10 Index Subject Introduction Principles of ECG ECG graph Comment on ECG Rhythm Rate Axis P wave P-R interval QRS complex S-T segment T wave Q-T interval U wave Abnormal ECG Chamber enlargement Bundle branch block Coronary Ischemia Heart block Others How to interpret an ECG How to diagnose an ECG Page 1 5 12 13 13 14 15 18 20 22 25 29 29 29 30 30 33 35 37 40 41 42 Simple ECG Innovation Introduction The electrocardiogram (ECG or EKG) is a special graph that represents the electrical activity of the heart from one instant to the next. Thus, the ECG provides a time-voltage chart of the heartbeat. For many patients, this test is a key component of clinical diagnosis and management in both inpatient and outpatient settings. The device used to obtain and display the conventional ECG is called the electrocardiograph, or ECG machine. It records cardiac electrical currents (voltages or potentials) by means of conductive electrodes selectively positioned on the surface of the body. This book is devoted to explaining the basis of the normal ECG and then examining the major conditions that cause abnormal depolarization (P and QRS) and repolarization (ST-T and U) patterns. Why is the ECG so clinically useful ? The ECG is one of the most versatile and inexpensive of clinical tests. Its utility derives from careful clinical and experimental studies over more than a century showing the following: It is the essential initial clinical test for diagnosing dangerous cardiac electrical disturbances related to conduction abnormalities in the AV junction and bundle branch system and to brady- and tachyarrhythmias. It often provides immediately available information about clinically important mechanical and metabolic problems, not just about primary abnormalities of electrical function. Examples include myocardial ischemia/infarction, electrolyte disorders, and drug toxicity, as well as hypertrophy and other types of chamber overload. It may provide clues that allow you to forecast preventable catastrophies. A good example is a very long QT(U) pattern preceding sudden cardiac arrest due to torsades de pointes. Physiological anatomy of the heart : The heart is a hollow muscular pump situated in the left side of the thoracic cavity partly behind the sternum, consisting of 4 chambers : 2 atria and 2 ventricles. The heart is covered externally by epicardium ( which is the visceral layer of the pericardial sac). The inside cavity of the heart lined by endothelial layer called the endocardium. An intermediate muscular layer lying in between the epicardium & endocardium known as the myocardium. Page | 1 Simple ECG Innovation Physiology of Cardiac Muscle : The heart is composed of three major types of cardiac muscle: atrial muscle, ventricular muscle, and specialized excitatory and conductive muscle fibers. The atrial and ventricular types of muscle contract in much the same way as skeletal muscle, except that the duration of contraction is much longer. Conversely, the specialized excitatory and conductive fibers contract only feebly because they contain few contractile fibrils; instead, they exhibit either automatic rhythmical electrical discharge in the form of action potentials or conduction of the action potentials through the heart, providing an excitatory system that controls the rhythmical beating of the heart. The cardiac muscle has certain special properties which are : 1. Rhythmicity: ability of the heart to beat regularly at constant rate. 2. Contractility: ability of the heart to contract and push blood into circulation. 3. Excitability: ability of the cardiac muscle to respond to an adequate stimulus contraction. 