Electrocardiography II Laboratory
Contents
1. ECG Samples Ventricular Bigeminy 1 shun Spectrogram Time Waveform residue F t n trend Az R 5 0E mea raw data R 0 0E mea 1 8E 1 5E 2 1 1E 1 1 3E 2 41 4E 1 3 5E 1 TEA 5 9E 1 7 5EH1 on 5 0E 1 2561 O 0E 0 m 4 3E 2 10000 12000 14 w Ee ooo 18 000 20 000 Spectrgoram m al CO ma Reassigned Analysis Window START d a AIN y Background 1 E Setup Sample ECG ECG Data Spectral Analysis Time Frequency Analysis Ventricular Trigeminy 1 fees alee Spectrogram Time Waveform 3 8E 1 1 1E 1 3 1 4E 1 3 4E 1 3 5 8E 1 y O 4 1 3E 3 Sawa vanian ata 50E nenveaven 0 0E 0 3 3E 2 10 000 12 000 14 000 1800 18 000 20 000 Tim f aaa gt Length a i j 2 now Samp 350 Trend Level 0 10 GO sae ho STFT Spectrgoram Reassigned Analysis Window l p Hanning 2006 Cleveland Medical Devices Inc Cleveland OH Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 21 Clevel_al E Laboratory Course System CleveLabs Laboratory Course System Teacher Edition Electrocardiography II Laboratory 30 Repeat step 24 for the ECG sample file ventricular flutter 3 ECG Il Laboratory Data Collection Interval ms 100 esse saveoara aero Background Anatomy Setup Sample ECG J2. Course System CleveLabs Laboratory Course System Teacher Edition Electrocardiography II Laboratory node block and first degree AV node block Correlate the ECG sketches with the physiological problem Premature Ventricular Contraction X Early QRS complex SA Node Block SA node block shows long time between T and P AV node block Notice prolonged PQ time 3 Describe any quantitative features you found in the time domain that may be useful for quantifying specific cardiac rhythms Student responses will vary based on their observations 4 Describe any quantitative features you found in the frequency domain that may be useful for quantifying specific cardiac rhythms Student responses will vary based on their observations 5 What are the benefits of using a JFTA method to analyze data compared to only using a spectral or temporal analysis technique 2006 Cleveland Medical Devices Inc Cleveland OH 26 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 Clevel_abs E amp Laboratory Course System CleveLabs Laboratory Course System Teacher Edition Electrocardiography II Laboratory Using a JFTA will illustrate how a power spectrum of a signal changes over time This allows someone to discover what frequencies are occurring at particular points of time instead of just examining frequency components of the signal as a whole Th
3. HE PhysioBank PhysioToolkit and PhysioNet Components of a New Research Resource for Complex Physiologic Signals Circulation 101 23 e215 e220 Circulation Electronic Pages http circ ahajournals org cgi content full 101 23 e215 2000 June 13 National Instruments Corporation Signal Processing Toolset User s Manual December 2002 Edition 2006 Cleveland Medical Devices Inc Cleveland OH 28 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0
4. P waves in the ECG for every QRS T complex Bradycardia is a term to describe the heart beating more slowly than normal Sinus bradycardia can occur in well conditioned athletes and during deep relaxation In the case of athletes the heart muscle is strong and efficient therefore fewer contractions are needed During deep relaxation the body is at rest and requires less oxygen consumption than during normal activity which allows the heart rate to slow However sinus bradycardia can also occur as a result of heart disease or as a reaction to medication Supraventricular tachyarrhythmias SVT consist of fast heart rates that occur in the atria or the AV junctional tissue area However SVT can be a strong predictor of mortality in patients with congestive heart failure Some examples of this arrhythmia can include atrial flutter Wolf Parkinson White syndrome a short circuit between the atria and ventricles and atrial fibrillation are all examples Ventricular tachycardia is a life threatening condition that results from electrical impulses arising from the ventricles instead of the SA node This results in an abnormally rapid heartbeat The formation of scar tissue from previous heart attacks can predispose a person to this condition Because of the rapid heart rate the ventricles are unable to completely fill with blood and less blood is pumped to the rest of the body Ventricular tachycardia can result in heart failure ventricular fibrill
5. methods Review each of these screen shots and determine the effects of each type of JTFA method on the resulting plot Pay particular attention to the differences in resolutions of the plots 7 During the experimental methods you should have created several screen shots to your report using the file Ventricular Tachycardia 2 and several JTFA methods Review each of these screen shots and determine the effects of each type of JTFA method on the resulting plot This particular signal and time scale was selected to illustrate the transition area from an abnormal cardiac signal to a normal ECG Pay particular attention to the difference between the two areas as well as the differences in resolutions of the plots 8 During the previous data analysis steps you should have noticed some quantitative features that are unique to particular cardiac signals using either only temporal only spectral or a JTFA method Using MATLAB or LabVIEW and your saved data files propose methods and write an automated algorithm that can detect these features and predict a cardiac rhythm The input to your algorithm should be your saved data files from this laboratory session and the output should be the type of cardiac rhythm Be sure to include the data files that you collected from a subject in your analysis as well as the data files that you saved from the abnormal clinical database Discussion Questions 1 In this laboratory session you learned about several c
6. sure the time scale is set to 3 seconds You may need to adjust the amplitudes to see the ECG clearly Instruct the subject to relax then click on the save button and record data for approximately 10 seconds Name the data file subjectECG1 Stop saving data Report a screen shot of this data to your report You may want to name your report Electrocardiography II Save two more data files each approximately 10s in length Name the data files subjectECG2 and subjectECG3 Later you will compare your 3 saved data files from the subject to the abnormal clinical database Now we will examine the abnormal clinical database Click on the tab labeled Sample ECG In the top right hand corner is a drop down menu of 27 ECG sample waveforms There are a total of 9 cardiac rhythms with 3 examples of each Examine each of the signals in the time domain as they scroll across the screen Report a screen shot of each of the 9 rhythms to include into your report Also save each type of abnormal cardiac rhythm to a file Call each file the same name as the cardiac arrhythmia You should save 8 abnormal cardiac files Now spend some time examining each of the signals in the frequency domain to quantify specific spectral characteristics of the signals Click on the tab labeled Spectral Analysis Click on the tab labeled Frequency Domain and then the tab labeled Sample Data Turn on a high pass filter and set th
