Focus: Electrocardiography (ECG)

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1 Focus: Electrocardiography (ECG)
©2016 free-icons-download.net Christopher Frey (s ), Dimitar Tahov (s ) Cradiac diagnostic Focus: Electrocardiography (ECG) topic of today‘s presentation

2 Structure Disambiguation Electrophysiology of the heart
Electrocardiography ECG Physically technological concept Standard leads Diagnostic significance ECG instrument technology Long-term ECG Safety and harm potential Sources C. Frey, D. Tahov

3  includes just surface detected cardiac action potentials
Cardiac (basic) diagnostic: „… non-invasive detection of electrical cardiac action potentials in rest and under physical stress to evaluate heart’s functions …“  includes just surface detected cardiac action potentials (R. Kramme , Medizintechnik, Springer, Berlin Heidelberg, 2011, S.113, translated by C. Frey) The term „cardiological basic diagnostics“ based on literature of Rüdiger Kramme he -> only non-invasive detection of electrical potentials by that ONLY surface detected ECG C. Frey, D. Tahov

4 Disambiguation besides Kramme’s other definitions include more methods of invasive and non-invasive cardiac diagnostics electrophysiological (invasive & non-invasive) acoustic (non-invasive) imaging e.g.: bundle of His EG (invasive) esophagus EG (partly invasive), surface detected ECG (non-invas.) phonocardiogram PCG e.g.: echocardiography Fig.: echocardiogram of diff. section plains Source: Patrick J. Lynch, Heart normal transthoracic echocardiography views, 2006, , CC Kramme: ONLY surface detected ECG other definit.: include further invasive and non-invasive diagnostic methods , e.g.: electrophysiological (invasive & non-invasive) acoustic (non-invasive) imaging (non-invasive) C. Frey, D. Tahov

5 The (human) heart muscular 4 chambered hollow organ
pump’s function of cardiovascular system Histo.: specialized transversally structured muscle tissue (similar to skeletal muscles) Morpho.: Layers of heart’s walls (Fig.): enveloped by heart sac (pericardium) Epicardium (outer skin / epithelium) Myocardium (specialized muscle tissue) Endocardium (inner skin / epithelium) muskuläres Hohlorgan mit 4 Kammern spezielle quergestreifte Muskulatur Verbindung Muskelzellen über Gap junctions Pumpfunktion im kardiovaskulären System umschlossen von Herzbeutel (Perikard) Schichtung der Herzwand (Fig.): Epikard (Außenhaut) Myokard (Herzmuskelgewebe) Endokard (Innenhaut) Source: NaWi Videos, Glanzstreifen Kontraktion TrMyokard Herzmuskel oponin I T Kontraktionskraft, 2016, URL: CC BY (Ausschnitt) C. Frey, D. Tahov

6 Electrophysiology of the heart
Fig.: animated crosssection of the human heart with syncronized Wiggers-Diagramm Source: Dr. Jana Official, CG Animated Human Heart cut section showing the atria, ventricles and valves, synced with wiggers diagram, 2016, CC 4.0c Herz: Pumpe im Blutkreislauf muskuläres Hohlorgan 4 Kammern C. Frey, D. Tahov

7 Excitation system of the heart: Pacemaker cells
functional role similar to neurons = initiation of excitations continuously depolarization of cell membrane until reaching action potential = autonomy of heart hormonal & neuronal influenced (stimulating, inhibitory) pacemaker cells (functional areas) rythm (min-1) t until excitation(ms) sinus node 60-80 70 AV node 40-50 60 bundle of His 20-30 20 Tawara branches Purkinje fibers kein Fig.: electrocardial signals of different heart areas Source: after Huppelsberg, Walter, Kurzlehrbuch Physiologie, Thieme, Myocard = 2 functional typs working myocard+ pacemaker cells no stable resting potential continuous depolarization action potential= excitation excitation transmitted to working myocard autorhythmic of heart cells hormonal sympathetic (adrenaline, noradrenaline) & parasympathetic (N. vagus) structure: hierarchic: pacemaker with highest ratio overlines the others C. Frey, D. Tahov

8 Excitation propagation , vector loop & electrocardiogram (ECG)
Fig.: Phase of heart excitation (red) and ECG graph Source: ©Georg Thieme Verlag KG, 2016, Fig.: Vector loop (slowed down) Source: ©Georg Thieme Verlag KG, 2016, (Ausschnitt) Erregungsphase bewirken Ladungsverschiebung = E-Feld Änderung (vektoriell) Verläufe der Summenvektoren (PFEILSPITZEN) beschreiben Schleife -> Vektorschleife Vektorschleife als 2D Graph = EKG-Linie [NEXT] C. Frey, D. Tahov

9 Electrocardiography ECG
Physical & technological concept Standard leads Diagnostic significance ECG instrument technology Long-term ECG Safety and harm potential Fig.: Electrocardiogram with labeled characteristic sections, waves, peaks Source: ©Georg Thieme Verlag KG, 2016, C. Frey, D. Tahov