4. Conductivity: ability of the cardiac muscle to conduct excitation wave from one part of the heart to another. In EKG study we are concerned with study of Rhythmicity and conductivity of the cardiac muscle. we will review a few simple principles of the heart’s electrical properties. The central function of the heart is to contract rhythmically and pump blood to the lungs for oxygenation and then to pump this oxygen-enriched blood into the general (systemic) circulation. The signal for cardiac contraction is the spread of electrical currents through the heart muscle. These currents are produced both by pacemaker cells and specialized conduction tissue within the heart and by the working heart muscle itself. Pacemaker cells are like tiny clocks (technically called oscillators) that repetitively generate electrical stimuli. The other heart cells, both specialized conduction tissue and working heart muscle, are like cables that transmit these electrical signals. Electrical Activation of the Heart : In simplest terms, therefore, the heart can be thought of as an electrically timed pump. The electrical “wiring” is outlined in Figure. Normally, the signal for heartbeat initiation starts in the sinus or sinoatrial (SA) node. This node is located in the right atrium near the opening of the superior vena cava. Page | 2 Simple ECG Innovation The SA node is a small collection of specialized cells capable of automatically generating an electrical stimulus (spark-like signal) and functions as the normal pacemaker of the heart. From the sinus node, this stimulus spreads first through the right atrium and then into the left atrium. Electrical stimulation of the right and left atria signals the atria to contract and pump blood simultaneously through the tricuspid and mitral valves into the right and left ventricles. The electrical stimulus then reaches specialized conduction tissues in the atrioventricular (AV) junction. The AV junction, which acts as an electrical “relay” connecting the atria and ventricles, is located at the base of the interatrial septum and extends into the interventricular septum. The upper (proximal) part of the AV junction is the AV node. (In some texts, the terms AV node and AV junction are used synonymously.) The lower (distal) part of the AV junction is called the bundle of His. The bundle of His then divides into two main branches: the right bundle branch, which distributes the stimulus to the right ventricle, and the left bundle branch, which distributes the stimulus to the left ventricle. The electrical signal then spreads simultaneously down the left and right bundle branches into the ventricular myocardium (ventricular muscle) by way of specialized conducting cells called Purkinje fibers located in the subendocardial layer (inside rim) of the ventricles. From the final branches of the Purkinje fibers, the electrical signal spreads through myocardial muscle toward the epicardium (outer rim). The His bundle, its branches, and their subdivisions are referred to collectively as HisPurkinje system. Normally, the AV node and His-Purkinje system form the only electrical connection between the atria and the ventricles (unless a bypass tract is present). Disruption of conduction over these structures will produce AV heart block. Just as the spread of electrical stimuli through the atria leads to atrial contraction, so the spread of stimuli through the ventricles leads to ventricular contraction, with pumping of blood to the lungs and into the general circulation. The initiation of cardiac contraction by electrical stimulation is referred to as electromechanical coupling. A key part of this contractile mechanism is the release of calcium ions inside the atrial and ventricular heart muscle cells, which is triggered by the spread of electrical activation. This process links electrical and mechanical function. The ECG is capable of recording only relatively large currents produced by the mass of working (pumping) heart muscle. The much smaller amplitude signals generated by the sinus node and AV node are invisible with clinical recordings. Depolarization of the His bundle area can only be recorded from inside the heart during specialized cardiac electrophysiologic (EP) studies. Heart has two types of action Mechanical: Contraction &relaxation Electrical: Depolarization & repolarization Page | 3 Simple ECG Innovation Blood supply of the heart through the coronary arteries Anatomy of the coronary arteries The left Coronary artery: It arises from the left sinus of Valsalva and passes forwards & to the left in the atrioventricular groove for a short distance and then divides into two branches: 1. The left anterior descending artery: it passes downwards in the anterior interventricular groove to the apex of the heart & then turns backwards to anastomse with the posterior descending artery. 