1. EKG 101 Deborah Goldstein Georgetown University
Department of Internal Medicine

2. Steps to Interpreting an EKG
Rate
Rhythm
Axis
Intervals (PR, QRS, QTc)
Hypertrophy
ST segments
T waves
Q waves

4. Rate

5. Naming stuff
P before every QRS

6. Normal Sinus Rhythm P before every QRS QRS after each P
Best places to look: II, V1
QRS after each P

7. Axis
1. The direction of the mean electrical vector, representing the average of current flow in the frontal plane.
2. Normal axis: –30 to +90 degrees.

8. Axis

9. Axis Look at lead I and aVF.
Then find the isoelectric lead (where the QRS complex is most nearly biphasic).
Then go 90 degrees perpendicular to the isoelectric lead.

10. Axis

11. Axis

12. Rate, Rhythm, Axis
normal axis

13. Rate, Rhythm, Axis
LAD

14. Rate, Rhythm, Axis
RAD

15. Ddx of Axis Deviation LAD
Left ventricular hypertrophy, Left anterior fascicular block, LBBB, Inferior wall MI
Pregnant, ascites, short/fat
RAD
Right ventricular hypertrophy, Left posterior fascicular block, RBBB, lateral wall MI PE

16. PR Interval Normal PR = 0.12 – 0.20 seconds (3-5 little boxes)
Long PR >0.20 seconds (>5 little boxes)
=Delayed conduction from atria to ventricles
First-degree AV block
PR>0.20 seconds
NO dropped QRS

17. Second Degree AV Block Wenckebach (Type 1) =block within AV node
PR interval progressively lengthens...then dropped QRS
Mobitz (Type 2)
=block within His-Purkinje system
Fixed PR with dropped QRS
WORSE!
Sarcoid, Lyme....
Pacemaker!

18. Third Degree AV Block
=Failure of conduction of any atrial impulses to get to the ventricles
=Complete AV block
Causes of Acute AV Block:
Calcium channel blockers
Acute RCA occlusion
Digoxin toxicity

19. What kind of AV Block?
1st degree AV block

20. What kind of AV Block?
3rd degree

21. What kind of AV Block?
2nd degree AV block Mobitz—fixed PR, dropped QRS

22. What kind of AV Block?
Type 1 Wenckebach; progressive PR progression, then dropped QRS

23. QRS Interval Normal = 0.06-0.10 seconds
Wide QRS = >0.12 seconds (>3 little boxes)
PVC...if >3 in a row or >6/min=VTach
RBBB, LBBB
Left fascicular hemiblock
Hyperkalemia
Narrow QRS= <0.06 sec
SVT ( bpm)
Idiojunctional rhythm (40-60 bpm)
Premature junctional complex

24. Chest Leads V6 V1

25. Bundle Branch Block V1-V2 = Right precordial leads
V5-V6 = Left precordial leads
LBBB
Rabbit ears in V6 represent delay between depolarization from the septum  to the LV
RBBB
Rabbit ears in V1 represent delay between depolarization from the septum to the RV

26. Normal: V1: rS complex V6: qR complex RBBB: V1: Rabbit Ears (rSR)
V V6
Normal:
V1: rS complex
V6: qR complex
RBBB:
V1: Rabbit Ears (rSR)
V6: qRS complex
LBBB:
V1: wide QS complex
V6: Rabbit Ears

27. Wide QRS—Why?
RBBB: V1: wide rSR. V6: qRS complex. TWI V1-V3= secondary t wave inversions

28. Wide QRS—Why?
LBBB: V1 has wide QRS, V6 with notched peak. Inv T in V5, V6

29. QT Interval Should be < ½ (R-R’ interval)
Measure from the start of the QRS to end of T wave
Varies with heart rate, so correct for RR interval
Normal QTc: women=0.44, men=0.42
QTc = QT (#of small squares) x 0.04
√RR
Long QT can lead to ‘R on T’Death

31. Causes of Long QT Macrolides, Quinolones
**Think ‘Lytes and Meds first!
Low K, Low Ca, Low Mg
Macrolides, Quinolones
All Antipsychotics (Haldol worst, Geodon least)
SSRIs
Sotalol, Quinidine, Ondansetron, Amio, TCAs
Pts w/LVH or CHF are predisposed to medication-related lengthening of QT interval!
Avoid Macrolides, Quinolones in them!

