MUNI MED ELECTROCARDIOGRAPHY ARRHYTHMIAS 1 Marie Nováková, Department of Physiology ELECTROCARDIOGRAPHY = methods enabling to register electrical changes caused by heart activity from body surface. 1893 Einthoven introduces the term 'electrocardiogram' 1895 Einthoven distinguishes five deflections - P, Q, R, S and T 1902 Einthoven publishes the first electrocardiogram 1905 Einthoven starts transmitting electrocardiograms from the hospital to his laboratory 1.5 km away via telephone cable 1924 the Nobel prize Willem Einthoven 1860- 1927 2 Marie Nováková, Department of Physiology MUNI ED ELECTRICAL DIPOLE stationary in homogenously conducting environment Local currents • Maximal in the dipole axis (1) • Zero in the centre (0) 1 3 Marie Nováková, Department of Physiology MUNI MED SPREADING OF DEPOLARIZATION FRONT ELECTRICAL FIELD OF THE HEART (can be described by a vector) • Consists of sum of momentary dipoles on the depolarization front • Its size is a function of number of dipoles and steepness of boundary line • Direction from depolarized (-) to (re)polarized (+) area REGIONAL VECTORS INTEGRAL VECTOR during excitation is changing: • Size of momentary dipoles • Their direction • They are spreading to body surface - ELECTROCARDIOGRAPHY 4 Marie Nováková, Department of Physiology Isoelectric segments T wave concordance Frequency dependence Conduction system -gradient of automaticity (p) <§>!®KD PQ interval 0.16 QRS 0,1 QT (L3 Atrial depolarisation { Ventricular complex (depolarisation) (repolarisation) HR - dependent 6 Marie Nováková, Department of Physiology MUNI ED ECG brings information about: 1. Frequency (changes of HR in SA node or arrhythmias, sick sinus syndrome) 2. Conduction (blocks - SA, AV) 3. Rhythm (ES - supraventricular, ventricular) 4. Ventricular gradient (relationship between depolarization and repolarization: origin - metabolic, hemodynamic, anatomic, physical... examples - ischemia, hypertrophy, dilatation, cardiomyopathy, inflammations, changes in electrolytes, drugs...) MUNI 7 Marie Nováková, Department of Physiology .. r n 3D LOOPS OF ELECTRICAL AXIS F - frontal plane S - sagittal plane H - horizontal plane 0 - electric center of the heart P - atrial depolarization QRS - ventricular depolarization T - ventricular repolarization 8 Marie Nováková, Department of Physiology MUNI MED 2D PROJECTION OF HEART AXIS ID PROJECTION OF HEART AXIS Projection on the chest surface into frontal plane (2D) And its projection to line (ID), axis of the I. ECG lead in time E - Einthoven triangle 10 Marie Nováková, Department of Physiology 100% 50% Einthoven, 1913 I, n, III 87% L Wilson, 1934, VR, VL, VF L 11 Marie Nováková, Department of Physiology Goldberger, 1947, aVR, aVL, aVF MUNI ED HEXAAXIAL SYSTEM 14 Marie Nováková, Department of Physiology MUNI MED LIMB LEADS aVR Frontal projection of vector! aVL WILSON GOLDBERGER augmented Bipolární (I, II, III) - standardní Unipolar (augmented) aVR, aVL, aVF 15 Marie Nováková, Department of Physiology MUNI ED CHEST LEADS Horizontal projection of vector! EL 16 Marie Nováková, Department of Physiology MUNI ED PROJECTION PLANES OF CARDIAC VECTOR and ECG LEADS Frontal plane Limb leads I., II., IN.,aVR, aVL, aVF Horizontal plane V1 - V6 Both planes are shifted into the level of electrical center of the heart (0) E - Einthoven triangle V1 V2 V3 17 Marie Nováková, Department of Physiology MUNI ED ELECTRICAL AXIS OF THE HEART Summary of all momentary vectors, which form ventricular depolarisation loop. It expresses the direction of ventricular activation. It reflects the asymmetry in ventricular wall thickness and the position of the heart in the chest. 19 Marie Nováková, Department of Physiology MUNI MED ELECTRICAL AXIS - in the frontal plane (R-Q-S) in lead I., II., • equilateral Einthoven triangle Terminology 180° Right deviat Left deviation Physiological range O o o o R S S 20 Marie Nováková, Department of Physiology MUNI ED LEFT DEVIATION, RIGHT DEVIATION Physiological 12-lead electrocardiogram 22 Marie Nováková, Department of Physiology MUNI MED ECG - information about: 1. Magnitude and position of the heart (electrical axis) 2. Site of impulse origin (P, QRS) 3. Conduction path (P-Q, QRS) 4. Impulse regression - repolarization (T) 5. Rhythm (P-P, R-R) 6. Action potential alterations (ST, T) 7. Effect of drugs, remedies, ion composition changes, 23 Marie Nováková, Department of Physiology MUNI ED HYPER K+ HYPO Ca 2+ 24 Marie Nováková, Department of Physiology Štejfa et al: Základy elektrokardiografie, 1991 HYPER Ca 2+ MUNI ED ARRHYTHMIAS disturbance of impulse generation or disturbance of impulse conduction 25 Marie Nováková, Department of Physiology MUNI MED RESPIRATORY (SINUS) ARRHYTHMIA 1847, Ludwig, ECG and breathing of dog - respiratory sinus arrhythmia Detectable already during