2. The circumflex artery: it continues its course in the left atrioventricular groove to anastomse with the right coronary. It gives several obtuse marginal branches. The right Coronary artery: It arises from the (right sinus) of Valsalva and runs in the right atrioventricular groove to the posterior surface of the heart to anastomse with circumflex artery. In the back of the heart it gives the (posterior descending artery which runs downwards, in the posterior interventricular groove, to anastomose with the anterior descending artery. Pattern of coronary supply Balanced circulation: The left coronary artery supplies left atrium, left ventricle & anterior part of the interventricular septum. While the right coronary artery supplies right atrium, right ventricle & posterior part of the interventricular septum. Right dominance: The right coronary supplies also the posterior part of the left ventricle. Left dominance: The left coronary supplies also the posterior part of the septum & the posterior wall of the right ventricle. Page | 4 Simple ECG Innovation Principles of ECG ECG Electrocardiogram Electro Cardio graph Gram ECG relaxed waves << ECG << ECG ECG << Lead positive wave Lead negative wave Lead biphasic wave negative right ventricle thickness of the muscle wave left ventricle right ventricle left ventricle Page | 5 << << ECG ECG << ECG Positive ECG Wave wave thickness of muscle Simple ECG Innovation lead wave left ventricular hypertrophy ECG heart Atria Ventricles septum left ventricle left ventricle ventricle right ventricle ventricle right ventricle ventricle septum septum right left septum left bundle branch right bundle septum septum ECG ECG waves positive wave << ECG negative wave << ECG Lead Lead right V1 left septum chest lead positive wave Page | 6 septum thickness of muscle wave r wave V6 chest lead negative wave Simple ECG Innovation septum right ventricle right ventricles V1 bundle branch thickness of muscle wave q wave septum waves septum chest lead cavity endocardium positive wave right ventricle thickness of muscle wave r wave V6 chest lead negative wave right ventricle thickness of muscle wave q wave waves right right right ventricle septum wave ECG septum small r wave in V1 wave septum q wave ventricle V6 ventricle right ventricle septum left ventricle waves left ventricle right ventricle V1 Page | 7 septum chest lead Simple ECG Innovation endocardium bundle branch cavity negative wave left ventricle thickness of muscle wave S wave V6 chest lead positive wave left ventricle thickness of muscle wave R wave chest leads r wave right ventricle V1 V1 right ventricular pattern S left ventricle V6 V6 s wave left ventricular pattern Five waves complex QRS P T wave Atrial depolarization P wave ventricular QRS complex depolarization ventricular T wave repolarization Page | 8 Simple ECG Innovation Multiple P waves before QRS ventricle absent P wave Atrial depolarization P wave atrium P wave P wave atrium P wave Atrium contraction atrium contraction atrium Atrium P wave ventricular depolarization QRS complex ventricle QRS ventricle ventricular tachycardia ventricle deformed QRS << ventricle arrhythmia QRS ventricle T wave Ventricular repolarization atrial depolarization Atrial contraction ventricular contraction ventricular depolarization ventricular relaxation ventricular repolarization Atrial repolarization which is small and masked by QRS complex QRS QRS A.V. node ECG PR interval PR interval A.V. nodal conduction A.V. node PR interval A.V. nodal conduction PR interval A.V. nodal block heart block