EKGs…The Basics for FP Residents

1. EKGs…The Basics for FP Residents Jess Fogler, MD University of California, San Francisco

2. Part III Arrhythmias

3. An Approach… Attempt to diagnose NSR: • Start with the rhythm strip • Rate • Regularity • Measure RR interval carefully if rate fast • Check for P wave before every QRS

4. An Approach… • Check leads I, II, aVF • If P waves upright and consistent morphology: originating from sinus node

5. An Approach… • If not NSR…evaluate: • Rate • Regularity • Width of QRS complex • Concentrate on finding P waves • V1 most sensitive for P waves • Ps are little “noses” that can deform other waves

7. Atrial Fibrillation • The most common sustained arrhythmia • Afib: rapid, small amplitude waves that have inconsistent morphology • Best seen in V1-2, or inferior leads

8. Atrial Fibrillation • Not all irregular rhythms are afib • Irregularly irregular • Aflutter with variable conduction • Multifocal atrial tachycardia • Multiple PAC’s or PVC’s • Regularly irregular • 2° A-V block (type I or II) • Repetitive PVC’s, PJC’s, PAC’s (bigeminy, trigeminy)

9. Atrial Fibrillation • Organized Afib: fibrillatory waves with peak-to-peak amplitude > 2 mm • Waves can look similar • Examine over several seconds to reveal variations in morphology • Differentiate from aflutter (treatment different)

11. Atrial Flutter • Continuous regular atrial activity • Re-entrant atrial circuit • Atrial rate 250-350/min • Flutter waves must have identical morphology • subtract for confounding effects of QRS, ST segment, T wave

12. Atrial Flutter • Classical aflutter (seen in 2/3) • Cover R waves and look for negative waves in II, III, F with rate 250-350 • Atypical flutter • Continuous regular atrial activity at 250-350

13. Atrial Flutter • Conduction of QRS complexes • 1:1 (rare) • 2:1 (QRS rate ~140-160) most common • 3:1 • Rhythmicity • Regular rhythm most common • Variable conduction possible • irregular rhythm • Can be irregularly irregular • Compare to afib, organized afib

14. Premature Atrial Complexes • PAC’s are the most common rhythm disturbance • Incidence increases with age • 13% healthy boys • 75% adult males • More common in patients with cardiac disease • Can trigger other arrhythmias • Afib, aflutter • PSVT

15. Premature Atrial Complexes PAC’s come in three flavors • 1. Premature P wave with normal QRS: • Ectopic atrial focus fires before the sinus node • Different morphology from sinus P wave • Normal QRS when AV node, conduction system repolarized and ready to go.

16. Premature Atrial Complexes • 2. Premature P wave with no QRS: • P wave occurs very early • between onset of QRS and peak of T wave • Check T’s carefully for deformations • A-V node and bundles in refractory period (ie asleep)

17. Premature Atrial Complexes • 3. Premature P wave with aberrant ventricular conduction • P wave falls after peak of T wave • A-V node “awake” • Other parts of the conduction system still “asleep” • Commonly has RBBB morphology • RB asleep, LB awake

18. Premature Atrial Complexes • All PAC’s are followed by a compensatory pause while the sinus node resets • With multiple PAC’s rhythm can become irregularly irregular

19. Multifocal Atrial Tachycardia • MAT: an irregularly irregular rhythm • P waves with ≥ 3 morphologies per lead • Mean atrial rate >100/min • Variable PR intervals • Non-conducted atrial activity common • Associated with pulmonary disease in 60%

21. First Degree A-V Block • Prolonged A-V conduction • Atrio-ventricular ratio 1:1 • P-R interval ≥ 210 msec

22. Type I (Wenckebach): PR prolongation Regularly irregular rhythm (group beating) Constant P-P interval Increase in PR interval (but not necessarily progressive) leading to a… Non-conducted P wave Pause < 2 x RR Next PR interval usually shortest Second Degree A-V Block

23. Second Degree A-V Block Type II (Mobitz): sudden failure • Constant P-R interval • Constant P-P interval • Dropped beats • Rare • Can progress to asystole, 3˚ A-V block, death • Permanent pacemaker required

24. Third Degree A-V Block • Complete failure of atrial impulse propagation with independent junctional or ventricular escape rhythm • P waves and QRS complexes have no relation to each other • Usually will see more P waves than QRS complexes

26. Paroxysmal Supraventricular Tachycardia (PSVT) • Atrial rhythm: narrow QRS (usually) • Paroxysmal • Rate 140-250 • AVRT • AVNRT • Atrial tachycardia

27. Paroxysmal Supraventricular Tachycardia (PSVT) • Differentiation between types usually not necessary as treatment for all similar • Unstable patients: DC cardioversion • Stable patients: vagal maneuvers, adenosine, verapamil etc. • Adenosine may reveal flutter waves • ST-T changes are frequent and a poor predictor of underlying CAD (even with chest pain)

28. Wide QRS Complex Tachycardia • First: is the rhythm regular? • Irregularity easily missed at fast rates • Use calipers or measure with paper • Treatment of irregular WCT different than regular WCT

30. Wide QRS Complex Tachycardia Irregular rhythm: • Afib with BBB or IVCD (pre-existent or rate related) • Afib with anterograde conduction over accessory pathway in WPW • Other causes of an irregular rhythm (aflutter with variable conduction, MAT etc) with BBB, WPW, IVCD

32. Wide QRS Complex Tachycardia Regular rhythm: • Ventricular driven rhythm: • Vtach - worst case scenario • Supraventricular rhythm with aberrant conduction: • Sinus tach with BBB (pre-existent or rate related) - most common • SVT (atrial tach, PSVT) with BBB • Antidromic reciprocating tachycardia in WPW

33. Wide QRS Complex Tachycardia Basic diagnostic algorithm for WCT with regular rhythm: • If QRS complex doesn’t fit the typical pattern of either RBBB or LBBB, the diagnosis defaults to Vtach • Remember that sinus tach with BBB is most common so scrutinize for P waves • When in doubt treat for Vtach

36. Train your eyes • Train your eyes for Rate: • Check the computer • Train your eyes for Rhythm: • Check the rhythm strip • Check I, II, avF • Train your eyes for Axis: • Check I, II • Train your eyes for Intervals: • PR: check II • QT: check the computer • QRS: check I, V1

37. Train your eyes • Train your eyes for LVH: • Look at…in order • avL • V3 • V1 • V5,V6 • Check your cheat sheet • Read the computer • Train your eyes for MI: • Look at all T waves • Look at all ST segments • Check for Q waves • Check for R waves in V1-2

38. Practice Makes perfect

39. Rate: 250 QTC: 410

40. Rate: 42 QTC: 375

41. Rate: 74 QTC: 410

42. Rate: 150 QTC: 410

43. Rate: 41 QTC: 360

44. Rate: 62 QTC: 390

45. Rate: 114 QTC: 445

47. Rate: 43 QTC: 440

48. Rate: 73 QTC: 390

49. Rate: 42 QTC: 420 I II III

50. Rate: 71 QTC: 380