7. 42643 Time Waveform ZE c Cele al Ny gt lata A 5 0E 2 Zoom 4 0E 17 1 1 1 j 1 10 000 12000 14 000 16 000 18000 20 000 Time ECG II Laboratory Electrocardiography IE Laboratory cacti Background Anatomy Setup Sample ECG ECG Data Spectral Analysis Time Frequency Analysis Atrial Flutter 3 5 6E 0 3 2E 1 5 7E 1 7 7E 1 1 0E 2 1 2E 2 ap mj 1 3640 Time Waveform DOED m gt ela ewe 40640 Zoot D a _ gt 2 3640 s i A gt 10 000 12000 14 000 16 000 18 000 20 000 gt Time 2006 Cleveland Medical Devices Inc Cleveland OH 20 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 CleveLabs Laboratory Course System Teacher Edition Electrocardiography II Laboratory Clevel_al E Laboratory Course System 27 Repeat step 24 for the ECG sample file ventricular tachycardia 3 ECG Il Laboratory START I __ MAIN MENI Lee iT Setup Sample ECG i ECG Data Spectral Analysis Time Frequency Analysis Ventricular Tachycardia3 Power Spectrum Spectrogram 1 8E 2 5 4E 0 Same 360 1 5E 2 2 9E 1 Trend Level en 1 3E 2 S 2E 1 ee eee 7 1E 1 9 2E 1 1 0E 2 7 5E 1 5 0E 1 2 5E 1 0 0E 0 STAR AIN Ji Barkgrauna a anata Setup i Sample ECG ECG Data See Analysis Time Frequency Analysis r
8. 460 4 70 480 4 90 5 00 5 10 5 20 5 30 5 40 5 50 5 60 5 70 5 80 5 89 y 3 Use some of the JTFA methods described above to examine all three subject ECG files that you collected You will compare this analysis to the database analysis that you completed earlier 4 During the experimental methods you should have created several screen shots to your report of a spectral analysis of the signals in the ECG database Review each of these screen shots and determine if there are any spectral features which are unique to particular cardiac abnormalities 2006 Cleveland Medical Devices Inc Cleveland OH 23 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 ClevelLabs E amp 8 Laboratory Course System CleveLabs Laboratory Course System Teacher Edition Electrocardiography II Laboratory 5 During the experimental methods you should have created three screen shots to your report using the file Normal Sinus Rhythm 3 and the STFT JTFA methods with window sizes of 60 360 and 720 Review each of these screen shots and determine the effects of window size on the resulting plot Pay particular attention to the differences in resolutions of the plots 6 During the experimental methods you should have created several screen shots to your report using the file Normal Sinus Rhythm 3 and each of the JTFA
9. 5 0E 1 Spectrgoram a 25E 1 mp 0 0E 0 ee TiendLevel 0 00 SETS E E EE PTET PR a ia 0 0 0 5 1 0 Time Waveform residue 1 6E 0 trend yxy 1 0E 0 Cinsor Cc rawdata 7 5 0E 1 Zoom fi gt 0 0E 0 4 7E 1 gt 0 000 2 000 4 00 S oo0 8 00 si 692 S Tim Figure 4 A joint time frequency analysis can be useful for analyzing many physiological signals including the cardiac potential Other algorithms that can be used in the JFTA method include an adaptive spectrogram a Choi Williams distribution a Cone shaped distribution Wigner Ville distribution and the Gabor spectrum Each algorithm has a unique impact on the time and frequency resolutions that can be achieved cross term interference and computational speed The Gabor algorithm expands the signal into a set of weighted frequency modulated Gaussian functions and is the inverse of the STFT It has good time and frequency resolution and the speed of the algorithm is moderate The Wigner Ville distribution gives high time and frequency resolution but suffers from cross term interference This algorithm is computationally fast and does not suffer from windowing effects The Cohen s class algorithms such as the Choi Willimas and Cone shaped distributions act to reduce this crossterm interference Both algorithms provide good time and frequency response but computationally they are very slow The appropriate method to use is based on the parti
10. 60 Then Click on Go Change the time scale on the plot to read from 2 0s to 2 5s Report a screen capture of the resulting plot for your report S ECG II Laboratory Electrocardiography IT Laboratory onsoastenmunaes ew savea o reor Background Anatomy Setup Sample ECG ECG Data Spectral Analysis Time Frequency Analysis ECG Samples Normal Sinus Rhythm 3 1 2E 1 3 6E 1 6 0E 1 77 9E 1 1 0E 2 v DE 33E 1 i 1 i f 2000 2100 2200 2300 2400 2500 Time 2006 Cleveland Medical Devices Inc Cleveland OH 16 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 CleveLabs Laboratory Course System Teacher Edition CleveLa E Laboratory Course System Electrocardiography II Laboratory 17 Select ECG sample file Normal Sinus Rhythm 3 Spectrogram Set the length to 360 Then Click on Go Report a screen capture of the resulting plot for your report Be sure to comment on the JTFA method used ECG II Laboratory ECG II Laboratory Set the JFTF method to STFT Background Anatomy Setup Sample ECG ECG Data Spectral Analysis Time Frequency Analysis Power Spectrum Normal Sinus Rhythm 3 Spectrogram 1 8E 2 1 2E 1 1 5E 2 3 6E 1 1 3E 2 poe 7 9E 1 1 0E 2 biie 7 5EH 1 2E 2 5 0E 1 25E 1 mej 0 0E 0 Ti
11. AV node nor the Purkinje fibers are responsible for setting the heart rate due to the discharge rate of the SA node The SA node fires fastest so other tissues are excited from the SA impulse rather than their own In normal conditions the SA node is the natural pacemaker of the heart However sometimes the AV node or Purkinje fibers begin pacing faster than the SA node This condition is known as an ectopic pacemaker An ectopic pacemaker occurs when electrical activation of the heart is initiated elsewhere than the SA node Another condition that can lead to an ectopic pacemaker is when signals from the SA node are prevented from conducting to the rest of the heart This may occur when the electrical impulses are blocked at the AV node or AV fibers that innervate the ventricles In this instance the SA node fires at its own normal rate but the signals do not conduct down to the ventricles Since the Purkinje fibers do not receive these impulses from the SA node they begin to fire at their own intrinsic rate between 15 40 times a second This leads to a very slow contraction rate of the ventricles failing to pump blood If this continues the brain may become deprived of oxygen and the person may faint Correlation of ECG to Physiological Events The ECG signal illustrates the electrical depolarization and repolarization of the heart during a contraction As described above the depolarization of the cardiac muscle cells in the atrium occurs f
