ecg machine training

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HOSPITAL SUPPORT SERVICES

ECG MACHINE

By: Armando Darino Ngojo

16 July 2014 Armando Darino Ngojo

ContentsContentsAims & ObjectivesAims & ObjectivesIntroductionIntroductionHistoryHistoryAnatomy and PhysiologyAnatomy and PhysiologyPrinciplePrincipleApplicationApplicationTypes Of ECG MachineTypes Of ECG MachineOperationOperationSafety PrecautionsSafety PrecautionsTroubleshootingTroubleshooting


AimsTo provide basic understanding on the use of ECG

Machine

To perform and understand the basic user’s troubleshooting steps

Armando Darino Ngojo 316 July 2014

Objectives - as a result of completing this module, the user should be able to:

describe what an ECG Machine is including its applications

perform and identify basic problems, errors and basic troubleshooting solutions.

Perform basic user maintenance

Armando Darino Ngojo 416 July 2014

*Introduction:What is an ECG?

An electrocardiogram or 'ECG' records the electrical activity of the heart. The heart produces tiny electrical impulses which spread through the heart muscle to make the heart contract.

ECG Machine…These impulses can be detected by the ECG

machine. You may have an ECG to help find the cause of symptoms such as palpitations or chest pain. Sometimes it is done as part of routine tests, for example, before you have an operation.

The ECG test is painless and harmless. (The ECG machine records electrical impulses coming from your body - it does not put any electricity into your body

16 July 2014 Armando Darino Ngojo 6

Brief History- Willem Einthoven (a Dutch physiologist; 1860-1927) made the first ECG recording in 1895.

- P, Q, R, S, T waves are also first defined by Willem Einthoven in 1895.

- In 1905, Willem Einthoven recorded ECGs in his laboratory which was located 1.5 km away from the hospital.

- The patient was in the hospital while his ECG was being recorded in the laboratory 1.5 km away.

- Willem Einthoven first published his normal and abnormal ECG recordings in 1906.



Old string galvanometer electrocardiograph showing the big machine with the patient rinsing his extremities in the cylindrical electrodes filled with electrolyte solution.

- In 1924, Willem Einthoven received Nobel prize for his invention of the ECG.

- Goldhammer ve Scherf were the first to suggest the use of exercise ECG for the diagnosis of coronary artery disease in 1932.

- Charles Wolferth ve Francis Wood were the first to report the use of precordial electrodes in 1932.

- In 1942, Emanuel Goldberger adds the augmented limb leads aVR, aVL and aVF to Einthoven's three limb leads and the six chest leads making the 12-lead electrocardiogram that is used today.


Cont… History

Chronology…


Anatomy of the Heart HeartCone shaped ,

muscular organ

Base above and apex below

Inclined at left side

Approx weight- 300gms.


AnatomyHeart is located between the lungs in the middle of chest, behind and slightly to the left of breastbone (sternum)

Heart is a size of ones fist and shaped like a cone.Heart pumps the blood about 5 liters.

16 July 2014 12Armando Darino Ngojo


-In an adult with a healthy heart, the heart rate is usually about 72 beats per minute / bpm-The excitatory and electrical conduction system of the heart is responsible for the contraction and relaxation of the heart muscle. -The heart is divided into four chambers, but it functions as a two sided pump.-Top is the right and left atria-Bottom is the right and left ventricles-The right side of the heart receives and pumps venous blood to the lungs.- The left side of the heart receives (from the lungs) and pumps arterial blood to the body.

Quick facts:

Anatomy

Heart is divided into four chambers

Right AtriumLeft AtriumRight VentricleLeft Ventricle

A wall of muscle called as a 'Septum', separates all chambers of heart.


Anatomy: The Heart Valves Four types of valves regulate blood flow through the heart:The Tricuspid Valve regulates blood flow between the right atrium and right ventricle.The Pulmonary Valve controls blood flow from the right ventricle into the pulmonary arteries, which carry blood to lungs to pick up oxygen.The Mitral Valve lets oxygen-rich blood from lungs pass from the left atrium into the left ventricle.The Aortic Valve opens the way for oxygen-rich blood to pass from the left ventricle into the aorta (body's largest artery), from where it is delivered to the rest of body.


