(VII.) Electrocardiography Physiology Electrocardiography Definition: the process of recording the electrical activity of the heart Keywords •Specialized excitatory and conductive system of the heart •equipment for ECG recording •unipolar and bipolar leads •bipolar limb leads; unipolar limb leds; unipolar chest leads •heart vector, electrical axis of the heart Purkynje fibers Sinoatrial node (SA) internodal pathways Atrioventricular node (AV) Bundle of His Bundle branches SA node atrial muscle AV node bundle of His bundle branches Purkynje fibers ventricular muscle Specialized excitatory and conductive system of the heart Electric dipole 7354523 Electrode: records electrical potential (Φ) Electric lead: connection of two electrodes •Recordes voltage between electrodes •Voltage: difference between el. potentials (V= Φ1- Φ2) • electrode lead Φ1 Φ2 Einthoven´s triangle (standard - limb, bipolar leads) I II III R L F Bipolar leads: both electrodes are active (variable potential en electrodes) Augmented leads (Goldberger´s, limb unipolar leads) aVF aVL avR R L F Unipolar leads: one electrode is active (variable el. potential) and the second one is indifferent (constant el. potential) Active electrode is always positive Chest leads Bez názvu-2 1 2 3 4 5 6 Wilson´s cental terminal Chest electrode: connection of chest electrode and Wilson´s central terminal Unipolar leads: chest electrodes are active (positive) and Wilson´s central terminal is indifferent (el. potential 0 mV, electrically centre of the heart) chest electrode Leads acording to Cabrera I aVF II III aVR aVL – + – + + + + + – – – – 120° 90° 60° 30° 0° -30° + - + R L F aVR - + - + aVL aVF – – + + – I III II ECG description name Norm P wave 80 ms Interval PQ (PR) 120-200 ms Segment PQ (PR) 50-120 ms Q - QRS 80-100ms R - S - segment ST 80-120 ms Interval QT >= 420ms wave T 160 ms P R T Q S P wave PQ interval PQ segment QRS complex ST segment T wave QT interval Electrical axis of heart Untitled-1 1. QRS of I,II or III leads 2. Sumation of QRS complex I II III Q = -1 Q = - 1 Q = 0 R = 5 R = 6 R = 4 S = -1 S = 0 S = 0 3 5 4 osa + R L F – – + + – I III II 3 5 3. Drawing in triangle: e.g.: combination results from I and II Physiological interval: -30° to +110° Average deviation of QRS complex in each lead Diagnostic use of ECG Arrhythmia: irregular heart beat Atrial fibrillation (absence of P, „jagged“ isolinia, irregular RR, HR 80 – 180 bpm) Ventricular fibrillation (heart cannot pump, brain damage after 3 – 5 min) https://upload.wikimedia.org/wikipedia/commons/thumb/6/64/Afib_ecg.jpg/400px-Afib_ecg.jpg http://www.qureshiuniversity.com/Ventricular%20Fibrillation.gif https://ekg.academy/ekgtracings/313.gif Fibrillation: is the rapid, irregular, and unsynchronized activity of cardiac muscle fibers Atrial fibrillation physiology AV block I. degree Atrioventricular block: conduction between the atria and ventricles of the heart is impaired AV block II. degree AV block III. degree P P P P P P Myocardial ischemia, heart-attack A B (ST elevation) hyperkalaemia Diagnostic use of ECG AEE89E4D 24-hour monitoring of ECG (Holter) Diagnostic use of ECG