where the recording is to be taken should be quiet and away from the hub-bub of the ongoing practice activities.Owner participation will also minimize anxiety, especially in cats. Excessive restraint is also not desirable. Dogs may be more comfortable on the floor than begin raised to tables. Cats could be left in the owners lap. Use of sedatives and anesthetics is not advisable for diagnostic recordings. If used, their likely affects should be understood and taken into consideration when assessing the interpretations provided.

Attach the electrodes to the skin and moisten with 70% alcohol or ECG gel. When using alcohol, avoid excessive amounts and having alcohol travel between leads.This in effect is the same as having the electrodes touch each other!

20

AATTTTAACCHHIINNGG TTHHEE LLIIMMBB EELLEECCTTRROODDEESS

Attach four limb electrodes to soft muscular, not bony, areas at the limb joints using the followingsteps.

1. Clean the skin with a cotton moistened with alcohol to remove oil.

2. Connect the patient cable to the electrodes.

3. Apply a small amount of 70% alocohol or electrode gel on thecontact surfaces of the electrodes.

4. Clip the cleaned electrode site with the electrode.

PPAATTIIEENNTT CCAABBLLEE TTIIPP CCOOLLOORR CCOOAATTIINNGG

Firmly insert the lead tip of the patient cable to the electrode, matching the tip color and electrodesite. Refer to the table below.

LLEEAADD CCOONNNNEECCTTIIOONNAAHHAA SSTTAANNDDAARRDD

SITE

RIGHT FORE LIMB

LEFT FORE LIMB

RIGHT REAR LIMB

LEFT REAR LIMB

CODE

RA

LA

RL

LL

COLOR

WHITE

BLACK

GREEN

RED

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PPRROOBBLLEEMM SSOOLLVVIINNGG WWIITTHH CCAATTSS

Unlike humans and most dogs, the cardiac axis is not aligned top right to bottom left in cats.Theheart has a tendency to lie more centrally with its apex more ventral than the atria, i.e., the heartpoints downward towards the ground when the animal stands.This gives rise to one of the common problems with monitoring cats, finding the strongest signal topresent to the RA and LL electrodes.

The best signal is derived top/bottom axis i.e. Lead II in humans, with RA looking at the top of theheart and LL at the bottom. In cats, as stated, the axis may not lie across the body. (see figure 1)

As lead II may not align with the cats axis, the signal is small and sometimes cancels.Therefore, bymoving RA more centrally onto the cats body above the top, and LL onto the cats body below thebottom of the heart, a much larger signal will be obtained.

The plane in which the cats heart lies within its body may also vary.

The top of the heart may be more dorsal and the bottom more ventral. In this case, we would referto the base/apex axis (see figure 2) when the following instructions should be followed.

1. Move LL to the left apex of the heart.

2. Move RA to the V10 position (over the dorsal spinous process of the seventh thoracic vertebra) and LL to the V4 position (sixth left intercostal space at the costochondrail junction). It will be necessary to annotate the printouts, if any, with actual configurations used to avoid later confusion.

Figure 1

Figure 2

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TTRROOUUBBLLEESSHHOOOOTTIINNGG

AACC IInntteerrffeerreennccee Appears on the ECG as even-peaked, regular voltages superimposed throughout the tracing. It may appear in conjunction with muscle tremor.

Causes: Dirty or corroded lead wire tips or electrodes Loose electrode connection Patient or technician touching an electrode during recording Patient touching any metal part of a bed or examination table Broken lead wire, patient cable or power cord Electrical devices in the immediate area, lighting, concealed

wiring in walls or floors Improperly grounded electrical outlet

MMuussccllee TTrreemmoorr Appears on the ECG as random, irregular voltages superimposedIInntteerrffeerreennccee ((EEMMGG)) on the tracing. It may resemble or occur in conjunction with AC

interference.

Causes: Patient is uncomfortable, tense, nervous or apprehensive Patient is cold and shivering Patient has neuro or muscular disorder Examination table is too narrow or short to support limbs

comfortably Patient may have white coat effect

See Getting a Quality ECG for suggestions

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WWaannddeerriinngg BBaasseelliinnee Appears on the ECG as a fluctuation of the tracing up and downward on the grid.