Page | 9 Simple ECG Innovation ECG 12 leads ECG Limb leads Chest leads Limb leads Bipolar Unipolar : both upper limbs right upper limb and left lower limb left upper limb and left lower limb right arm left arm left foot Bipolar limb leads L1 L2 L3 unipolar limb leads augmented voltage aVR augmented voltage aVL augmented voltage aVF Chest leads precordial leads chest wall 6 chest leads V1, V2, V3, V4, V5, and V6 ECG ECG ECG 6 leads chest leads Right 4 space adjacent to the sternum : V1 Left 4th space adjacent to the sternum : V2 th Page | 10 Simple ECG Innovation Between V2 and V4 Left 5 space mid clavicular line : at same horizontal level of V4 but at anterior axillary line at the same horizontal level of V4 but at mid axillary line : th Dextrocardia V1 and V2 V3 V4 V5 V6 chest leads as V3 but on right side V3R as V4 but on right side : V4R as V5 but on right side : V5R as V6 but on right side : V6R heart section V1 and V2 Right ventricle V5 and V6 left ventricle V3 and V4 Septum << ischemia right ventricle ischemia left ventricle ischemia V5 and V6 leads of ECG topographism Wall of the heart Leads Wall II - III - aVF Inferior I - aVL High lateral wall V1 - V2 Septal ( antro-septal) V3 - V4 Strict anterior V5 - V6 Low lateral V1 - V3R V6R RV free wall Louis Leads Atrial Activity N.B. posterior wall potentials are recorded in the anterior leads as a mirror image for waves provided to be drawn in the posterior leads because posterior leads are technically difficult to be made. wall Page | artery 11 topographism Leads Simple ECG Innovation ECG Graph paper ECG 5X5 voltage duration duration ECG 25 mm 0.04 0.20 0.04 X 5 1/5 300 60 X 1500 Standard 5 60 X 2 big squares 1 mV signal 10mm 1mV Caliberation 25 Voltage ECG half caliberation one big square waves double caliberation 4 big squares Page | 12 Simple ECG Innovation Comment on ECG ECG 1. Rhythm 2. Rate 3. Axis 4. P wave 5. P-R interval 6. QRS complex 7. S-T segment 8. T wave 9. Q-T interval 10. U wave 1. Rhythm ECG Rhythm Sinus or not Regular or irregular complex S R sinus P wave is followed by QRS complex QRS complex Q R S Q ventricular complex P wave regular Numbers of big squares between each R-R interval are equal << R-R interval R-R interval rhythm is irregular Atrial fibrillation extra systole irregular rhythm marked irregularity occasional irregularity long strip Page | 13 rhythm Simple ECG Innovation 3 lead long strip R-R interval 2. Rate rate normal beat per minute << 90 60 tachyarrhythmia << 100 bradycardia << 60 R-R interval rate rhythm << regular rhythm 1500 300 = heart rate R-R interval Irregular << rhythm rate R-R interval 300 average mean 300 15 30 15 5 10 10 30/3 10 RR interval 9 3 100 beats per min. 300/3 << Page | 14 300 3 9/3 rate Simple ECG Innovation 2 3 Lead 2 6 30 30 10 rate heart rate 50 10 X 5 30 15 rhythm rate ECG 3. Axis aVF lead lead aVF QRS Page | 15 Simple ECG Innovation QRS Positive << QRS Lead lead positive QRS normal lead positive << QRS aVF lead Positive << QRS Axis is normal Axis is normal Lead negative << QRS aVF lead positive << QRS QRS QRS right axis deviation QRS positive lead Page | 16 Simple ECG Innovation negative lead left axis deviation lead Normal positive Negative aVF left axis lead aVF Positive Lead lead deviation negative positive aVF right axis deviation Lead lead axis deviation Left axis deviation right axis deviation Normal axis deviation normal axis deviation Normal axis is not deviated right and left axis deviation Causes of right axis deviation Children Tall thin adults Right ventricular hypertrophy Chronic lung disease Anterolateral myocardial infarction Pulmonary embolus Atrial septal defect Ventricular septal defect Causes of left axis deviation Q waves of inferior MI Artificial cardiac pacing Left ventricular hypertrophy Hyperkalemia Ostium primum ASD Injection of contrast into left coronary artery Note : pt. of left ventricular hypertrophy not usually has LAD Page | 17 Simple ECG Innovation 4. P wave Atrial depolarization 1st positive wave before complex