prenatal life. Present in numerous species in animal kingdom - in all vertebrates. Physiological meaning ???? STABILISATION OF MEAN BP (protection against mechanical effect of intrathoracic pressure on arterial BP) Key effect of parasympathetic NS (decrease of its tonus), sympathetic NS only modulates!!! MECHANISMS: 1) CENTRAL 2) REFLEXES FROM LUNGS 3) REFLEXES FROM BARORECEPTORS 4) REFLEXES FROM RECEPTORS IN THE RIGHT ATRIUM 5) LOCAL EFFECTS ON SA NODE 6) EFFECT OF OSCILLATIONS OF pH, pa02, paC02 26 Marie Nováková, Department of Physiology Central mechanisms Central generator of RSA Respiratory neurons in medulla oblongata hyperpolarise preganglionic vagal neurons Vagal tonus decreases during inspiration - HR increases Lung reflexes - inflation reflexes Stimulation of vagal stretch-receptors during inspiration supresses inspiratory centre and also cardio-inhibitory centre in medulla oblongata 27 Marie Nováková, Department of Physiology MUNI MED Reflexes from baroreceptors Diverse opinions about the effect of arterial baroreceptors on RSA Fluctuation of sensitivity of baroreceptors during respiratory cycle Reflexes from receptors in the right atrium Bainbridge, 1915 Reflex increase of HR during atria stretching Applicable in explanted (denerved) heart MUNI 28 Marie Nováková, Department of Physiology » « i- n Local effects on SA node Stretching of SA node causes faster spontaneous depolarisation Effect of mechanosensitive chloride channels Changes of SAnode perfusion (a. centralis) and possible compression of SA node by expanding lungs Effect of pH, pa02 and paC02 oscillations Oscillatory activity of peripheral chemoreceptors contributes to formation of RSA and increases its amplitude 29 Marie Nováková, Department of Physiology MUNI MED ARRHYTHMIAS = disturbance of impulse generation or conduction Description of ECG curve: RAFO RHYTHM, ACTION, FREQUENCY, („Osa" =) AXIS: Rhythm - sinus or ectopic rhythms: nodal (below 40 bpm), ventricular (below 20 bpm) Action regular vs. irregular : sinus respiratory arrhytmia (physiological) sick sinus syndrom extrasystoles (ES) single or coupled (bigeminia, trigeminia), according to site or origin - sinus, atrial, junction, ventricular Regular 1) Resting HR range: 60-100 bpm; effect of age) 2) Sinus tachycardia (over 100 bpm; exercise; aging) 3) Sinus bradycardia (below 60 bpm; athletes' heart) 30 Marie Nováková, Department of Physiology MUNI MED RHYTHM SITE OF ORIGIN SINUS ATRIA JUNCTION VENTRICLES P+ p- (p-) (p-) >P wave polarity >PQ (QP) interval(physiological PQinterval: 0.12 - 0.2 s) 31 Marie Nováková, Department of Physiology MUNI ED CONDUCTION DISTURBANCES (BLOCKS) • Sick sinus syndrom • AV blocks • bundle branch block (BBB) - left, right 1° PQ>0.2sec n° Wenckebach periodes LBBB RBBB 32 Marie Nováková, Department of Physiology nr A-V disociation MUNI ED REENTRY Common mechanism of (paroxysmal) tachycardias, extrasystoles, bigeminy, etc. • Double pathway Diverging and converging of excitation pathways • Unidirectional block 1. Long refractory period 2. Slowed conduction 3. Reentry 33 Marie Nováková, Department of Physiology 1. 2. Loops most often at the level of AV junction Determinants of re-entry: Proper dimension of the loop Proper timing of the trigger ES MUNI ED TACHYARYTMIAS • SINUS TACHYCARDIA • PAROXYSMAL TACHYCARDIA (supraventricular, ventricular) • FLUTTER (>250/min; atrial) • FIBRILLATION (>600/min; atrial, ventricular; breakdown of electrical homogeneity) MUNI 34 Marie Nováková, Department of Physiology » « i- n ATRIAL FLUTTER 35 Marie Nováková, Department of Physiology Frequency 250 - 600/min Atrioventricular block n:l MUNI MED ATRIAL FIBRILLATION 36 Marie Nováková, Department of Physiology Irregular Ventricular rhythm + f-waves VENTRICULAR FIBRILLATION aVR VI V4 II V2 V5 m V3 V6 flHVTHM STRiPi H 25 (mi/mo; 1 cm/mV c ooooo-oooo rr-4 37 Marie Nováková, Department of Physiology Frequency above 600/min, LETHAL HEART ISCHEMIA A B A: exercise angina pectoris B: acute non-Q myocardial infarction C: acute Q myocardial infarction 38 Marie Nováková, Department of Physiology ANTIARRHYTHMICS • BLOCKERS OF Na CHANNEL - prolong inactivation of INa, e.g. refracterity, „blocking" fast ways • BLOCKERS OF Ca CHANNELS - „blocking" fast ways • BLOCKERS OF K CHANNEL - prolonging refractory period • ß-SYMPATOLYTICS - slowing HR MUNI 39 Marie Nováková, Department of Physiology » « i- n Schémata a animace zpracovalo Servisní středisko pro e-learning na MU http ://is. m u n i. cz/stech/ CZ. 1.07/2.2.00/28.0041 Centrum interaktivních a multimediálních studijních opor pro inovaci výuky a efektivní učení evropský sociální ■Wfr MINISTERSTVO ŠKOLSTVÍ. ■-■K -. -■ - r ir y. fond V CR EVROPSKÁ unie .'i wěžě a tělovýchovy INVESTICE DO ROZVOJE VZDĚLÁVÁNÍ 40 Marie Nováková, Department of Physiology MUNI ED