Causes: Dirty or corroded electrodes Loose electrodes or electrodes positioned on a bony area Insufficient or dried out Alcohol or Electrode Gel Rising and falling of chest during normal or apprehensive

respiration

When wandering baseline occurs: Clean skin with alcohol or acetone if necessary Reposition electrodes Check the electrode connections Assist the patient in relaxation

OOtthheerr When an electrosurgical unit is used with the cardiograph, noise generated by an ESU is superimposed on the ECG waveforms.

Equipment in the same room as the cardiograph may generate noise which is superimposed on the ECG waveforms. Noise generated by an electrosurgical unit Noise from AC power line Spike noise caused by electrostatic energy as shown below

..

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So you are a veterinary technician and you would like tolearn how to interpret electrocardiograms (ECGs). Great idea!What is reasonable to expect of yourself? Even veterinarianscan be somewhat daunted by all those squiggly lines.

After 20 years as a technician in the cardiology section of theVeterinary College at the University of Minnesota, I can testifythat learning to read ECGs is fun, well within your grasp, andcan be a tremendously satisfying skill to have tucked underyour belt.

You can master the technique of recording an ECG as well aslearning the fundamentals of arrhythmia interpretation.Although, measuring the ECG to assess heart chamber enlarge-ment is certainly not beyond your skill level, it can be a tediousphase of the learning process. The good news is that your vet-erinarian can use other tools, such as radiographs and ultra-sound to determine heart chamber size. This allows us to focuson arrythmias which are more fun and require almost no meas-uring. Recording the ECG

The ECG can be recorded with the patient right side down orin a standing position with any standard ECG strip chartrecorder.1. Attach the electrode clips directly to the skin (taking care toattach the correct electrodes to the appropriate limbs) and mois-ten with alcohol or gel to assure good contact.2. Enter a 1 cm = 1 m V calibration signal.3. Record lead II for about a minute at 25 mm/sec to assessarrythmias. Increase the length of the tracing if an arrhythmia isseen. If you are determined to measure waveforms as well,record a brief tracing at 50 mm/second.

Its helpful to center the tracing on the paper so that both thetop and bottom of the waveforms can be seen. Also, decreasethe sensitivity to 1/2 cm = 1 mV if the QRS complexes go offthe paper.The Normal ECG

Next on the agenda is learning what a normal ECG looks like- and why.

You probably already know all the anatomy you need. Theheart has four chambers: two atria and two ventricles. They areconnected by a conduction system that spreads an electricalcurrent that enables the heart to contract. The ECG is simply agraphic recording of this electrical activity during the differentphases of the cardiac cycle.

Read Between the LinesLearning to interpret electrocardiograms will prove invaluable to your patients and practiceBy: Naomi L. Burtnick, MT (ASCP)

The normal sequence of electrical activation in the heart is asfollows:1. Sinoatrial (SA) node - located in the right atrium.2. Atrioventricular (AV) node - conduction link between theatria and ventricles.3. Left and right bundle branches - located in the left and rightventricles.

The following waveforms are part of a single heart beatP wave - corresponds to atrial contractionPR interval - corresponds to the time it takes for the impulse topass through the AV nodeQRS waves - correspond to ventricular contractionQ is the first negative deflection.R is the first positive deflection.S is the negative deflection that follows the S wave.

Note: Not all QRS complexes have a Q and an R and an S.Thats OK.T wave - represents ventricular relaxation. T waves can be posi-tive or negative, but every QRS complex has to have one. If itcontracts it has to relax before it can contract again.

Calculating the Heart RateThe heart rate (beats/min) can be calculated easily by count-

ing the number of beats (R-R intervals) between two sets ofmarks in the margin of the ECG paper (3 seconds at 25mm/sec) and multiplying by 20. ECG rulers are also available.this is all the measuring thats necessary.

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Recognizing ArrythmiasThis is where you will be of most help to you patient and the

staff at your clinic. Think how much more interesting your jobwill be if you watch a monitor during a surgery; you can beresponsible for alerting the doctor if abnormal beats occur.

To recognize arrythmias you need to know two things:1. The site of origin of the abnormal beat.2. Recognize deviations from the normal rate of automaticityfor that site.Site of Origin

Three different sites can be identified on lead II by the following features:

Atrial origin - These beats originate from nowhere in the atria other than the SA mode. They look just like a normally conducted beat except that their timing is very early. A big hint is that the P wave of the atrial beat touches the T wave of the beat before it.

Junctional origin - These beats originate near the AV node and have a negative deflection P wave, or no P wave, with a normally conducted, short duration QRS complex.

