SMI - ISTAalborg University KDN/2004

The ElectrocardiogramECG

SMI - ISTAalborg University KDN/2004

Content

• Heart and Electrocardiography• Recording exersize• Selfstudy using multimedia

SMI - ISTAalborg University KDN/2004

Vital Signs

1. Cardiovascular system2. Respiratory system3. Renal functions4. Central nerveous system5. Fluid, electrolytes and

bloodgas levels

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Vital Signs Monitoring

Observation

Decision

Plan

Patient

Info

diagnosistherapy

data

Diagnostic Therapeutic Cycle

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The Heart and ECG

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The Heart

•Muscle tissue

•Self-pacing

•1/200 * body mass

•4 chamber pump

•Transport O2, CO2• and metabolites

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Circulatory system

•The heart is a four chamber pump divided in twosides.

•Each side has one chamber (atrium) receiving the blood and one (ventricule) pumping the blood away

•The right side receive blood loaded with CO2 from the body to the lungs, and the left side moves blood loaded with O2 from the lungs to the body

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The Heart

Superior cava venaSinuatrial node

Right atriumInferior cava vena

Opening of coronary sinusAtrioventricular node

Interventricular septum

Right bundle branchPapillary muscles with

Purkinje fibers

Left atrium

Atrioventricular bundle (bundle of His)Bifurcation of atrioventricular bundle

Left bundle branchPapillary muscles

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Circulatory system

•The circulatory systems delivers oxygen, nutrients and hormones throughout the body,

•Provides mechanisms for body temperature regulation and removing the heat generated by the metabolic activities

•Diffusion of oxygen, carbon dioxide and others small solutes from cells to capillary and vice-versa

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Circulatory system

•Pulmonary circulation: vessels that lead from and to the lungs

•Systemic circulation: vessels that lead from and to the rest of the body tissues

•Arteries: blood vessels that carry blood way from the heart

•Veins: blood vessels that carry blood towards the heart

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Heart and circulation

1-way valves keep the blood moving in the correct direction during the systole.

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1. Cardiac cells are linked and tightly coupled so that action potentials spread (1 m/s)

2. Cells depolarisation results in contraction in the atria (atrialsystole - move blood in the from right/left atrium to right/left ventricule)

3. The activation wave moves to the atrioventricular node (0.05 m/s) - ventricules are completely filled with blood

4. Then, the activation wave moves to the Purkinje system (specialised conduction tissue) which spreads the wave very rapidly (3 m/s) to many cells in both ventricules resulting in simultaneous contraction of both ventricules (ventricular systole)

PQ

R

S

T

Electrocardiogram (ECG)

SMI - ISTAalborg University KDN/2004

Electrocardiogram (ECG)

The ECG is the electrical measure of the sum of ionic changes in the heart during pumping – it forms a vectorfield.

P

Q

R

S

T

•P: Depolarisation of the atria

•QRS: Depolarisation of the ventricules

•T: Repolarisation of the ventricules

P

Q

R

S

T

T

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ECG

Phases of contraction

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ECG andcirculation

Average Pulse Rates

Adult Males about 72

Adult Females 76 to 80

Newborns up to 140

Children about 90

Elderly 50 to 65

Average Blood Pressure Rates

Systolic 110 to 150 mm Hg

over

Diastolic 60 to 80 mm Hg

Normal Heart Sound S1 and S3Lupp Dupp

Aortic StenosisS1 and S3Lupp Dupp

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Multimedia Tutorial

Blaufuss multimedia www.blaufuss.org

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Measurement of ECG

Einthoven I, II og III

+

- Lead I - measures the potential difference between the right arm electrode and the left arm electrode. The third electrode (left leg) acts as neutral.

Lead II - measures the potential difference between the right arm and left leg electrode.

Lead III - measures the potential difference between the left arm and left leg electrode.

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Normal ECG

20 msec per div

0.1 mV per div

Derivation I ECG

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Normal ECG – Pre Cordial Derivations

Einthoven I isekvivalent withV5 derivation

+

-

Wilson reference scheme

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Non-Normal ECG

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Non-Normal ECG

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Non-Normal ECG

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ECG electrodes

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ECG Instrumentation biomedical applications

Feature

extraction.TransducingPhysiological

dataUser /

Decision

support

Conditioning Sampling

A/D

Classifikation

EEG

EKG

EMG

ENG

EOG

BP

Temp

.

Thresholding

Boolean inference

Fuzzy logic

Neural network

Bayesian net

.

Averaging

Amplitude

Bin integ.

FFT

AR(MA)

Kalman filters

TFA

Single Val. Dec.

Prime Comp. Ana.

.

Resolution

Sampling frequency

Amplification

Filtering

Noise reduction

Safety

Signalprocessing

.

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Bandwidths, Amplitude Ranges, and Quantization of Some Frequently Used Biosignals

Signal Bandwidth Amplitude Quantization(Hz) (range) (bits)

Electroencephalogram 0.2-50 600 µV 4-6

Electrooculogram 0.2-15 10 mV 4-6

Electrocardiogram 0.15-150 10 mV 10-12

Electromyogram 20-8000 10 mV 4-8

Blood pressure 0-60 400 mm Hg 8-10

Spirogram 0-40 10 L 8-10

Phonocardiogram 5-2000 80 dB 8-10

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ECG instrumentation

Gain: 10000.1 – 150Hz

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Normal ECGand

Artefacts

Mains-noise +movements

Loose electrodes +movements

Respiration +EMG

Amplifier saturation

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Normal ECGand bad

instrumentation HF-limitation

LF-limitation

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Noise removal and detection

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0 10 20 30 40 50 60-2000

-1000

0

1000

2000

3000

seconds

Am

plitu

deInputsignal

0 10 20 30 40 50 60-1.5

-1

-0.5

0

0.5

1x 10

5

seconds

Slo

pe

Differentialquotient

MATLAB

» EcgCounting

Number_of_QRS_Complexes =

68

Elapsed_time =

2.4700

Matlab

SMI - ISTAalborg University KDN/2004

Demonstration of ECG recording and vital signs monitoring

ECGSaO2NI-BPTemp

Propaq ICU-monitor