Function Of HeartFunction Of Heart

PUMP THE BLOODPUMP THE BLOODTo receive the pure blood and pump to whole body

Receive impure blood and send to lungs for purification


Cross section of the HeartCross section of the Heart

Pure BloodPure Blood

- - RED COLOURRED COLOUR

Impure bloodImpure blood

- - BLUE BLUE COLOURCOLOUR


Conduction Of the HeartConduction Of the HeartNodes - SA Node

- AV NodeBundle of His

Chordae Tendinea ( AV Valve - Ventricles)

Right & Left Ventricle contraction



- The sinoatrial node (SA node) is the pacemaker where the electrical impulse is generated. This node is located along the posterior wall of the right atrium right beneath the opening of the superior vena cava. It is crescent shaped and about 3 mm wide and 1 cm long. The impulse travels from the SA node through the internodal pathways to the atrioventricular node (AV node).

-The AV node is responsible for conduction of the impulse from the atria to the ventricles. The impulse is delayed slightly at this point to allow complete emptying of the atria before the ventricles contract. The impulse continues through the AV bundle and down the left and right bundle branches of the Purkinje fibers.

- The Purkinje fibers conduct the impulse to all parts of the ventricles, causing contraction (Guyton, 1982).

ECG tracingElectrical pattern

Normal Cardiac Conduction


Principle of ElectrocardiogramElectrocardiogram is an electrical activity

of heart .

The basic principle of the ECG is that stimulation of a muscle alters the electrical potential of the muscle fibers. Cardiac cells, unlike other cells, have a property known as automaticity, which is the capacity to spontaneously initiate impulses. These are then transmitted from cell to cell by gap junctions that connect cardiac cells to each other.1


Cont… Principle


Cont… Principle

The electrical impulses spread through the muscle cells because of changes in ions between intracellular and extracellular fluid. This is referred to as action potential. The primary ions involved are potassium, sodium and calcium.

The action potential is the potential for action created by the balance between electrical charges (positive and negative) of ions on either side of the cell membrane.2


Bio Electric Signal


Bio- Electric Potential

RepolarizationRepolarization

DepolarizationDepolarization

PolarizationPolarization


Cont… Principle

When the cells are in a resting state, the insides are negatively charged compared to the outsides. Membrane pumps act to maintain this electrical polarity (negative charge) of the cardiac cells. Contraction of the heart muscle is triggered by depolarisation, which causes the internal negative charge to be lost transiently.

However, following depolarisation, the cardiac cells return again to their resting charge, known as repolarisation.



-These waves of depolarisation and repolarisation represent an electrical current and can be detected by placing electrodes on the surface of the body.2 After the current has spread from the heart through the body, the changes are picked up by the ECG machine and the activity is recorded on previously sensitised paper. - The ECG is therefore a graphic representation of the electrical activity in the heart. The current is transmitted across the ECG machine at the selected points of contact of the electrode with the body.

Cont… Principle

Bio Electric Signal

Polarization Potassium ions pumped in Sodium ions pumped outDepolarization Potassium ions pumped out Sodium ions pumped in Repolarization Potassium ions pumped in Sodium ions pumped out


Generation of ECGP Wave – Depolarization of Atrium (0.08 to .1 Sec)QRS Wave – Depolarization of Ventricles (0.06 to 0.1 Sec)T wave – Ventricular Re-polarizationST segment - Abnormalities of the ST segment and the T waves are often seen when the heart muscle is ischemic (not getting enough oxygen, cause of a blockage in coronary artery.)



Lets look at how the conduction system related to what we record on the ECG.

P wave: the sequential activation (depolarization) of the right and left atriaQRS complex: right and left ventricular depolarization (normally the ventricles are activated simultaneously)ST-T wave ventricular repolarization U wave: origin for this wave is not clear - but probably represents "afterdepolarizations" in the ventricles

PR interval: time interval from onset of atrial depolarization (P wave) to onset of ventricular depolarization (QRS complex)QRS duration: duration of ventricular muscle depolarizationQT interval: duration of ventricular depolarization and repolarizationRR interval: duration of ventricular cardiac cycle (an indicator of ventricular rate)PP interval: duration of atrial cycle (an indicator of atrial rate)

Normal ECG


12-LEAD ECG LAYOUT


Circulatory SystemCirculatory System

P u lm o na ry C ircu la tion S ys te m ic C ircu la tion

C irculato ry System


Pulmonary CirculationPulmonary CirculationHeart Heart

Right VentricleAortic ValvePulmonary Artery

LungsLungsPulmonary Vein

Right AtriumRight Atrium


Systemic CirculationSystemic CirculationHeart Left

Ventricle

Aorta

Body Upper Part Lower Part


Application of ECG MachineApplication of ECG Machine

Government Hospital CasualtyICU, ICCUWardsCardiac Dept

Private Hospital

General Practitioner


Purpose of ECG Heart Rate Heart Rhythm Analysis of “conduction abnormalities” whether there has been a prior heart attack whether there may be coronary artery disease whether the heart muscle has become

abnormally thickened


Types of ECG MachineTypes of ECG Machine

ECG MACHINEECG MACHINE

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Single ChannelSingle Channel MultichanneMultichannel

InterpretativeInterpretative



Single Channel ECG

Multi-channel ECG

Interpretative ECG

Limitations of ECGThe ECG reveals the heart rate and rhythm only

during the time that the ECG is taken. If intermittent cardiac rhythm abnormalities are present, the ECG is likely to miss them. Ambulatory monitoring is needed to record transient arrhythmias.

