cardiology ecg – basic informationnoel.feld.cvut.cz/vyu/x31let/lectures/05_ekgdanek.pdf ·...

CARDIOLOGY ECG – basic information

ČVUT, March 2010Jan Daněk, BTL

Cardiology, ECG, ČVUT, March 20102

BTL Holdings Limitedwww.btlnet.com

BTL Zdravotnická technika a.s.www.btl.cz

Medical Technologies CZ a.s.vývojové centrum BTL

1992 – založení, obor fyzioterapie, česká společnost1997 – obor kardiologie1998 – expanze do zahraničí2005 – obor estetická medicína2009 – CZ, RO, PL, BG, SK, UK, KZ, IT, IN, PT, CY, GB, US

O společnosti BTL BT

L


BTL 2010 ve světě BT

L


BTL 2010 v Čechách

V České republice:

vývojové oddělení (50 kolegů)

výroba elektroniky a prototypových sérií (35)

zahraniční obchod (18)

domácí obchod pro ČR (35)

servisní oddělení pro ČR a okolní státy (4)

Každý rok uvést nejméně dva / tři nové produktyna světový trh – představení na světové výstavěMEDICA Düsseldorf (www.medica.de).

BT

L


Kardiologie

1997 – počítačové EKG

1998 – spolupráce s firmou Aspel, PL

2001 – 1. vlastní přímopíšicí EKG

2004 – kompletní řada EKG

2006 – začátek spolupráce s firmou Spacelabs

2008 – SW BTL-08 MEW „kardiologické pracoviště“

2009 – SW BTL-08 MEW Spiro

budoucnost? –> být nejlepší!

Schiller Swiss, General Electric, Philips (býv. HP)

BT

L –

KA

RD

IOLO

GIE


Vývoj zdravotnické techniky

Mezinárodní řada norem IEC (www.iec.ch):

IEC 60601-1 (základní norma o bezpečnosti)

IEC 60601-1-2 (EMC, EMI)

IEC 60601-2-25 (EKG bezpečnost)

IEC 60601-2-47 (EKG Holtery)

IEC 60601-2-51 (EKG parametry)

v ČR zastoupen ÚNMZ (www.unmz.cz)

Certifikace v CB systému (www.iecee.org):

v ČR zastoupen EZÚ Praha (www.ezu.cz)

CE značka, FDA schválení, systém jakosti ISO

VÝ

VO

J Z

DR

AV

OT

NIC

KÉ

TE

CH

NIK

Y -

EK

G


EKG – bezpečnost

Tzv. příložná část typu CF, odolná defibrilaci:

unikající proud do pacienta max. 10 µA (NC)

pomocný proud pacientem max. 10 µA (NC)

unikající proud do pacienta max. 50 µA (SFC)

pomocný proud pacientem max. 50 µA (SFC)

NC – Normal Condition, SFC – Single Fault Condition

Pro napájecí napětí 250 Vac:

Rizol > 25 MΩ

Cparasit < 127 pF

VÝ

VO

J Z

DR

AV

OT

NIC

KÉ

TE

CH

NIK

Y -

EK

G


Electrocardiogram - history

It is a record of the electrical activity of the heart over time.

Alexander Muirhead, St Bartholomew's Hospital, London

1st record of the patient’s heartbeat, 1872

Augustus Waller, St Mary's Hospital, Paddington, London

1st electrocardiograph machine, 1887

ECG signal was projected to a wall

Willem Einthoven, Leiden, The Netherlands

1st clinically used machine, 1901 – 1903

signal was recorded on a moving roll of photographic paper

CA

RD

IOLO

GY

–E

CG

HIS

TO

RY


Willem Einthoven – early ECG device

• 1st machine weighted 600 lb / 270 kg and required strong water cooling for powerful electromagnets