12. Clevel_abs E Laboratory Course System CleveLabs Laboratory Course System Teacher Edition Electrocardiography II Laboratory 2006 Cleveland Medical Devices Inc Cleveland OH Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 CleveLabs Laboratory Course System Teacher Edition Clevel_abs E Laboratory Course System Electrocardiography II Laboratory Introduction As we saw in the first electrocardiography ECG laboratory session surface electrodes can be used to measure the cardiac potential in the heart The ECG signal can be correlated with specific regions of cardiac excitation in the heart The cardiac rhythm relies on synchronous electrical activity from specialized tissues of the heart to effectively pump blood throughout the body The ECG has several applications such as evaluating cardiac function calculating heart rate and detecting cardiac arrhythmias However sometimes cardiac electrical activation can become irregular and cause abnormal cardiac function The abnormal electrical activation can be caused by areas of dead cardiac tissue caused by a myocardial infarction extra pace makers or congenital defects When the heart does not contract in a normal rhythmic pattern blood does not get pumped effectively and may lead to several Symptoms in a person or even death The ECG can be used to detect and diagnose several types
13. Version 5 0 Clevel_abs E amp 8 Laboratory Course System CleveLabs Laboratory Course System Teacher Edition Electrocardiography II Laboratory Cardiac Defibrillators In some cases a cardiac arrhythmia can drive the cardiac output down to almost zero and create a life threatening condition In these cases a cardiac defibrillator can be used to shock the heart out of an abnormal cardiac rhythm In general a large electrical shock may reestablish a normal cardiac rhythm Current is passed though electrodes that are placed either directly on the heart or transthoracically using large area surface electrodes placed against the chest Two basic types of defibrillators include capacitive discharge and rectangular wave The capacitive discharge DC defibrillators produce a short high amplitude pulse Approximately 50 to 100 J is required for defibrillation using electrodes applied directly to the heart External electrodes can require up to 400 J for defibrillation Electrodes should have excellent contact with the body If good contact is not maintained energy intended to reach the heart can be dissipated at the electrode skin interface and cause serious burns Electrodes should also be well insulated to prevent current from flowing through the person applying the defibrillation Electrocardiography Analysis Methods As explained above and as you will see in lab course software examples there are several types of cardiac arrhythmias The m
14. and OH 9 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 Clevel_abs E amp 4 Laboratory Course System CleveLabs Laboratory Course System Teacher Edition Electrocardiography II Laboratory Ventricular trigeminy occurs when there is a premature beat every third beat The premature beat has a widened QRS complex occurs earlier than normal and is followed by a compensatory pause Premature beats are caused by an irritable focus of cardiac tissue in the ventricles that may result in early depolarization of the ventricles Ventricular Flutter In this cardiac arrhythmia the verticals can be paced at more than 200 beats per second This can be triggered by an extrasystole or ectopic pacemaker that occurs in the ventricles The pumping of blood becomes extremely inefficient There is no visible P wave in the ECG recording and the QRS complex and T wave are merged in regularly occurring waves with a frequency between 180 and 250 beats per minute Several examples of all the abnormal cardiac arrhythmias described above are included with the laboratory course software You will explore these in this laboratory session These data files were obtained from the Physionet website at www physionet org 2006 Cleveland Medical Devices Inc Cleveland OH 10 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System
15. ardiac abnormalities Discuss each of these cardiac arrhythmias and relate the abnormality in the recorded electrical rhythm to the underlying physiology Atrial fibrillation AF occurs as a result of rapid irregular electrical impulses stimulating the atria Causes include heart lesions that prevent the atria from emptying adequately into the ventricles and ventricular failure that causes excess damming of blood in the atria These conditions cause dilated atrial walls which make the heart susceptible to the long conduction pathways and slow conduction that can result in AF The frequent irregular waves stimulating the atria are weak and often of opposite polarity which results in either no P waves or a high frequency low voltage wavy ECG recording The QRS T complexes are normal but irregular as a result of impulses arriving at the AV node irregularly 2006 Cleveland Medical Devices Inc Cleveland OH 24 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 Clevel_abs E amp Laboratory Course System CleveLabs Laboratory Course System Teacher Edition Electrocardiography H Laboratory Atrial flutter 1s a condition where there are multiple atrial contractions for every ventricular contraction The electrical signals enter the AV node at a rate that is too rapid to create a ventricular contraction for every atrial contraction As a result there are multiples
16. ation and cardiac arrest Ventricular bigeminy occurs when there is a premature beat every other beat The premature beat 1s broad occurs earlier than normal and is followed by a compensatory pause Premature beats are caused by an irritable focus of cardiac tissue in the ventricles that may result in early depolarization of the ventricles Ventricular trigeminy occurs when there is a premature beat every third beat The premature beat has a widened QRS complex occurs earlier than normal and is followed by a compensatory pause Premature beats are caused by an irritable focus of cardiac tissue in the ventricles that may result in early depolarization of the ventricles During ventricular flutter the verticals can be paced at more than 200 beats per second This can be triggered by an extrasystole or ectopic pacemaker that occurs in the ventricles The pumping of blood becomes extremely inefficient There is no visible P wave in the ECG recording and the QRS complex and T wave are merged in regularly occurring waves with a frequency between 180 and 250 beats per minute 2 Sketch two cycles of a typical ECG recording labeling each of the components Now draw ECG graphs for the following symptoms premature ventricular contractions SA 2006 Cleveland Medical Devices Inc Cleveland OH 25 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 Clevel_abs E Laboratory