The ECG can often be normal or nearly normal in patients with undiagnosed coronary artery disease or other forms of heart disease (false negative results.)

Many “abnormalities” that appear on the ECG turn out to have no medical significance after a thorough evaluation is done (false positive results).


Telltale of HeartTelltale of HeartHolter RecorderHolter Recorder


Other InstrumentsOther InstrumentsStress Test MachineStress Test Machine



Stress Test MachineStress Test Machine

Other InstrumentsOther InstrumentsPacemaker

Internal pacemaker

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External Pacemaker


OperationOperation

Preparation of Patient

Placement of Electrode

Bipolar Lead – I, II, II

Unipolar Lead – aVR, aVL, aVF,

Pre-cordial Lead - V1 to V6


OperationOperationPreparing the patientPreparing the patient

The patient or the person whose ECG is to be taken should be in supine position. Patient limbs, legs and chest should be exposed to fix ECG electrodes.

Clean the portion where electrodes has to be attached. If patient's chest is hairy, shave the portion and clean the area by alcohol swab or spirit, till reddening of skin occurs so as to reduce the skin impedance.

The skin or area where electrodes to be placed should be dry and clean.



Patient position

Operation……contdOperation……contd

Placement of ElectrodesPlacement of Electrodes

Apply Gel on electrodes evenly. Place the limb electrodes to hand (near the

wrist) and legs (near the ankle). The electrodes need to be in proper contact

with the skin at all times to maintain a good reading throughout the ECG monitoring process.

The patient is now ready for the electrode placement. Apply the electrodes and if needed add ECG conductive gel to the electrodes.



Both re-usable and disposable electrodes rely on the electrolyte in the electrodes to make an effective connection between the machines electrode and the patient’s electro-physiological signals. These signals are not picked up just off the surface of the skin, where dead or dry skin, oils and hair all prevent the signals from being detected.The signals are under this surface, and thus we have to prepare the patient so that the electrolyte can reach the signals beneath. This is achieved by:

Removing oil, greasy and dirt from the skins sites with alcohol.

Important notes for patient preparation:


ELECTRODE PLACEMENT

The standard 12-Lead ECG is a collection of tracings of electrical activity occurring in the heart. Each lead provides a tracing, which is characteristic of a different view of the same electrical activity. Other words we take 12 different angles (pictures) of the same activity.

In a standard 12-lead ECG there are 6 limb leads with a three-electrode connection made to the Right arm, Left arm and Left leg. The right leg is also hooked up to the machine but this is your ground lead and does not generate a signal on the ECG.


ECG Leads placement

Limb leads


6 UNIPOLAR LEADS

The chest electrodes are labelled “V” and are numbered from 1 to 6.The placement of these electrodes needs to be exact to give the optimum information as possible. If the electrodes are placed incorrectly on the chest, the tracing will reveal duplication of some information, while other areas will not be represented properly.

Incorrect placement of the electrodes can lead to serious errors of interpretation.

There are six chest leads: V1, V2,V3,V4, V5 and V6.V1 -at the fourth intercostal space, at the right margin of the sternumV2 - at the fourth intercostal space, at the left margin of the sternumV3 - midway between the position of leads V2 and V4 (in a straight line)V4 -at the fifth intercostals space at the junction of the left midclavicular lineV5 - midway between the position of leads V4 and V6 (straight down from the axillary Line on the same horizontal position as V4 and V6 V6 - at the horizontal position of V4, at the left of the midaxillary line.

CHEST LEADS

BASIC CRITICAL VALUES

Bradycardia – HR < 40bpmTachycardia HR > 120bpmPVC’s - 4 or more in a row ST Elevation


Placement of LeadsPlacement of LeadsThe LEAD is used to

measure the resulting tracing of voltage difference at any two sites due to electrical activity of Heart.

There are two types of leads- Bipolar Leads and Unipolar Leads.


