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Flashcards in CPR Physiological Basis of ECG Deck (21)
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1

What does an ECG illustrate?

Changes of electrical activity of cardiac muscle tissue (depol and repol)
At baseline = no active depol or repol happening

2

Why does an ECG not report electrical differences between atria and ventricles?

They are electrically isolated from each other. ECG only reports voltage differences between both atria or both ventricles

3

What is the P wave?

Atrial depol. First cells near SA node to depolarize, goes until last cells of L atrium depolarize

4

What is the QRS wave?

Ventricular depol. First cells in septum to depolarize, goes until last cells of upper ventricles depolarize

5

What does the baseline line between QRS and T waves represent? (ST segment)

Phase 2, ventricular cells all depolarized, waiting on repolarization

6

What is the T wave?

Repolarization of ventricles

7

What is a U wave?

Sometimes follows normal repolarization (T wave), unknown cause

8

What does a segment represent?

Duration of a single event on an ECG
Ex: P wave or time between QRS and beginning of T wave

9

What does an interval represent?

Duration of two or more events
Ex: P wave plus beginning of QRS

10

What does a solid vertical line on an ECG represent?

0.2 seconds
5 large boxes = 1 sec

11

What does a solid vertical line on an ECG represent?

0.5 mv
2 large boxes = 1.0 mv

12

What is the PR interval?

Distance between beginning of P wave and beginning of QRS (usually 0.16 ms)

13

What is the QT interval?

Beginning of QRS until end of T wave (usually 0.35 ms)

14

What is the PR segment?

End of atrial depol until beginning of QRS, not super clinically relevant

15

What is the ST segment?

End of QRS until beginning of T wave

16

What are the normal values for QRS complex, P wave, and T wave voltages?

QRS: 1.0-1.5 mv
P: 0.1-0.3 mv
T: 0.2-0.3 mv

17

How many electrodes are used for a 12 lead ECG?

9

18

Which electrodes look at inferior regions of the heart?

II, III, AVF

19

Which electrodes look at septal regions of the heart?

V1 and V2

20

Which electrodes look at anterior regions of the heart?

V2, V3, V4

21

Which electrodes look at lateral regions of the heart?

V4, V5, V6, I, AVL