Introduction to Electrocardiography P. Strumillo

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1 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, Łódź, tel. (042)

2 2 electron - kardia - grapho amber - heart - write The Bakken

3 Electrophysiology the beginning 3 Frog leg moves after stimulating it with an electrical pulse Luigi Galvani ( )

Electrophysiology the beginning 4 Alessandro

heart Emil Reymond is the first to use action

4 Electrophysiology the beginning 4 Alessandro Volta ( ) 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)

5 Electrocardiography the beginning 5 The Bekken D.Waller ( ) and his ECG recorder from 1887

6 Cell membrane The resting (polarized) cell Cell resting potential -90mV Na + 1 K + 1 Na + 10 K + Voltmeter

7 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 +

8 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 +

9 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

10 Tissue depolarization mv Voltmeter Deplolarization wavefront but we do not have access to cardiac cells Single cardiac cell

11 Tissue depolarization Voltmeter 3 mv Surface electrode Body volume

12 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

13 Example ECG recording 13

14 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

15 Generation of ECG cycle 15 Atria Diastole Systole Diastole Chambers Diastole Systole Diastole Activation of the sinus node Depolarization of the atria

16 Generation of ECG cycle 16 Atria Diastole Systole Diastole Chambers Diastole Systole Diastole Activation of the atrioventricular node Activation of the atria

17 Generation of ECG cycle 17 Atria Diastole Systole Diastole Chambers Diastole Systole Diastole Activation of the atrioventricular node Bundle of His activation

18 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

19 Generation of ECG cycle 19 Atria Diastole Systole Diastole Chambers Diastole Systole Diastole Repolarization of ventricle muscles Depolarization of ventricle muscles

20 The cardiac oscillators 20 Autonomous oscillators ferequency 70 /min 40 /min 20 /min Sinus node Atrioventricular node Purkinje fibres

21 The cardiac oscillators 21 Sinus node oscillator Atrioventricular node oscillator Oscillator cycle Purkinje fibres Oscillator cycle

22 ECG waveforms 22 R 0.1s T 1mV P Q S Izoelectric line

23 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

24 Willem Einthoven ( ) the father of modern electrocardiography 24 Einthoven Foundation

25 Einthoven s string galvanometer 25 Einthoven Foundation

26 First Einthoven s recordings 26 ~1 mv Einthoven Foundation

27 First Einthoven s recordings Nobel Prize in 1924, for explaining the mechanism of electrocardiogram

28 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

29 I 29 Izopotential lines II III +1 Electric field lines + + Electric dipole

30 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

31 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

32 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

33 ECG graph paper 33

34 ECG intervals and segments 34 See also :

35 12 lead ECG plot example 35 QTc QT RR sec - QT interval corrected for the heart rate (normal range <0.3, 0.44> )

36 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

37 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!

38 Amplitude [mv] Amplitude [mv] Powerline interferences Common signal ms Time [ms] Difference signal a) Time [s] 500ms

39 amplitude [mv] Amplitude [mv] Common signal Powerline interferences Amplitude ok. 150mV 20ms Time [ms] Difference signal a) Amplitude 1-5mV Time [s] 500ms

40 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

41 Active right leg electrode P. Strumillo, P. Romaniuk: 41 * V out _ By using an active right leg electrode one can minimise powerline interferences

42 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!

43 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 technical standard for the safety of medical electrical devices IEC - International Electrotechnical Commission

44 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

45 ECG recorder - inside P. Strumillo, P. Romaniuk: Medical electronics 45 ku = High-pass filter Low-pass filter ADC ku = Galvanic isolation

46 amplitude [mv] amplitude [mv] amplitude [mv] Artefacts and noise in ECGs Power line noise time [s] 0.6 Muscle activity noise time [s] time [s] Base line wander

amplitude amplitude Wavelet-based ECG filtering 47 1.5 1 0.

47 amplitude amplitude Wavelet-based ECG filtering Noisy signal Filtered signal czas czas dr P. Romaniuk Cooperation with Institute of Cardiology Stwierdzono poprawę jakości sygnału potwierdzoną przez kardiologów

48 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)

49 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

50 Electrical model of cardiac tissue 50 Normal rhythm

51 Myocardial infarction heart attack 51 Heartpoint heart attacks in Poland yearly! Ichaemic region

52 Electrical model of cardiac tissue 52 Ventricur fibrillation

53 MIT-BIH Explorer demo 53

54 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 Analog ECG

55 Multilead ECG very many cables 55 Schiller CNSystems

56 Wireless ECG recording 56 Base station ranseiver Patient transeiver Disposable electrodes System LifeSync ECG

58 Implanted defibrillator J 36 cm 3

59 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

60 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

61 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, Łódź, tel. (042)

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