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OSCEW ebinarSeries ECGInterpretation Delivered by: Dr Alireza SherafatMBBS (Hons.) FY1 Doctor at Kettering General Hospital Specialised (Academic) Foundation ProgrammeDisclaimer BIDA SW teaching is led by students with supervision of junior doctors and consultants across the UK. These teachings are created to support students’ learning but should not replace your local Medical School teaching material.OSCE series • You can be asked about common clinical emergencies • Your approach must be safe • Practice common stations • Escalate appropriatelyECG Interpretation • Basics of ECG recording • Systematic approach • ECG abnormalitiesBasics of ECG • ECG: Electrocardiogram or Electrocardiograph • When explaining in lay terms (to avoid jargon): use the term “Heart trace”. • Sinoatrial node (SAN) generates the heart rate. It works as the natural pacemaker in the cardiac conduction system. It is located in right atrium. • Atrioventricular node plays an important role in passing the electrical conduction and controlling the rate of heart rate. It is located near the interatrial septum and is usually supplied by right coronary artery. • Bundle of His and Purkinje fibres carry the electrical impulses across the heart muscle resulting in contractions.Electrical system of the heart Figure 1)Conduction system of heart (1).Electrical conductions on ECG Figure 2) electrical conduction seen on ECG(2). ECG leads placement Figure 3) ECG leads placement (3).Einthoven’s triangle Figure 4) Einthoven’s triangle (4).Normal ECG • When you are asked to look at an ECG in an OSCE station , do the basics to show you are safe! • Check name, date of birth and hospital number for the patient. • Ask if the patient had chest pain or palpitation? What was the reason for recording the ECG? • Check paper speed (25 mm/s usually) and voltage (10 mm/mV usually).Normal ECG trace Figure 5) Normal ECG trace with p-wave, QRS and T-wave (5).Normal ECG in a young person Figure 6) Normal ECG recorded in a young healthy person (6).Systematic approach to interpretation of ECG • Check rate (Normal, Tachycardia or Bradycardia?) – Age dependent • Check Cardiac axis (Left or Right axis deviation?) • Check Rhythm (Sinus rhythm or Arrhythmia? ) • Check p-waves (Present? Normal length?) • Q-waves (pathological ? Previous infarction?) • Check QRS complexes (normal? Narrow? Wide? ) • Check T-waves (Normal? Tall? Flat?) • U-waves present? • Check PR interval (Heart block?) • Check QT interval (Prolonged?) –always check medication history • Check ST segment (Elevation ? Depression?) • Check progression and Transition point Rate • Normal adult heart rate :60 to 100 bpm(some references 50-100 bpm)- Check NEWS • Children have a higher normal heart rate (Use PEWS instead of NEWS) • infection, sepsis, temperature, arrhythmia, pain, PE, anxiety etc).as • Reduced Heart Rate : Bradycardia (can be due to conduction system problems, cardiomyopathy, drugs, electrolyte imbalances, hypothermia, hypothyroidism, etc ).Rate (1) Figure 7) The diagram explains how to calculate rate of heart (7).Rate (2) Figure 8) another method to calculate the heart rate (7).Tachycardia Figure 9) The diagram shows Sinus tachycardia (HR 150) (8).Bradycardia Figure 10) The diagram shows Sinus bradycardia (HR 35) (9).Normal Axis Figure 11)Normal heart axis (10).Left Axis deviation Figure 12) Left axis deviation on ECG (11).Right Axis deviation Figure 13) Right Axis Deviation (RAD) on ECG (12).Rhythm • Normal heart rhythm is referred to as the sinus rhythm. Normal heart cycles can be seen on the ECG. • You can clearly note the P, QRS, T waves . The key is to check if you can note a P-wave before every QRS complex. • We have already seen an example of sinus tachycardia on slide 17. Sinus tachycardia can be present due to a variety of reasons such as fever or PE. • The next few slides will go through some causes of presence of an abnormal rhythm.SVT Figure 14) Narrow-complex tachycardia (regular pattern) (13).AF Figure 15)Irregularly irregular pattern of tachycardia with no p-waves (14). Atrial Flutter Figure 16) Saw tooth appearance of the ECG pattern is consistent with atrial flutter (15).VT Figure 17) Broad complex