CARDIOLOGY ECG – basic information

Transkript

CARDIOLOGY
ECG – basic information
ČVUT, March 2010
Jan Daněk, BTL
BTL
O společnosti BTL
BTL Holdings Limited
www.btlnet.com
BTL Zdravotnická technika a.s.
www.btl.cz
Medical Technologies CZ a.s.
vývojové centrum BTL
1992 – založení, obor fyzioterapie, česká společnost
1997 – obor kardiologie
1998 – expanze do zahraničí
2005 – obor estetická medicína
2009 – CZ, RO, PL, BG, SK, UK, KZ, IT, IN, PT, CY, GB, US
Cardiology, ECG, ČVUT, March 2010
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BTL
BTL 2010 ve světě
3
BTL
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 produkty
na světový trh – představení na světové výstavě
MEDICA Düsseldorf (www.medica.de).
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BTL – KARDIOLOGIE
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)
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VÝVOJ ZDRAVOTNICKÉ TECHNIKY - EKG
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
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VÝVOJ ZDRAVOTNICKÉ TECHNIKY - EKG
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
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CARDIOLOGY – ECG HISTORY
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
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• 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
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CARDIOLOGY – ECG HISTORY
Willem Einthoven – early ECG device
CARDIOLOGY – ECG SIGNAL
ECG signal & heart
Detail description:
http://en.wikipedia.org/wiki/Ecg#Waves_and_intervals
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CODE 1 / EU
CARDIOLOGY – ECG LEAD SYSTEMS
Electrocardiogram – lead systems
CODE 2 / US
Right Arm
R
Red
RA White
Left Arm
L
Yellow
LA
Black
Left Leg
F
Green
LL
Red
Right Leg
N
Black
RL
Green
Chest 1
C1
White/Red
V1
Brown/Red
Chest 2
C2
White/Yellow
V2
Brown/Yellow
Chest 3
C3
White/Green
V3
Brown/Green
Chest 4
C4
White/Brown
V4
Brown/Blue
Chest 5
C5
White/Black
V5
Brown/Orange
Chest 6
C6
White/Violet
V6
Brown/Violet
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Standard ECG 12-lead system is the group of the
3 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)
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LEADS
ELECTRODES
I
I=L–R
II
II = F – R
III
III = F – L
aVR
aVR = R – (L + F) / 2
aVL
aVL = L – (R + F) / 2
aVF
aVF = F – (L + R) / 2
V1
V1 = C1 – (L + R + F) / 3
V2
V2 = C2 – (L + R + F) / 3
V3
V3 = C3 – (L + R + F) / 3
V4
V4 = C4 – (L + R + F) / 3
V5
V5 = C5 – (L + R + F) / 3
V6
V6 = C6 – (L + R + F) / 3
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Electrocardiogram – Einthoven lead system
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Electrocardiogram – Goldberger lead system
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Electrocardiogram – Wilson lead system
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Electrocardiogram – Wilson lead system
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STANDARD
CABRERA
I
aVL
II
I
III
- aVR
aVR
II
aVL
aVF
aVF
III
Electrocardiogram – Cabrera lead system
The Cabrera leads order makes it easier to visualize
waveform progression in the frontal plane.
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8 electrodes
Electrocardiogram – FRANK lead system
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).
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LEADS
ELECTRODES
I
I=L–R
II
II = F – R
III
III = F – L
aVR
aVR = R – (L + F) / 2
aVR = (III – 2*II) / 2
aVL
aVL = L – (R + F) / 2
aVL = (I – III) / 2
aVF
aVF = F – (L + R) / 2
aVF = (II + III) / 2
V1
V1 = C1 – (L + R + F) / 3
V2
V2 = C2 – (L + R + F) / 3
V3
V3 = C3 – (L + R + F) / 3
V4
V4 = C4 – (L + R + F) / 3
V5
V5 = C5 – (L + R + F) / 3
V6
V6 = C6 – (L + R + F) / 3
I = II – III
(L + R + F) / 3 = “NOISE” = – N
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Electrocardiogram – BTL lead system
Electrocardiograph – BTL lead system
The output meets with requirements of IEC 60601-2-51:2003.
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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
BTL lead system – practical results
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How to reduce noise – 1st possibility
Connect extremity electrodes close to patient body:
It is used mainly for ergometry investigation to reduce
extremity muscles artifacts.
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Calculation of the heart’s electrical axis
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.
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BTL ECG
Internal Design
ČVUT, March 2009
Jan Daněk, BTL
CARDIOLOGY – ECG DESIGN
Electrocardiograph – BTL lead system
The output meets with requirements of IEC 60601-2-51:2003.
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ECG – inputs connection
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ECG – defibrillator protection
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
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ECG – input impedance
Resistor R300 define “ground” potential.
Used amplifier is type J-FET with high impedance input.
Final input impedance ≈ 330MΩ || 220pF
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ECG – input radio filter
1st stage – good ECG cable
2nd stage – low pass filter, band width 12 kHz
(without any influence on the ECG signal)
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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)
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ECG – amplifier
ECG – amplifier 1st differential stage
Used resistors have accuracy 0.1%.
Used capacitor are linear with accuracy 5%.
It guarantees perfect removing of the common signal.
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ECG – high pass filter
High pass filter, according IEC 60601-2-51.
1st order, bandwidth 0.05Hz (3.2 sec)