• he assigned the letter P, Q, R, S and T to the deflections of the ECG signal

• Nobel Prize 1924 CA

RD

IOLO

GY

–E

CG

HIS

TO

RY


ECG signal & heart

Detail description: http://en.wikipedia.org/wiki/Ecg#Waves_and_intervals

CA

RD

IOLO

GY

–E

CG

SIG

NA

L


Electrocardiogram – lead systems

CA

RD

IOLO

GY

–E

CG

LE

AD

SY

ST

EM

S

Chest 6

Chest 5

Chest 4

Chest 3

Chest 2

Chest 1

Right Leg

Left Leg

Left Arm

Right Arm

Brown/VioletV6White/VioletC6

Brown/OrangeV5White/BlackC5

Brown/BlueV4White/BrownC4

Brown/GreenV3White/GreenC3

Brown/YellowV2White/YellowC2

Brown/RedV1White/RedC1

GreenRLBlackN

RedLLGreenF

BlackLAYellowL

WhiteRARedR

CODE 2 / USCODE 1 / EU



CA

RD

IOLO

GY

–E

CG

LE

AD

SY

ST

EM

S

Standard ECG 12-lead system is the group of the3 systems:

Einthoven bipolar extremity leads – I, II, III

Goldberger unipolar extremity leads – aVR, aVL, aVF

Wilson unipolar chest leads – V1, V2, V3, V4, V5, V6

10 electrodes (9 active / 1 neutral)

(R L F C1 C2 C3 C4 C5 C6 / N)

12 leads

(I II III aVR aVL aVF V1 V2 V3 V4 V5 V6)



CA

RD

IOLO

GY

–E

CG

LE

AD

SY

ST

EM

S

V6 = C6 – (L + R + F) / 3V6

V5 = C5 – (L + R + F) / 3V5

V4 = C4 – (L + R + F) / 3V4

V3 = C3 – (L + R + F) / 3V3

V2 = C2 – (L + R + F) / 3V2

V1 = C1 – (L + R + F) / 3V1

aVF = F – (L + R) / 2aVF

aVL = L – (R + F) / 2aVL

aVR = R – (L + F) / 2aVR

III = F – LIII

II = F – RII

I = L – RI

ELECTRODESLEADS


Electrocardiogram – Einthoven lead system

CA

RD

IOLO

GY

–E

CG

LE

AD

SY

ST

EM

S


Electrocardiogram – Goldberger lead system

CA

RD

IOLO

GY

–E

CG

LE

AD

SY

ST

EM

S


Electrocardiogram – Wilson lead system

CA

RD

IOLO

GY

–E

CG

LE

AD

SY

ST

EM

S



CA

RD

IOLO

GY

–E

CG

LE

AD

SY

ST

EM

S


Electrocardiogram – Cabrera lead system

IIIaVF

aVFaVL

IIaVR

- aVRIII

III

aVLI

CABRERASTANDARD

The Cabrera leads order makes it easier to visualize waveform progression in the frontal plane.

CA

RD

IOLO

GY

–E

CG

LE

AD

SY

ST

EM

S


Electrocardiogram – FRANK lead system

8 electrodes 3 leads

Vx = 0.610 A + 0.171 C – 0.781 I

Vy = 0.655 F + 0.345 M – 1.000 H

Vz = 0.133 A + 0.736 M – 0.264 I– 0.374 E – 0.231 C

Frank lead system is not supported

by ECG diagnostic (Glasgow, BTL).

CA

RD

IOLO

GY

–E

CG

LE

AD

SY

ST

EM

S


Electrocardiogram – BTL lead system

CA

RD

IOLO

GY

–E

CG

LE

AD

SY

ST

EM

S

V6 = C6 – (L + R + F) / 3V6

(L + R + F) / 3 = “NOISE” = – N

V5 = C5 – (L + R + F) / 3V5

V4 = C4 – (L + R + F) / 3V4

V3 = C3 – (L + R + F) / 3V3

V2 = C2 – (L + R + F) / 3V2

V1 = C1 – (L + R + F) / 3V1

aVF = F – (L + R) / 2 aVF = (II + III) / 2aVF

aVL = L – (R + F) / 2 aVL = (I – III) / 2aVL

aVR = R – (L + F) / 2 aVR = (III – 2*II) / 2aVR

III = F – LIII

II = F – RII

I = L – R I = II – IIII

ELECTRODESLEADS


Electrocardiograph – BTL lead system

CA

RD

IOLO

GY

–E

CG

LE

AD

SY

ST

EM

S

The output meets with requirements of IEC 60601-2-51:2003.