regular tachycardia consistent with Ventricular tachycardia (16).VF Figure 18) Irregular heart rate without identifiable p-waves, QRS complexes and T-waves (17).PEA (Pulseless Electrical Activity) Figure 19) Patient is in cardiac arrest without a pulse, however the ECG is showing conduction (18).Asystole Figure 20) Pulseless patient in cardiac arrest with no obvious conductions on ECG (19).P pulmonale Figure 21) Tall over 2.5 mm p-wave seen in Right atrial enlargement. It can be seen due to pulmonary hypertension (20).P mitrale Figure 22) Bifid p-waves called P mitrale seen in left atrial enlargement most commonly due to mitral stenosis (21).Pathological Q-waves Figure 23) Pathological (inferior) Q waves seen due to previous MI (22).QRS Complex Figure 24) Normal length of QRS complex (5).QRS complexes Figure 25) Narrow QRS complex (23). Figure 26) Wide QRS complex (23).T-wave and U-wave Figure 27) T-wave changes in hypo and hyperkalaemia. Both require urgent treatment (24).Heart Block (1 degree) st Figure 28) Constant prolonged PR interval. It can be normal in young healthy adults (25). nd 2 degree Heart block Mobitz type 1 (Wenckebach phenomenon) Figure 29) Continuous increase in PR length leads to a dropped beat. Usually asymptomatic and harmless but can lead to complete heart block. Patients usually respond well to atropine and permanent pacing is rarely required (26). nd 2 degree Heart block Mobitz type 2 Figure 30) Non-conducted p-wave seen in Mobitz type 2. PR intervals remain constant. The risk pacing followed by insertion of permanent pacemaker (27).gnificant. It can require temporaryComplete Heart Block Figure 31) Complete dissociation of atrial and ventricular conductions. Life-threatening and requires urgent treatment with atropine and pacing (28).BBB • Impulses should travel equally down the left and right bundle brunch. • In LBBB , conduction moves to right ventricle first via Right bundle branch before travelling to left ventricle via the ventricular septum. • In RBBB, there is a delay in activation of right ventricle as impulses come from the left ventricle through the septum.Left BBB (29).e 32)Appearance of LBBB on ECG with M pattern in V6 and W in V1Right BBB Figure 33) M pattern in V1 and W pattern in V6 consistent with RBBB (30).ECG (patient has pacemaker) Figure 34) Dual Chamber pacing seen on ECG (31).QT interval Figure 35) Q-T interval on ECG (32)Causes of Prolonged Q-T (>440 ms) (32) • Hypokalaemia • Hypomagnesemia • Hypocalcaemia • Hypothermia • Myocardial Ischaemia • Raised ICP • Congenital • MedicationsCauses of Short Q-T (<350 ms) (32) • Hypercalcaemia • Congenital • Digoxin effectTorsades de pointes pointes (33).S complexes are twisting around the isoelectric line. QT-prolongation can result in Torsades deSTEMI • ST elevation MI • Life-threatening cardiac ischaemia • Due to blocked Coronary arteries • Different areas of the heart affected depending on the blocked arteryAnatomy of Coronary Arteries Figure 37) Coronary arteries of the heart (34). ECG examples (Clinical Junior .com) Figure 38) ECG leads and potential leads for presentation of various types of MI (35). STEMI (Anterior) Figure 39) ST elevation in V2-V4 consistent with an anterior MI (36).STEMI (Inferior) Figure 40) ST elevation in leads II, III and aVF consistent with inferior STEMI (37).STEMI (Anterolateral) Figure 41) Anterolateral ST elevation (V2-V6) consistent with Anterolateral STEMI (38).STEMI (Posterior) 42) Posterior MI presenting with ST depression in V2-V3 and Tall, broad R waves in V2-V3 (39).NSTEMI • Can present without typical changes of ST elevation • Can present with ST Depression • Can present with T-wave inversion • Other abnormalities on ECG • The key is to take a good history (taking CVS risk into consideration), do a full examination and request investigations such as troponin. It is also helpful to use risk assessment tools and scores. Serial troponin and a period of observation with cardiac monitoring would also be helpful.Progression and Transition point Figure 43) Normal ECG with normal progression of R waves from most negative in V1 to most positive in V6. The transition point is at V4 (V3-V4 normal transition point) (40).Normal ECG • ECG is a cheap and