17. block can cause the heart to develop an asynchronous 2 1 rhythm In this case there are 2 atrial contractions for each ventricular contraction Third degree block occurs when the signal from the SA node never reaches the ventricles due to complete block of the AV node In this case the ventricles never receive the cardiac impulses and begin to beat at their own natural rate which is much slower than the rate from the SA node 2006 Cleveland Medical Devices Inc Cleveland OH 5 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 Clevel_abs E 8 Laboratory Course System CleveLabs Laboratory Course System Teacher Edition Electrocardiography II Laboratory Consequently the relation between P waves and QRS complexes disappear The P wave will be regular but QRS T complexes will appear at a much slower rate In a normal ECG the T wave is of positive amplitude denoting the repolarization of the ventricles In some abnormal ECG the T wave can be inverted having negative amplitude One reason for this is slow conduction of the depolarization wave In this instance the conduction delay occurs in the left ventricle due to a left bundle branch block Consequently the right ventricle depolarizes first then the left ventricle depolarizes causing a shift of the mean QRS vector to the left Then as repolarization occurs the right ventricle repolarizes before the
18. boratory Course System Teacher Edition Electrocardiography II Laboratory Data Analysis 1 Using the post processing toolbox open the ECG file named SubjectECG1 that you recorded during this laboratory session Post Processing Toolbox Laboratory man mew Raw Data Spectral Analysis Correlation Time Frequency Analysis iim BLALAS BL 00 10 20 30 40 50 60 70 80 90 100 110 12 0 13 0 140 15 0 Time Seconds Deel 2 Click on the spectral analysis tab then click on the time domain tab Turn on the high pass filter and set the cutoff to 0 01 to help remove any DC component of the signal Report a screen shot of the temporal and spectral characteristics of the signal to your report Post Processing Toolbox Laboratory MAIN MENU Post Processing Toolbox Laboratory anmew Revista Spectral Analysis Eureen tine reser Seales Raw Data Spectral Analysis Correlation Time Frequency Analysis paerewa s Time Domain Frequency Domain Sampling Rate 360 a ERNE Time Domain Frequency Domain Select Channel requen ai Estimated Peak Frequency Hz 1 2330 Y Units HBvrms Normal Sinus v ot Peskin gee Filter Parameters Raw Data SED Filtered Data a e a aw Data BE Filtered Data filter type Highpass v fiter type Highpass 7 soo F T ji He Cutoff 3 01 HP Cutoff Spor order p 60 0 4 234 30 4 40 450
19. c Cleveland OH CleveLabs E Laboratory Course System 19 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 i Lm CleveLabs E Laboratory Course System CleveLabs Laboratory Course System Teacher Edition Electrocardiography II Laboratory 24 Select ECG sample file normal sinus rhythm 1 Set the JFTF method to STFT Spectrogram Set the length to 360 Set the trend level to 0 1 Then Click on Go Change the time scale on the plot to read from 10s to 20s Report a screen capture of the resulting plot for your report and note the type of arrhythmia B ECG II Laboratory Data Collection Interval ms 100 o sa l savenara J Background Anatomy Setup Sample ECG ECG Data Spectral Analysis Time Frequency Analysis Power ect 1 8E 2 1 5E 2 1 3E 2 1 0E 2 7 5E 1 5 0E 1 2 5E 1 0 0E 0 1 2643 Time Waveform 1 0E 3 ata 50E 2 gt ent THEM apne mane gt 10 000 12 000 14 000 16 000 18000 20 000 Time m Data Collection Interval ms 0 sant A eve a aonr Background Anatomy Setup Sam le ECG ECG Data Spectral Analysis Time Frequency Analysis ECG Samples Atrial Fibrillation 1 Power Spectrum Spectrogram 1 8E 2 1 5E 2 5 7E 0 1 3E 2 pre 3 1E 1 1 0E 2 a 7 5E 1 7 1E 1 5 0E 1 25E 1 x 0 0E 0
20. ckground Anatomy Setup Te ECG ECG Data al ee Analysis Time Frequency Analysis Frequency Domain Time Domain EE Samples Ventricular Tachycardia 1 Frequency Domain Time Domain ECG Samples Supraventricular Tachyarrhythmia 2 Real Time ECG Sa imple ECG Real Time ECG Sample ECG Frequency Domain for Samples Estimated Peak Frequency Hz 2 0339 Units ems 13 We will use the JTFA to analyze ECG signals Click on the tab labeled Time Frequency Analysis Select ECG sample file Normal Sinus Rhythm 3 Set the JFTF method to STFT Spectrogram Set the length window size to 360 Then Click on Go Report a screen capture of the resulting plot for your report Be sure to comment that the length was Set to 360 ECG II Laboratory IAIN Mi ENU p ERA Anatomy Setup T ECG ECG Data i Spectral Analysis Time Frequency Analysis Normal Sinus Rhythm 3 1 2E 1 Sae 380 E mae Aoo 6 0E 1 Pei ees a EE 1 0E 2 1 2E 2 m l o m E a C 0 0E 0 47E p odoo 2000 4000 _ 5000 8 000 9 692 14 Reset the length to 60 Then Click on Go Report a screen capture of the resulting plot for your r
21. cular application at hand Experimental Methods Experimental Setup During this laboratory you will record a standard three lead ECG You should watch the setup movie included with the software prior to setting up the experiment 1 Your BioRadio should be programmed to the LabECGII configuration 2006 Cleveland Medical Devices Inc Cleveland OH 12 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 Clevel_abs E Laboratory Course System CleveLabs Laboratory Course System Teacher Edition Electrocardiography II Laboratory UJ O a O S O O LA Q J O ae O o RL i Jumper 1 1 to 3 y Jumper 2 1 to 2 A HoRadio Inputs 3 Jumper3 2to 3 BioRadio CleveMed Figure 5 Setup for Lab ECG II 2 For this laboratory you will use four snap electrodes from the CleveLabs Kit Remember that the electrode needs to have good contact with the skin to get a high quality recording The surface of the skin should be prepared and cleaned prior to electrode placement For the best recordings it 1s best to mildly abrade the surface with pumice or equivalent to minimize contact resistance by removing the outer dry skin layer Attach one electrode on the palmar side of the right wrist one on the palmar side of the left wrist one on the left leg and one on the right leg NOTE The electrodes on the ar
22. cycle This is known as a current of injury When cardiac tissue is consistently depolarized it affects the ECG by causing a deflection in the graph due to a strong current of injury Using vector analysis a physician can use the ECG to determine the location of this ischemic tissue by looking at the polarity of the current of injury Abnormal rhythms can be analyzed using ECG recordings Rhythm disorders such as tachycardia and bradycardia are quite evident Tachycardia is when the heart rate exceeds 100 beats per minute and is usually caused by increased body temperature stimulation by the sympathetic nervous system or chemical stimulation of the heart tissue Bradycardia is when the heart rate slows to less than 60 beats per minute Bradycardia is not always harmful Some athletes demonstrate bradycardia due to the fact that their heart has become extremely efficient at pumping blood This reduces the need for a faster heart rate But bradycardia can also be a result of vagal stimulation which has an inhibitory effect on heart rate A description of several other cardiac arrhythmias is listed below Atrial Fibrillation 2006 Cleveland Medical Devices Inc Cleveland OH 6 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 Clevel_abs E Laboratory Course System CleveLabs Laboratory Course System Teacher Edition Electrocardiography II Laboratory The most co