BTL lead system – practical results

CA

RD

IOLO

GY

–E

CG

LE

AD

SY

ST

EM

S

Extremity electrode R – wrong contact

I, II, aVR, aVL, aVF leads disappear (III – distorted)

Extremity electrode L – wrong contact

I, III, aVR, aVL, aVF leads disappear (II – distorted)

Extremity electrode F – wrong contact

all extremity leads disappear

other leads can be distorted

Extremity electrode N – wrong contact

all leads disappear or are distorted

Chest electrode Cx – wrong contact

only chest lead Vx disappear

other leads are not affected


How to reduce noise – 1st possibility

CA

RD

IOLO

GY

–E

CG

LE

AD

SY

ST

EM

S

Connect extremity electrodes close to patient body:

It is used mainly for ergometry investigation to reduce extremity muscles artifacts.


Calculation of the heart’s electrical axis

CA

RD

IOLO

GY

–E

CG

LE

AD

SY

ST

EM

S

The heart's electrical axis is usually oriented in a right shoulder to left leg direction, although -30° to +90° is considered to be normal.

BTL ECGInternal Design



Electrocardiograph – BTL lead system

CA

RD

IOLO

GY

–E

CG

DE

SIG

N

The output meets with requirements of IEC 60601-2-51:2003.


ECG – inputs connection

CA

RD

IOLO

GY

–E

CG

DE

SIG

N


ECG – defibrillator protection

CA

RD

IOLO

GY

–E

CG

DE

SIG

N

1st stage – implemented in the ECG cable

2nd stage – on the Analog board in the ECG machine(1st components on the input)

maximal energy of the pulse could be 500 J


ECG – input impedance

CA

RD

IOLO

GY

–E

CG

DE

SIG

N

Resistor R300 define “ground” potential.

Used amplifier is type J-FET with high impedance input.

Final input impedance ≈ 330MΩ || 220pF


ECG – input radio filter

CA

RD

IOLO

GY

–E

CG

DE

SIG

N

1st stage – good ECG cable

2nd stage – low pass filter, band width 12 kHz(without any influence on the ECG signal)


ECG – amplifier

CA

RD

IOLO

GY

–E

CG

DE

SIG

N

1st stage – differential amp. – gain 10, bandwidth 1.59 kHz

2nd stage – gain 22.4, band width 339 Hz, 2nd order(without any influence on the ECG signal)


ECG – amplifier 1st differential stage

CA

RD

IOLO

GY

–E

CG

DE

SIG

N

Used resistors have accuracy 0.1%.

Used capacitor are linear with accuracy 5%.It guarantees perfect removing of the common signal.


ECG – high pass filter

CA

RD

IOLO

GY

–E

CG

DE

SIG

N

High pass filter, according IEC 60601-2-51.

1st order, bandwidth 0.05Hz (3.2 sec)

Used capacitors is linear foil type, accuracy 5%.


ECG – high pass filter / restart circuit

CA

RD

IOLO

GY

–E

CG

DE

SIG

N

Activated when you press button RESTART.

Fast discharging of high pass filter.


ECG – amplifier 2nd stage / low pass filter

CA

RD

IOLO

GY

–E

CG

DE

SIG

N

Low pass filter, bandwidth 339Hz, 2nd order.

It is last filter in front of A/D converter, reduce signal above1000Hz (sample frequency is 2000Hz).


ECG amplifier – frequency response

CA

RD

IOLO

GY

–E

CG

DE

SIG

N

Final frequency response, include response of the ADC and basic digital filters meets requirements of IEC 60601-2-51.


ECG amplifier – phase response

CA

RD

IOLO

GY

–E

CG

DE

SIG

N

All used filters are designed with the respectto have linear phase response –to do not change time parameters of the ECG signal.


ECG – neutral electrode

CA

RD

IOLO

GY

–E

CG

DE

SIG

N

Calculation of neutral signal – accuracy resistor 0.1%.



CA

RD

IOLO

GY

–E

CG

DE

SIG

N


Compensation of ECG cable.



