12-Lead EKG Interpretation I work for Virginia Garcia Memorial - - PDF document

▶
12 lead ekg interpretation
SMART_READER_LITE
LIVE PREVIEW

12-Lead EKG Interpretation I work for Virginia Garcia Memorial - - PDF document

Aug 29, 2022 320 likes •644 views

Disclosures: 12-Lead EKG Interpretation I work for Virginia Garcia Memorial Health Center, Beaverton, Oregon. Jon Tardiff, BS, PA-C And I am a medical editor for Jones & Bartlett Publishing.

slide-1
SLIDE 1

Jon Tardiff, BS, PA-C

  • 12-Lead EKG Interpretation
  • I work for Virginia Garcia

Memorial Health Center, Beaverton, Oregon.

  • And I am a medical editor for Jones & Bartlett Publishing.

Disclosures:

3

Goals for today’s ECG Review:

  • Determine Right vs Left bundle branch block
  • Diagnose Acute MI
  • Diagnose old MI
  • Location of the infarct
  • Other Acute Coronary Syndromes
  • Determine Axis
  • Other ECG confounders
  • Pfun!

“Ask questions any time—I like answering them”

What a 12-Lead EKG can help you do

  • Diagnose ACS / AMI
  • Interpret arrhythmias* (computer Dx)
  • Identify life-threatening syndromes (WPW,

LGL, Long QT synd., Wellens synd., etc)

  • Infer electrolyte imbalances
  • Infer hypertrophy of any chamber
  • Infer COPD, pericarditis, drug effects, and

more!

slide-2
SLIDE 2

5

  • 73 y.o. male with nausea, syncope

6

Acute Inferior MI

ST elevation

What rhythm?

(look at V1 for P waves)

(w/septal MI?)

slide-3
SLIDE 3

9

another example…

  • 10

WPW with Atrial Fib

  • WPW Graphic
  • Wolff-Parkinson-White synd.
  • short PR
  • wide QRS
  • delta wave

12

Same pt, converted to SR

slide-4
SLIDE 4

Limitations of a 12-Lead ECG

  • Truly useful only ~40% of the time
  • Each ECG is only a 10 sec. snapshot
  • Serial ECGs are necessary, especially for ACS
  • Other labs help corroborate ECG findings

(cardiac markers, Cx X-ray)

  • Confounders must be ruled out (dissecting

aneurysm, pericarditis, WPW, LBBB, digoxin, RVH)

The Problem with Bundle Branch Blocks

  • Desynchronized contraction of the ventricles
  • Reduced cardiac output
  • Worsened heart failure
  • 15

Confounder: Left Bundle Branch Block

  • 16

Bundle Branch Blocks

(QRS > 120 msec.)

Left BBB

(L I, V5, V6: upright QRS with a notch)

Right BBB

(V1, V2, MCL1: rsR’ pattern) R’ S r notch

I

V1

(left-sided lead) (right-sided lead)

slide-5
SLIDE 5

17

Bundle Branch Blocks

Two QRSs

notch

I

Healthy ventricle Blocked bundle R’ S r

V1

slur

I

V1 & V2 RBBB V5 V6 (& I, aVL) LBBB

20

Practice: Bundle Branch Block

slide-6
SLIDE 6

RBBB

  • Which Bundle Branch is Blocked?

1

RBBB

  • Right Bundle Branch Block (Lead V1)

1

LBBB 12-Lead

  • Which Bundle Branch is Blocked?

2

LBBB 12-Lead

  • Left Bundle Branch Block

(L I, V5, V6)

2

slide-7
SLIDE 7

Where is the Pathology? Right Bundle Branch Block

27

Where is the Pathology?

28

Left Bundle Branch Block

slide-8
SLIDE 8

Limitations of a 12-Lead ECG

  • They are occasionally wrong!

30

Impending AMI with ECG!

31

13 hrs later — Acute Anterior MI

Elevated ST segments

ECG Pearls

  • Lead II is the easiest lead to read / most intuitive
  • But Lead V1 is our single best lead.
  • “A Q in III is free.” (isolated Q in L III)
  • If you know where the + electrode is, you can

read any ECG

slide-9
SLIDE 9

33

ECG Lead Placement & Electrophysiology Review

34

I II III

Limb Leads

(standard leads)

  • ±

+

35

Leads I, II, III

I II III

Normal 12-Lead ECG

slide-10
SLIDE 10

37

Rapid Interpretation Tips

  • Dr. Willem Einthoven
  • Invented the electrocardiograph
  • Discovered atrial
  • Won Nobel Prize for Medicine 1924

39 39

SA Node AV Node His Bundle BBs Purkinje Fibers P Q R S T

II

U

Conduction System

40

Q R S P wave axis R wave axis …upright in L II …upright in L II

Lead II

slide-11
SLIDE 11

41 41

PR

II

Intervals

PR Interval: 120 – 200 mSec (3 – 5 boxes) QRS width: 60 – 120 mSec (1 – 3 boxes) QT/QTc interval: 400 mSec (10 boxes) QT QRS

42

300, 150, 100, 75, 60, 50 Quick, easy, sufficient

  • Count PQRST

in a 6- second strip & multiply x 10

Easy, & more accurate

  • 300 150 100 75 60

6 seconds

Horizontal axis is (mS); vertical axis is electrical (mV)

43

Normal Sinus Rhythm

What is the heart rate?