10 Physical & technological concept
variation of electric potentials induces moving electric field = voltage (just working myocardium) measureable with electrodes between two electrodes (differential) signal strength (ECG): 50µV ~ 1mV theor. everywhere at body’s surface diff. positions of electrodes = diff. signal forms nearby heart  higher amplitudes (peaks, waves) interference factors could easily falsify results Fig. upper: Electrocardiogram Source: ©Georg Thieme Verlag KG, 2016, changing potentials heart muscle cells detected as voltages by using electrodes (surface attached & by catheter) between two different electric potentials theor. everywhere at body’s surface or inner nearer to heart „stronger“ R-amplitude interference factors falsify results: 4exmpl: junction voltage between electrode-skin artifacts by system, other devices rhythmic skeletal muscle innervation Fig. lower: surface measured ECG+ His bundle EG Source: R. Kramme , Medizintechnik, Springer, Berlin Heidelberg, 2011, C. Frey, D. Tahov

11 Standard leads for resting ECG / clinical ECG
Thatswhy  leads were standardized for resting / clinical ECG called standard leads C. Frey, D. Tahov

12 augmented limb leads by Goldberger
bipolar limb leads by Einthoven augmented limb leads by Goldberger precordial leads by Wilson (unipolar) Figures: Surface leads of rest ECG le.top: electrode pos. by Einthoven limb leads (frontal) mid.: signals & electrode pos. by Goldberger augmented limb lead (frontal) ri.: signals & electrode pos. by Wilson precordial leads (frontal & horizontal) Source: R. Kramme , Medizintechnik, Springer, Berlin Heidelberg, 2011, just non-invasive surfaces leads every lead with specific signal form contains other diagnostic information thus always multiple leads were detected & recorded today: mostly all of 12 std. leads simultaneously differentiated by: polarity: bipolar  unipolar mounting position: limbs  precordial (chest) also modifications & reduced setups Fig. left: Einthoven-Triangle with leads I,II,III Source: R. Kramme , Medizintechnik, Springer, Berlin Heidelberg, 2011, C. Frey, D. Tahov

13 Diagnostic significance resting ECG/ clinical EKG
no directly informative value about mechanical heart functions (contraction, volumetric output) (R. Kramme , Medizintechnik, Springer, Berlin Heidelberg, 2011, S.121) great informative value of ECG about: rhythmic processes: thoracic position heart frequency Locating signals: excitation rhythm excitation’s origin relative positioning: excitation’s back-formation impulse propagation distribution of musculature Pathological disorders heart position/orientation (e.g. Cabrera’s circle) Fig.top.: Cabrera’s circle heart position (type) Source: Silber, 2007 , , CC BY-SA 3.0 only changes of bio potentials (expl.: lines of constant excitation) no mechanical information: e.g. good excitation  but heart output lowered / bad valueable for: rhythmic processes: heart frequency excitation rhythm (vestibular, ventricular) relative positioning: type of heart position via electric heart axis thoracic position via magnification ratio Locating signals Disorders of before mentioned C. Frey, D. Tahov

14 ECG technology analogue & digital
special role of digitals: PC-EKG-Module general properties of ECG systems: classified as electrical medical diagnostic devices / systems regularized e.g. by EN , MPBetreibV general working concept: low-noise differential amplifier (DC) measuring section: patient  electrode  signal processing  data storage  electronic data processing  graphic recording/ video output analogue & digital special role: PC-EKG-Module general properties of ECG systems: electrical medical diagnostic devices high requirements to Safety: strict regulations for: permission / operation / maintenance general working concept: low-noise differential amplifier (DC) measuring section: patient  electrode  signal processing  data storage  electronic data processing  graphic recording/ video output C. Frey, D. Tahov

15 Device technology Fd storage device Software with UI ( a)
Fig.: Scheme of signal processing and data processing of a ECG system Source: electrodes: stainless steel, Ag/AgCl & also capacitive differ. in kind of: techn. funct., adhesion, (electrolyte), skin preparation A pre-amplifier B galvan. decoupler C-E : signal processing (filtering, forming…) Fd : digital: saving data / send to software ( F a) post-amplification for analogrecording C. Frey, D. Tahov

16 Ways for output ECG results
Fig. top ri.: neadle plotting ECG measurement on ECG paper Source: CardioNetworks, Normal sinus rhythm, 2007, CC BY, Fig.bot.ri.: anesthesia monitor with different surveillance parameters (top: ECG) Source: Kalumet,2005, CC BY-SA 3.0 Fig. bot.le.: PC-ECG-module / -system (module, PC with software, inkjet printer with withe paper) Source: CardioNetworks, Normal sinus rhythm, 2007, CC BY, C. Frey, D. Tahov

