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Fall 2024 > Cardiac numbers (exam 4) > Flashcards

Cardiac numbers (exam 4) Flashcards

1
Q

How often does the SA node generate an action potential in a normal adult? (in seconds)

A

0.83 seconds

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2
Q

Normal HR

A

72 BPM

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3
Q

If we took out all the influence from the vagus nerve and sympathetic chain on the SA node, what would our HR be? (SA node by itself)

A

110 BPM

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4
Q

What would the HR be if the SA node and SNS were impacting it? (No vagal influence)

A

120 BPM

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5
Q

What would our HR be if it was only impacted by SA node and vagus nerve? (NO SNS input)

A

60-62 BPM

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6
Q

What would our HR be if it was controlled by the AV node?

A

40-60 BPM

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7
Q

What would our HR be if it was controlled by the purkinje fibers?

A

15-30 BPM

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8
Q

Vrm of SA node

A

-55 mV

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9
Q

Threshold potential for SA node

A

-40 mV

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10
Q

What phases are in a slow (nodal) action potential?

A

4,0,3 (maybe 2)

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11
Q

How many internodal pathways are there?

A

3 (anterior, middle and posterior)

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12
Q

Time it takes for an AP to move from SA node to AV node

A

0.03 seconds

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13
Q

How long does it take for the entire right atria to depolarize under normal conditions?

A

0.07 seconds

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14
Q

How long does it take for the very last part of the left atrium to depolarize?

A

0.09 seconds

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15
Q

How long does it take for the very last part of the left ventricle to depolarize?

A

0.22 seconds

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16
Q

How long is the delay for an action potential to make it through the AV node?

A

0.12 seconds

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17
Q

How long is the delay in the bundle of His?

A

0.01 seconds

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18
Q

Duration of the P wave

A

0.09 seconds

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19
Q

Total delay of AV node + Bundles of His

A

0.13 seconds

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20
Q

Total time it takes for an action potential to get from SA node to the interventricular septum where we have the two main bundle branches

A

0.16 seconds

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21
Q

Angle of electrical current during a typical heartbeat

A

59 degrees

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22
Q

Magnitude of depolarization of a fast action potential

A

100 mV

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23
Q

QRS complex magnitude of deflection

A

1.5 mV

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24
Q

How many boxes tall x long is the P wave?

A

2.5 X 2.5 small boxes

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25
P-R interval duration
0.16 seconds
26
Ideal duration of QRS complex
0.06 seconds
27
How do we do the math for the ideal QRS complex duration?
0.22 seconds (entire left ventricle depolarized) - 0.16 seconds (AP reaches interventricular septum) = 0.06 seconds This is how long it took for the ventricles to depolarize
28
Duration of endocardial fast action potential
0.25-0.35 seconds
29
QT interval duration
0.25-0.35 seconds
30
Normal R-R interval
0.83 seconds
31
How to calculate HR with RR interval?
60 seconds / RR interval = HR
32
How many mV is a big box on an EKG?
0.5 mV
33
How many mV is a small box on an EKG?
0.1 mV
34
How many seconds is a big box on an EKG?
0.2 seconds
35
How many seconds is a small box on an EKG?
0.04 seconds
36
How quickly was paper fed into EKG machines in the olden days?
25 mm/second
37
Vrm of purkinje fibers
-90 mV
38
Vrm of ventricular muscle
-80 mV
39
Threshold potential of ventricular muscle
-70 mV
40
Threshold potential of purkinje fibers
-70 mV
41
If you have a heart block, how long will it take for the ventricles to initiate their own action potential the first time?
30 seconds
42
Cranial nerve V
trigeminal nerve
43
Cranial nerve X
vagus nerve
44
What is it called when a surgeon operates on an eyeball and it generates a complete heart block in the patient?
Five and dime reflex (V + X)
45
Ohm's law
V = IR
46
What is the peak of an action potential in a ventricular myocyte?
+20 mV
47
Angle of lead II
60 degrees
48
Angle of lead III
120 degrees
49
Angle of lead I
0 degrees
50
Angle of aVF
90 degrees
51
This augmented lead gives you a view that looks in the middle of leads II and III
aVF
52
This augmented lead is rarely used
aVR
53
Angle of aVL
150 degrees
54
Angle of aVR
210 degrees
55
How many "extra" leads are the precordial leads
6 extra leads (V1-V6)
56
What are the anterior chest leads (#)?
V3 and V4
57
These precordial leads are placed on either side of the sternum
V1 and V2
58
These are known as the septal leads
V1 and V2
59
These are known as the lateral chest leads
V5 and V6
60
Where are leads V4, 5 and 6 located?
5th intercostal space on the patient's left side
61
Where is lead V3 located?
sandwiched in-between lead V4 and V2
62
Where is V1 located?
Right side of the sternum, fourth intercostal space
63
Where is V2 located?
Left side of the sternum, fourth intercostal space
64
This precordial lead helps us differentiate if we have an anterior or posterior injury to the heart
V2
65
This precordial lead will see almost all of the electrical activity of the heart and will have a big deflection
V4
66
In incomplete heart block the PR interval is > ____ seconds
>0.20 seconds
67
In second degree heart block the PR interval increases ___ to ____ seconds
0.25-0.45 seconds
68
Which is more dangerous - Mobitz one or Mobitz 2?
Mobitz type 2
69
What are the ratios in Mobitz Type II; P waves: QRS complexes
2:1 3:2 3:1
70
What is the ventricular escape in BPM in a complete heart block?
15-40 BPM
71
In Stokes-Adams syndrome ventricular escape is delayed __ - __ seconds
5-30 seconds
72
What is the threshold (in seconds) for maintaining consciousness without a heartbeat?
7-8 seconds
73
What is the length in ms of a fast action potential?
~200 milliseconds
74
In which phase are you most permeable to calcium in a fast action potential?
Phase 2
75
This % of the population has a bundle of Kent
0.2%
76

Fall 2024 (86 decks)

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