Types of LeadsTypes of LeadsBipolar Leads - In Bipolar Leads the ECG is

recorded by using two electrodes and a reference point is conventionally taken as "Right Leg". The three standard bipolar leads are LEAD I, LEAD II, LEAD III. Each of these three leads forms one side of configuration known as “Einthoven's triangle”, as shown below


Einthoven Einthoven TriangleTriangle

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Lead I

Lead IIILead II


Bipolar LeadsBipolar Leads


Unipolar LeadsUnipolar Leads


Pre-cordial LeadPre-cordial LeadIt employs to record potential of Heart

action on chest at six different positions. (designated as V1 to V6)


ECG InterpretationECG Interpretation


Recorded on graph paper.Time is measured across Voltage is measured up and down.Small squares = 1mm high, 0.04 secs wide5 small squares = 1 large square 1 large square is 5mm high and 0.20 sec wide

time

voltage

Colour Code ListColour Code List


Safety - Safety - General Avoid moisture or contact with water,

excessive humidity and temperature. The ECG machine should keep in clean and dry place whenever not in use.

Keep away the ECG machine from any x-ray, Ultrasonic or other electronic instruments.

Use only 3-prong power cord provided with ECG machine.

Clean all the accessories and reusable electrodes, wipe out extra jelly and clean patient cable properly. 6416 July 2014 Armando Darino Ngojo

Safety - Safety - GeneralThe ECG machine which to be tested should be

dry and clean.Check the patient lead wire and cable for any

damage or mishandling, otherwise replace the same immediately.

Recommend using proper size and placement of recording paper.

Clean the print head regularly for clear printout


SafetySafetyBattery :The ECG machine battery should be kept

charging before and after use.Check the battery status regularly or as per

the manufacturer recommendation, otherwise replace the same.

Always install the battery when the ECG machine is used on AC power.

Do not short the battery plus (+) terminal and minus (-) terminal.

If battery is damaged, disassemble or leak, replace immediately.


SafetySafetyElectrical :Check that instrument is grounded properly.ECG machine should have proper grounding to

reduce interference. Attach ground terminal for interference free

ECG. Storage :The prolonged storage under high

temperature, direct sunlight and fluorescent light and excessive humidity may cause the fading of recording result. Which may deteriorate the print head of recorder. Store the recording paper in cool, dry and dark place.


Trouble Shooting - Trouble Shooting - User ChecklistUser ChecklistHOSPITAL : DEPARTMENT:

CHECKLIST PASS FAIL

PHYSICAL CONDITIONS- Panel, keypad, chassis, controls, cables

CLEANLINESS- Are Chassis, Paddles clean?

ACCESSORIES- Are Leads, extension cables, gel pads, recording paper, chest Electrodes present?

POWER UP- No abnormal heat, smell, smoke, electrical shock?

INDICATORS- Is AC Mains, Battery lit?

DISPLAY- Is display well lit and normal?

CONTROLS- Is all keys/controls operating properly?

BATTERY - Is battery fully charged?

ALARM- Is alarm functioning properly?


Trouble Shooting – User ChecklistCHECKLIST PASS FAIL

MONITORCan lead selection and sensitivity be changed?Are HIGH/LOW alarm ranges set?Can QRS volume be adjusted?Is test waveform displayed properly?

RECORDER Is Paper feed working?Is waveform printout is clear and satisfactory?Is date and time printed on paper correctly?

PACER (if applicable) Is Fixed/DEMAND modes get selected and working ?Is rate and intensity setting working properly?


Trouble Shooting

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ERROR MESSAGE DESCRIPTION CORRECTIVE ACTION

No Display Display Blank Check for AC mains.Check contrast for Display.Call Service.

No Power Instrument not switching ON

Check for AC mains.Check power cord.Check for Fuses.Call Service.

Battery? Battery Charge not enough

Battery to be charged.Battery needs replacement.Charging voltage not present.Call Service.

Leads OFF? Leads not connected properly.

Leads not connected properly.Lead contact with patient not good.Leads broken or worn out.Replace ECG / Patient cable



Noise in ECG Waveform No QRS waveform is generated.

Check for lead connection.Check for chest electrode.Check for external interference.

Baseline Drift. Baseline shifted out and waveform is clear.

Check for dry electrodes. Replace the electrodes.Check leads.Check for patient movements.

No ECG print on paper No print on paper Check for sides on thermal paper.Change the paper.

ERROR MESSAGE DESCRIPTION CORRECTIVE ACTION

Paper Empty? No Paper Replace recording paper.Check for proper placement of paper.Paper sensor faulty.

Trouble Shooting

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SAMPLE PROBLEMS WITH THE ECG

ArtifactElectrical interferenceSomatic tremorWandering baseline


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FIND THE ARTEFACT


Let’s summarize!!!


How do we produce an excellent ECG?

1. Proper skin preparation 2. Correct electrode placement 3. Recognize and know how to correct problems 4. Recognize basic critical values

Questions!!!


THANK YOU


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