17 Long-term ECG (ambulant ECG / Monitoring)
Holter-Monitoring Event-Recorder Recording mode permanent getriggert, zufällige Stichproben, manuell Saving / storing data entirely all measured data temporally for analytics; permanent just events lead non-invasive surface measurement non-invasive & invasive (subcutan.) Duration of measurement generally 24h (day-night-circle) up to 3 days up to 3 years Indication suspicion of any rhythmic disorders surveillance of cardiac high-risk patients & rehabilitations Fig.: Posibility for electrode positioning by long-term ECG (Holter- Monitoring) Source: Tristaess, BTL holter lead system, 2010, BTL holter lead system, public domain, _lead_system.jpg C. Frey, D. Tahov

18 Long-term ECG: technology
ongoing development on flash storage, battery, radio, information und microtechnology enable: long periods of saving different sensor parameters highly integrated & automated analysis (complex algorithm with microcomputer techn.) wireless transfer of measurement / control data (e.g. low-current technologies) Telemedicine for remote analysis, remote maintenance, emergency management Fig.: Telemedicine in case of Holter-Monitoring (long-term ECG) C. Frey, D. Tahov

19 Safety and harm potentials
resting ECG: just in case of invasive lead irritation, sepsis subcutaneous long-term ECG: immunological reactions/ rejections, fault current (electric shock) cardiac stress test: cause of heavy cardiac disorders  therefore strictly defined abort criteria ECG-Sytsems: maintenance & usage strictly normalized (e.g. EN , MPBetreibV, …) ECG-Systems as electronic medical systems  every time ensure patients’s safety most importaint: galvanic decoupling of the electrodes  ECG-electrodes specially positioned that current is flowing by passing the heart  fault current would go directly throw heart and could cause effects dangerous to life ECG in general: surface detected: no real harm potential , just some allergic reactions / irritations possible caused by electrolytes invasive methods: ( catheter , subcutaneous implants ) general danger/possibility of a operation with open wounds (infection, sepsis) intracardiac catheter possibility of „cause of heavy irregular heartbeat“ (R. KRAMME, Medizintechnik, 2011, Springer, Kap. 10, p. 121©) esophagus EG: could be advisable to sedate some patients (very fearful, children, very sensitive throat) C. Frey, D. Tahov

20 Thanks for your attention

21 Sources Thieme, ViaMedici Bildungsplattform, Lernmodule Physoiologie , R. Kramme , Medizintechnik, Springer, Berlin Heidelberg, 2011, Kap. 10 DocCheck Flexikon, F. Antwerpes, m=web&utm_campaign=DC%2BSearch Bundesministeriums der Justiz und für Verbraucherschutz, „Verordnung über das Errichten, Betreiben und Anwenden von Medizinprodukten (Medizinprodukte-Betreiberverordnung –MPBetreibV)“, 2002 Kantonspital Winterthur, Departement Medizin, „Kardiologie, CH Winterthur, Holter-EKG, Event- Recorder, Telemetrie“, C. Frey, D. Tahov

22 Belastungs-EKG / Ergometrie
elektrokardiografische Veränderung während und nach definierten Belastungsprofilen Messung der Belastung über mechanische geleistete Arbeit versch. Varianten: Fahrrad- / Laufbandergometer mit / ohne Messung von Blutdruck, Sauerstoffaufnahme und Sättigung Wertigkeit: Diagnostik von koronaren Herzerkrankungen Fig.: Ergometriemessplatz mit Fahrradergometer Source: Ergoline C. Frey, D. Tahov

23 Standardableitungen (Ruhe-EKG / klinisches EKG)
differenziert nach: 12 Standardableitungen für Ruhe-EKG Polarität: bipolar  unipolar auch Abwandlungen & Reduzierungen Position: Extremitäten  Brustwand insgesamt 12 (R. Kramme , Medizintechnik, Springer, Berlin Heidelberg, 2011, S.118) nur nichtinvasive Oberflächenableitung jede Abl.pos. andere Information (Signalform) Kombination / Gesamtheit Ableitungen heute: i.d.R. alle 12 gleichzeitig gemessen C. Frey, D. Tahov

24 Elektrokardiogram (EKG)
Source: ©Georg Thieme Verlag KG, 2016, Fig.: animierter Herzquerschnitt mit synchronisiertem Wiggers-Diagramm Vektorschleife als Graph Spannungsänderung über Zeit (∆U/t) Erregungsvorgänge in Abhängigkeit bestimmter Ableitungen erfasst (R. Kramme nur Änderungen ∆U bzw. ∆φ Potential = Erregung Auf- / Figau = Bildung / Rückbildung Verschiebung = Ausbreitung Source: Dr. Jana Official, CG Animated Human Heart cut section showing the atria, ventricles and valves, synced with wiggers diagram, 2016, CC 4.0c C. Frey, D. Tahov