Electrocardiography basics

Question 1

Purpose of ECG training

Answer 1

• recognize benign vs life threatening situations
• be able to make clinical decisions based on HR/rhythm as seen on a rhythm strip

Question 2

what does the hearts ability to pump depend on

Answer 2

1. automaticity:
2. rhythmicity:
3. excitability:
4. conductivity
5. contractility

Question 3

1. automaticity:

Answer 3

the ability to initiate it’s own electrical impulse

Question 4

2. rhythmicity:

Answer 4

the ability to repeat the cycle with regularity

Question 5

3. excitability:

Answer 5

the ability to respond to an electrical impulse

Question 6

4. conductivity

Answer 6

the ability to transmit electrical impulses from cell to cell within the heart (coordinates)

Question 7

5. contractility

Answer 7

the ability to stretch as a single unity and then passively recoil while actively contracting

Question 8

Depolarization vs repolarization

Answer 8

• depolarization: depolarization is when the membrane potential becomes less negative (more positive)
• repolarization returns it to its resting negative state (more negative)

Question 9

Sympathetic NS with the heart

Answer 9

• equated with acceleration
• branches of the sympathetic trunk
• discharges norepineprhrine resulting in increase velocity and force of contraciton

Question 10

parasympathetic NS with the heart

Answer 10

• equated with deceleration or braking
• discharges acetycholine
• vagus nerve is main component and acts primarily on SA node as an inhibitor rate and velocity of impulse

Question 11

Nodal myocytes

Answer 11

• within the SA/AV node
• susceptible to change and depolarization

Question 12

transitional myocytes

Answer 12

• along the internodal pathways/bundle branches/purkinjie cells
• regular working myocytes
• myocytes have ability to fire automatically due to automaticity

Question 13

SA node firing rate

Answer 13

• 60-100
• drives HR

Question 14

AV node firing rate

Answer 14

• 40-60 and will take over if SA node is not firing properly

Question 15

Myocytes firing rate

Answer 15

• <40
• can throw off rate
• etopci folki cells especially

Question 16

ECGs - how many leads
1. diagnositc
2. bedside monitoring
3. holter monitoring
4. New technology

Answer 16

1. diagnostic: 10-12 lead system
2. bedside monitoring: 3-5 leads/rhythm strip
3. holter monitoring: establish baseline/monitor change
4. New technology: establish baseline/monitor change

Question 17

what does a 12 lead ECG mean

Answer 17

• really only 10 leads
• 12 views of the heart that can tell where the irregularity is coming from
• diagnositic

Question 18

bed side monitoring

Answer 18

• 3-5 leads
• used to monitor rate and rhythm
• may reflect issues that then require diagnostic EKG
• looks at ventricle

Question 19

Holter monitor

Answer 19

• 24-48 hour EKG
• analyzed afterward
• electrodes attached at doctors
• wires attach to a small device
• record activities

Question 20

New technology

Answer 20

• kardio mobile app
• zio mobile monitor system
• smart watch
• pick up the most common problems

Question 21

ECG paper

Answer 21

• displays the time on horizontal axis
• runs at 25mm/sec
• at this speed each small box is 0.04 seconds
• each large box = 0.2 seconds
• 5 boxes = 1 sec
• 15 boxes = 3 seconds
• 30 boxes = 6 seconds

Question 22

What do each part of the ECG mean

Answer 22

• P-wave: atrial depolarization n
• QRS: ventricular depolarization and contraction
• ST segment: beginning of ventricular repolarization to prepare for next beat
• T-wave: ventricular repolarization

Question 23

Can QRS vary explain?

Answer 23

• yes
• can be different from individual to individual and from different views

Question 24

5 rules when determining heart rhythm/dysrhythmias

Answer 24

1. is the rhythm regular or irregular
2. determine HR
3. What atrial activity is evident
4. what ventricular activity is present
5. is there a relationship between Atrial and ventricular activity (p-wave with QRS complex)

Question 25

1. is the rhythm regular or irregular (5 rules)

Answer 25

- are there pauses - early beats - are R-R intervals equal ***CANNOT COUNT HR IF IT IS NOT EQUAL***

Question 26

2. determine HR - what about HR?

Answer 26

- is it regular or irregular - fast or slow

Question 27

3. What atrial activity is evident

Answer 27

- are P waves present, are they alike in appearance - are there more Pwaves than QRS?

Question 28

4. what ventricular activity is present

Answer 28

- are QRS of normal duration (<.12seconds) - are they uniform across the tracing

Question 29

5. is there a relationship between Atrial and ventricular activity

Answer 29

- is each P wave producing a QRS - are there P waves without QRS - is there QRS without a P wave

Question 30

Calculating Heart rhythm (sinus rhythm)- what to use

Answer 30

- inspection - calipers: see if they are the same distance - marking paper to measure distance as well

Question 31

Calculating HR

Answer 31

- IF rhythm is regular - heart ruler - # in 6 second intervals x 10