ECG Basics And Interpretation Flashcards
1
Q
Reference electrode is always
A
Positive
2
Q
What do electrodes measure
A
Change in polarity
3
Q
Waves are recorded as
A
Depolarization moves toward or away from electrode
4
Q
Depolarizations moving towards an electrode
A
Positive
5
Q
Depolarizations moving away from electrode are
A
Negative
6
Q
Depolarizations moving towards an electrode
A
Negative
7
Q
Repolarizations moving away from electrode
A
Positive
8
Q
Moving at a right angle to electrode
A
Generates no wave
9
Q
What do the electrodes ultimately measure
A
Sum and vector of everything
10
Q
Most EKGs are what kind
A
12 leads
11
Q
Limb leads
A
6
- 3 standard leads
- 3augmented leads
Requires a lead on each limb
12
Q
Precordial leads
A
6
-arranged along chest wall
13
Q
What do multiple leads allow
A
Entire heart to be viewed in (basically) 3D
14
Q
Lead I
A
Left arm (+). Right arm (-)
15
Q
Lead II
A
Right arm (-), legs (+)
16
Q
Lead III
A
Left arm (-), legs (+)
17
Q
Augmented leads
A
One +, other 2 are -
Up in atria
18
Q
Precordial leads
A
Around heart at mid chest Gives horizontal view Used to localize infarcts Always have V in front of it Number gets bigger as you move towards the left
19
Q
P waves in leads
A
Small and positive in the left and inferior leads
20
Q
QRS in leads
A
- Large and positive R eaves are seen in left and inferior leads
- R wave progresses from negative to more positive through V1-V5
V1-V5, R wave gets taller (more +), breaks down during MI
21
Q
T waves in leads
A
Variable, but positive in large R wave leads
22
Q
How many beats on each lead?
A
2-3
23
Q
What is a quick dirty diagnosis of morphology of heart
A
Mean electrical axis
24
Q
Vector that shows where most depolarization occurs
A
Mean electrical axis
Shows most muscle mass is
25
Sum of all QRS vectors is usually
60 degrees
26
Why does the mean electrical axis go to 60 degrees normally?
Goes down and to the left because left ventricle is largest chamber
27
What happens if mean electrical axis changes?
The heart has changed shape
28
What changes in the heart would causes MEA to change
Hypertrophy/dilation in response to cardiac disease. Causes change in MEA because more muscle in heart needs to be treated
29
What are the two leads you need to look at when calculating MEA?
lead I and aVF
| -covers all the ventricles
30
Where will aVF be positive?
Towards base
31
Where will Lead I be positive
Towards the left
32
Where will aVF be negative
Towards apex
33
Where will lead I be negative
Towards the right
34
Where is there normally overlap?
Bottom left, both leads are positive
35
Deviations of MEA are indicative of what
Structural changes
36
What are two functional changes of hte heart that will affect MEA?
Hypertrophy
| Dilation
37
Heart cells get bigger
Hypertrophy
Response to hypertension
Heart will get thicker
38
Chamber gets bigger of heart
Dilation
Response to volume overload
39
What do both dilation and hypertrophy result in?
Shift towards THE AFFECTED area, usually the ventricles.
40
Why do atrial problems not normally showing in MEA changes?
Ventricles will hide the atrial dysfunction because the atria are smaller. Also, the left side can obscure right side changes
41
You receive an ECG with a positive R wave in lead I and a negative R wave in aVF. What is this persons MEA?
Left axis
42
You receive an ECG with a positive R wave in lead I and a negative R wave in AVF. Which of the following could result in such an ECG change?
Left ventricular hypertrophy, and maybe left atrial hypertrophy
43
Any alteration to normal rhythm, regularity, origin or condition of the heart beat
Arrhythmias
44
Are all arrhythmias bad?
Not all are dangerous, but some are fatal
45
Symptoms of arrhythmias
Palpitations and or sudden light-headedness
46
What can arrhythmias excacerbate?
Underlying conditions like heart failure
47
What do you do to diagnose arrhythmias?
Use rhythm strip. Gives a longer recording like 10s of lead II
48
How do you determine arrhythmia?
Rate and rhythm
49
How to determine rate
300/# of large squares between successive R waves.
50
What do you check when looking at rhythm?
Does it look normal
- P waves?
- QRS narrow or wide?
- 1:1 ratio between P and QRS?
- is it regular?
51
HR under 60BPM?
Bradycardia
52
Where does sunis bradycardia and tachycardia originate?
SA node
53
What kind of drug could cause sinus bradycardia?
M2 agonist
54
What changes on the EKG in bradycardia?
