Introduction to Electrocardiography P. Strumillo Prezentacja multimedialna współfinansowana przez Unię Europejską w ramach Europejskiego Funduszu Społecznego w projekcie pt. Innowacyjna dydaktyka bez ograniczeń - zintegrowany rozwój Politechniki Łódzkiej - zarządzanie Uczelnią, nowoczesna oferta edukacyjna i wzmacniania zdolności do zatrudniania osób niepełnosprawnych Politechnika Łódzka, ul. Żeromskiego 116, 90-924 Łódź, tel. (042) 631 28 83 www.kapitalludzki.p.lodz.pl
2 electron - kardia - grapho amber - heart - write The Bakken
Electrophysiology the beginning 3 www.geocities.com/bioelectrochemistry/ Frog leg moves after stimulating it with an electrical pulse Luigi Galvani (1737-1798)
Electrophysiology the beginning 4 Alessandro Volta (1745-1827) postulates that electricity can occur only in metals Carlo Matteucci in 1842 shows there are rhythmic biocurrents in frog heart Emil Reymond is the first to use action potential term to connote electrical activation of cells (1848)
Electrocardiography the beginning 5 The Bekken D.Waller (1856-1922) and his ECG recorder from 1887
Cell membrane The resting (polarized) cell Cell resting potential -90mV - + 6 10 Na + 1 K + 1 Na + 10 K + Voltmeter
Depolarization of a cell 7 Electrochemical stimulus (e.g. from other cell) is braking the resting potential balace and cell depolarization sets in K + K + Na + Na + K + Na + Na+ K + K +
Depolarization of a cell 8 Cell action potential K + K + depolarization 20mV repolarization -90mV 2ms Na + Na + K + Na + Na+ for most cells K + K +
Depolarization of a cell 9 Cell action potential K + K + depolarization 20mV repolarization -90mV 200 ms! Na + Na + K + Na + Na+ for cardiac cells K + K + There are more than ten ion channels in myocardiac cells
Tissue depolarization 10 - + 110 mv Voltmeter Deplolarization wavefront but we do not have access to cardiac cells Single cardiac cell
Tissue depolarization 11 - + Voltmeter 3 mv Surface electrode Body volume
Inverse problem of electrocardiography (diagnosis) 12 Diagnosed organ Inverese problem -1 : Y X Medical Diagnosis Signal space : X Y Forward problem Elsevier 2002 Y Cardiac signals and images
Example ECG recording 13
The heart conduction system 14 Sinus node Right atrium Left atrium Atrioventricular node Left bundel branch Right ventricle Left ventricle Bundle of His Purkinje fibres Left bundel branch
Generation of ECG cycle 15 Atria Diastole Systole Diastole Chambers Diastole Systole Diastole Activation of the sinus node Depolarization of the atria
Generation of ECG cycle 16 Atria Diastole Systole Diastole Chambers Diastole Systole Diastole Activation of the atrioventricular node Activation of the atria
Generation of ECG cycle 17 Atria Diastole Systole Diastole Chambers Diastole Systole Diastole Activation of the atrioventricular node Bundle of His activation
Generation of ECG cycle 18 Atria Diastole Systole Diastole Chambers Diastole Systole Diastole Bundle of His activation Activation of Purkinje Fibres Activation of bundle branches
Generation of ECG cycle 19 Atria Diastole Systole Diastole Chambers Diastole Systole Diastole Repolarization of ventricle muscles Depolarization of ventricle muscles
The cardiac oscillators 20 Autonomous oscillators ferequency 70 /min 40 /min 20 /min Sinus node Atrioventricular node Purkinje fibres
The cardiac oscillators 21 Sinus node oscillator Atrioventricular node oscillator Oscillator cycle Purkinje fibres Oscillator cycle
ECG waveforms 22 R 0.1s T 1mV P Q S Izoelectric line
The electrocardiogram 23 ~7500 liters daily! SA node AV node P R 0.1s T 1mV Q S P -R S -T Q -T Izoelectric line
Willem Einthoven (1860-1927) the father of modern electrocardiography 24 Einthoven Foundation
Einthoven s string galvanometer 25 Einthoven Foundation
First Einthoven s recordings 26 ~1 mv Einthoven Foundation
First Einthoven s recordings 27 2003 Nobel Prize in 1924, for explaining the mechanism of electrocardiogram
Izopotential lines The Einthoven triangle (limb leads) 28 Electric field lines Einthoven vector Heart as electrical dipole I III
I 29 Izopotential lines -3-3 + -2-1 II -2-1 +2 +1 III +1 Electric field lines + + Electric dipole
Izopotential lines The Einthoven triangle (limb leads) 30 I = V L V R V Electric field lines Einthoven vector V II = V F V R III = V F V L - III + V F
Augmented limb leads Izopotential lines Augmented limb leads (unipolar leads) 31 avr =V R (V F +V L )/2 avl =V L (V R +V F )/2 Electric field lines Einthoven vector V avf =V F (V R +V L )/2 + avl - R V F R www.cvphysiology.com
Aarhus University Hospital, Denmark Precordial leads 32 V 1 V 2 RV LV V 3 V 4 V 5 V 6 V j = V Vj - V CT, where: j = {1, 2,..., 6} V CT =(V L +V R +V F )/3 V CT
ECG graph paper 33
ECG intervals and segments 34 See also : http://en.ecgpedia.org/wiki/
http://www.youtube.com/watch?v=wncw3vniwai 12 lead ECG plot example 35 QTc QT RR sec - QT interval corrected for the heart rate (normal range <0.3, 0.44> )
ECG recording noise sources 36 ~1-3 mv Electric field Thermal, shot noise (1/f) Magnetic field Frequency characteristics Amplifier Display Skin-electrode potential Ground loops
Interferences magnetic field 37 Electromagnetic induction B s S i = B s The area formed by the lead wires and the body We should minimize this area!
