Bundle Branch Block and the Imitators of ACS

1. MODULE 6 Bundle Branch Block and the Imitators of ACS

2. Bundle Branch Block • Can be pre-existing condition • Can be caused by ACS

3. Bundle Branch Block • BBB caused by AMI • 60%-70% association with pump failure • 40%-60% mortality without reperfusion

4. Bundle Branch Block • Can mimic ACS • Can hide evidence of ACS

5. May Produce ST elevation ST depression Tall T waves Inverted T waves Wide Q waves May Hide ST elevation ST depression Tall T waves Inverted T waves Wide Q waves Bundle Branch Block

6. The Problem • Critical to reperfuse patients with BBB produced by ACS • ACS harder to identify on ECG when BBB present

7. The Solution • BBB Problem • New or presumably new BBB is an indication for fibrinolytic therapy

8. The Solution Fibrinolytic Therapy Trialists’ (FIT) Collaborative Group, 1994

9. BBB Recognition Forget About the Notch!

10. BBB Recognition • Wide QRS • > 120ms • Supraventricular rhythm

11. BBB Recognition

12. RBBB vs LBBB • RBBB in V1

13. RBBB vs. LBBB • LBBB in V1

14. RBBB vs. LBBB • Use V1 • Identify direction of terminal force

15. Bundle Branch Block • V1

16. BBB Recognition

17. BBB Recognition

18. BBB New onset BBB, or presumably new BBB, is an indication for acute reperfusion therapy

19. Ventricular Rhythms • Paced rhythms • Idioventricular rhythms • AIVR • V-Tach • PVC

20. Ventricular Rhythms • Can mask or mimic every ECG change suggestive of ACS

21. Ventricular Rhythms

22. Left Ventricular Hypertrophy • Enlarged left ventricle • Pumping against increased resistance • Chronic overfilling

23. May Produce ST elevation ST depression Tall T waves Inverted T waves May Hide ST elevation ST depression Tall T waves Inverted T waves LVH

24. LVH • Does not abnormally widen QRS • Increases height and depth of QRS • Recognized by this increase • Three step recognition formula

25. LVH

26. LVH Recognition • Step 1 • Look in V1 and V2 • Pick the deepest negative deflection • Count small boxes of negative deflection in that lead • Remember that number

27. LVH

28. LVH Recognition • Step 2 • Look in V5 and V6 • Pick the tallest positive deflection • Count small boxes of positive deflection • Remember that number

30. LVH Recognition • Step 3 • Add the two numbers together • Suspect LVH if the sum equals 35 or more

31. LVH

32. LVH

33. Ventricular Aneurysm • NOT Aortic Aneurysm • “Bleb” in ventricle secondary to infarct • Bleb is dyskinetic • “Pops out” when ventricle contracts

34. Ventricular Aneurysm

35. Ventricular Aneurysm • Associated with persistent ST elevation • Often in V1-V4 • Can occur in any lead

36. Ventricular Aneurysm

37. Benign Early Repolarization

38. Benign Early Repolarization • Normal variant • Produces • ST elevation • Tall T waves

39. Benign Early Repolarization • Changes usually seen in anterior and lateral leads • Most often seen in males ages 20-40 • African-American males

40. Benign Early Repolarization • Look for notch at J-point • ST segment and J-point create a “fish hook” appearance

41. Benign Early Repolarization

42. Pericarditis

43. Pericarditis • May be viral, bacterial or metabolic • Clinical presentation may include chest pain • Often produces ST elevation on ECG

44. Pericarditis • Clinical presentation • Sharp chest pain • Can be localized • Radiates to base of neck, between shoulder blades

45. Pericarditis • Pain affected by movement and respiration • Pain improves when patient leans forward • Pain worsens when patient supine

46. Pericarditis • May produce ST elevation in any lead • May be in all leads • May not be anatomically grouped • J-point notching often present • Fish hook

47. Medications • Some medications affect the ECG • Digitalis • ST depression • Characteristic sag

48. Digitalis Effect

49. Summary • Imitators can produce ST elevation or depression • Imitators can eliminate ST elevation or depression

50. Summary • Imitators can produce T wave inversion • Imitators can hide T wave inversion