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FS Exam 4 > Cardiac Electrophysiology > Flashcards

Cardiac Electrophysiology Flashcards

1
Q

Wave of depolarization ____ contraction

A

Preceeds

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2
Q

Pacemaker

A

SA node

Where the impulse is initiated = rate of about 70 impulses/min

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3
Q

1 cardiac cycle: SA Node –>

A

AV node –> Delay –> AV bundle –> L/R bundle branches –> Purkinje fibers

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4
Q

Resting Cardiac Ventricular Cell

Na Ca and K

A

Na and Ca higher outside
K higher inside
So at rest, inside is negative and outside is positive

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5
Q

Action Potentials differ depending on

A

Location in heart

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6
Q

What sets the pace

A

SA node

No nerves needed, everything starts here

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7
Q

Automaticity

A

SA node is leaky to Na –> Threshold

AP is similar in AV node, but slower so SA node is what is setting the pace

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8
Q

What causes the upstroke

A

Ca

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9
Q

What is happening during repolarization

A

K is leaving the cell

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10
Q

Influence of ANS on Heart Rate - NE

A

B1 –> cAMP –> (+) Ltype Ca channel

Inc if –> inc slope of phase 4 –> reach threshold faster –> inc heart rate

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11
Q

Influence of ANS on Heart Rate - Ach

A

Muscarinic receptors –> dec cAMP –> (-) L type Ca channel
Dec if –> dec slop of phase 4 –> reach threshold slower –> dec heart rate
Ach hyperpolarizes the membrane and shifts the threshold upward

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12
Q

Effective Refractory Period

A

No new AP can form

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13
Q

Relative Refractory Period

A

Is possible for a new AP to form but is very difficult

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14
Q

What is purpose of refractory period

A

Helps control AP direction, prevents tetany, and allows chambers time to fill

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15
Q

Phase 0

A

Influx of Na

Upstroke

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16
Q

Phase 1

A

Kto = transient outward

Lets K squeak out

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17
Q

Phase 2

A 
Calcium channels (influx)
Maintain depolarization
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18
Q

Phase 3

A

Repolarize

K leaves the cell

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19
Q

How is electrical activity measured in the heart

A

3 major waves

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20
Q

3 major waves

A

P wave = atrial depolarization
QRS complex = ventricular depolarization
T wave = ventricular repolarization
- Tau wave = atrial repolarization masked by QRS complex

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21
Q

Clinical Uses of measuring heart activity

A

Arrhythmias
Ischemia and infarction
Heart orientation
Abnormal electrolytes and drugs

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22
Q

Inflections occur due to

A

Electrical activity (potential) traveling toward the positive electrode

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23
Q

Fibrous Skeleton

A

Plate of fibrous dense CT btw atria and ventricles
Electrical insulation
Site for muscle attachment

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24
Q

ECG provides signal info on

A
  1. Direction that signal is moving
  2. Speed at which signal is moving (r-r interval; basis for heart rate)
  3. Mass of tissue through which it is moving (thicker mass, higher peak will be)
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25
Q

P Wave

A

Atrial Depolarization +

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26
Q

QRS Complex

A

Ventricular Depolarization

- + -

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27
Q

T Wave

A

Ventricular Repolarization +

28
Q

How many electrodes does a 12 lead ECG use

A

10 electrodes

RU, LU, RL, LL, V1-V6 (precordial/chest)

29
Q

Bipolar, Limb, Standard Leads

A

I, II, III - frontal plane

30
Q

Augmented Leads

A

aVL, aVR, aVF - frontal plane

31
Q

Chest or Precordial Leads

A

V1 - V6 - Transverse plane

32
Q

Biggest QRS complex from which lead

33
Q

V1 and V2 give more info on what

A

Right side of the heart

Located on either side of sternum

34
Q

V3 - V6 give more info on what

A

Left side of the heart

V3/V4 - septal area

35
Q

Purpose of an augmented lead

A

Designed to start in the center of the heart
To where it is exploring to
aVR - starts at center and goes to right

36
Q

How does augmented start in middle of heart?

A

Vector of two different sites.
aVR for Ex
Vector of LU and LL to start in center of heart

37
Q

aVR pos or neg deflection

A

Negative deflection

Starts in center and goes to right towards negative electrode

38
Q

aVL pos or neg deflection

A

Positive deflection

Starts in Center and goes to left side

39
Q

aVF goes towards

A

Starts in center and goes towards feet

40
Q

Why is there positive deflection

A

heart signal going toward positive electrode

41
Q

Bipolar Leads

A 
Ex: Right arm to Left arm
One end is - and one is +
Hash mark = 0 point in center of the two
Current flowing to the left of hashmark would be neg deflection and to right  would be positive deflection 
R(-)  0    L(+)
42
Q

Augmented Unipolar Lead

A

Inc size of signal by tying 2 electrodes together and have them brought to ground
Current flowing toward exploring electrode causes positive deflection

43
Q

Chest Unipolar Lead

A

Bipolar and augmented leads all look at heart in coronal plane
Chest does it in transverse place - allows us to collect info about anterior/posterior heart

44
Q

12 leads provide how many views of heart

A

12

more views = more diagnostic info

45
Q

Mean Electrical Axis

A

Tells us net direction the depolarization or repolarization is headng

46
Q

Normal value for mean electrical axis

A

between -30 and +90 toward the apex of the heart

47
Q

1 box =

A

300 beats per mnute

48
Q

If number of boxes is 3?

A

300/3 = 100 beats per minute

49
Q

If number of boxes is 2?

A

300/2 = 150 beats per minute

Sinus Tachycardia

50
Q

If number of boxes is 4?

A

Normal Sinus Rhythm

300/4 = 70 beats per minute

51
Q

1st step when look at ECG

A

Make sure P wave preceeds QRS and T follows

52
Q

2nd step when look at ECG

A

Check rate - number of boxes between

53
Q

3rd step when look at ECG

A

Check for inconsistencies or potential pathologies

54
Q

If number of boxes is 6?

A

Sinus Bradycardia
300/6 = 35 beats per minute
Can be pathological or athlete

55
Q

Bradycardia in athletes?

A

Hypertrophy
More filling time
Parasympathetic inc.

56
Q

Extopic Beat

A

Beat that riginates outside of the SA node

57
Q

Multiform PVCs

A

Premature ventricular contraction
Ectopic foci in the ventricle
Could happen to anyone - coffee, exam
Pathological if happens like every 4 beats or something but generally is fine

58
Q

PACs

A

Early triggering of beat
Premature atrial contraction - ectopic foci in the atria
Wouldn’t really feel this - is more common

59
Q

Atrial Fibrillation

A

Most common cardiac arrhythmia
May be asymptomatic but often results in palpation, chest pain, and fainting
Primary worry = can lead to stroke
No P before QRS

60
Q

Ventricular Fibrillation

A

Medical emergency
Leads to cardiac arrest
Early AED use improves diagnosis
No performance from the heart at all - need to get AD out

61
Q

Heart Block

A

Signal is partially or completely blocked from reaching the ventricles

62
Q

First Degree Heart Block

A

Slowed from A to V - common in athletes

63
Q

Third Degree Heart Block

A

More dissociation between atria and ventricle
No P wave
Atria and ventricles acting at their own tune

64
Q

ST Segment Issues

A

ST segment depression - ischemia
T wave inversion - ischemia
ST segment elevation - ischemia

65
Q

What percent of individuals with angina show normal ECGs

66
Q

Stress Test

A

detects silent ischemia - changes in heart that can occur in absence of anginal pain

FS Exam 4 (6 decks)

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