ELECTROCARDIOGRAPHY 1893 Einthoven introduces the term 'electrocardiogram' 1895 Einthoven distinguishes five deflections - P, Q, R, S andT 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 ELECTROCARDIOGRAPHY = methods enabling to register electrical changes caused by heart activity from body surface. ECG - information about: 1. Frequency disorders (changes of HR in SA node or arrhythmias, sick sinus syndrome) 2. Conduction disorders (blocks - SA, AV) 3. Rhythm disorders (ES - supraventricular, ventricular) 4. Disorders of ventricular gradient (relationship between depolarisation and repolarisation: origin - metabolic, haemodynamic, anatomic, physical.. .ischemia, hypertrophy, dilatation, cardiomyopathy, inflammations, changes in electrolytes, drugs...) ELECTRICAL DIPOLE Local currents • Maximal in dipole axis (1) • Zero in the place of the centre (0) SPREADING OF DEPOLARIZATION FRONT ELECTRICAL FIELD OF THE HEART (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 0 0 REGIONAL VECTORS INTEGRAL VECTOR during excitation is changing: •Size of momentary dipoles •Their direction •They are spreading to body surface - ELECTROCARDIOGRAPHY PQ interv. QRS QT 0,16 0,1 0,3 - i_ ■ HR - dependent Atrial depol. Ventricular complex _i i_ (depol.) (repol.) F Goldberger, 1947, aVR, aVL, aVF HEXAAXIAL SYSTEM aVF LIMB LEADS aVR aVL WILSON Bipolar (I, I Unipolar (au GOLDBERG augmented aVR, aVL, aVF 1 aVF Frontal projez L3f vector! CHEST LEADS Horizontal projection of vector! PROJECTION PLANES OF CARDIAC VECTOR AND ECG LEADS E - Einthoven triangle ELECTRICAL AXIS - in frontal plane (R-Q-S) in lead I., II., III. triangle ELECTRICAL AXIS OF THE HEART Summary of all momentary vectors, which form ventricular depolarisation loop. Expresses the direction of ventricular activation. Reflects asymmetry in ventricular wall thickness and the position of the heart in the chest. LEFT DEVIATION, RIGHT DEVIATION i -tl_A— I + i -^^"y— v+ 1 + \ kp^*, / \ V m Normal 12-lead electrocardiogram 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 (T) 5. Rhythm (P-P, R-R) 6. Action potential alterations (ST, T) HEART ISCHEMIA A: exercise angina pectoris B: acute non-Q myocardial infarction C: acute Q myocardial infarction ARRHYTHMIAS DISTURBANCES OF IMPULSE GENERATION OR CONDUCTION RHYTHM: Regular HEART RATE (normal range: 70 - 220 bpm; effect of age) 1. Sinus tachycardia (60 - 100 bpm; exercise) 2. Sinus bradycardia (below 60 bpm; athletes' heart) (nodal rhythm below 40 bpm, ventricular rhythm below 20 bpm) RHYTHM: Irregular sinus respiratory arrhythmia (physiological) extrasystoles (ES) single, coupled (bigeminy, trigeminy) sinus, atrial, junction, ventricular • Sick sinus syndrome • Syncope BLOCKS •SICK SINUS SYNDROM •AV BLOCKS Wenckebach periods (phenomenon) A-V dissociation •BUNDLE BRANCH BLOCK (BBB) - LEFT, RIGHT REENTRY Common mechanism of (paroxysmal) tachycardias, extrasystoles, bigeminy, etc. ES 1. 2. 66 Loops most often at the level of AV junction Determinants of re-entry: Proper dimension of the loop Proper timing of the trigger ES 1. 2. 3. Double pathway Diverging and converging of excitation pathways Unidirectional block Long refractory period Slowed conduction Reentry TACHYARYTHMIA • SINUS TACHYCARDIA • PAROXYSMAL TACHYCARDIA (supraventricular, ventricular) • FLUTTER (>250/min; atrial) • FIBRILLATION (>600/bpm; atrial, ventricular; breakdown of electrical homogeneity) ATRIAL FLUTTER vi »vi Iii Frequency 250 - 600/bpm Atrioventricular block n.T ATRIAL FIBRILLATION VENTRICULAR FIBRILLATION oVR VI V4 V2 V5 m ovr V3 V6 flHVTHM STRtPi I] SS m/mo; 1 CTv/mY C 00000-0000 [7-4 Frequency above 600/bpm