5 - EKG #1

Question 1

What are the learning objectives?

Answer 1

1) Describe the principle of how an EKG works
2) Describe the electrical physiology within the heart including:
a) Myocardial action potential generation
b) Overall direction of electrical activity
c) Intrinsic rates of specialized cells
3) Recall the names of the 12-leads on an EKG and list the anatomic area of the heart they represent
4) Label the 5 waves (PQRST) on a normal EKG
5) Calculate heart rate on an EKG using an equation and a visual method
6) State a normal adult heart rate

Question 2

What is an electrocardiogram?

Answer 2

A medical device that provides a recording of electrical activity of the heart

Question 3

What does an EKG provide?

Answer 3

Information regarding abnormal electrical activity

Question 4

Who developed the first electrocardiogram?

Answer 4

Willem Einhoven

Question 5

Myocardial Action Potential:

Describe Phase 0

Answer 5

K+ moves out
Na+ moves in

+30mV

Question 6

Myocardial Action Potential:

Describe Phase 1

Answer 6

K+ moves out
Na+ channels close
Cl- comes in

+10mV

Question 7

Myocardial Action Potential:

Describe Phase 2

Answer 7

K+ moves out
Ca2+ moves in

+5mV

**plateau phase

Question 8

Myocardial Action Potential:

Describe Phase 3

Answer 8

K+ moves out (3x amount)
Ca2+ channels close

-90mV

Question 9

Myocardial Action Potential:

Describe Phase 4

Answer 9

K+ moves out
Na+/Ca2+ moves in

• 70mV
• gap junction

Question 10

What is resting membrane potential?

Answer 10

-70mV

Question 11

_____:

Pacemaker, pathways transmit signal to AV node

Answer 11

SA Node (internodal pathways)

Question 12

_____:

Communicates signal from atria to ventricles

Answer 12

AV node

Question 13

________:

From AV node to the left and right bundle branches

Answer 13

Bundle of His

Question 14

__________:

Facilitates ventricular contraction

Answer 14

Pukinje Fibres

Question 15

How fast does it fire?

SA node (pacemaker)

Answer 15

60-100 bpm

Question 16

How fast does it fire?

Atrial cells

Answer 16

55-60 bpm

Question 17

How fast does it fire?

AV node

Answer 17

45 - 50 bpm

Question 18

How fast does it fire?

Bundle of His

Answer 18

40 - 45 bpm

Question 19

How fast does it fire?

Bundle branch

Answer 19

40 - 45 bpm

Question 20

How fast does it fire?

Purkinje cells

Answer 20

35 - 40 bpm

Question 21

How fast does it fire?

Myocardial cells

Answer 21

30 - 35 bpm

Question 22

Where does V1 and V2 go?

Answer 22

septum

Question 23

Where does V3 and V4 go?

Answer 23

anterior left ventricle

Question 24

Where does V5 and V6 go?

Answer 24

lateral left ventricle

Question 25

V1-V6 are called _____ leads

Answer 25

precordial

Question 26

Where does aVR go?

Answer 26

Right atria

Question 27

Where does 2, 3, and aVR go?

Answer 27

inferior wall (RCA)

Question 28

Where does 1, aVL, V5 and V6 go?

Answer 28

lateral wall (circ/LAD)

Question 29

What does P represent?

Answer 29

atrial contraction (depolarization)

Question 30

What does QRS represent?

Answer 30

ventricular contraction (depolarization) & atrial repolarization

Question 31

What does T represent?

Answer 31

ventricular depolarization

Question 32

The rhythm strip:

Each small box = ____

Answer 32

0.04 seconds

Question 33

The rhythm strip:

Each large box (containing 5 small boxes) = _____

Answer 33

0.2 seconds

Question 34

Formula for rate (bpm) ?

Answer 34

Rate (bpm) = 1500/# of small boxes between R waves

Question 35

What is a normal PR interval?

Answer 35

120-200ms

Question 36

What is a normal QT interval?

Answer 36

360-440ms

Question 37

Where does PR start and end?

Answer 37

Atrial depolarization to the beginning of the QRS complex

Question 38

Where does QT start and end?

Answer 38

The duration of ventricular depolarization & repolarization

Question 39

Drugs can prolong PR and QT intervals and lead to ______

Answer 39

arrhythmias