8/5- Electrocardiography at the Bedside 2 Flashcards Preview

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Flashcards in 8/5- Electrocardiography at the Bedside 2 Deck (36):
1

Recap- Normal intervals:

- Normal PR interval:

- Normal QRS interval:

- Normal QTc interval:

- Normal PR interval: 3-5 small boxes = 120-200 ms

- Normal QRS interval: 2-3 small boxes = 80-120 ms

- Normal QTc interval: 9-11 small boxes = 360-440 ms

2

What may cause long PR?

Drugs

- Digoxin

- BB

- CCB

Ischemia or infarction;

Degeneration or calcification of AVN or His bundle

3

What may cause long QT?

- Drugs

- Electrolytes (low K, low Ca, or low Mg)

4

What are the ECG criteria for LVH? RVH? (Left/right ventricular hypertrophy)

Are these concentric or eccentric hypertrophy? 

LVH:

- Left axis deviation

- R (V5/V6) + S (V1/V2) > 35 mm

RVH:

- Right axis deviation

- Tall R in V1/V2 (> 5 mm or R > S)

This is for concentric hypertrophy

5

What is this showing? 

Q image thumb

Left Ventricular Hypertrophy

- Deep S waves in V1 and V2

- Tall R waves in V5 and V6 

A image thumb
6

What is this showing? 

Q image thumb

Right ventricular hypertrophy

- Right axis deviation "RAD" (from looking at leads 1 and aVF)

- Tall R in V1, V2: R>S or R > 5mm

(QRS are positive in V1 and V2!) 

A image thumb
7

ECG signs of pressure vs. volume overload?

Pressure Overload:

- Concentric hypertrophy

- LVH or RVH

Volume Overload:

- Eccentric hypertrophy

- LBBB or RBBB

8

What are pathologic Q wave characteristics?

What are they indicative of?

- Small Q waves are normal in I, aVL, V5, and V6

Two features of pathologic Q waves

1. Wider than 0.04 sec in duration

2. Deeper than 1/3 of the R wave in same lead

Pathologic Q waves are indicative of old MI

9

Analyze this? 

Q image thumb

Pathologic Q waves

- Pathologic Q waves

- ST elevation

- Inverted T waves

10

What are some ST segment abnormalities (broadly)? What are these indicative of?

- ST depression: indicates sub-endocardial ischemia

- ST elevation: indicates acute myocardial infarction

11

What is the pathophysiologic difference between ST depression and ST elevation? on EKG?

A image thumb
12

What are the different types of ST segment depression?

- Downsloping

- Horizontal

- Upsloping

13

What is this showing? 

Q image thumb

Classical downsloping ST segment depression

- Lower than isoelectric line and keeps going down (Sub-endocardial ischemia)

14

ST depression most specific for sub-endocardial ischemia is:

A. Downsloping

B. Horizontal

C. Upsloping

ST depression most specific for sub-endocardial ischemia is: 

A. Downsloping

B. Horizontal

C. Upsloping

15

What are some possible causes of ST segment elevation?

- Acute myocardial infarction

- Coronary vasospasm (Prinzmetal angina): artery only becomes smaller transiently as muscle of artery contracts

- Acute pericarditis

- Early repolarization

16

Differentiation of Acute MI and Pericarditis by ECG?

Acute MI:

- LOCALIZED ST elevation (only a few leads)

- Pathologic Q waves

- NO PR depression

Acute Pericarditis (inflammation throughout pericardium):

- DIFFUSE ST elevation

- NO pathologic Q waves

- PR depression

17

What is shown here? 

Q image thumb

Acute Anterolateral Myocardial Infraction

- ST segment elevations in leads I, aVL, and V2-V6

- Very marked elevation

18

What is shown here? 

Q image thumb

Acute Pericarditis

- Diffuse ST segment elevation in all ECG leads

- More subtle elevation

19

What is shown here?

Q image thumb

PR segment depression in acute pericarditis

- Depressed PR segments between P and QRS

20

3 characteristics of Evolving Infarction?

- Pathologic Q waves

- ST elevation

- Inverted T waves

A image thumb
21

Evolution of Myocardial Infarction (EKG)

Q image thumb

A image thumb
22

Characteristics that determine which phase of evolution the myocardial infarction is in?

- Acute MI:

- Evolving MI:

- Old MI:

- Acute MI: ST elevation ONLY

- Evolving MI: ST elevation AND T wave inversion or pathologic Q waves

- Old MI: pathologic Q waves only (never goes away)

(ST elevation typically subsides in 2-3 days; if it persists more than 14 days, should suspect ventricular aneurysm --)

(T wave normalization is variable... days or never)

23

Steps in evolution of myocardial infarction? Recovery?

- ST segment is elevated immediately

- Pathologic Q waves and T wave inversions appear at 8-12 hours

- ST segments normalize in 2-14 days

- Pathologic Q waves stay usually indefinitely

- T wave inversions are highly variable

24

In what conditions do we see T wave inversions?

- Myocardial ischemia

- LVH or RVH (called strain changes)

- LBBB or RBBB

- Digoxin (called digoxin effect)

*NOT specific for sub-endocardial ischemia

25

What characterizes "tall" T waves?

In what conditions do we see tall T waves?

T waves > 10mm in at least 2 chest leads

- Myocardial ischemia

- Acute myocardial infarction

- Hyperkalemia!!

26

What is this showing?

Q image thumb

Progression of R waves in precordial leads

27

Steps in abnormal R wave progression?

- Early R/S transition:

- Late R/S transition:

Early R/S transition: bigger R waves in V1 and V2

Later R/S transition: smaller R waves in V5 and V6

(resulting in overall negative QRS complex)

28

Tall R waves in V1 and/or V2 may be present in which conditions/diseases?

- Old posterior myocardial infarction

- Right ventricular hypertrophy (RVH)

- Right bundle branch block (RBBB)

- Wolf-Parkinson-White (WPW)

- Duchenne muscular dystrophy

29

LVH ECG Criteria?

R (V5/V6) + S (V1/V2) > 35

and

LAD

30

RVH ECG Criteria?

R > 5 or R/S > 1 in V1/2

and

RAD

31

Pathologic Q waves are characterized how?

Indicative of?

Q > 0.04 ms or > 1/3 of R wave

- Indicative of OLD myocardial infarction

32

ST elevation seen in what conditions?

AMI, pericarditis or spasm

- Acute pericarditis if diffuse ST elevation, no pathologic Q waves, depressed PR

33

ST depression seen in what conditions?

ischemia (horizontal or downsloping ST); otherwise nonspecific

34

Peaked T is caused by what?

High K, AMI, or ischemia

35

Tall R in V1 is caused by what?

Post MI, RVH, RBBB, and WPW

36

Pathologic Q waves are characterized by all of the following except?

A.

-