Lead II and V1 Less than (2.5 X 2.5 ) small squares Width (duration ) : = ˂ 2.5 small square ( ˂ 0.12 sec. ). Height (amplitude) : = ˂ 2.5 small square ( ˂ 2.5 mm). P wave Present Absent Lead II and V1 less than 2.5 X 2.5 small squares left atrial enlargement P wave Normal Abnormal << abnormal << P wave P mitral M shaped 2.5 P wave left atrial strain 1 P pulmonale Peaked and high voltage P 2 2.5 P wave right atrial strain Pulmonale Mitral 3 P wave 2.5 Biphasic 4 P wave negative positive Mitral Page | 18 Normal Simple ECG Innovation V1 biphasic V1 P wave right atrium left atrium activate SA node right atrium Left atrium activate right SA node wave right atrium wave Left atrium P wave biphasic Positive negative negative Positive right atrial strain (enlargement) left atrial strain ( enlargement) Lead absent << P wave irregular << rhythm AF regular << rhythm P wave QRS QRS wide << QRS Page | 19 Simple ECG Innovation wide 3 QRS 3 3 Wide QRS Ventricular tachycardia Ventricular fibrillation narrow << QRS supra ventricular tachycardia Nodal rhythm rate << supra ventricular tachycardia Nodal rhythm Sawtooth appearance atrial flutter 5. P-R interval AV conduction (physiological delay) Lead II 3-5 small squares (0.12 - 0.20 sec. ) PR QRS complex P P-R interval 3 - 5 small squares Normal 5 small squares Prolonged Page | 20 Simple ECG Innovation 3 small squares Shortened prolonged << P-R interval << P-R interval 1 just prolongation of P-R interval First degree heart block << P-R interval 2 beat progressive prolongation of P-R interval until dropped beat Wenckebach phenomena peace maker << << peace maker not fixed << P-R interval 3 ventricles atria atrio-ventricular dissociation ventricle S.A. node atrium variable P-R P-R interval QRS complex P wave complete heart block Page | 21 Simple ECG Innovation shortened << P-R interval Wolff-Parkinson-White ventricle A.V. node impulse delay atria impulses accessory pathway P-R interval normal pathway 3 small squares wide QRS complex << Wolff-Parkinson-White type B type A QRS complex waves complex Criteria Short P-R interval 1 Wide QRS complex 2 Delta wave 3 Wolff-Parkinson-White V1 right ventricular pattern left ventricular pattern 6. QRS complex Ventricular depolarization T P complex Right ventricle (V1,2) Left ventricle (V5,6) first negative wave in the complex << Q wave first positive wave in the complex << R wave following R the negative wave following R << S wave Q wave first negative wave in the complex Page | 22 Simple ECG Innovation one small square R wave pathological Q Deep and wide ECG myocardial infarction Q wave infraction Non Q wave infarction Q wave ( deep and wide ) anterior infarction << V1,2 septal infarction << V3,4 Lateral infarction << V5,6 antro-septal infarction << V1,2,3,4 Extensive anterior infarction << V1,2,3,4,5 Normal ECG aVL pathological Q pathological Q pathological Q the cavity of the heart << lead of aVR Q wave << Normally aVR dextrocardia << pathological Q S wave V1 r wave pathological Q ( deep and wide ) V1 Lead aVR and V1 pathological Q Page | 23 Simple ECG Innovation anterior V2 V1 << infarction V1 r wave is too small to be detected pathological Q R wave first positive wave in complex voltage criteria only positive in the complex big squares 3 small squares Vent. Tachycardia RBBB or LBBB small squares wide complex S wave first negative wave following R Chest leads V6 S and R wave V1 S R wave principles V1 right ventricle r V6 left ventricle V5 V1 R S in V2 is ˃ S in V1 S progress from V2 to V5 S usually absent in V6 5 mm small 5 mm capital s r << Waves capital and small wave amplitude << wave amplitude << Small R, S << capital Not every “QRS” contain “Q”,”R” & “S”, but it may be : Monophasic (R or QS) Page | 24 Simple ECG Innovation Biphasic (RS or QR) Triphasic (QRS or RSR’) high voltage low voltage R wave ˃ 5 big squares (high voltage ) Ventricular hypertrophy ˂ 1 big square (low voltage) Terminal heart failure Cardiomyopathy IHD Obesity Emphysema Pericardial effusion 7. S-T segment Ventricular