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ECG T utorial Sponsored by:Learning Outcomes: • Understand how to interpret an ECG • Axis • Bundle Branch Block • Bradyarrhythmias • Tachyarrhythmias • Ischaemia • MCQs How to read an ECG? 1. Correct patient, correct time 5. Define Axis 2. Correct calibration (25mm/s) 6. P Wave Morphology 3. ?Symptoms 7. QRS Morphology 4. Initially focus on the rhythm strip 8.T Wave Morphology • Rate 9. Segments • Identify P Waves • PR Interval • Identify QRS complexes and • ST Segment their relationship to each P • QT Interval wave Ventricular Depolarisation & Atrial Repolarisation Atrial Depolarisation Ventricular RepolarisationRhythm Strip:• Rate P Waves = • Identify P Waves • Identify QRS complexes and their relationship to each P wave Rate: 13 QRS segments in 10 seconds • Does each P Wave have QRS after it? Therefore; • Does each QRS have P wave before it? 13x6= 78bpm • Are the intervals equal? Sinus Rhythm: • Regular rhythm at a rate of 60-100 bpm • Each QRS complex is preceded by a normal P wave • Normal P wave axis: P waves upright in leads I and II, inverted in aVR • The PR interval remains constantNormal AxisAxis: EXTREME LEFT AXIS AXIS DEVIATION DEVIATION RIGHT AXIS NORMAL DEVIATION AXISRight Axis DeviationRight Axis Deviation EXTREME LEFT AXIS AXIS DEVIATION DEVIATION RIGHT AXIS NORMAL DEVIATION AXISLeft Axis DeviationLeft Axis Deviation EXTREME LEFT AXIS AXIS DEVIATION DEVIATION RIGHT AXIS NORMAL DEVIATION AXISDefine Axis:Axis: EXTREME LEFT AXIS AXIS DEVIATION D VIATION LEFT AXIS AXIS DEVIATION Lead I DEVIATION RIGHT AXIS NORMAL DEVIATION AXIS RIGHT AXIS NORMAL DEVIATION AXIS Lead aVFAxis: Rule of positivity • Focus on QRS Segment • QRS is predominantly above isoelectric line • Therefore ‘positive’ Extreme Axis Left Axis • Positive = moving towards lead • Negative = moving away from lead Lead I Normal Axis Right Axis Lead aVFP Wave Morphology:P Waves should be: - Upright in all leads except aVR - Smooth contours - Monophasic in all leads except V1 ` ` ` ` ` ` ` ` `QRS Morphology:QRS Segments should be: - <120ms in duration (3 small squares) - Have natural ‘R Wave Progression’ from V1 to V6Ventricular DepolarisationVentricular Depolarisation (Normal) V6 V1Ventricular Depolarisation (Normal) V6 V1Ventricular Depolarisation (Normal)Left Bundle Branch Block: V6 V1Left Bundle Branch Block: V6 V1Left Bundle Branch BlockRight Bundle Branch Block: V6 V1Right Bundle Branch Block V6 V1Right Bundle Branch Block V6 V1Right Bundle Branch Block V6 V1Right Bundle Branch BlockT Wave Morphology:T Waves should be: - Upright in all leads except aVR & V1 - Smooth - <10mm in height V1-V6 - <5mm in I, II, III, aVL, aVR, aVFSegments: PR IntervalPR Interval - Between 120-200ms in length (3 to 5 small squares) - Along the isoelectric line - PR interval should be equal throughout the ECG - Relevant in identifying heart blocksConduction System:1 Degree Heart Block: •There is delay, without interruption, in conduction from atria to ventricles •PR >200msConduction System: 1 Degree Heart Block: - Delayed Conduction Between SA Node and AV Node - Benign condition SA Node AVNode Bundle of His nd 2 Degree Heart Block (Mobitz I) Progressive prolongation of the PR interval culminating in a non-conducted P wave: •PR interval is longest immediately before dropped beat •PR interval is shortest immediately after dropped beatConduction System: 2ndDegree Heart Block (Mobitz I): - Reversible block at level of AV Node - AV Nodal Cells progressively fatigue - Low risk rhythm SA Node AVNode Bundle of His nd 2 Degree Heart Block (Mobitz II) A form of 2nd degree AV block in which there is intermittent non-conducted P waves without progressive prolongation of the PR intervalConduction System: 2ndDegree Heart Block (Mobitz II): - Failure to conduct at the level of His-Purkinje System (Below AV Node) - High Risk rhythm - Can progress to 3 Degree HB & risk of asystole SA Node AVNode Bundle of His rd 3 Degree Heart Block (Complete Heart Block) • Severe bradycardia due to absence of AV conduction • The ECG demonstrates