23. e cut off to 0 01 This will help to remove the DC component from the ECG signals Now examine each type of ECG signal in the database in the frequency domain Add several screen shots to your report for each type of abnormal rhythm 2006 Cleveland Medical Devices Inc Cleveland OH 14 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 C leve Labs E Laboratory Course System CleveLabs Laboratory Course System Teacher Edition Electrocardiography H Laboratory ECG Il Laboratory gt ECG II Laboratory SIAR p sh ENU START IN MENI Background Anatomy Setup sample ECG ECG Data Spectral Analysis Time Frequency Analysis e SET Anatomy Setup Pey ECG T ECG Data Spectral Analysis Time Frequency Analysis Frequency Domain Time Domain i E ECG Samples Najina gece Bha L Frequency Domain Time Domain ECG Samples Real Time ECG Sample ECG Real Time ECG Sample ECG Eren Donasan SEEE 5 AES Ye Atrial Fibrillation 1 RT MAIN MENU Baikara Anatomy Setup Sails ECG ECG Data Spectral Analysis Time 4 Frequency Analysis Ba
24. eport Be sure to comment that the length was set to 60 2006 Cleveland Medical Devices Inc Cleveland OH 15 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 i e j s T M Aric r ee ed eres E Laboratory Course System CleveLabs Laboratory Course System Teacher Edition Electrocardiography II Laboratory I ECG II Laboratory coe Ye conta ner START P bi hea Background Anatomy Setup Sample ECG ECG Data Spectral Analysis Time Frequency Analysis Normal Sinus Rhythm 3 Powe 1 8E 2 1 6E 1 1 5E 2 3 9E 1 1 3E 2 6 1E 1 AREH 1 0E 2 7 5E 1 5 0E 1 2 5E 1 0 0E 0 1 0E 2 1 2E 2 a E 1 6E 0 Time Waveform AZ 1 00 rawdata 5 0E 1 0 0E 0 47E1 i 1 i 0 000 2000 4000 6000 8000 9 692 Time 15 Reset the length to 720 Then Click on Go Report a screen capture of the resulting plot for your report Be sure to comment that the length was set to 720 ECG II Laboratory ECG Samples Normal Sinus Rhythm 3 Power Spectrum Spectrogram 1 8E 2 came 360 noes meaa 0 00 1 3E 2 1 0E 2 7 5E 1 STFT 5 0E 1 Spectrgoram TTC TPAC 05 1 0 2 5E 1 O 0E 0 3 Ta Time Waveform Reassigned AAs a l s 10E 0 lata 50E 1 0 0E 0 4 7E 1 j T r 4 0 000 2 000 4 000 6 000 8 000 9 692 Time 16 Reset the length to 3
25. ger to conduct through the tissue elongating the QRS complex In these cases the QRS might last between 0 9 to 0 12 seconds Another cause for lengthened QRS complexes are conduction blocks in the Purkinje fibers As described above these fibers conduct the impulse from the Bundle of His node into the ventricles If a complete block of the Purkinje fibers occurs the QRS complex can be lengthened to 14 seconds or more Conduction from the SA node can also be blocked In this case the signal from the SA node is blocked before it ever reaches the atria causing the sudden disappearance of the P wave meaning the atria fail to contract Since the ventricular tissues have their own rhythm the AV node creates the QRS T complex but at a slower rate Blocks and conduction delays can also be found in the AV node One type of block that comes from AV conduction problems is indicated by an elongated P R or P Q interval The normal time from the beginning of the P wave until the beginning of the QRS complex is 0 16 seconds A first degree block occurs when that time is greater than 0 20 seconds In first degree block the QRS is delayed but not actually blocked When the PR interval begins to grow longer to 0 25 to 0 30 seconds some impulses may not be strong enough to pass through the AV node This leads to dropped beats where the QRS complex disappears even though there is a preceding P wave These cases are called second degree block A second degree
26. gner Ville method ECG II Laboratory ECG Samples Ventricular Tachycardia 2 Power Spectrum Spectrogram Samm 360 Tee 010 A ee or orm TAS 0 0 05 1 0 wigner Ville Distribution m Zoom Analytical Signal gt ess 7500 8000 8800 4000 Time ECG Il Laboratory Background Anatomy Setup Sample ECG ECG Data Spectral Analysis Time Frequency Analysis ECG Samples Ventricular Tachycardia 2 Power Spectrum Spectrogram 1 8E 2 2 5E 0 Sa 350 1 5E 2 eee TBE A 010 1 3E 2 FAGEI o ee TROIS PE Gos E Ao ap 6 461 ITFA Method 7571 8 0E 1 choi Witliams 5 0E 1 Distribution m 25671 O 0 0E 0 Time Waveform residue 1 1E 0 trend a raw data A7 Tues Analytical Signal 1 0E 0 Alpha 1 5E 0 916 7000 7500 soo 850 9000 23 Repeat step 19 for the Cone Shaped method IS ECG II Laboratory Electrocardiography II Laboratory Data Collection Interval ms 100 sa ER eve savepata J Background Anatomy Setup Sample ECG ECG Data Spectral Analysis Time Frequency Analysis ECG Samples Ventricular Tachycardia 2 wl Sp am 1 8E 2 1 5E 0 1 5E 2 1 9E 1 3E 2 paua 5 0E 1 0642 H Ea 7 5E 1 8 2E 5 0E 1 25E 1 0 0E 0 a E Time Waveform 0 0E 0 GAN v Analytical Signal Alpha Es lata 750 8000 8500 Time 2006 Cleveland Medical Devices In
27. i ECG Data Spectral Analysis Time Frequency Analysis ECG Samples Ventricular Flutter 3 Ean ir Spectrogram 1 8E 2 4 8E 0 1 5E 2 2 2E 1 4 9642 4 7E 1 6 7E 1 1 0E 2 lnea 5E 1 1 1E 2 5 0E 1 g 25E 1 o m 0 0E 0 Time Waveform residue 230 A keea m C a iii keea Zoo gt 4 0E 0 gt 0 000 5 000 10 000 15000 20 000 25 000 29 997 Tim I ECG Il Laboratory Data Collection Interval ms 100 Background Anatomy Setup Sample ECG ECG Data Spectral Analysis Time Frequency Analysis 1 9E 1 O a ae le Ey Seat a0 05 1 0 5 9E 1 8 0E 1 2 6E 1 cam 30 hes me 0 10 STFT Spectrgoram Time Waveform l l 1 2E 3 10643 ren Az ra a A7 50E 2 FEA 1 1 1 1 f 10 000 12 000 14 000 16 000 18 000 20 000 Time ECG II Laboratory REPORT MAIN MEN Background Anatomy Setup I Sample ECG Ti ECG Data Spectral Analysis Time Frequency Analysis Supraventricular Tachyarrhythmia 1 v 3 8E 1 1 3E 1 9 6E 0 2 8E 1 5 0E 1 7 2E 1 G a rawdata 7 50E 2 1 9E 2 10 000 42 000 4b _ sin 18 000 20 000 gt 2006 Cleveland Medical Devices Inc Cleveland OH 22 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 Clevelabs E Laboratory Course System CleveLabs La
28. icular contraction for every atrial contraction As a result there are multiples P waves in the ECG for every QRS T complex Sinus Bradycardia 2006 Cleveland Medical Devices Inc Cleveland OH 7 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 Clevel_abs E Laboratory Course System CleveLabs Laboratory Course System Teacher Edition Electrocardiography II Laboratory Bradycardia is a term to describe the heart beating more slowly than normal Sinus bradycardia can occur in well conditioned athletes and during deep relaxation In the case of athletes the heart muscle is tremendously strong and efficient at pumping blood therefore less contractions are needed During deep relaxation the body is at rest and requires less oxygen consumption than during normal activity which allows the heart rate to slow Therefore it may be perfectly normal However sinus bradycardia can also occur as a result of heart disease or as a reaction to medication Supraventricular Tachyarrhythmia Supraventricular tachyarrhythmias SVT can occur in patients of all ages This arrhythmia consists of fast heart rates that occur in the atria or the AV junctional tissue area However SVT can be a strong predictor of mortality in patients with congestive heart failure Some examples of this arrhythmia can include atrial flutter Wolf Parkinson White syndrome a short circuit betwee