widely available investigation • Many patients present with chest pain and have a normal ECG • can be diagnosed using other investigations such as bloodson which (troponin). Risk stratification scores/tools are very helpful. • depending on local guidelines.ion and serial ECGs would be helpful • Some patients presenting with chest pain or palpitation with normal anxiety. be diagnosed with other problems such as MSK pain orSummary • Systematic approach • Patient details including symptoms • Rate and Rhythm • Axis • P-wave, QRS complex, T-wave, ?U-wave • PR, ST, QT • BBB • Progression and transition of R waves • Other ECG changes (NSTEMI?)References • 1. Johns Hopkins Medicine. Anatomy and Function of the Heart’s Electrical System [Internet]. Johns Hopkins Medicine. 2019. Available from: https://www.hopkinsmedicine.org/health/conditions- and-diseases/anatomy-and-function-of-the-hearts-electrical-system • 2. Electrocardiograms [Internet]. hyperphysics.phy-astr.gsu.edu. Available from: http://hyperphysics.phy-astr.gsu.edu/hbase/Biology/ecg.html • 3.Habásko J. EKG (elektrokardiogram) - Myokarditida [Internet]. Myokarditida. 2016 [cited 2023 Jan 17]. Available from: https://myokarditida.cz/en_US/diagnostika-a- lecba/diagnostika/elektrokardiogram-ekg/ • 4.CV Physiology | Electrocardiogram Standard Limb Leads (Bipolar) [Internet]. www.cvphysiology.com. Available from: https://www.cvphysiology.com/Arrhythmias/A013a • 5.The Normal ECG Trace [Internet]. medschool.co. Available from: https://medschool.co/tests/ecg-basics/the-normal-ecg-trace • rhythm-ecg-library/R. Normal Sinus Rhythm • LITFL Medical Blog • ECG Library Basics [Internet]. Life in the Fast Lane • LITFL • Medical Blog. 2018. Available from: https://litfl.com/normal-sinus- • 7.Cadogan M, Buttner R. ECG Rate Interpretation • LITFL Medical Blog • ECG Library Basics [Internet]. Life in the Fast Lane • LITFL • Medical Blog. 2019. Available from: https://litfl.com/ecg-rate- interpretation/ • 8. Sinus tachycardia • LITFL • ECG Library Diagnosis [Internet]. Life in the Fast Lane • LITFL • Medical Blog. 2018. Available from: https://litfl.com/sinus-tachycardia-ecg-library/ • 9. Burns E, Buttner R, Buttner EB and R. Sinus Bradycardia [Internet]. Life in the Fast Lane • LITFL. 2018. Available from: https://litfl.com/sinus-bradycardia-ecg-library/ • 10. ECG Axis Interpretation • LITFL Medical Blog • ECG Library Basics [Internet]. Life in the Fast Lane • LITFL • Medical Blog. 2018.Available from: https://litfl.com/ecg-axis-interpretation/ • 11. Left Axis Deviation (LAD) • LITFL • ECG Library Diagnosis [Internet]. Life in the Fast Lane • LITFL • Medical Blog. 2018. Available from: https://litfl.com/left-axis-deviation-lad-ecg-library/ • 12. Right Axis Deviation (RAD) • LITFL • ECG Library Diagnosis [Internet]. Life in the Fast Lane • LITFL • Medical Blog. 2018. Available from: https://litfl.com/right-axis-deviation-rad-ecg-library/ • https://litfl.com/supraventricular-tachycardia-svt-ecg-library/TFL • ECG Library Diagnosis [Internet]. Life in the Fast Lane • LITFL • Medical Blog. 2018. Available from: • 14. Burns E, Buttner R. Atrial Fibrillation • LITFL Medical Blog • ECG Library Diagnosis [Internet]. Life in the Fast Lane • LITFL • Medical Blog.2018. Available from: https://litfl.com/atrial-fibrillation- ecg-library/References continued • 15. Atrial Flutter • LITFL Medical Blog • ECG Library Diagnosis [Internet]. Life in the Fast Lane • LITFL • Medical Blog. 2019. Available from: https://litfl.com/atrial-flutter-ecg-library/ • 16. Ventricular Tachycardia – Monomorphic VT • LITFL • ECG Library [Internet]. Life in the Fast Lane • LITFL • Medical Blog. 2019. Available from: https://litfl.com/ventricular-tachycardia- monomorphic-ecg-library/ • 17. Ventricular Fibrillation (VF) • LITFL • ECG Library Diagnosis [Internet]. Life in the Fast Lane • LITFL • Medical Blog. 2019. Available from: https://litfl.com/ventricular-fibrillation-vf-ecg-library/ • 18. Buttner R, Thomson H, Thomson RB and H. ECG Case 120 [Internet]. Life in the Fast Lane • LITFL. 