Clinical Medicine Intro to EKG Flashcards
(107 cards)
1
Q
What is the function of Pacemaker Cells?
A
generate AP on their own; depolarize spontaneously
2
Q
These ______ cells spread AP; they have a distinct pathway in the ventricles; a variable pathway in the atrias
A
Conducting Cells
3
Q
These are known as the “working cells” of the heart.
A
Contractile Cells
4
Q
The majority of heart tissue is composed of what type of cells? Contractile, Conducting, or Pacemaker Cells?
A
Contractile
5
Q
What is known as the Pacemaker of the heart?
A
SA Node
6
Q
What is the firing rate of the SA Node?
A
70-80 bpm
7
Q
What is the firing rate of the AV node?
A
40-60 bpm
8
Q
What is the firing rate of the Bundle of His?
A
40 bpm
9
Q
What is the firing rate of the Purkinje Fibers?
A
15-20 bpm
10
Q
When can a Latent Pacemaker drive (control) the heart rate? (3 reasons)
A
- when their rate is faster than SA node
- when SA node firing rate decreases or stops
- When conduction from SA node to rest of heart is blocked due to condition pathway disease
11
Q
List 6 benefits of an EKG. What does it show?
A
Shows:
- Cardiac Rhythm
- conduction system abnormalities
- MI
- cardiomyopathies
- pericarditis
- metabolic derangements
12
Q
How large are the small square boxes on an EKG paper
A
1mm
13
Q
The horizontal axis on EKG measures?
A
Time
14
Q
What is the normal paper speed on an EKG?
A
25 mm/sec
15
Q
Horizontal Reading:
1 mm box = ____ sec or ______ msec
A
0.04 sec or 40msec
16
Q
Horizontal Reading:
5mm box = ____ sec or ____ msec
A
0.2sec or 200 msec
17
Q
How many seconds are represented on one piece of EKG paper?
A
10 seconds
18
Q
The vertical axis on EKG measures?
A
voltage
19
Q
Vertical Reading
1mm = __ mV
A
1 mm = 0.1 mV
20
Q
How many mm = 1 mV
A
10 mm= 1 mV
21
Q
Chest wall shape and young people have what differences on their EKG compared to normal sized adults?
A
They have a higher voltage reading
22
Q
Electrical Vectors measure ____ & ______.
A
magnitude & duration
23
Q
What is the net duration of positive charge relative to negative charge on a vector?
A
Average of Electrical Current
24
Q
What leads are assigned to the limbs?
A
Leads I, II, III
25
What leads are "augmented limb leads"
Leads: aVR, aVL, aVF
26
What do limb leads mostly measure?
upward / downward / leftward / rightward forces
27
What are the precordial leads? Where are they located?
vI - v6: electrodes on anterior chest
28
What leads measure anterior / posterior forces?
v1 - v6
29
___ lead records the difference between R arm and L leg. Impulse are directed toward L leg are recorded as a positive deflection on the EKG
Lead II
30
____ lead records difference between R arm and L arm. Impulses direct toward L arm are recorded as a positive deflection on an EKG
Lead I
31
____ lead records difference between L arm (+) and average of R arm and L leg (-). Impulses directed toward L arm are recorded as positive deflection on EKG.
Lead aVL
32
____ lead records difference between L arm and L leg. Impulses directed toward L leg are recorded as a positive deflection on EKG.
Lead III
33
____ lead records difference between R arm (+) and average of L leg and L arm (-). Impulse directed toward R arm recorded as a positive deflection on EKG.
Lead aVR
34
____lead uses a limb electrode for one electrode and the average of other 2 as the other electrode.
One electrode is positive and others are negative.
Leads aVR, aVL, aVF
35
_____ lead records difference between L leg (+) and average of R arm and L arm (-). Impulse directed toward L leg are recorded as a positive deflection on EKG.
Lead aVF
36
Leads vI - v6 are knowns as _____.
Precordial Leads
37
Precordial leads compares electrical activity of one place on the chest with a _____ ______.
"reference electrode"
38
What does reference electrode mean?
connecting the 3 limb electrodes - L and R arms with L leg; equals zero potential when added together
39
What leads represent the Right Ventricle?
Leads v1 and v2
40
What leads represent the Left Ventricle?
Leads v5 and v6
41
What are the inferior leads?
Leads II, III, aVF
42
Leads II, III, aVF view what portion of the heart?
Inferior portion of heart
43
What leads view the anterior chest wall?
Leads v1 - v 4
44
what lead is known as the "loner lead"
Lead aVR
45
On an EKG what represents atrial Depolarization?
P Wave
46
What occurs first? R or L atrial depolarization?
R atrial depolarization precedes L atrial depolarization
47
What is the width and height of a normal P Wave? Give boxes and time.
Width:
48
In what leads can a p wave be notched?
Limb Leads ( I, II, III)
49
In what leads can a p wave be biphasic?
Lead v1
50
What is the PR Interval?
P wave + PR segment = PR Interval
51
What is the PR segment?
conduction through AV node; measures from beginning of P wave to beginning of QRS complex
52
The ____ represents delay for ventricular filling.
PR ____
53
What is the width/duration of the PR Interval?