29. interval ns Background Anatomy Setup Sample ECG ECG Data Spectral Analysis Time Frequency Analysis Normal Sinus Rhythm 3 ii 380 me 0 00 SET 0 0 05 1 0 TFA Method 8 Adaptive Spectrogram Residual 26 90 Mode 3 Chirplet of Terms p 10 19 Select ECG sample file Ventricular Tachycardia 2 Set the JFTF method to STFT Spectrogram Set the length to 360 Set the time scale from 7 to 9 seconds Set the trend level to 0 1 Then Click on Go Report a screen capture of the resulting plot for your report Be sure to comment on the JTFA method used Si ECG II Laboratory ii OPENER E Background Anatomy Setup Sample ECG ECG Data Spectral Analysis Time Frequency Analysis Ventricular Tachycardia 2 9 1E 0 3 3E 1 5 5E 1 7 3E 1 9 5E 1 1 2E 2 v Time Waveform Reassigned Spectrgoram de pE EA as 0 0E 0 ata A 1 0E 0 1 5E 0 F A A 7 000 7 500 8 000 8 500 9 000 Time Ventricular Tachycardia 2 7 6E 0 3 2E 1 5 6E 1 7 5E 1 9 7E 1 v 0 1 1 1 7 000 7 500 8 000 8 500 Time 2006 Cleveland Medical Devices Inc Cleveland OH 18 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 CleveLabs Laboratory Course System Teacher Edition Electrocardiography II Laboratory 21 Repeat step 19 for the Wi
30. irst Therefore the first wave in the ECG signal corresponds to the depolarization of the atrium This is known as the P wave Similarly the start of ventricular contraction is the QRS wave The ventricles stay contracted for a few milliseconds until ventricular repolarization occurs which is seen as the T wave Atrial repolarization typically occurs between 0 15 and 0 20 seconds after the P wave However this is the same time when the QRS complex occurs The QRS complex is of much greater amplitude than atrial repolarization so it dominates the signal 2006 Cleveland Medical Devices Inc Cleveland OH 4 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 Clevel_abs 8 Laboratory Course System CleveLabs Laboratory Course System Teacher Edition Electrocardiography II Laboratory Figure 3 Normal ECG signal Abnormalities in the ECG As stated previously ECG recordings can be used as a diagnostic tool to determine abnormalities in cardiac function or it can be used to visualize the effects of cardiac tissue damage Abnormalities in the QRS complex indicate problems in the ventricles or ventricular conduction A normal QRS complex lasts between 6 8 seconds Times longer than this indicate a change in ventricular conduction One cause is ventricular dilation or hypertrophy In this case the ventricles are larger than normal causing the impulse to take lon
31. is method is particularly useful for non stationary signals 6 Discuss the tradeoffs between using each type of JFTA method to analyze a biomedical signal Are there particular reasons to use a specific type of method Each algorithm has a unique impact on the time and frequency resolutions that can be achieved cross term interference and computational speed The Gabor algorithm expands the signal into a set of weighted frequency modulated Gaussian functions and is the inverse of the STFT It has good time and frequency resolution and the speed of the algorithm is moderate The Wigner Ville distribution gives high time and frequency resolution but suffers from cross term interference This algorithm is computationally fast and does not suffer from windowing effects The Cohen s class algorithms such as the Choi Willimas and Cone shaped distributions act to reduce this crossterm interference Both algorithms provide good time and frequency response but computationally they are very slow The appropriate method to use is based on the particular application at hand 7 What effect does the window size have on a JTFA plot using the STFT method What impact does it have on the resolution of the plot The size of the discrete intervals determines the time accuracy In other words the smaller the discrete blocks of time are the better the time resolution However there is a tradeoff to this method The frequency resolution is inversely proporti
32. left ventricle causing the mean axis for the T wave to shift to the right which is opposite of the QRS complex in the same measurement So with delay of the conduction of the depolarization wave in the ventricles the inversion of the T wave occurs Another cause for inverted T waves 1s delayed depolarization In this case repolarization does not occur at the same place as it normally does Instead repolarization occurs at the apex of the heart Delayed depolarization causes the base of the ventricles to repolarize before the apex causing the vector to point from the apex to the base of the ventricles which is opposite to the repolarization vector in normal cases inverting the T wave The most likely cause for this type of depolarization delay is mild ischemia of the heart tissue which can be caused by coronary occlusion or coronary insufficiency that may occur during exercise Coronary ischemia caused either by myocardial infarction or other damage to the heart muscle can cause changes to the ECG signal Since ischemia means a loss of blood flow to the muscle tissue there is a loss of nutrients due to decreased blood flow a lack of oxygen and a buildup of carbon dioxide Consequently ischemic cardiac muscle is unable to repolarize and remains depolarized so long as the muscle is ischemic Since this muscle remains depolarized at all times current flows between this injured depolarized muscle and the normal polarized areas during the cardiac
33. me Waveform fesidue LEAD trend N 1 0E 0 rawdata A 7 5 0E 1 0 0E 0 4 7E 4 Q WAL oo 20o 4000 600 8000 3 692 Time ___ Electrocardiography II Laboratory ata colection intervat ns o sm SC oo Background Anatomy Setup Sample ECG ECG Data Spectral Analysis Time Frequency Analysis 1 8E 2 1 5E 2 1 3E 2 1 0E 2 7 5E 1 5 0E 1 2 5E 1 0 0E 0 Power Spectrum Spectrogram Time Waveform savepata __rerorr__ Normal Sinus Rhythm 3 360 Tierdkeval 0 0 Ee EO EI tect 0 0 05 1 0 ITFA Method Gabor spectrogram Freq Bins g5 residue 1 6640 trend 7 1 0E 0 rawdata 7 50E 0 0E 0 47E1 1 I 1 g 1 0 000 2 000 4 000 6 000 8 000 Time Length Var g 256 5 164 50 Order J 2 360 Terateval D O CRO A 1 0 S Spectrgoram Reassigned Analysis Window Hanning Power Spectrum 1 8E 2 1 5E 2 1 3E 2 1 0E 2 75E 1 5 0E 1 2 5E 1 O 0E 0 Spectrogram Time Waveform Background Anatomy Setup Sample ECG ECG Data Spectral Analysis Time Frequency Analysis Normal Sinus Rhythm 3 Wigner Ville Distribution residue 1 6640 trend A 1 0E 0 rawdata v 50E 0 0E 0 4 7E 1 0 ooo 2000 Analytical Signal 8 000 9 692 gt ECG II Laboratory gt ECG Il Laboratory Electrocardiography II Laboratory oanatutninuva