Used capacitors is linear foil type, accuracy 5%.
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ECG – high pass filter / restart circuit
Activated when you press button RESTART.
Fast discharging of high pass filter.
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Low pass filter, bandwidth 339Hz, 2nd order.
It is last filter in front of A/D converter, reduce signal above
1000Hz (sample frequency is 2000Hz).
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ECG – amplifier 2nd stage / low pass filter
Final frequency response, include response of the ADC and
basic digital filters meets requirements of IEC 60601-2-51.
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ECG amplifier – frequency response
ECG amplifier – phase response
All used filters are designed with the respect
to have linear phase response –
to do not change time parameters of the ECG signal.
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ECG – neutral electrode
Calculation of neutral signal – accuracy resistor 0.1%.
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Compensation of ECG cable.
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Compensation of ECG cable.
Defibrillator protection.
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ECG cable – active shielding
To reduce influence of ECG cable on the ECG signal.
Signal of Neutral Electrode is connected to shielding.
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Detection of disconnected leads – how works
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)
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Pacemaker detection
Bandwidth gate – 159 Hz
>> derivative + integrative element – 47 µs
>> negative part – integrative element 10 ms
>> comparator
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A/D converter
15-bits, 1 kHz / lead, 8 inputs, sensitivity 3.9 µV
Power Filtration:
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ECG block scheme
Stepper
motor
Touch-Panel
+
LCD
073-51SHCPUxxx
CPU BOARD
Main Microprocessor
Watch-Dog
Supply Supervisor
RAM & ROM Memory
Drivers for LCD
Drivers for LED
Sound generator
Power supply for
processor board
1,9V; 3,3V; 5V; 21V
Power supply for CFL
USB
in/out
073-51POWERxxx
POWER SUPPLY BOARD
RS232
in/out
Main switch
Mains
Filter
F1
Mains
Filter
P1
S1
F2
32V
POJ3
external fuse folder
Pulse
power supply
Main transformer
TR2
P2
S2
Battery charger
28V/1A
2n2/250V
Mains inlet
F200
Battery
24V (2x12V)
Power & Communication line
Insulation 4kV, creepage distance 8mm.
Insulation 1.5kV, creepage distance 4mm.
070-51ANALOGxxx
MEASURE INPUT BOARD
ADC
Monitoring Circiuts
Protection Circuits
Interference Filter
Supply Supervisor
Microprocessor
Program Memory
Data Memory
Patient
Intput
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BTL ECG
Implemented filters
ČVUT, March 2009
Jan Daněk, BTL
CARDIOLOGY – ECG FILTERS
ECG Filters – 0.07-80Hz adaptive
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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
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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
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Practical example:
original ECG signal
signal for the control function
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Final filtration (momentary bandwidth):
90Hz
88Hz
12Hz
18Hz
13Hz
18Hz
20Hz
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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 removes
just one – mains frequency –
no damage frequency spectrum.
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ECG Filters – 50/60Hz adaptive
ECG Filters – baseline spline filters
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.
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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.
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ECG Filters – baseline spline filters
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...
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ECG Filters – baseline filters ADS 0.05 – 1.5 Hz
ECG Filters – baseline filters ADS 0.05 – 1.5 Hz
no damage ECG signal
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ECG Filters – muscular filters
The muscular filters removes high frequencies from the
ECG signal
35Hz – acceptable affect on the QRS complex
25Hz – just for rhythm measurements
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ECG Filters – muscular filters
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BTL ECG
Processing of ECG signal
ČVUT, March 2009
Jan Daněk, BTL
CARDIOLOGY – ECG SIGNAL PROCESSING
ECG signal processing
Setting of the user’s filters has no effect
on the measuring and diagnostic interpretation.
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COMPUTING
Beat Computing
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CARDIOLOGY – TYPICAL ECG RECORD
Typical ECG record
3 pages A5, print format 6x2+1 + interpretation
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BTL
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
66
BTL
Další výborné české firmy
LINET, www.linet.com
světový výrobce nemocničních postelí
EGO, www.egozlin.cz
mobilní nemocnice
Beznoska, www.beznoska.com
kloubní náhrady
BMT, www.bmt.cz
vybavení operačních sálů, sterilizace...
Cheirón, www.cheiron.cz
dýchací zařízení a odsávačky krve
BTL, www.btlnet.com

...a další viz www.medica.de
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CARDIOLOGY – LITERATURE
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.
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CARDIOLOGY – CONTACT INFORMATION
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
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Thank you very much
for your attention.
ČVUT, March 2009
Jan Daněk, BTL
[email protected]

CARDIOLOGY ECG – basic information

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