Lengthened PR interval
55
What does the lengthened PR interval on the EKG during bradycardia tell us?
Lengthened nodal delay
56
Which is worse, bradycardia or tachycardia?
Tachycardia
57
HR over 100 bpm
Sinus tachycardia
58
Is there a greater change in diastole or systole when the HR is increased?
Diastole, heart doesn't stay relaxed long enough, decreased output because it didnt have proper time to fill
59
Rapid, irregular atrial depolarizations with a sawtooth pattern on EKG. Normal QRS
Atrial flutter
60
Why is the QRS complex normal in atrial flutter?
AV node refractory for most atrial depolarizations
61
What node is affected in atrial flutter
SA
62
No coordination of atrial depolarization. Irregular QRS
Atrial fibrillation
63
Why is the QRS irregular in A fib?
AV node will fire as soon as it is no longer in refractory. There is uncoordinated contraction between the atria and the ventricles
64
What kind of meds do you want to make sure someone with A fib is on?
Anticoagulants
65
Occur when depolarization is not conducted properly from atria to ventricle (AV node or bundle branches)
Conduction block
66
What is 1st degree conduction block?
- normal HR, but prolonged PR interval (>.2s)
- due to increased AV node delay
- can be seen in highly trained athletes. Each P wave has QRS, not a big deal. Prolonged pause between atrial and ventricular depolarization
67
What is 2nd degree conduction block?
- not all P waves are conducted via AV node
- P waves to QRS ratio is >1:1
- dropped beats (more P than QRS)
68
What are the types of 2nd degree conduction block?
- mobitz type I (Wenckebach)
| - Mobitz type II
69
PR interval gets progressively longer until a beat is dropped
2nd degree conduction block: Mobitz type I (wenckebach)
70
PR interval is set, but still drop beats
Second degree conduction block: Mobitz type II
71
What is a 3rd degree conduction block?
No conduction via AV node between atria and ventricles
- both P waves and QRS have a regular rhythm but are not in sync.
- QRS can be wide
72
What does a wide QRS mean?
Ventricular origin of depolarization
73
What kind of conduction block kills every P wave as it tries to cross AV node?
3rd degree
74
What can ventricular arrhythmia lead to?
Ischemia
75
Disturbances arise from below the AV node and produce wide QRS and are life threatening
Ventricular arrhythmias
76
Ventricular tachycardia
- fast depolarization
- ischemic event
- no P waves
- can lead to fibrillation (still ejected a little blood but screwed up the filling of blood)
77
Ventricular fibrillation
- uncoordinated depolarization
- rapid death
- no ejection of blood
78
What kind of heart disturbance do you shock for
Ventricular arrhythmias
79
Disruption of oxygen delivery affects the EKG. What is this called?
Ischemia
80
What is something that can cause ischemia?
Atherosclerosis
81
Why does disruption of O2 delivery affect the heart?
Can't make energy, cant pump ions for contraction
82
What is the first thing you will see if an ischemic attack is just happening
Peaked T waves, transitioning into inverted waves T waves.
- early sign
- reversible damage
83
What is a sign of hyperkalemia on an EKG?
Peaked T waves, transitioning into inverted T waves
84
What is the second thing you will see as ischemia progresses on the EKG?
ST-segment elevation
| -approaching permanent damage
85
What is the third thing you see on EKG with old ischemic attacks or ones that are far along?
Q waves
- permanent damage
- also present with healed infarct
86
What does hyperkalemia resemble on EKG?
Early ischemia
87
Hyperkalemia affects on EKG
Progressive changes in QRS
- peaked T waves
- prolonged PR interval
- widens QRS, merges with T wave
88
Hypokalemia affects on EKG
- ST depression
- flattened T wave and long QT
- U wave
89
Why is EKG good for detecting ionic imbalances?
It is much quicker to do an EKG than it is to draw blood and wait for the results to return from the lab
90
What do you need to be able to do every time you read an EKG?
Check for:
- rate
- rhythm
- axis
- infarction
91
When you check rate on the EKG, what are you looking for?
Normal
Tachycardia
Bradycardia
92
When you check rhythm on EKG, what are you looking for?
Sinus or ventricular (1st-3rd degree blocks, fibrillation or flutter)
93
When you check axis on EKG, what are you looking for?
Determine the mean electrical axis (normal, left shift, right shift, intermediate shift) and predict pathology associated with that shift
94
When you are looking for infarction on EKG, what are you looking for
Is there active ischemia (peaked/inverted T waves), active infarction (ST-segment elevation), old/resolved infarct (Q waves)
95
What could result in widened QRS complex?
Sodium channel (Nav) blocker
