02 - Basic Principles of the ECG Flashcards Preview

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Flashcards in 02 - Basic Principles of the ECG Deck (39):
0

What is the pathway of the typical cardiac electrical activity?

SA node
Right atrium
AV node
Bundle of His
Purkinje fibers
Ventricles

1

With atrial depolarization, atrial contraction begins and correlates to which wave?

P

2

When atrial contraction finishes, the myocardium stops depolarizing and there is another isoelectric point in the ECG which is called

P-R interval

3

When depolarization moves from the apex of the ventricles toward the outflow tracts, this complex is generated?

QRS

4

Why is the QRS complex bigger than the P wave?

Ventricular myocardial muscle has greater mass

5

The first downward portion of the QRS complex corresponds to what electrical activity?

Septal depolarization

6

The first upward portion of the QRS complex corresponds to what electrical activity?

Left ventricle depolarization

7

The second downward portion of the QRS corresponds to what electrical activity?

Right ventricle depolarization

8

The second upward portion of the QRS corresponds to what electrical activity?

Return to baseline

9

What electrical event occurs when ventricular contraction finishes?

None

10

What is happening during the refractory period?

Depolarization can not occur while ion channels are balancing potassium and calcium

11

What is happening during ventricular relaxation? What wave does this correspond to?

Ventricular repolarization
T

12

Changes to the T wave are often due to

Ventricular tissue not being able to repolarize or relax correctly

13

Why is atrial repolarization/relaxation not shown on the EKG waveform?

It is usually swallowed up in the QRS complex

14

The SA node paces the heart at what rate? What is its height and width?

60-100 bpm
Height - 2.5 mm
Width - .11 sec

15

First half of the P wave is ______ depol while the second half is ______ depol

Right atrium
Left atrium

16

Slow conduction through the AV node is carried by

Calcium ion channels

17

The AV node responds to ______ from the sympathetic nerves and ______ from the vagus nerve

Stimulation
Inhibition

18

The PR interval measures? How many seconds does it last?

Beginning of atrial contraction to ventricular contraction
.12-.20 sec

19

Upon reaching the ventricular conducting system, depolarization is

Rapid

20

How long is the QRS complex?

.12 sec

21

What does a very wide or deep Q wave indicate?

MI that involves full depth of the myocardium and has left a scar

22

Physical contraction and pull back of the heart from the electrode during contraction

S wave - any neg deflection after R wave

23

Displacement of the ST segment indicates

Damage to the cardiac muscle or strain on ventricles

24

How long does the ST segment last?

0.08 sec

25

Electrolyte imbalances will be reflected on the

T wave

26

What is the height of the T wave?

One to two thirds of the corresponding R

27

Repolarization is accomplished by ________ leaving the myocytes

Potassium

28

What does the QT segment represent?

The entire systolic cycle
Begins with QRS until the end of T wave

29

How long does the QT segment last?

.4 sec

30

Ventricular contraction stands

Depol and repol of the ventricles

31

Each small division is

1 mm
Each large division is 5 mm

32

Vertically, each small block is

0.1 mV

33

0.2 seconds is representative of the

Horizontal measurement of a large block
So each small block is 0.04 sec

34

Three distinct characteristics of a wave?

Duration
Amplitude
Characteristics (oh)

35

Septal

V4, V5

36

Anterior

V1, V2

37

Lateral

I, aVL, V5, V6

38

Inferior

II, III, aVF