2021 [cited 2023 Jan 17]. Available from: https://litfl.com/ecg-case-120/ • 19. B20: Cardiac Asystole: ECGs at St Emlyn’s [Internet]. St.Emlyn’s. Available from: https://www.stemlynsblog.org/b20-cardiac-asystole/ • 20. Right Atrial Enlargement • LITFL Medical Blog • ECG Library Basics [Internet]. Life in the Fast Lane • LITFL • Medical Blog. 2018.Available from: https://litfl.com/right-atrial-enlargement-ecg- library/ • 21. Left Atrial Enlargement • LITFL Medical Blog • ECG Library Basics [Internet]. Life in the Fast Lane • LITFL • Medical Blog. 2018.Available from: https://litfl.com/left-atrial-enlargement-ecg- library/ • 22. Q Wave • LITFL • ECG Library Basics [Internet]. Life in the Fast Lane • LITFL. 2020. Available from: https://litfl.com/q-wave-ecg-library/ • 23. Larkin J. QRS Interval • LITFL Medical Blog • ECG Library Basics [Internet]. Life in the Fast Lane • LITFL • Medical Blog. 2018. Available from: https://litfl.com/qrs-interval-ecg-library/ • 24. Hypokalaemia ECG changes • LITFL • ECG Library Diagnosis [Internet]. Life in the Fast Lane • LITFL • Medical Blog. 2018. Available from: https://litfl.com/hypokalaemia-ecg-library/ • 25. Dr John Larkin. First Degree Heart Block • LITFL • ECG Library Diagnosis [Internet]. Life in the Fast Lane • LITFL • Medical Blog. 2019. Available from: https://litfl.com/first-degree-heart-block- ecg-library/ • 26. Burns DE. AV Block: 2nd degree, Mobitz I (Wenckebach Phenomenon) • LITFL [Internet]. Life in the Fast Lane • LITFL • Medical Blog. 2018. Available from: https://litfl.com/av-block-2nd- degree-mobitz-i-wenckebach-phenomenon/ • 27. AV Block: 2nd degree, Mobitz II (Hay block) • LITFL [Internet]. Life in the Fast Lane • LITFL • Medical Blog. 2018. Available from: https://litfl.com/av-block-2nd-degree-mobitz-ii-hay-block/ • 28. Dr John Larkin. AV block: 3rd degree (complete heart block) • LITFL [Internet]. Life in the Fast Lane • LITFL • Medical Blog. 2019. Available from: https://litfl.com/av-block-3rd-degree-complete- heart-block/References continued • 29.Buttner R, Burns E. Left Bundle BranchBlock (LBBB) • LITFL • ECG Library Diagnosis [Internet]. Life inthe Fast Lane • LITFL • Medical Blog. 2019. Available from: https://litfl.com/left-bundle-branch-block-lbbb-ecg-library/ • 30. Burns E. Right Bundle BranchBlock (RBBB) • LITFL • ECG Library Diagnosis [Internet]. Life inthe Fast Lane • LITFL • Medical Blog. 2018. Available from: https://litfl.com/right- bundle-branch-block-rbbb-ecg-library/ • normal-patterns/ythms – Normal Patterns • LITFL • ECG Library Diagnosis [Internet]. Life inthe Fast Lane • LITFL. 2018. Available from: https://litfl.com/pacemaker-rhythms- • 32. Burns E, Buttner R. QT Interval • LITFL Medical Blog• ECG Library Basics [Internet]. Life inthe Fast Lane • LITFL • Medical Blog. 2022. Available from: https://litfl.com/qt- interval-ecg-library/ • 33. Polymorphic VT andTorsades de Pointes (TdP) • LITFL [Internet]. Life inthe Fast Lane • LITFL • Medical Blog. 2019. Available from: https://litfl.com/polymorphic-vt-and- torsades-de-pointes-tdp/ • https://www.hopkinsmedicine.org/health/conditions-and-diseases/anatomy-and-function-of-the-coronary-arteriesealthLibrary. 2019. Available from: • 35. clinical junior.com- ECG EKG Interpretationbasics howtoreadMI myocardial infarctionangina AFatrial fibrillationST elevationdepression[Internet]. www.clinicaljunior.com. Available from: http://www.clinicaljunior.com/cardiologyecg.html • 36. Burns E, Buttner R. Anterior Myocardial Infarction• LITFL • ECG Library Diagnosis [Internet]. Life inthe Fast Lane • LITFL • Medical Blog. 2019. Available from: https://litfl.com/anterior-myocardial-infarction-ecg-library/ • library/rior STEMI • LITFL Medical Blog• ECG Library Diagnosis [Internet]. Life inthe Fast Lane • LITFL • Medical Blog. 2019. Available from: https://litfl.com/inferior-stemi-ecg- • 38. Lateral STEMI ECG changes • LITFL • ECG Library Diagnosis [Internet]. Life inthe Fast Lane • LITFL • Medical Blog. 2018. Available from: https://litfl.com/lateral-stemi-ecg- library/ • 39. Posterior Myocardial Infarction• LITFL • ECG Library Diagnosis [Internet]. Life inthe Fast Lane • LITFL • Medical Blog. 2018. Available from: https://litfl.com/posterior- myocardial-infarction-ecg-library/ • 40. Normal ECG [Internet]. Queensu.ca. 2019. Available from: https://elentra.healthsci.queensu.ca/assets/modules/ts-ecg/normal_ecg.htmlFOR FEEDBACK AND QUERIES: Email @ info@bidasw.com