Please meet outside ‘Hippocrates room’ of

Directions to DSO building for LSM3212 – ECG practical

DSO (Kent Ridge) BuildingDMERI@DSO

DSO building. To get there, go to level 2 of MD9 and cross the link bridge between MD9 and the DSO building. DO NOT come through the main entrance of the DSO buildingDMERI@DSO

27 Medical Drive, Singapore 117510

the main entrance of the DSO building.

LSM 3212 Electrocardiogram (ECG)g ( )DSO building (16th February, 2011)

Assistant Professor TRAN ThaiLung Disease Research LaboratoryLung Disease Research Laboratory

Department of Physiology, MD9, level 4National University of Singapore

( h tt@ d )(phstt@nus.edu.sg)

Objecti esObjectives

• Understand the relationship between heart rate response and exercise intensityresponse and exercise intensity.

B bl t d t i ECG d• Be able to determine common ECG waves and intervals.

• Be able to calculate heart rate using ECGBe able to calculate heart rate using ECG recordings.

• Experience placing leads for 12-lead ECG.

AssessmentAssessment

• Mini Quiz constitutes 5% of overall year mark

Li Jiawei, Feng Tianwei & Wang YueguNg Rainer, Boy’s 50m Backstroke, Silver

The dual application of Sports ScienceBiomechanics Ex cis Ph si l Sp t Ps ch lBiomechanics Exercise Physiology Sport Psychology

Motor Learning Growth and Development

The importance of Pre-Exercise Screening

Screening for any pre-existing health conditionshealth conditions

The importance of Pre-Exercise Screening

Graded Exercise Testing (GXT)Graded Exercise Testing (GXT)

• Process of imposing stress• Process of imposing stress in the heart to induce a responseresponse.

• Useful for:diagnosis of heart disease– diagnosis of heart disease

– assessment of aerobic fitness

• Exercise protocol used is• Exercise protocol used is dependent on purpose of the test and profile of testthe test and profile of test population.

Clinical cases are done• Clinical cases are done under medical supervision

Lab Activity 1: Graded Exercise TestingLab Activity 1: Graded Exercise Testing

Pl l d bj t• Place leads on subject.• Resting 1 min: _____bpm• Resting 2 min: bpm• Subject gets on cycle

ergometer.h i ht f l t i

• Resting 2 min: _____bpm• Resting 3 min: _____bpm• 25W: bpm

– height of cycle ergometer is adjusted so that there is a 15o to 20o bend at the

_____ p• 50W: _____bpm• 75W: _____bpm

knees at full extension.

H k ECG l d t

• 100W: _____bpm• 125W: _____bpm

R 1 i b• Hook-up ECG leads to monitor.

• Recovery 1 min: _____bpm• Recovery 2 min: _____bpm• Recovery 3 min: bpm

• Record heart rate at rest, exercise and recovery

Recovery 3 min: _____bpm• Recovery 4 min: _____bpm• Recovery 5 min: _____bpmexercise and recovery. y _____ p

Exercise 1Calculation of Maximum Heart Rate (MHR)

HRX 100%( (

MHR%MHR = MHR = 220 - Age ( (

MHR

HRX 100%( (

220 - Age%MHR =

A 20 E i HR t 75W 95 b

Example MHR = 220 – 20 = 200bpm

Age 20; Exercise HR at 75W = 95 bpm

95X 100% = 47.5% ( (

%MHR = 200

Electrocardiogram = ECGThe ECG is a graphical representation of the heart’s electrical activity.

R

QRS complex

R

P T

Q

P

QS

V t i lV t i l d l i tiAt i l Ventricle repolarization

Ventricle depolarization (& atrial repolarization)

Atrial depolarization

Representative heart conditions detectable through electrocardiography

C l l ti f H t R t f ECG t iExercise 2

RR

Calculation of Heart Rate from ECG tracings

RR interval

V

RR

V)

1 x 5mm Square

1mV

0.1m

V

0.2sec

Q

P T

Q

P T

Vo

ltag

e (m

V

0.2sec

QS

QS Time (sec)

V

Speed of recording = 25 mm/sec (or 1mm/0.04sec)

0.04sec

Heart Rate from ECG tracings =300

Number of 5mm squares in an RR interval Heart Rate from ECG tracings =

Eg: if there are 2.5 (5mm) squares between 2 R waves, then the HR would beHR = 300/2.5 = 120bpm

Lab Activity 2: Placement of ECG leadsy

There are 12 such leads in a regular 12 lead ECG, each of which analyze a different plane of the heart and are therefore useful in diagnosing differentdifferent plane of the heart and are therefore useful in diagnosing different conditions and localizing disease.

BIPOLAR l d

1) Limb leads (Bipolar)

BIPOLAR leads: Have a single (+) and a single (-) electrode between which electrical Three types of ECG leads:

1) Limb leads (Bipolar)2) Augmented limb leads (Unipolar)3) Chest leads (Unipolar)

potentials are measuredTWO electrodes are used to record a lead

UNIPOLAR leads: Have a single (+) electrode and uses a combination of the other electrodes to serve as a composite (-) electrode.ONE electrode is used to recordEach lead records from a

diff t l ( i i t)different angle (viewpoint) provides different view of the

same cardiac activity

Leads: LIMB & AUGMENTED LIMB

LIMB LEADS (Bipolar)

Records the difference in

RA LA

Records the difference in potential between two electrodes.RL = serves as a ground

d i t d fand is not used for recording.

RL LL

AUGMENTED LIMB LEADS (Unipolar)AVR = Right arm (+)AVL = Left arm (+)AVF = Foot – Left (+)

AV A t d V lt

Records the potential reaching one

AV = Augmented Voltage

p gelectrode (+) in comparison to the rest of the body

Leads: CHEST CHEST LEADS (Unipolar)

Th 6 h l d bThese 6 chest leads may be visualized as lying in the

HORIZONTAL plane (the plane cuts the body into top and

bottom halves)

Leads V1 &V2 orient over the RIGHT side of the heart

Leads V5 & V6 orient over the LEFT side of the heart

Leads V3 &V4 orient over the INTERVENTRICULAR SEPTUM (the right and left branches course through th i t t i l t )the interventricular septum)

Each lead records from a different angle (viewpoint) provides different view of the

same cardiac activitysame cardiac activity