Ventricular origin - These beats originate somewhere in the ventricles. No P waves are evident. QRS complexes arewide and bizarre appearing

and may be positive or negative polarity.

Intrinsic Rates of AutomaticityAtrial, junctional and ventricular sites each have a normal rate

of automaticity (the ability to initiate impulses), buy mayrespond in the following abnormal ways:Too fast (tachycardia) Too irritable (premature)Too slow (bradycardia) Absent (block)Normal pacemaker rates in the dog:

A great rule of thumb: Whichever site is fastest will drive theheart.

A Case ExampleHeres an example to get you thinking along these lines. a 7-

year-old male boxer lethargically walks into the exam roomwith a history of exercise intolerance. You run a lead II rhythmstrip that looks like the following:

How are we going to analyze it? Scanning from left to rightyou see a P wave, PR interval, R wave (its OK for a QRS com-plex not to have a Q an R and an S) and a negative T wave. Inother words, a normally conducted heat, which is followed bytwo more normally conducted heats. The fourth beat has alarge, wide QRS complex with a big negative T wave. Whatsite do you think it originates from? It cant be atrial becausethere is no P wave. It cant be junctional (near the AV node)because its too wide and sloppy looking and junctional beatsshould be of normal duration. But it definitely fits the criteriafor a ventricular origin beat! To further describe it we also usethe term premature because it comes before the next expectednormal beat. Next, are four more normally conducted beats fol-lowed by another VPC (ventricular premature contraction).Wouldnt it be nice if they all came labeled! Can you spot thenext VPC on the strip?

This strip is recorded from the same dog one hour later. Asyou can see, there are five normally conducted beats followedby a long run of ventricular origin beats.

We have already decided the site of origin. the next step is todecide if this an appropriate rate for that site. Heres a chance topractice the technique for calculating heart rate. Countingbetween the markers (3 seconds at 25mm/second) we have 15beats. If we multiply by 20 we will have the number of beats in60 seconds. therefore, 20 x 15 = 300 beats per minute. Thatsway above the normal healthy ventricular conduction tissue rateof 20-40 beats per minute indicated on the illustration of nor-mal pacemaker rates in the dog. Now we want to apply the termtachycardia to imply that the rate is too fast for that particu-lar site. Ventricular premature contractions and ventriculartachycardia are a significant finding in boxers. This breed ispredisposed to a form of dilated cardiomyopathy which haslife-threatening arrythmias.A Second Case Example

A middle aged female miniature schnauzer faints while walk-ing into the exam room, then gets up as if nothing happened.The ECG you run looks like this:

Clearly, that long flat line is not normal. But how do we decidewhat site in the heart is creating the problem? As was men-tioned earlier, in the normal sequence of electrical activation in

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the heart the SA node (the primary pacemaker of the heart)stimulates the atria generating a P wave, the impulse continuesthough the AV node (PR interval) , and down into the ventricles(QRS complex). But in this case, there is no P, PR or QRSwhich implies that the SA node never started the wholesequence or was blocked in the process. Hence, the term SAblock to describe this abnormality. SA block is a feature of aconduction disease called sick sinus syndrome. Surgicallyimplanting an artificial pacemaker will restore almost normalquality of life.

Dont feel pressured to learn everything at once. It will beextremely helpful even if you only learn how to record an ECGwell. Simply recognizing that an abnormal beat has occurredand alerting your veterinarian will be appreciated. The key isrunning lots of ECGs and trying to learn a little more from eachone.

NNaaoommii LL.. BBuurrttnniicckk,, MMTT ((AASSCCPP)) wwoorrkkss aatt VVeetteerriinnaarryySSppeecciiaallttyy RReeffeerrrraall CCeenntteerr,, VVEETTMMEEDD ((DDrr.. TTiilllleeyy &&AAssssoocciiaatteess)),, iinn SSaannttee FFee,, NNMM..

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Some electrocardiographic complexes to emphasize differences in rate, rhythm, and shape.

