ECG Changes in Myocardial ischemia, myocardial infarction.pptx

ECG PPT

1. Identification Of Myocardial Ischemia, Myocardial Infarction and Angina in ECG

2. Important to remember! ECG is not sufficiently specific or sensitive to be used without a patient's clinical history

3. Myocardial ischemia and injury Mismatch between perfusion and demand Ischemic myocardium goes for anaerobic metabolism to sustain itself Can survive but cannot function Remains in resting state and does not participate in contraction Reversible if blood supply is restored or demand is lowered

4. If blood flow is restored before glycogen gets depleted, cells resume contraction promptly ( ischemia ) If severe depletion of glycogen has occurred, it becomes stunned and recovery is delayed ( injury ) If complete depletion of glycogen occurs, necrosis of the cells results, leading to infarction

5. Why is it clinically important? When ECG changes occur in association with chest pain but without frank infarction, they confer prognostic significance. About 20% of patients with ST segment depression and 15% with T wave inversion will experience severe angina, myocardial infarction, or death within 12 months of their initial presentation.

6. ECG CHANGES IN ISCHEMIA

7. ECG effects of myocardial ischemia Manifest by changes in T waves

8. T waves may become Flattened Inverted Tall or Biphasic ECG effects of myocardial ischemia

9. T waves that are deep and symmetrically inverted (arrowhead) strongly suggest myocardial ischaemia. At least 1 mm deep Present in ≥ 2 continuous leads that have dominant R waves (R/S ratio > 1) Dynamic — not present on old ECG or changing over time T wave inversion

10. Widespread T wave inversion due to myocardial ischaemia

11. Point to note Inverted T waves are normal in leads III, aVR, and V1 Associated with a predominantly negative QRS complex.

12. A – T wave in coronary insufficiency B – T wave in LVH with strain C – T wave in digitalis effect Other causes of T inversion

13. ECG CHANGES IN MYOCARDIAL INJURY

14. ECG effects of myocardial injury Deviation of the ST segment ST segment deviated towards the surface of the injured tissue Patterns of deviation ST depression St elevation

15. Forms of ST depression Horizontality Upward sloping ST depression Downward sloping ST depression

16. ST depression Horizontal or downsloping ST depression ≥ 0.5 mm at the J-point in ≥ 2 contiguous leads indicates myocardial ischaemia. ST depression ≥ 1 mm is more specific and conveys a worse prognosis. ST depression ≥ 2 mm in ≥ 3 leads is associated with a high probability of NSTEMI and predicts significant mortality (35% mortality at 30 days). Upsloping ST depression is non-specific for myocardial ischaemia.

17. Normal ST segment Horizontality of ST segment Plane ST segment Upwards sloping ST Downsloping ST segment

18. Horizontal ST segment depression

19. Upwards sloping ST depression in V2 – V5

20. Downsloping ST depression with T inversion in I, aVL, V5, V6

21. Other causes for ST depression DEPRESSED ST ---> D - Drooping valve (MV Prolapse) E - Enlargement of the left ventricle P - Potassium low R - Reciprocal ST Depression (eg. Inferior MI) E - Encephalon (Intracerebral) Haemorrhage S - Subendocardial Infarct S - Subendocardial Ischaemia E - Embolism (Pulmonary) D - Dilated Cardiomyopathy S - Shock T - Toxicity (Digitalis/Quinidine

22. ST

23. ST elevation Epicardial injury – ST deviated towards epicardial surface Leads oriented towards the epicardial surface eg Lead V6 will have a raised ST segment Leads oriented away will have a depressed ST segment eg aVR

24. ECG Changes in Acute and Chronic Myocardial Infarction

25. Characteristic Changes in Acute Myocardial Infarction ST segment elevation over area of damage ST depression in leads opposite infarction Inverted T waves Pathological Q waves

26. Hyperacute MI Q waves and prominent doming ST segment elevation in II, III, and aVF, findings which are characteristic of an acute inferior myocardial infarction. ST elevation in the right precordial leads - V4R, V5R, and V6R - indicates right ventricular involvement

27. Acute MI Evolving Q-wave anterior MI: loss of R waves in leads V1 to V3, ST segment elevations in V2 to V4, and T wave inversions in leads I, aVL, and V2 to V5. Sinus bradycardia (55 beats/min) is present due to concurrent therapy with a beta blocker

