1,ELECTROCARDIOGRAPHY,Bian Bo Tianjin Medical University General Hospital,2,Focus of ECG,Rate and rhythm Ishemia Hyperthrophy others,3,Questions to answer in order to identify an unknown arrhythmia:,1. Is the rate slow (100 bpm)? Slow Suggests sinus bradycardia, sinus arrest, or conduction block Fast Suggests increased/abnormal automaticity or reentry 2. Is the rhythm irregular? Irregular Suggests atrial fibrillation, 2nd degree AV block, multifocal atrial tachycardia, or atrial flutter with variable AV block 3. Is the QRS complex narrow or wide? Narrow Rhythm must originate from the AV node or above Wide Rhythm may originate from anywhere,4,Questions to answer in order to identify an unknown arrhythmia:,4. Are there P waves? Absent P waves Suggests atrial fibrillation, ventricular tachycardia, or rhythms originating from the AV node 5. What is the relationship between the P waves and QRS complexes? More P waves than QRS complexes Suggests 2nd or 3rd degree AV block More QRS complexes than P waves Suggests an accelerated junctional or ventricular rhythm 6. Is the onset/termination of the rhythm abrupt or gradual? Abrupt Suggests reentrant rhythm Gradual Suggests altered automaticity,5,Steps to Interpreting an ECG,Rate Rhythm Axis Intervals (PR, QRS, QTc) Amplitudes, Morphology(P, QRS) ST segments T waves Q waves,6,Rate - Paper,What are the time intervals between lines?,0.2 sec,200 msec,0.04 sec,40 msec,Normal paper speed is 25 mm/sec,7,Steps to Interpreting an ECG,Rate Rhythm Axis Intervals (PR, QRS, QTc) Amlitudes, Morphology(P, QRS) ST segments T waves Q waves,8,Normal Sinus rhythm features,(1) Every P wave is following by a QRS complex; (2) P wave is upright in lead I, II, aVF, V4-V6, inverse in aVR; Same morphology (3) P-R interval: 0.12-0.20sec (4) Normal rate is 60-100 beats/min,9,Normal Sinus rhythm,10,11,12,First Degree A-V Block,Prolonged P-R interval: P-R interval 0.20sec. in adults (varies with heart rate),13,1st Degree AV Block,EKG Characteristics: Prolongation of the PR interval, which is constant All P waves are conducted,14,Second Degree A-V Block,(1) Mobitz type I (Wenckebach phenomenon). The pattern is a progressive prolongation of the P-R interval until a beat is dropped. The first beat after the pause has the shortest P-R interval, which may or may not be normal.,15,16,2nd Degree AV Block,Type 1 (Wenckebach),EKG Characteristics: Progressive prolongation of the PR interval until a P wave is not conducted. As the PR interval prolongs, the RR interval actually shortens,EKG Characteristics: Constant PR interval with intermittent failure to conduct,Type 2,17,(2) Mobitz type II,There is a fixed numerical relationship between atrial and ventricular impulses, which may be 2:1 (2 atrial beats to one ventricular beat) or 3:1 or 4:1.,18,19,Third Degree A-V Block (Complete heart block),The atrial and the ventricular rhythms are absolutely independent of one another. (There is no relationship of P to QRS.) (2) atrial rate ventricular rate. QRS is 0.12 sec. or greater.,20,3rd Degree (Complete) AV Block,EKG Characteristics: No relationship between P waves and QRS complexes Relatively constant PP intervals and RR intervals Greater number of P waves than QRS complexes,21,Steps to Interpreting an ECG,Rate Rhythm Axis and Intervals (PR, QRS, QTc) Amlitudes, Morphology(P, QRS) ST segments T waves Q waves,22,The QRS Axis,By near-consensus, the normal QRS axis is defined as ranging from -30 to +90. -30 to -90 is referred to as a left axis deviation (LAD) +90 to +180 is referred to as a right axis deviation (RAD),23,Intervals,Normal PR 0.12 0.20 QRS 0.12 QT 0.44,24,Steps to Interpreting an ECG,Rate Rhythm Axis and Intervals (PR, QRS, QTc) Amplitudes, Morphology(P, QRS) ST segments T waves Q waves,25,tall P waves in lead II (right atrial abnormality）,26,an abnormally large terminal negative component of the P wave in lead V1 (left atrial abnormality),27,LVH “S V1+ R V5 or V6 35mm”,28,If the initial component of a biphasic P wave (inV1) is largest, this is Right atrial enlargement. Positive component of the P wave in lead V1 or V2 1.5mm If the height of the P wave in any of the limb leads exceeds 2.5mm(p pulmonale), suspect Right Atrial enlargement,RIGHT ATRIAL ABNORMALITY,29,LEFT ATRIAL ABNORMALITY,Prolonged P wave duration of 110 msec in lead II Prominent notching of the P wave, usually most obvious in lead II, with an interval between the notches of 40 msec (p mitrale) Increased duration and depth of the terminal negative portion of the P wave in lead V1 (the P terminal force) so that the area subtended by it exceeds 0.04 mm-sec,30,Steps to Interpreting an ECG,Rate Rhythm Axis and Intervals (PR, QRS, QTc) Amlitudes, Morphology(P, QRS) ST segments and T waves Q waves,31,Types Of ST Segment Depression,32,The QS complexes, resolving ST segment elevation and T wave inversions in V1-2 are evidence for a fully evolved anteroseptal MI. The inverted T waves in V3-5,