6 seconds

44

I II III aVR aVL aVF

Limb (frontal plane) Leads

(augmented leads) (standard leads)

slide-12
SLIDE 12

Normal 12-Lead ECG

  • 46

6 Frontal Plane Leads

(limb leads) I II III R L F

Axis

  • 47

Leads

I II III aVR* aVL aVF

  • 48
slide-13
SLIDE 13

49

I II III aVR aVL aVF V1 V2 V3 V4 V5 V6

Limb (frontal plane) Leads

(augmented leads) (standard leads) (anterior leads) (lateral leads)

Chest (precordial) Leads

50

V Lead Cutaway

V Lead Progression

slide-14
SLIDE 14

Normal 12-Lead ECG

  • 54

New 12-Lead ECG Format

aVL I

  • aVR

II aVF III

New 12-Lead ECG Format

aVL I

  • aVR

II aVF III New Old

Axis Determination

slide-15
SLIDE 15

57

Why We Care About Axis Deviations

The axis shifts &

58

Axis Deviation

Horizontal heart (0°): obesity, 3rd trimester pregnancy. Ascites Vertical heart (90°): slender build Left Axis Deviation: LBBB, Anterior MI, Inferior MI, Left anterior hemiblock, LVH Right Axis Deviation: Anterior MI, Lateral MI, RBBB, COPD, RVH, Left posterior hemiblock Extreme RAD: Ectopic rhythm (VT), massive MI

  • 59

QRS Morphology in Lead II II

60

How to calculate Axis

the computer does it for you!

  • (if tallest is Lead II = )

Thumbs up / Thumbs down

slide-16
SLIDE 16

61

Thumbs Up / Down Method

Lead I —Your Left thumb Lead aVF —Your Right thumb

62

Practice: Axis

3

I F

63

Axis Practice

1

Normal Axis

I F

64

4

I F

slide-17
SLIDE 17

65

4

Left Axis Deviation

I F

66

5

67

5

Right Axis Deviation

68

6

slide-18
SLIDE 18

69

6

Extreme Right Axis Deviation

Lots of ways to read EKGs…

  • QRSs wide or narrow?
  • Regular or irregular?
  • Fast or slow?
  • P waves?
  • Sinus rhythm or not?
  • If not, is it atrial fibrillation?
  • BBB?
  • MI?

Symptoms:

  • Syncope is bradycardia, heart blocks, or VT
  • Rapid heart beat is AF, SVT, or VT

71

Step-by-step method for reading a 12-Lead

Rapid Interpretation Tips

Rapid Interpretation Tips

  • Identify the rhythm. If supraventricular*,

If no LBBB, If present,

  • Rule out other confounders: WPW, pericarditis, LVH,

digoxin effect

  • Identify location of infarct, and consider appropriate

treatments: MONA, PCI [or fibrinolytic], nitrate infusion, heparin infusion, GP IIb, IIIa inhibitor, beta- blocker, clopidogrel, statin, etc.

slide-19
SLIDE 19

Supraventricular rhythms

  • Sinus rhythm
  • Atrial fibrillation
  • Junctional rhythm
  • PSVT / AVNRT
  • Atrial tachycardia
  • Atrial flutter
  • Wandering atrial pacemaker
  • MAT

Normal 12-Lead ECG

  • Rapid Interpretation Tips

Rapid Interpretation Tips

  • Identify the rhythm. If supraventricular,

If no LBBB, If present,

  • Rule out other confounders: WPW, pericarditis, LVH,

digoxin effect

  • Identify location of infarct, and consider appropriate

treatments: MONA, PCI [or fibrinolytic], nitrate infusion, heparin infusion, GP IIb, IIIa inhibitor, beta- blocker, clopidogrel, statin, etc.

Rapid Interpretation Tips

Rapid Interpretation Tips

  • Identify the rhythm. If supraventricular,
  • Rule out left bundle branch block. If no LBBB,
  • Check for: ST elevation, or ST depression with T

wave inversion, and/or pathologic Q waves. If present,

  • Rule out other confounders: WPW, pericarditis, LVH,

digoxin effect

  • Identify location of infarct, and consider appropriate

treatments: MONA, PCI [or fibrinolytic], nitrate infusion, heparin infusion, GP IIb, IIIa inhibitor, beta- blocker, clopidogrel, statin, etc.