repolarization leads T S S-T segment Iso-electric line Elevated Depressed iso-electric line depression elevation J point J point Point where QRS complex returns to isoelectric line. Beginning of S-T segment. Critical in measuring S-T elevation. iso-electric line T-P line Page | 25 P-R Simple ECG Innovation S-T elevation ST segment elevation Pericarditis Myocardial infarction Prinzmetal’s angina PR Pericarditis ST segement elevation Leads Myocardial infarction Angina some leads myocardial infarction angina Cardiac enzymes infarction timing elevated clinical diagnosis << angina S-T ECG myocardial infarction angina S-T depression ST segment depression Digitalis Hypokalemia ischemia angina Myocardial infarction Pericarditis cardiac hypertrophy bundle branch block Digitalis hypokalemia pericarditis Page | 26 Simple ECG Innovation diffuse ST segment depression Leads iso-electric line digitalis ST segment depression sagging J point hypokalemia serum potassium stitchy << pain Pericarditis clinically some leads ischemia angina myocardial infarction hypertrophy bundle branch block clinical diagnosis << angina V3 V2 V1 right ventricle Leads ST segment depression V3 V2 V1 right ventricular hypertrophy strain pattern right ventricular hypertrophy With strain pattern secondary changes V5 V4 left ventricular enlargement ST segment depression V3 V2 V1 right bundle branch block ST segment depression V6 left bundle branch block Page | 27 Simple ECG Innovation V6 V5 V4 ST segment depression rSR’ V1 Right bundle branch block ST segment depressed right bundle right ventricular hypertrophy left ventricular enlargement V6 left ventricular enlargement V6 V5 V4 ST segment depression left ventricular hypertrophy secondary clinical diagnosis << angina ventricular hypertrophy bundle branch block ischemia angina ST segment depression ischemia hypertrophy leads iso-electric line J point iso-electric line J point << digitalis toxicity ECG changes cardiac muscle Pericarditis ECG pericarditis very superficial myocarditis Page | 28 Simple ECG Innovation 8. T wave (Never absent ) Ventricular repolarization Less than 6 small squares R wave 1/3 positive Upright negative wave Inverted T wave ( positive ) T Normal Hyperacute hyperkalemia ECG T wave inverted normal T wave inversion dynamic T Upright 9. Q-T interval T wave QRS complex 11 small square 0.44 sec Long Q-T interval Drugs ( many antiarrhythmics, tricyclics & phenothiazines) Electrolyte abnormalities (K+, Ca++, Mg++) CNS disease (especially subarachnoid hemorrhage, stroke, trauma) Hereditary LQT 10. Page | U wave 29 Simple ECG Innovation These waves, usually most apparent in chest leads V2-V4, may be a sign of hypokalemia or drug effect or toxicity (e.g., amiodarone, dofetilide, quinidine, or sotalol). Abnormal ECG Chamber enlargement Bundle branch block (BBB) Coronary ischemia (MI & ischemia) Heart block Others 1 2 3 4 5 1. Chamber enlargement Atrial enlargement Ventricular enlargement atrial enlargement Right atrial enlargement Left atrial enlargement ventricular enlargement Right ventricular enlargement Left ventricular enlargement atrial enlargement atrium P wave P wave atrium Lead II and V1 P wave peaked << P wave << P pulmonal right atrial enlargement broad << P wave P mitral << Left atrial enlargement Page | 30 Simple ECG Innovation Mitral Normal biphasic right atrium left atrium V1 P wave activate SA node right atrium Left atrium activate right SA node wave right atrium wave Left atrium P wave biphasic Positive negative negative Positive right atrial strain (enlargement) left atrial strain ( enlargement) Lead Ventricular enlargement ventricular depolarization QRS QRS complex abnormalities ventricle V1,2,5,6 QRS V1,2 r wave S wave V5,6 s wave R wave r wave S wave Normal Page | 31 V1,2 deep << S wave Simple ECG Innovation s wave R wave normal V5,6 << R wave exaggeration of normal exaggeration of normal voltage criteria V2 V1 5 big squares S V6 V5 5 big squares R 7 big squares S+R left ventricle left ventricular enlargement left ventricle