CA

RD

IOLO

GY

–E

CG

DE

SIG

N


Compensation of ECG cable.

Defibrillator protection.


ECG cable – active shielding

CA

RD

IOLO

GY

–E

CG

DE

SIG

N

To reduce influence of ECG cable on the ECG signal.

Signal of Neutral Electrode is connected to shielding.


Detection of disconnected leads – how works

CA

RD

IOLO

GY

–E

CG

DE

SIG

N

1st stage – measuring of DC offset of each lead

2nd stage – amplitude of 50Hz (60Hz) noise signal(it is possible to change the level of the detection)


Pacemaker detection

CA

RD

IOLO

GY

–E

CG

DE

SIG

N

Bandwidth gate – 159 Hz>> derivative + integrative element – 47 µs

>> negative part – integrative element 10 ms>> comparator


A/D converter

15-bits, 1 kHz / lead, 8 inputs, sensitivity 3.9 µV

Power Filtration:

CA

RD

IOLO

GY

–E

CG

DE

SIG

N


ECG block scheme

CA

RD

IOLO

GY

–E

CG

DE

SIG

N

Insulation 4kV, creepage distance 8mm.

Insulation 1.5kV, creepage distance 4mm.

Battery24V (2x12V)

Steppermotor

Touch-Panel+

LCD

Main MicroprocessorWatch-Dog

Supply SupervisorRAM & ROM Memory

Drivers for LCD Drivers for LEDSound generator

Power supply for processor board

1,9V; 3,3V; 5V; 21VPower supply for CFL

073-51SHCPUxxxCPU BOARD

PatientIntput

Supply SupervisorMicroprocessorProgram MemoryData Memory

ADCMonitoring CirciutsProtection CircuitsInterference Filter

Power & Communication line

070-51ANALOGxxxMEASURE INPUT BOARD

P1

P2

S1

S2

Pulse

powe

rsup

ply

MainsFilter

MainsFilter

RS232in/out

USBin/out

32V

Battery charger28V/1A

073-51POWERxxxPOWER SUPPLY BOARD

POJ3external fuse folder

Mains inlet

Main switch

Main transformerTR2

F2

F200

F1

2n2/250V

BTL ECGImplemented filters



ECG Filters – 0.07-80Hz adaptive

CA

RD

IOLO

GY

–E

CG

FIL

TE

RS



CA

RD

IOLO

GY

–E

CG

FIL

TE

RS

The “adaptive” filter was developed according requirements of users

they want to have ECG signal without distortion of QRST complex (amplitude + time parameters)

they want to have smooth curve between QRST complexes (mainly with respect to time parameters)

Similar problem solved by HP / Philips, GE, Schiller

solution – adaptive filter which change parameters according ECG signal

QRST – almost without filtration

T-P-Q – strong filtration



CA

RD

IOLO

GY

–E

CG

FIL

TE

RS

The 0.07-80Hz adaptive filter is combination of these filters:

muscle adaptive filter

mains 50 / 60 Hz adaptive filter

baseline spline filter (ADS cubic).

Muscle adaptive filter:

detects of the dynamic changes of the signal (QRS)

according its chooses between 5 low pass filters

typical bandwidth is 80 Hz



CA

RD

IOLO

GY

–E

CG

FIL

TE

RS

Practical example:

original ECG signal signal for the control function



CA

RD

IOLO

GY

–E

CG

FIL

TE

RS

Final filtration (momentary bandwidth):

88Hz90Hz

18Hz

13Hz

12Hz

20Hz

18Hz


ECG Filters – 50/60Hz adaptive

CA

RD

IOLO

GY

–E

CG

FIL

TE

RS

It is designed as sinus software oscillator which works like phase-loop circuit

searches harmonic mains frequencies in the ECG signal in the range 45 to 65 Hz

when the signal is found starts to subtract the found signal from the original

for quick response is good to set correct starting condition – 50 Hz <> 60 Hz

It has no affect on the ECG signal because it removesjust one – mains frequency –no damage frequency spectrum.