34. method may be appropriate to analyze the signal A graphical representation illustrates how the signal power spectrum changes over time The basic approach 1s to divide the signal into several discrete intervals that can be overlapped A Fourier transform can then be applied to each block of data to illustrate the frequency components of each block The size of the discrete intervals determines the time accuracy In other words the smaller the discrete block of time is the better the time resolution However there is a tradeoff to this method The frequency resolution is inversely proportional to the time resolution This is known as the 2006 Cleveland Medical Devices Inc Cleveland OH 11 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 Clevel_abs E Wi Laboratory Course System CleveLabs Laboratory Course System Teacher Edition Electrocardiography II Laboratory window effect The smaller the discrete interval of time the less resolution of frequency is provided The algorithm described above is known as a short time Fourier transform STFT gt ECG Il Laboratory wien avena O REPORT EA u Setup Sample ECG ECG Data Spectral Analysis Time Frequency Analysis i ECG Samples Normal Sinus Rhythm 3 Power Spectrum Spectrogram 1 8E 2 E Sampe 380 1 5E 2 1 3E 2 1 0E 2 7 5E 1 6 3E 1 8 2E 1 1 1E 2 1 3E 2 STFT
35. mmon type of sustained arrhythmia is atrial fibrillation AF which occurs as a result of rapid irregular electrical impulses stimulating the atria This prevents the atria from contracting normally though blood can continue to flow passively through the atria Some common causes include heart lesions that prevent the atria from emptying adequately into the ventricles and ventricular failure that causes excess damming of blood in the atria These conditions cause dilated atrial walls which make the heart susceptible to the long conduction pathways and slow conduction that can result in AF The frequent irregular waves stimulating the atria are weak and often of opposite polarity which results in either no P waves or a high frequency low voltage wavy ECG recording The QRS T complexes are normal but irregular as a result of impulses arriving at the AV node irregularly Heart failure and valvular heart disease are both associated with AF Atrial Flutter Atrial flutter 1s a condition where there are multiple atrial contractions for every ventricular contraction Itis caused by a single large electrical signal that propagates around the atria The rate of atrial contraction can be between 200 and 350 beats per minute The amount of blood being pumped by the atria can be very small as a result of one side of the atria being contracted while the other is being relaxed The electrical signals enter the AV node at a rate that is too rapid to create a ventr
36. ms can be placed at the wrists and the electrodes on the legs can be placed near the ankles 3 After the electrodes have been placed on the subject connect one snap lead to each of the four electrodes Then connect those snap leads to the harness inputs channels 1 2 3 references and the ground using the picture above as a reference Fig 5 The leads on the harness are stackable allowing one snap lead to be plugged into more than one connector lead 2006 Cleveland Medical Devices Inc Cleveland OH 13 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 Clevel_abs E amp 8 Laboratory Course System CleveLabs Laboratory Course System Teacher Edition Electrocardiography II Laboratory Procedure and Data Collection I 10 11 12 Run the CleveLabs Course software Log in and select the Electrocardiography II lab session under the Advanced Physiology subheading and click on the Begin Lab button Turn the BioRadio ON Click on the ECG data Tab and then on the green Start button Three channels of ECG should begin scrolling across the screen The first part of the lab will record normal resting ECG with the subject sitting up It is important that the subject is relaxed and still during this procedure in order to minimize artifacts from contaminating the ECG signal For the first test have the subject sit in a chair Make
37. n sa verve Tsavepata Background Anatomy Setup Sample ECG ECG Data Spectral Analysis Time Frequency Analysis Power Spectrum Spectrogram 1 8E 2 1 5E 2 1 3E 2 1 0E 2 7 5E 1 5 0E 1 2 5E 1 0 0E 0 Time Waveform Normal Sinus Rhythm 3 Samp Fren m 000 A Bt 000 oe 4 0 Choi Williams Distribution fesidue IBEN trend 1 0E 0 rawdata 7 506 1 O 0E 0 47E 1 1 1 1 0 000 2 000 4 000 6 000 8 000 Time v Analytical Signal Alpha J 1 066 oo r O Background Anatomy Setup Sample ECG ECG Data Spectral Analysis Time Frequency Analysis Power Spectrum 1 8E 2 1 5E 2 1 3E 2 1 0E 2 7 5E 1 5 0E 1 2 5E 1 0 0E 0 Spectrogram Time Waveform Normal Sinus Rhythm 3 Samp Frea meee 0 00 OO use 10 TFA Method Cone Shape Distribution residue Zao 16E 0 trend A N 1 0E 0 rawdata 7 50E 1 0 0E 0 4 7E 1 ooo 2000 Analytical Signal Alpha J 1 066 a000 9 692 2006 Cleveland Medical Devices Inc Cleveland OH Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 17 Clevelabs E Laboratory Course System CleveLabs Laboratory Course System Teacher Edition Electrocardiography II Laboratory ECG II Laboratory ____Electrocardiography II Laboratory vata Colection
38. n 5 0 Clevel_abs E amp 8 Laboratory Course System CleveLabs Laboratory Course System Teacher Edition Electrocardiography II Laboratory Origin of the ECG Signal In normal cases the SA node is the heart s natural pacemaker with the autonomic nervous system regulating its excitation Pulses from the SA node propagate via the internodal fibers of the right atrium and then to the left atrium causing immediate atrial contraction This electrical potential then travels to the AV node At the AV node the depolarization potential is then delayed allowing the atria to fully contract This delay allows the atrium to empty its contents into the ventricles before ventricular contraction After the delay in the AV node the potential travels down the Bundle of His which splits into right and left branch bundles These bundles innervate the ventricular walls via the Purkinje fibers When the signal reaches the Purkinje fibers ventricular contraction occurs sending blood from the right ventricle into the lungs and blood from the left ventricle out the aorta This process repeats for each heartbeat Other cardiac tissues also have natural pacing rates controlled by the autonomic nervous system The AV node without outside stimulation has a natural discharge rate of 40 to 60 times a minute while the Purkinje fibers fire between 15 and 40 times a minute This is in contrast to the SA node that fires between 70 and 80 times a minute Neither the