0.12 - 0.2sec duration (3-5 small boxes)
54
The PR interval is shorter or longer with slower heart rates? Why?
Slower; due to decreased speed of AV nodal conduction (SNS)
55
A faster speed through the AV node will create a longer or shorter PR Interval?
shorter PR Interval
56
Septal depolarization occurs in what area of the heart?
Q Wave
57
A Q wave is the first deflection and always present?
| True or False
False, A Q wave is the 1st deflection but NOT always present
58
In a normal heart, what leads would you find a Q wave?
Leads I, aVL, v4 - v6; due to septal depolarization
59
How many small boxes make up a Q wave?
Should not be more than 1 small box = 0.04sec (max)
60
A wider and deeper Q wave can indicate what type of disease state?
MI
61
What is the 1st upward deflection in the QRS wave?
R - wave
62
What is causing the upward deflection of the R wave?
Depolarization of LV myocardium (RV depolarization usually hidden as muscle mass of LV is much greater than RV)
63
What leads would show an increase in amplitude of the
| R wave?
Leads v1-v6
64
The first downward deflection following the R wave is ____ wave.
S wave
65
What is occurring in the heart during the S wave?
terminal depolarization of high lateral wall
66
What will you notice about the s wave on leads v1 - v6?
becomes smaller from v1 - v6
67
What does R1 indicate if you see it on an EKG?
R1: second upward deflection; RBB
68
If there are no upward deflections on a QRS Complex, what is it called?
QS wave
69
What is the duration of the QRS wave?
70
What is buried in the QRS complex ?
Atrial depolarization
71
What is the ST segment?
time from ventricular DEPOLARIZATION to Repolarization
72
This location on the EKG should be isoelectric.
ST segment
73
What type of disease can influence the configuration of the ST segment?
ischemia
74
Where is the J point on an EKG?
Intersection of the end of the QRS and beginning of the ST segment
75
The T wave represents what type of activity in the heart?
ventricular REPOLARIZATION
76
The T wave should be same direction to what other wave?
QRS complex (pos or negative)
77
What wave is highly susceptible to cardiac and non cardiac influences making it more variable in appearance?
T wave
78
What is the QT Interval?
QRS complex + ST segment + T wave = QT interval
79
What is occurring with the ventricles during the QT interval
Ventricular depolarization and repolarization
80
Is the QT interval shorter or longer with a faster HR?
Shorter
81
Normal Men QTc = _______ sec
0.44sec
82
Normal women QTc = ______sec
0.45 - 0.46sec
83
Prolonged QT will be seen in what type of rhythm?
V-tach, V- Fib
84
QT interval should be less than half the _____ interval?
R to R Interval
85
What lead has an axis of 0 degrees?
Lead I
86
What lead has an axis of -30 degrees?
Lead aVL
87
What lead has an axis of 120 degrees?
Lead III
88
What lead has an axis of 60 degrees?
Lead II
89
What lead has an axis of -150 degrees?
Lead aVR
90
What lead has an axis of 90 degrees?
aVF
91
If the rhythm is regular divide ____ by the number of large boxes between R wave to R wave
300
92
If 2 large boxes between successive R waves the the HR is ____ bp?
300/2 = 150 bpm
93
What is the method to calculate HR with the large boxes starting with 300, ___, ___, ____, ___, ____
300, 150, 100, 75, 60, 50 43
94
If the HR is irregular, to calculate HR you would count the number of (QRS complexes) on EKG and multiply by __.
or
Can take the avg of shortest and longest _____
6 or take the avg of shortest and longest R - R interval
95
What is the AV conduction Ratio?
Atrial impulses to ventricular impulse
| Normally is 1:1 (A:V)
96
True or False: If a conduction is slowed, another atrial impulse may be transmitted before conduction is started in the ventricles.
True: 2:1 AV Conduction
| 2 Atrial Impulses (p waves) are followed by 1 Ventricular impulse (QRS Complex)
97
The mean electrical vector is the _______
Axis
98
A normal axis is between ____ and _____ degrees.
between -30 and 90 degrees
99
Left axis deviation is ____ to _____ degrees.
-30 to -90 degrees
100
Right Axis deviation is ____ to ___ degrees
90 to 180 degrees
101
Extreme RAD (right axis deviation) is ____ to ____ degrees.
-90 to -180 degrees
102
What leads do you look at to determine axis?
Leads I and aVF
103
```
Determine the Axis:
If QRS (+)in leads and aVF then between -30 and 90. The axis is ____.
```
Normal
104
Determine the Axis:
| if QRS is (-) in lead I and (+) aVF. The axis is ___?
rightward
105
Determine the Axis:
| If QRS is (+) in lead I and (-) in aVF. The axis is ___?
leftward
106
```
Determine the Axis:
If QRS (-) in lead I and aVF. The axis is ____?
```
extreme RAD
107
List Causes of Left Axis Deviation.
1. Normal (increases w/ age)
2. Mechanical (expiration, high diaphragm)
3. LV hypertrophy
4. LBBB
5. congenial heart disease
6. emphysema
7. hyperkalemia
8. WPW
9. inferior wall MI
10. artificial cardiac pacing