hypertrophy Strain ischemia ventricle strain ischemia strain ischemia depressed ST segment inverted T wave Left ventricle V5 and V6 V5 and V6 Strain ischemia Left ventricle right ventricle V1,2 s wave R wave Normal V5,6 Page | 32 r wave S wave Simple ECG Innovation Normal I can diagnose right ventricle from V1 V6 V5 V2 Right ventricle right ventricle Strain ischemia strain ischemia Inverted T wave depressed ST segment V1 and V2 right ventricle V5 and V6 V2 V1 Strain ischemia left ventricle Bi ventricular hypertrophy V5 and V6 V1 and V2 strain ischemia ECG bi ventricular hypertrophy R S exaggeration of normal reversal of normal exaggeration of normal V1 reversal of normal V2 2. Bundle Branch Block (BBB) Right bundle branch block Left bundle branch block bundle branch block M QRS RSR' right bundle branch block left bundle branch block Page | 33 V2 V6 V1 V5 Simple ECG Innovation right and left bundle branch block Right V2 V1 RSR' pattern left V6 V5 RSR' QRS QRS shape direction voltage QRS voltage direction shape shape M shaped bundle branch block direction direction V1 and V2 R S V6 V5 S R reversal of normal direction right ventricular hypertrophy Normal << shape Normal << direction voltage voltage exaggeration of normal Left ventricular hypertrophy QRS Page | 34 Simple ECG Innovation shape direction voltage shape abnormality bundle branch block voltage direction ventricle direction Normal shape Normal shape direction direction reversal of normal voltage 3. Coronary Ischemia ( MI & ischemia ) myocardial infarction central area of necrosis surrounded by an area of tissue damage surrounded by an ischemic pattern pathological Q << area of necrosis elevated ST segment << tissue damage inverted T << ischemia wave or peaked T infarction necrosis pathological Q Once Page | 35 Simple ECG Innovation pathological Q Old myocardial infarction pathological Q Myocardial infarction finger print of MI is the pathological Q Infarction elevated ST segment recent MI << Elevated ST segment recent MI old MI topographism anterior wall recent MI Lateral wall Inferior wall old MI topographism topographism Elevated ST segment MI pathological Q Recent Old Infarction artery Infarction necrosis elevated ST segment recent Page | 36 Simple ECG Innovation ECG pathological Q ST pathological Q elevated ST segment Once elevated ST segment Q Q recent MI recent anterior MI Old inferior MI << Old inferior leads recent anterior leads Lead artery Ischemia Depressed ST segment topographism Depressed lateral ischemia anterior Inferior topographism 4. Heart Block ECG Mainly hear block A.V. nodal block A.V. node first degree heart block second degree heart block ventricle Atrium third degree heart block heart block first degree heart block second degree heart block third degree heart block Page | 37 Simple ECG Innovation first degree heart block A.V. node Just prolonged PR interval Just prolonged PR interval first degree heart block sinus brady cardia S.A. node sinus bradycardia first degree heart block P QRS T sinus brady cardia : definition of first degree heart block just prolonged PR interval second degree heart block A.V. node A.V. node Mobitz one progressive prolongation of PR interval until dropped QRS Mobitz one Mobitz two A.V. node Long strip RR interval Mobitz one irregular Page | 38 Simple ECG Innovation dropped beat Long strip Mobitz Two A.V. node atrium system Mobitz Two regular drop of QRS P P QRS T P P QRS T QRS P P A.V. node second degree heart block Mobitz one Mobitz Two Irregular Regular third degree heart block A.V. node Atrium ventricle S.A. node idioventricular rhythm ectopic focus atrium Page | 39 Simple ECG Innovation P wave QRS ventricle bizarre shaped ventricle QRS deformed A.V. node narrow normal P wave P QRS third degree heart block A.V. dissociation atrio ventricular dissociation ventricle atrium QRS P QRS deformed Bizarre shaped .Mobitz one << All type of heart block are regular except . third degree heart block << All types of heart block with normal QRS complex except Mobitz one