Normal Sinus Rhythm

Impulses originate at SAnode at normal rate

Sinus Bradycardia

Impulses originate at SAnode at slow rate

Sinus Tachycardia

Impulses originate at SAnode at rapid rate

Sinus Arrhythmia

Impulses originate at SAnode at varying rate

Nonsinus Atrial (Coronary sinus) Rhythm

Impulses originate low inatrium travel retrogradeas well as distally

Normal Sinus Rhythm

Impulses originate at SAnode at normal rate

Variations in P wave con-tour, PR interval, PP, andRR intervals

All complexes evenly spaced; rate 60 to 100 / minute

All complexes normal, evenly spaced; rate 100 / minute

All complexes normal but rhythmically irregular. Longest PP orRR interval exceed shortest by 0.16 second or more

P waves inverted in leads II, III, and a VF

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Some electrocardiographic complexes to emphasize differences in rate, rhythm, and shape.

Idioventricular Rhythm

Accelerated Idioventricular Rhythm (AIVR)

VentricularTachycardia

Ventricular Fibrillation

Pacer Rhythm

Rate < 40 / minute

Rate 40 to 120

Rate > 120

Pacemaker spike

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PP WWaavvee:: the P wave is the first positive deflection and represents atrial depolarization. It normallyappears smoothly rounded and recedes each QRS complex at a specific interval.PP--RR IInntteerrvvaall:: the P-R interval represents impulse conduction through the atria and into the AV node.It extends from the beginning of the P wave to the onset of the Q wave.QQRRSS CCoommpplleexx:: the QRS complex represents ventricular depolarization. It consists of three deflec-tions.The Q-wave is the first negative deflection after the P wave. it results from the initial left-to-rightseptal depolarization. the R wave is the first positive deflection after the P wave.The S wave is thenegative deflection following the R wave.SS--TT IInntteerrvvaall:: the S-T segment extends from the end of the S wave to the beginning of the T wave.T Wave: the T wave represents ventricular repolarization. Normally this wave is positive and symmet-rical, but drugs, change in position, electrolyte imbalance, and food intake may alter the T wave.QQ--TT IInntteerrvvaall:: the Q-T interval extends from the beginning of the QRS complex to the end of the Twave. it represents ventricular depolarization and repolarization.UU WWaavvee:: the U wave is a small positive deflection after the T wave. It reflects repolarization of thePurkinje fibers.This wave is not usually visible on the ECG.

Technical or mechanical problems that are superimposed on the normal P-QRS-T complexes areknown as artifacts. Other equipment in the area that uses electrical current may cause artifacts.Muscle tremor or body movement may also cause artifacts, and efforts should be made to calm theanimal and make it comfortable. It is important to place the electrode clips correctly and hold thelimbs away from the body during right recumbent position to prevent the electrodes from moving withthe thoracic respiratory motions.

IInnddiiccaattiioonnss ffoorr EElleeccttrrooccaarrddiiooggrraapphhyyElectrocardiography is useful in clinical veterinary practice:1. In the definitive diagnosis of cardiac arrythmias.2. As an adjunct to determine cardiac enlargement (dilatation or hypertrophy)3. As an indicator of certain electrolyte, acid-base, systemic, or metabolic disorders.4.To individualize heart failure therapy.

TThhee AAbbnnoorrmmaall EElleeccttrrooccaarrddiiooggrraammThe first and most important step in ECG interpretation is differentiating between normal and abnor-mal waveforms.The second step is differentiating between the various abnormal ECG patterns andcorrelating them with known cardiac entities.

A Simple Checklist:1. Are the P waves present?

a. If not, is there other evidence of atrial activity (fibrillatory waves)?2. What is the relationship between atrial activity and QRS complexes?

a. What are the atrial and ventricular rates?b. Is a P wave related to each QRS complex?c. Does a P wave precede or follow the QRS complex?d. Is the P-R and R-R interval constant?

3. Are the P waves and QRS complexes regular or irregular?4. Are the QRS complexes wide or normal?5. Is the ventricular rhythm regular or irregular?6. Are there pauses or premature complexes that require explanation?

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EElleeccttrrooccaarrddiiooggrraapphhiiccaall SSiiggnnss ooff PPaatthhoollooggiiccaall CChhaannggeess iinn tthhee HHeeaarrttRight atrial enlargementP wave is usually tall, slender, and peaked.

Left atrial enlargementIncreased duration of the P wave, notching of the P wave.

LLeefftt VVeennttrriiccuullaarr EEnnllaarrggeemmeennttAs a result of the increased muscle mass the height of the R wave is increased, the QRS complexis delayed or altered in conduction, the S-T segment is depressed, and the T wave is changed.