complete AV dissociation, with independent atrial and ventricular ratesConduction System: 3 Degree Heart Block (Complete): - End product of Mobitz I or Mobitz II - Involving AV Node/His-Purkinje System - High risk of ventricular standstill & cardiac arrest SA Node AVNode Bundle of HisSegments: ST SegmentST Segment - Flat and on the isoelectric line - Between end of S wave (J-Point) and start of T Wave - Important in Myocardial IschaemiaST Segment - TerritoriesST Segment - TerritoriesCommon T achyarrythmias • Atrial Fibrillation • Atrial Flutter • Supraventricular Tachycardia • Ventricular Tachycardia • Ventricular FibrillationAtrial Fibrillation: • Irregularly irregular rhythm • No P waves • Absence of an isoelectric baseline • Variable ventricular rate • QRS complexes usually < 120ms, unless pre-existing bundle branch blockAtrial Fibrillation:Atrial Flutter • Narrow complex tachycardia • Regular atrial activity at ~300 bpm • “Saw-tooth” pattern of inverted flutter waves in leads II, III, aVF • Upright flutter waves in V1 that may resemble P waves • Loss of the isoelectric baseline • Ventricular rate depends on AV conduction ratioAtrial FlutterSupraventricular T achycardia The term supraventricular tachycardia (SVT) refers to any tachydysrhythmia arising from above the level of the Bundle of His, and encompasses regular atrial, irregular atrial, and regular atrioventricular tachycardias • AVNRT • Atrial Tachycardia • Sinus Tachycardia • Atrial Fibrillation • Atrial FlutterSupraventricular achycardiaVentricular T achycardia • Broad Complex Tachycardia (QRS >120ms) • Originates from the ventricles • Can be life threateningVentricular achycardia Ventricular Fibrillation • Chaotic irregular deflections of varying amplitude • No identifiable P waves, QRS complexes, or T waves • Rate 150 to 500 per minute • Amplitude decreases with duration (coarse VF –> fine VF) • Incompatible with lifeVentricular FibrillationA Few Example MCQs:1. 82-Year-Old Lady presenting with palpitations and dizziness1. 82-Year-Old Lady presenting with palpitations and dizziness a. Atrial Flutter b. Atrial Fibrillation c. Sinus Tachycardia d. Ventricular Tachycardia e. Anterior STEMIb. Atrial Fibrillation2. 61-Year-Old Man presenting with chest pain2. 61-Year-Old Man presenting with chest pain a. Anterior NSTEMI b. Pericarditis c. Inferolateral STEMI d. Long QT Syndrome e. Anterior STEMIc. Inferolateral STEMI3. 74 -Year-Old Man presenting with AKI3. 74-Year-Old Man presenting with AKI a. Supraventricular Tachycardia b. Pericarditis c. Sinus Tachycardia d. Left Bundle Branch Block e. Hyperkalaemiae. Hyperkalaemia4. 92-Year-Old Lady presenting with syncope4. 92-Year-Old Lady presenting with syncope a. Complete Heart Block b. Sinus Bradycardia c. Mobitz II 2ndDegree Heart Block d. Slow Atrial Fibrillation e. Normal Sinus Rhythma. Complete Heart Block5. A 54-Year-Old Man with hypertension presents to the GP for a routine ECG5. A 54-Year-Old Man with hypertension presents to the GP for a routine ECG a. Normal Sinus Rhythm b. Anterior STEMI c. Left Bundle Branch Block d. Right Bundle Branch Block e. Pulmonary Embolismc. Left Bundle Branch Block6. A 78-Year-Old Man complains of intermittent palpitations6. A 78-Year-Old Man complains of intermittent palpitations a. Paroxysmal Atrial Fibrillation b. Complete Heart Block c. Sinus Arrhythmia d. 2nd Degree Heart Block (Mobitz I) e. Sick Sinus Syndromed. 2nd Degree Heart Block (Mobitz I)7. A 59-Year-Old Female is brought to the CCU following a collapse and chest pain7. A 59-Year-Old Female is brought to the CCU following a collapse and chest pain a. RCA STEMI b. LAD STEMI c. Right Bundle Branch Block d. Electrical Alternans e. Complete Heart Blocka. RCA STEMI & e. Complete Heart Block8. A 16-Year-Old Female is brought to Resus unresponsive8. A 16-Year-Old Female is brought to Resus unresponsive a. Atrial Tachycardia b. Ventricular Tachycardia c. Ventricular Fibrillation d. Sinus Tachycardia with LBBB e. Atrial Fibrillationb. Ventricular Tachycardia Finished! Dr James Moggridge James.Moggridge@wales.nhs.uk