Amplitude [mv] Amplitude [mv] Powerline interferences Common signal 200 100 0-100 20ms 38-200 0 10 20 30 40 50 60 70 80 90 100 Time [ms] Difference signal a) 1 0.5 0-0.5-1 - 1.5 0 0.5 1 1.5 2 2.5 Time [s] 500ms
amplitude [mv] Amplitude [mv] Common signal 200 100 0-100 Powerline interferences Amplitude ok. 150mV 20ms 39-200 0 10 20 30 40 50 60 70 80 90 100 Time [ms] Difference signal a) 1 0.5 0-0.5 Amplitude 1-5mV - 1-1.5 0 0.5 1 1.5 2 2.5 Time [s] 500ms
P. Strumillo, P. Romaniuk: Medical electronics Operational amplifier 40 V + + V out V - _ V out = k u (V + -V - ) + CMRR(V + + V - ) CMRR [ ang.common mode rejection ratio ] CMRR = 10e -5-10e -6
Active right leg electrode P. Strumillo, P. Romaniuk: 41 * V out _ By using an active right leg electrode one can minimise powerline interferences
Safety during medical measurements P. Strumillo, P. Romaniuk: Medical electronics 42 Risks Direct contact of electrical devices with patient s skin Low resistance of electrodes (spacial gel electrodes) risk of device mulfunction Even a faulty medical equipment should be safe for the patient!
Safety during medical measurements P. Strumillo, P. Romaniuk: Medical electronics 43 Regulations maximum admissible current 0.1mA maximum admissible current during device mulfunction 1mA there are special standards the medical equiment must conform to: IEC 60601 technical standard for the safety of medical electrical devices IEC - International Electrotechnical Commission
Safety during medical measurements P. Strumillo, P. Romaniuk: Medical electronics 44 Galvanic isolation - transoptors (for analog and discrete signals) - isolation amplifiers - DC-DC converters (biasing) limiting the current entering the patient s body (resistors in series) small voltages of the power supply (3V, 6V) no current conduction elements the patient can touch
ECG recorder - inside P. Strumillo, P. Romaniuk: Medical electronics 45 ku = 10-20 High-pass filter Low-pass filter ADC ku = 50-100 Galvanic isolation
amplitude [mv] amplitude [mv] amplitude [mv] Artefacts and noise in ECGs 46 0.3 0.2 0.1 0-0.1-0.2-0.3-0.4-0.5 Power line noise 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 time [s] 0.6 Muscle activity noise 0.4 0.2 0-0.2-0.4-0.6-0.8 0 0.5 1 time [s] 1.5 0.4 0.2 0-0.2 0 2 4 6 8 10 time [s] Base line wander
amplitude amplitude Wavelet-based ECG filtering 47 1.5 1 0.5 Noisy signal 1.5 1 0.5 Filtered signal 0 0-0.5 0 0.25 0.5 0.75 czas -0.5 0 0.25 0.5 0.75 czas dr P. Romaniuk Cooperation with Institute of Cardiology Stwierdzono poprawę jakości sygnału potwierdzoną przez kardiologów
Heartbeat abnormalities - arrhythmias Abnormalities in heartbeat are called arrhytmias. 48 Arrhytmias can be classified according to the site of abnormality: Atria (Atrial Flutter, Atral Fibrillation, Abnormal pacemaker Atrio-ventricular (reentant tachycardia, Ventricular (Premature Ventricular Contraction, Ventricular Fibrillation, Ectopic foci Conduction blocks: first degree (in atrium) second degree (between atria and ventricles) third degree (in ventricles, e.g. branch blocks)
Phase plots from ECGs Normal rhythm Ventriclular fibrillation 49 Poincare sections t=40ms t i + t t=70ms t i + t t i t i
Electrical model of cardiac tissue 50 Normal rhythm
Myocardial infarction heart attack 51 Heartpoint 100 000 heart attacks in Poland yearly! Ichaemic region
Electrical model of cardiac tissue 52 Ventricur fibrillation
MIT-BIH Explorer demo 53
Artificial patient system 54 Digital ECG recordings Bit-beat is a device generating analog ECG signals from digital recordings from a database; Useful for testing recording devices and for teaching 100110011010 Analog ECG
Multilead ECG very many cables 55 Schiller CNSystems
Wireless ECG recording 56 Base station ranseiver Patient transeiver Disposable electrodes System LifeSync ECG
Body surface mapping (BSM) 57 2003 CNRG Copyright 2000 Meridian Medical
Implanted defibrillator 58 40 J 36 cm 3
Detection of heartbeat by remote radar 59 Detection of Human Breathing and Heartbeat by Remote Radar S. Ivashov, V. Razevig, A. Sheyko, I.Vasilyev Remote Sensing Laboratory, RUSSIA
Other diagnostic methods in cardiology 60 Echocardiography ACCF Coronarography Aarhus University Hospital MRI Yale University Radioizotope images R. McLeod BSM ECG PZWL Hemodynamics PZWL Fonokardiography
Prezentacja multimedialna współfinansowana przez Unię Europejską w ramach Europejskiego Funduszu Społecznego w projekcie pt. Innowacyjna dydaktyka bez ograniczeń - zintegrowany rozwój Politechniki Łódzkiej - zarządzanie Uczelnią, nowoczesna oferta edukacyjna i wzmacniania zdolności do zatrudniania osób niepełnosprawnych Politechnika Łódzka, ul. Żeromskiego 116, 90-924 Łódź, tel. (042) 631 28 83 www.kapitalludzki.p.lodz.pl