It works with 10 sec strips of ECG signal

looks for “null” points in ECG signal in the middle between P and Q wave(the part with smallest change in the time)

insets a curve in the “null” points

subtract the curve from original ECG signal

The filter use special type of “spline hermit function”.

This type of filter used first GE.

ECG Filters – baseline spline filters

CA

RD

IOLO

GY

–E

CG

FIL

TE

RS


The name of spine filter (cubic – 3rd, square – 2nd, linear –1st order of function) says which curve will be used for connection of the nearby “null” points.

ECG Filters – baseline spline filters

CA

RD

IOLO

GY

–E

CG

FIL

TE

RS


ECG Filters – baseline filters ADS 0.05 – 1.5 Hz

CA

RD

IOLO

GY

–E

CG

FIL

TE

RS

It is a linear simulation of the basic 1st order high pass filter designed in hardware variant by RC elements

linear characteristics (frequency, phase)

but small filtration power

0.05Hz (3.20sec) & 0.10Hz (1.50sec)small influents on the signal

0.25Hz (0.60sec)influents on ST segments

0.50Hz (0.30sec) & 1.50Hz (0.10sec)use just for rhythm measurement (ergometry)damage QRS amplitude, ST segments...


ECG Filters – baseline filters ADS 0.05 – 1.5 Hz

CA

RD

IOLO

GY

–E

CG

FIL

TE

RS

no damage ECG signal


ECG Filters – muscular filters

CA

RD

IOLO

GY

–E

CG

FIL

TE

RS

The muscular filters removes high frequencies from the ECG signal

35Hz – acceptable affect on the QRS complex

25Hz – just for rhythm measurements


ECG Filters – muscular filters

CA

RD

IOLO

GY

–E

CG

FIL

TE

RS

BTL ECGProcessing of ECG signal



ECG signal processing

CA

RD

IOLO

GY

–E

CG

SIG

NA

L P

RO

CE

SS

ING

Setting of the user’s filters has no effecton the measuring and diagnostic interpretation.


Beat Computing

CO

MP

UT

ING


Typical ECG record

CA

RD

IOLO

GY

–T

YP

ICA

L E

CG

RE

CO

RD

3 pages A5, print format 6x2+1 + interpretation


Competitors

Cardiology:

Schiller, www.schiller.ch

Philips, www.medical.philips.com

General Electric, www.gehealthcare.com

Mortara, www.mortara.com

Physiotherapy:

Enraf-Nonius, www.enraf-nonius.com

Gymna-Uniphy, www.gymna-uniphy.com

Chattanooga, www.chattanoogagroup.com

BT

L


Další výborné české firmy

LINET, www.linet.comsvětový výrobce nemocničních postelí

EGO, www.egozlin.czmobilní nemocnice

Beznoska, www.beznoska.comkloubní náhrady

BMT, www.bmt.czvybavení operačních sálů, sterilizace...

Cheirón, www.cheiron.czdýchací zařízení a odsávačky krve

BTL, www.btlnet.com ...a další viz www.medica.de

BT

L


Used literature and sources

http://www.wikipedia.com

http://en.wikipedia.org/wiki/Ecg

http://www.btlnet.com

Jan Havlík, Czech Technical University at Prague.

International Standard IEC 60601-2-51:2003.

Malmivuo, J. – Plonsey, R: Bioelectromagnetism. Oxford University Press, New York, 1995.

BTL marketing and production materials.

GE marketing materials.

PHILIPS / HP marketing materials.

CA

RD

IOLO

GY

–LI

TE

RA

TU

RE


Contact information

Medical Technologies CZ a.s.

Jan Daněk

Development Department

Radimova 36

169 00 Praha 6

Czech Republic

[email protected]

tel. +420 602 163 525

fax +420 270 001 699

www.btlnet.com, www.btl.cz, www.medictech.com

CA

RD

IOLO

GY

–C

ON

TA

CT

IN

FOR

MA

TIO

N

Thank you very muchfor your attention.

ČVUT, March 2009Jan Daněk, [email protected]

cardiology ecg – basic informationnoel.feld.cvut.cz/vyu/x31let/lectures/05_ekgdanek.pdf ·...

Documents