CCoonndduuccttiioonn AAbbnnoorrmmaalliittiieessSSiinnooaattrriiaall BBlloocckkSinoatrial (SA) block is a disturbance of conduction in which the SA nodal impulse is blocked fromdepolarizing the atria.Causes: dilatation, fibrosis, cardiomyopathy, drug toxicity, and electrolyte imbalances.ECG: SA block is suggested when pauses in the rhythm are precise multiples of normal R-R inter-vals.The P wave and the QRS complexes are usually of normal configuration.

Figure 4-17 sinoatrial block or arrest in a female miniature schnauzer with syncope. Note the ventric-ular escape complex (arrow).

FFiirrsstt DDeeggrreeee AAVV BBlloocckkA delay or interruption in conduction of a supraventricular impulse through the AV junction and bun-dle of His is called AV block.First-Degree AV block may occur in animals that are clinically normal and healthy.ECG: Prolonged P-R interval, QRS complex and P wave are usually normal.

Figure 4-19: First-Degree and second-degree AV block in a dog with syncope.The P-R interval isprolonged (0.14 second). Every other atrial impulse is conducted (2:1 second-degree block).

SSeeccoonndd--DDeeggrreeee AAVV BBlloocckkSecond-degree Av block is characterized by an intermittent failure or disturbance of AV conduction.The second-degree AV block can further be characterized as Mobitz type I (Wenckebach phenome-non) usually type A and Mobitz type II, usually type B.

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ECG: One or more P waves are not followed by QRS-T complexes.

CCoommpplleettee HHeeaarrtt BBlloocckkComplete heart block occurs when AV conduction is absent and the ventricles are under the controlof pacemakers below the area of the block.Clinical signs associated with complete heart block are syncope, sudden death, and congestiveheart failure.ECG:The ventricular rate is slower than the atrial rate (more P waves than QRS complexes).

Figure 4-21 Complete heart block with an indioventricular escape rhythm (arrows) of 30 beats/min.from a dog with syncope and severe ascites. A cardiac neoplasm was found at necropsy. (Tilley LP:Essentials of Canine and Feline Electrocardiography. 2nd Ed. Lea & Febiger, Philadelphia, 1885.)

AArrrryytthhmmiiaassAn arrhythmia is an abnormality in the rate, regularity, or site of cardiac impulse and/or disturbanceof impulse conduction. during normal sinus rhythm, the cardiac impulse originates in the SA nodeand spreads throughout the atria, AV node and His-Purkinje system, and ventricles.

AArrrryytthhmmiiaass OOrriiggiinnaattiinngg iinn tthhee SSiinnuuss NNooddee SSiinnuuss TTaacchhyyccaarrddiiaaSinus tachycardia is the most common arrhythmia in the dog and the cat. All ECG criteria are nor-mal except that the heart rate is above 160 bpm in the dog and above 240 bpm in the cat.Examples of physiologic conditions associated with sinus tachycardia include pain, fright, or excite-ment. Pathological conditions include fever, shock, anemia, infection, congestive heart failure, hypox-ia, and hyperthyroidism. Drugs that can cause sinus tachycardia include atropine, epinephrine, keta-mine, and vasodilators.

SSiinnuuss BBrraaddyyccaarrddiiaaA regular sinus rhythm slower than the normal sinus heart rate is sinus bradycardia. Sinus bradycar-dia can occur from severe systemic disease (e.g. renal failure), from toxicities, with dilated cardiomy-opathy in the cat, or during end-stage heart failure.Physiologic causes of sinus bradycardia include increased vagal tone due to carotid sinus pressure,eyeball compression, or elevated intracranial pressure.Drug induced causes include tranquilizers, digitalis, quinidine, morphine, and various anestheticagents.ECG criteria are normal except that the heart rate is less than 70 bpm in the dog and less than 160bpm in the cat.

SSiinnuuss AArrrreessttSinus arrest is a failure of SA nodal impulse formation caused by depressed automaticity.ECG:The rhythm can be regular or irregular with pauses demonstrating a lack of P-QRS-T complex-es.

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AArrrryytthhmmiiaass OOrriiggiinnaattiinngg iinn tthhee AAttrriiaall MMuussccllee

AAttrriiaall PPrreemmaattuurree CCoommpplleexxeessAtrial premature complexes arise from ectopic atrial foci.They are frequently caused by cardiac dis-ease and may progress to atrial tachycardia or atrial fibrillation.Atrial premature complexes are often caused by atrial enlargement from acquired chronic valvularinsufficiency, primary myocardial disease, right atrial hemangiosarcoma, hyperthyroidism, digitalis tox-icity, general anesthesia, and various drug, chemical or noxious stimuli.