28. Evolved MI Later stage in the evolution of an acute anterior myocardial infarction. There is a QS pattern in leads V1 to V3 and T wave inversion in leads V2 to V4. The ST segment elevations in these leads have almost disappeared

29. ST Elevation MI

30. According to the ACC/AHA guidelines for STEMI, there must be “ New ST elevation at the J point in at least 2 contiguous leads of >= 2 mm (0.2 mV) in men or 1.5 mm (0.15 mV) in women in leads V2- V3 and/ or Of >=1 mm (0.1mV) in other contiguous chest leads or the limb leads Thus, 1 mm in any 2 contiguous leads EXCEPT leads V2 or V3 where the elevation must be 2 mm in men or 1.5 mm in women.

31. ECG evaluation in Non-Perfused MI

32. Location of Infarct Combinations

33. Anterior Wall ST Elevation MI ECG Findings: ST segment elevation in the anterior leads at J point and sometimes in septal or lateral leads depending on the extent of the myocardial infarction Reciprocal ST segment depression in the inferior leads (II, III and aVF )

34. Inferior Wall ST Elevation MI ECG Findings: ST segment elevation in the inferior leads (II, III, aVF ) Reciprocal ST segment depression in the lateral and/or high lateral leads (I, aVL , V5, and V6)

35. Posterior Wall MI ECG Findings : ST segment depression in the septal and anterior precordial leads (V1 to V4) The ratio of the R wave to S wave in leads V1 or V2 is > 1 ST elevation in the posterior leads of a posterior ECG (leads V7 to V9) ST elevation in the inferior leads (II, III, and aVF ) may be seen if an inferior MI is also present[

36. Reciprocal Changes in MI Commonly observed on ventricular wall opposite to the transmural injury Increases the specificity of STEMI In AWMI- Reciprocal changes in inferior leads are seen in 40-70% of the cases In IWMI- Reciprocal depression in I and aVL and lateral leads

37. NON ST Elevation MI ECG feature can be any of the following: ST depression (70-80% sensitivity) T wave inversion (10-20% sensitivity) Both ST depression and T wave insertion Normal ECG

38. STEMI vs Acute Pericarditis

39. Wellen’s Syndrome Wellens’s syndrome (or sign) is a pattern of deeply inverted or biphasic T waves in V2-3, which is highly specific for a critical stenosis of the left anterior descending artery (LAD) Subacute LAD Occlusion (within the next week)

40. De Winter ST/T Waves

41. Brugada Syndrome A hereditary syndrome, marked by right bundle branch block and ST segment elevation in the right precordial leads, and a high risk of sudden death from ventricular arrhythmias

42. Benign Early Repolarization Widepread concave ST elevation Notching or slurring at the J-point Prominent, slightly asymmetrical T-waves that are concordant with the QRS complexes No reciprocal ST depression to suggest STEMI (except in aVR ) ST changes are relatively stable over time (no progression on serial ECG tracings)

43. Hypothermia Osborne waves (= J waves) Prolonged PR, QRS and QT intervals Shivering artefact Ventricular ectopy Cardiac arrest due to VT, VF, or asystole

44. Sgarbossa’s Criteria ST elevation >=1 mm in a lead with a positive QRS complex ( ie : concordance)- 5 points ST depression >= 1 mm in lead V1, V2, or V3- 3 points ST elevation >= 5 mm in a lead with a negative (discordant) QRS complex- 2 points >= 3 points = 90% specificity and 20% sensitivity

45. ECG in Chronic MI

46. LV Aneurysm ST elevation seen > 2 weeks following an acute myocardial infarction Most commonly seen in precordial leads May exhibit concave or convex morphology Usually associated with well- formed Q or QS waves T- waves have a relatively small amplitude in comparison to the QRS complex

47. Factors Favouring Left Ventricular aneurysms ECG identical to previous ECGs Absence of dynamic ST segment changes Absence of reciprocal ST depression Factors Favouring Acute STEMI New ST changes compared with previous ECGs Dynamic/progressive ECG changes- the degree of ST elevation increases on serial ECGs Reciprocal ST depression High clinical suspicion of STEMI- ongoing ischemic chest pain, sick looking patient ( eg . Pale, sweaty ), h emodynamic instabilty

48. ECG changes during Angina ECG at rest ECG during angina

49. THANK YOU