32. Long QT: Less common causes
Hypothyroid
Hypothermia
AV Block MI
CVA
Head injury
Congenital long QT

33. Atrial Enlargement RAE P wave is tall and peaked (>2.5mm high)
OR Biphasic P wave with initial positive inflection
Ddx: Pulmonary HTN, COPD, PE
LAE
P wave is wide (>0.12 sec) and notched in the middle “M”
OR Biphasic P wave with terminal negative inflection
Ddx: Systemic HTN, Aortic Insufficiency, Mitral Stenosis

35. Which Atria is Enlarged?
Right Atrial enlargement

36. Which Atria is Enlarged?II V1
LAE

38. LVH Criteria Sokolow + Lyon S V1+ R V5 or V6 > 35 mm
Cornell criteria (Circulation, 1987;3: )
S V3 + R avl > 28 mm in men
S V3 + R avl > 20 mm in women
Framingham criteria (Circulation,1990; 81: )
R avl > 11mm, R V4-6 > 25mm
S V1-3 > 25 mm, S V1 or V2 +
R V5 or V6 > 35 mm, R I + S III > 25 mm
Romhilt + Estes (Am Heart J, 1986:75:752-58)
Point score system
(Am Heart J, 1999;37:161)

39. LVH “S V1+ R V5 or V6 > 35mm”

40. ST changes: axis + anatomy
Lateral:
I, aVL
LCA, CFX
Anterior:
V1, V2, V3, V4
LAD
Inferior:
-II, III and aVF
-RCA (or LCA)
Memorize this slide

41. Q waves Normal Q wave: Pathologic Q wave:
Small septal Qs in I, aVL, V5, V6
Isolated Qs in III, V1
Pathologic Q wave:
wider than 1 small box (0.04 sec)
OR >25% height of the R wave in that complex

42. Normal Q waves

43. Abnormal Q Waves

44. nonSTelev MI w/diffuse ST depr

45. Non-ST Elevation MI =Severe subendocardial ischemia
Marked, diffuse ST depressions in I, II, III, aVL , aVF , V2-V6

46. 2 EKGs, several hours apart
A: hyperacute T waves. B: Hours later: ST elev, Q V1/V2 (likely LAD lesion)

47. Acute ST Elevation MI Normal Hyperacute T wave Elevation Acute
Hours Later
ST Elev, Q begins to form, T wave inverts
Days Later
Q wave, T wave inversion
Weeks Later
Q wave

48. A 55 year old man with 4 hours of "crushing" chest pain.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
Acute inf wall MI

49. Acute Inferior Wall MI ST elev in II, III, AVF
Reciprocal ST depression in anterior leads (V2-V4)
=RCA occlusion (some LCx)

50. A 53 year old man with Ischemic Heart disease
prior inf wall MI

51. Old Inferior Wall MI Pathologic Q wave in II, III, AVF:
wider than 1 small box (0.04 sec)
OR >25% height of the R wave in that complex

52. An 83 year old man with aortic stenosis.
LAE, LVH

53. LVH, LAE 3 points for: Romhilt-Estes LVH Point System:
3 points for Left Atrial Enlargement
M shaped P wave in II
P has prominent terminal negative component in V1
3 points for:
R wave in V5 or V6 >30mm
or S wave in V1 or V2 >30mm
or R or S in limb leads>20mm
>5 points: definite LVH

54. A 76 year old man with breathlessness.
Afib RVR

55. Afib with RVR Irregularly irregular ventricular rhythm.
Must look carefully to see it is NOT regular

56. A 72 year old man on routine office visit
V paced

57. Ventricular Pacemaker
Pacer spikes—hard to see!
Wide QRS complexes
Pacemaker starts after a long R - R interval following a blocked atrial premature beat...then NSR

58. A 58 year old man on hemodialysis presents with
profound weakness after a weekend fishing trip.

59. Hyperkalemia K >8.0 Wide, tall and tented T waves Wide QRS
Small or absent P waves
Atrial fibrillation
Shortened or absent ST segment
Ventricular fibrillation

60. Aflutter

61. Atrial Flutter Saw tooth baseline with rate of 250-300 Causes:
Ischemic heart disease
Hypertension
Mitral valve disease
Thyrotoxicosis
Cardiomyopathy

62. PR depression V4-5 and I/AVL , ST elev concave up I, AVl

63. Pericarditis Evolves over hours-weeks
PR depression, ST elevation (concave up) in same leads, upright T
Normal P, normal ST, flat T
Normal P, normal ST, T Wave inversion
normal P, normal ST, upright T

64. Hypocalcemia: long Qt, inv Ts

65. Hypocalcemia
Long QT
Inverted T waves

66. Hyperkalemia