regular complete heart block Third degree normal QRS 5. Others ECG as a Clue to Acute Life-Threatening Conditions without primary Heart or Lung Disease Cerebrovascular accident (especially intracranial bleed) Drug toxicity Tricyclic antidepressant overdose, digitalis excess, etc. Electrolyte disorders Hypokalemia Hyperkalemia Hypocalcemia Hypercalcemia Endocrine disorders Page | 40 Simple ECG Innovation Hypothyroidism Hyperthyroidism Hypothermia How to interpret an ECG ECG Relax and take a deep breath Rhythm 1 Sinus or not Regular or not Rate 2 R-R interval 10 300 30 R waves << regular << rhythm << Irregular << rhythm Axis 3 Normal axis << positive aVF left axis deviation << negative aVF right axis deviation << positive aVF lead Positive lead positive lead negative Lead lead lead P wave 4 2.5 right atrial strain << peaked left atrial strain << m shaped 2.5 2.5 2.5 P-R interval 5 complex P wave 5 3 QRS complex 6 first negative wave in the complex << Q wave first positive wave in the complex << R wave Page | 41 Simple ECG Innovation following R the negative wave following R << S wave R wave Q wave R wave S wave R wave T wave ST segment 7 T wave 8 S MI absent 6 R wave diagnosis diagnosis How to diagnose an ECG rhythm regular irregular irregular irregular Atrial fibrillation Extra systole Mobitz one atrial fibrillation absent P tachy irregular Normal QRS Absent P P wave atrial fibrillation absent P wave Page | 42 Simple ECG Innovation fibrillation some time Absent P AF slow AF rapid Slow AF digitalis Beta blocker Heart block associated lone AF slow AF AF irregular ECG With absent P wave AF Extra systole refractory period stimlus compensatory pause irregular irregular ventricular extra systole Mobitz one Progressive prolongation of PR interval until dropped QRS Page | 43 Simple ECG Innovation tachy cardia rhythm rate << regular regular Tachycardia bradycarida normo cardia Regular tachycardia Sinus tachycardia Ventricular tachycardia Supra ventricular tachycardia Atrial flutter Sinus Tachycardia Sinus tachy cardia S.A. node Peace maker of the heart ECG P followed by QRS T P QRS T Ventricular tachycardia Ventricular tachycardia ventricle Arrhythmia ventricle QRS Page | 44 Simple ECG Innovation T deformed QRS P wide QRS Supra ventricular tachycardia supra ventricular tachycardia supra ventricualr atrium A.V. node P P ( atrium deformed A.V. node P ) Inverted P Inverted P wave A.V. node absent P Masked by QRS supra ventricular tachy cardia absent Inverted P deformed P P P Supra ventricular tachycardia Atrial flutter Atrial flutter atrium Page | 45 Simple ECG Innovation A.V. node reduction Atrial beat in mathematical fashion atrium Atrial flutter specific atrial fibrillation Atrial flutter regular atrial flutter regular atrial fibrillation regular long strip tachycardia rate QRS deformed Narrow normal deformed ventricular tachycardia Narrow normal P P wave single multiple sinus tachycardia QRS T single P wave multiple P Atrial flutter Page | 46 Simple ECG Innovation Supra ventricular tachycardia Regular bradycardia Sinus bradycardia first degree heart block Mobitz two third degree heart block Nodal rhythm Sinus bradycardia regular bradycardia sinus bradycardia First degree heart block first degree heart block Just prolonged PR interval Page | 47 Simple ECG Innovation Mobitz two Mobitz two regular drop of QRS complex Third degree heart block third degree heart block deformed QRS AV dissociation peace maker peace maker Page | 48 Nodal rhythm nodal rhythm A.V. node A.V. node P inverted Simple ECG Innovation absent QRS regular bradycardia QRS deformed Narrow normal third degree heart block deformed Narrow normal P wave single Multiple first degree heart block sinus bradycardia P wave single first degree heart block just prolonged PR interval multiple Atrial flutter bradycardia tachycardia P wave Mobitz two Mobitz two Mobitz two atrial flutter Noda rhythm long strip QRS diagnostic approach rate rhythm P segmented P QRS Page | 49 Simple ECG Innovation ST segment Long strip Page | 50