slide-20
SLIDE 20

Ischemia Injury Infarction Normal

STEMI

ST elevation, ST depression, T wave inversion, pathologic Q waves

78

Percutaneous Coronary Intervention

slide-21
SLIDE 21

81

RCA before and after stenting

Before stenting After stenting

STEMI: ECG Changes

  • A. Normal ECG
  • B. Hyperacute T wave changes -

increased T wave amplitude and width; may also see ST elevation

  • C. Marked ST elevation with

hyperacute T wave changes (transmural injury)

  • D. Pathologic Q waves, less ST

elevation, terminal T wave inversion (necrosis)

  • E. Pathologic Q waves, T wave

inversion (necrosis and fibrosis)

  • F. Pathologic Q waves, loss of R

waves (fibrosis)

(w/onset cx pn) (20 minutes) (1 hour) (1 week – years) (>1 hr) (normal)

MI ECG Patterns

84

Why Pathologic Q Waves Form

Normal q Pathologic Q

slide-22
SLIDE 22

85

STEMI — Typical Progression

Acute Inferior MI#1

Acute Inferior MI

ST elevation Qs Qs

Axis is shifting leftward…

Acute Inferior MI #2

Same Patient~2 hrs later

Worsened ST elevation Qs Qs New ST elevation

Acute Inferior MI #3

Same Patient 9 days later

Permanent Q waves (inferior wall scar) But NO anterior infarct (no Qs)

Permanent left axis deviation

slide-23
SLIDE 23

Acute Anterior MI Page

45% of MIs

Acute Inferior MI Page

40% of MIs Acute R Ventricle MI Page 1/3 of Inferior MIs

Acute Lateral MI Page

15% of MIs

slide-24
SLIDE 24

Acute Posterior MI Page

94

Practice: Infarct Location

Acute Anterior MI

Where is the Pathology?

7 Acute Anterior MI

(ST elevation in V1 - V4)

ST Elevation What is the R wave axis?

7

slide-25
SLIDE 25

Acute Inferior MI

Where is the Pathology?

8

Acute Inferior MI

Acute Inferior MI

(ST elevation in II, III, F)

8

Acute Inferolateral MI

Where is the Pathology?

9

Acute Inferolateral MI

Acute Inferolateral MI

(ST elevation in II, III, F, V5, V6) Note the axis has not shifted yet, because it is early in the AMI, and there are no loss of R waves yet.

9

slide-26
SLIDE 26

Where is the Pathology?

10

Acute Inferior & Right Ventricle MI

Acute Inferior MI & Right Ventricle MI 10

Where is the MI?

Normal V1 – V3

  • V1, V2, V3
  • Large R Waves
  • Depressed STs

ST Depression Large R waves

11

Acute Posterior MI

Normal V1 – V3

  • V1, V2, V3
  • Large R Waves
  • Depressed STs

ST Depression Large R waves

11

slide-27
SLIDE 27

105

Confounders

Rapid Interpretation Tips

Rapid Interpretation Tips

  • Identify the rhythm. If supraventricular,
  • Rule out left bundle branch block. If no LBBB,

If present,

  • Rule out other confounders: WPW, pericarditis,

LVH, digoxin effect

  • Identify location of infarct, and consider appropriate

treatments: MONA, PCI [or fibrinolytic], nitrate infusion, heparin infusion, GP IIb, IIIa inhibitor, beta- blocker, clopidogrel, statin, etc.

WPW Graphic

  • Wolff-Parkinson-White synd.

Wolff-Parkinson-White synd.

  • Short PR, Wide QRS, “Delta” wave
  • Short PR

Widened QRS Delta wave

slide-28
SLIDE 28

109 False Q Waves (the Delta wave)

WPW

  • False Q waves mimic MI

Other Confounders

111

Benign Normal Variant ST Elevation

Mild upsloping ST segments

Pericarditis

Elevated STs in multiple leads Depressed PR segments

  • NO loss of R waves •

Elevated STs in multiple leads Depressed PR segments

slide-29
SLIDE 29

Other Confounders

Left Ventricular Hypertrophy

  • Tall R waves in V5, V6; deep S waves in V1, V2

Tall R waves V5, V6 Deep S waves V1, V2

“strain”

Other Confounders: Digoxin

(ST Depression)

Depressed ST segments

116

ST Depression

(a diagnostic challenge) Can be caused by:

  • Ischemia
  • Digoxin effect
  • Tachycardia
  • LVH, BBB
  • Hypokalemia
  • NSTEMI (Non Q wave MI)
slide-30
SLIDE 30

Ischemic ST Depression (a positive exercise ECG)

118

Practice: Confounders

12

44 y.o. female with history of tachycardia

WPW (short PR, Wide QRS, Delta waves)

false Q waves delta waves short PR

12

slide-31
SLIDE 31

121

13

30 y.o. male with chest pain

122

13

Pericarditis

Depressed PR segments Elevated ST segments in multiple leads Elevated ST segments in multiple leads

123

Rhythm? Pathology?

14

124

Large Old Anterolateral MI

Large Qs V1–V6

Ventricular aneurysm

  • 14