Figure 4-36 Atrial premature complexes (arrows) and P mitrale in a dog with congestive heart failure.

ECG: Usually normal heart rate, but the rhythm is irregular due to the premature P wave that dis-rupts the normal sinus-initiated P wave rhythm.

AAttrriiaall FFiibbrriillllaattiioonnAtrial fibrillation is common in the dog and is usually associated with severe organic heart disease. itis usually associated with chronic AV valvular insufficiency in small breeds, dilated cardiomyopathyin large and giant breeds, and congenital heart defects.

ECG: Atrial and ventricular rates are rapid an totally irregular. Large oscillations waves replace thenormal sinus P waves.

AArrrryytthhmmiiaass OOrriiggiinnaattiinngg iinn tthhee VVeennttrriiccuullaarr MMuusscclleeVVeennttrriiccuullaarr PPrreemmaattuurree CCoommpplleexxeessVentricular premature complexes (VPCs/PVCs) are impulses that arise from an ectopic ventricularfocus.Cardiac causes of VPCs include congestive heart failure, myocardial infarction, neoplasia, pericardi-tis, traumatic myocarditis, idiopathic myocarditis in boxers and Doberman pinschers, and bacterialendomyocarditis. Secondary changes include changes in autonomic tone, hypoxia, anemia, uremia,pyometra, gastric-volvolus, pancreatitis, and parvovirus. Drugs that can cause VPCs include digitalis,epinephrine, anesthetic agents and atropine.

33

ECG: Heart rate is usually normal. the ectopic QRS complex is premature, bizarre, and often of largeamplitude.The T wave is directed opposite to the QRS deflection. VPCs of identical shape are calledunifocal when the QRS is variable, they are termed multiformed.

VVeennttrriiccuullaarr TTaacchhyyccaarrddiiaaVentricular tachycardia is a continuous series of three or more VPCs.The same conditions thatcause VPCs also cause ventricular tachycardia.

ECG: QRS complexes are wide and bizarre with T waves directed opposite to the QRS deflection.There is no relationship between the QRS complexes and the P waves; the P waves may precede,be hidden within, or follow the QRS complexes.

VVeennttrriiccuullaarr FFiibbrriillllaattiioonnVentricular fibrillation causes cardiac arrest and is often a terminal event. Ventricular contractions areweak and uncoordinated. Cardiac output is essentially nonexistent.

ECG:The heart rate is rapid with irregular chaotic and bizarre waves. P waves cannot be recognized.

34

EEffffeecctt ooff SSeelleecctteedd DDiisseeaasseess oonn tthhee EElleeccttrrooccaarrddiiooggrraammHHyyppeerrkkaalleemmiiaaHyperkalemia is a common clinical problem in cats with urinary tract obstruction. Addisons diseaseis a common cause of hyperkalemia in the dog.ECG Changes:K+>5.5 mEq/l:T waves larger and peaked.K+>6.5 mEq/l: R wave decreased, QRS prolonged, P-R interval prolonged.K+>7.0 mEq/l: P wave amplitude decreased, P wave duration increased, QRS longer, P-R intervallonger, Q-T interval prolonged.K+>8.5 mEq/l: P wave disappearance, atrial standstill, sinoventricular rhythm.K+>10.0 mEq/l: Ventricular fibrillation or ventricular asystole.

Figure 4-30 (A) Hyperkalemia in a dog presenting with hypovolemic shock due to addisonian crisis.P waves are absent and T waves are tall and peaked. Serum potassium was 8.4 mEq?L. (B) Afterinstitution of therapy, P waves are present and the QRS-T complex is of smaller amplitude. Serumpotassium was 4.8 mEq/L. (Tilley LP: Essentials of Canine and Feline Electrocardiography, 2nd Ed.Lea & Febiger, Philadelphia, 1985.)

PPeerriiccaarrddiiaall EEffffuussiioonnECG: Decreased QRS amplitude, S-T segment elevation in lead II and P-R segment depression inlead II.

Figure 4-31 Electrical alternans in a dog with pericardial effusion. Every other R wave alternates inamplitude.