39. n the atria and ventricles and atrial fibrillation are all examples Ventricular Tachycardia 2006 Cleveland Medical Devices Inc Cleveland OH Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 Clevel_abs E Wi Laboratory Course System CleveLabs Laboratory Course System Teacher Edition Electrocardiography II Laboratory Ventricular tachycardia is a life threatening condition that results from electrical impulses arising from the ventricles instead of the SA node This results in an abnormally rapid heartbeat Heart attacks cardiomyopathy and valvular heart disease are a few of the causes of ventricular tachycardia The formation of scar tissue from previous heart attacks can predispose a person to this condition Because of the rapid heart rate the ventricles are unable to completely fill with blood and less blood is pumped to the rest of the body Ventricular tachycardia can result in heart failure ventricular fibrillation and cardiac arrest Ventricular Bigeminy Ventricular bigeminy occurs when there is a premature beat every other beat The premature beat 1s broad occurs earlier than normal and is followed by a compensatory pause Premature beats are caused by an irritable focus of cardiac tissue in the ventricles that may result in early depolarization of the ventricles Ventricular Trigeminy 2006 Cleveland Medical Devices Inc Clevel
40. of abnormal cardiac function including bradycardia slow heart Figure 1 Atria and ventricles of the heart with blood flow patterns red oxygenated blue deoxygenated rate tachycardia fast heart rate and other electrical conduction problems Quantitative features of the ECG signal can be analyzed and correlated to specific cardiac abnormalities The ability to quantify and classify the type of cardiac event that a person may be experiencing is critical for properly treating the abnormal rhythm For example many cardiac defibrillators and pace makers currently include a set of ECG monitoring electrodes Smart algorithms are included in the devices that detect the type of arrhythmia that is occurring If the type of cardiac event warrants a defibrillating shock the system then delivers it to the patient There are several quantitative temporal and spectral tools that can be used to analyze physiological signals that will be introduced in this session and may be used throughout the rest of this laboratory course Equipment required CleveLabs Kit CleveLabs Course Software Four 4 Snap Electrodes and Snap Leads MATLAB or LabVIEW 2006 Cleveland Medical Devices Inc Cleveland OH 2 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 Clevel_abs E amp 8 Laboratory Course System CleveLabs Laboratory Course System Teacher Edition Elec
41. onal to the time resolution This is known as the window effect The smaller the discrete interval of time the less resolution of frequency is provided 8 You should have designed an automated algorithm to detect particular cardiac arrhythmias based on quantitative features of the signal Describe in detail the methods that you used to create this algorithm Discuss any difficulties that you had in designing these algorithms Which arrhythmias could you successfully identify Student responses will vary based on the methods that they used to create their own algorithms for classification 2006 Cleveland Medical Devices Inc Cleveland OH 21 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Version 5 0 Clevel_abs E amp 8 Laboratory Course System CleveLabs Laboratory Course System Teacher Edition Electrocardiography II Laboratory References Webster John G Medical Instrumentation Application and Design 3 Edition John Wiley and Sons New York 1998 Guyton and Hall Textbook of Medical Physiology g h Edition Saunders Philadelphia 1996 Normann Richard A Principles of Bioinstrumentation John Wiley and Sons New York 1988 Rhoades R and Pflanzer R Human Physiology Third Edition Saunders College Publishing Fort Worth 1996 Goldberger AL Amaral LAN Glass L Hausdorff JM Ivanov PCh Mark RG Mietus JE Moody GB Peng CK Stanley
42. ost effective treatment depends upon which type of arrhythmia a person is experiencing The types of treatment can range from nothing to pharmaceutical interventions to implanting electrical pacemakers to cardiac defibrillation Therefore it is important to identify which type of abnormality exists One method for accomplishing this is through a visual inspection of the ECG signals by a trained clinician As explained above there are several visual features that can be extracted to detect which cardiac event is occurring However a physician is not always readily available to review these recordings Therefore it may be advantageous to use a computer based program to quantitatively assess the ECG signal and classify it as a particular rhythm These intelligent algorithms can be integrated into medical devices such as implanted cardiac pace makers and cardiac defibrillators Several tools are available to provide quantitative analysis of temporal and spectral components of the cardiac signal In addition this laboratory session will introduce a joint time frequency analysis JFTA This method allows users to analyze signals in both the time and frequency domains simultaneously Fig 4 It is a useful tool to analyze non stationary signals Essentially this method yields which frequencies are occurring at what times A normal ECG signal can be a fairly stationary signal However an abnormal cardiac signal can become non stationary in which case this
43. trocardiography II Laboratory Background Special Conductive Tissues in the Heart There are several specialized regions within the heart to initiate electrical signals that cause cardiac contraction Fig 2 The primary area responsible for cardiac activation is the sinus node also known as the sinoatrial or SA node The SA node is located at the top of the right atrium and is the major structure responsible for pacing the heart Connecting the SA node to the atrioventricular AV node are the internodal pathways These internodal pathways are located along the walls of the right atrium The electrical signal propagates down the internodal pathways and enters the AV node At the AV node the signal is slightly delayed The AV node is located in the heart septum between the right and left atrium After the AV node the electrical signal flows through the Bundle of His located in the septal wall between the left and right ventricles The Bundle of His then divides into two branches the right branch and left branch These branches continue along the septal wall and then go into the Purkinje fibers which innervate the right and left ventricular walls SA Node i AV Node Bundle of His Perkinje Fibers Figure 2 Electrical conducting structures and pathways of the heart 2006 Cleveland Medical Devices Inc Cleveland OH 3 Property of Cleveland Medical Devices Copying and distribution prohibited CleveLabs Laboratory Course System Versio
Download Pdf Manuals
Related Search