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CV Final > Action Potential/ECG > Flashcards

Action Potential/ECG Flashcards

1
Q

hierarchy of conduction system

A

SA node - 60-80

AV node - 30-40

Purkinje - 20-30

Ventricular muscle - slowest

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2
Q

E-C coupling in the heart

A

AP - triggers Ca release - responsible for contraction

coupling! not same signal

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3
Q

Slow AP Conduction Tissues

A

SA Node

AV Node

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4
Q

I(k1)

A

highly expressed in most myocytes except the node!

keeps resting potential at about -80

basis of resting membrane potential in cell

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5
Q

Fast response action potential

A

Atrial, Purkinje, Ventricular Action Potentials

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6
Q

Phase 0

Fast response

A

Upstroke

Sodium is entering - I(Na)

I(K1) is closed - resting potential, close because Mg in the cell is trying to leave and it plugs the channel

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7
Q

Phase 1

Fast response

A

Early repolarization

I(to) - channel opens when in depolarized range and opens just for a short time

outward K+ current

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8
Q

Phase 2

Fast Response

A

Plateau

I(to) inactivated

I(k) - delayed rectifier! open and potassium leaves

I(ca) - trigger Ca - L type channels - voltage gated

plateau - balance of K out and Ca in

when inactivate I(Ca), delayed rectifier WINS and repolarization happens because K leaves

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9
Q

Phase 3

Fast Response

A

Final repolarization

I(k) [delayed rectifier] and I(k1) [resting current] both open and both letting out K!

back to rest

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10
Q

Phase 4

Fast response

A

Rest

I(K1) open - keeping resting potential

Na/K transporter working

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11
Q

Structure of Voltage gated K+ channel

A

4 separate subunits form channel

voltage sensor

Pore region

N-terminal - V-dependent inactivation

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12
Q

voltage sensor of K channel

A

S4

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13
Q

Pore region of votage gated K channel

A

S4-S5 linker

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14
Q

Voltage gated Na/Ca channel

A

same structure as K channel but single subunit has 4 repeats

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15
Q

I(K1)

A

inward rectifier current

resting membrane potential

outward current during phase 3

NOT voltage gated

closes at DEPOLARIZED membrane potentials

NOT in pacemaker cells

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16
Q

I(K)

A

delayed rectifier current

Outward current during phase 2 and 3

2 components:R and S

EXIST in pacemaker cells

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17
Q

Phase 0

Slow response

A

upstroke due to inward Ca current (L type Ca current

resting potential was already less negative (there is no I(K1))

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18
Q

Phase 3

Slow response

A
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19
Q

Phase 4

Slow response

A

slow diastolic depolarization

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20
Q

I(f)

A

current that contributes to phase 4 diastolic depolarization

inward Na+

induced by hyperpolarization and allows to oscillate toward depolarization

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21
Q

currents that contribute to diastolic depolarization in nodal cells

A

I(f) - inward Na - induced by hyperpolarization

I(ca) - inward Calcium

I(k) - outward delayed rectifier current (R and S

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22
Q

factors that influence pacemaker rate

A

slope of diastolic depolarization

threshold potntial

min diastolic potential

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23
Q

effect of parasympathetic stimulation

A

Activate I(k)ACH channels

lowers minimum diastolic potential

decreases slope of phase 4

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24
Q

effect of sympathetic stimulation

A

activate I(f) channels

Increases slope of phaes 4

no change in min diastolic potential

25
Q

unipolar limb leads

A

aVR, aVL, aVF

Wilson’s Central Terminal - average the other two!

impossimble to flip

26
Q

bipolar limb leads

A

I (right arm to left arm)

II (right arm to left leg)

III (left arm to left leg)

possible to flip - true + and true -

27
Q

precordial leads

A

V1-V6

28
Q

lead diagram

A
29
Q

augmented lead

A

aVR, aVL, aVF

averaged vector

30
Q

ventricle depolarization and ECG

A

starts on left side of septum moving toward right

31
Q

Normal value of PR

A

.12-.2 seconds (less than 1 big box)

32
Q

Normal QRS duration

A

.06-.10 seconds (less than half of a box

33
Q

Normal QT interval duration

A

less than .44 in men and .46 in women (less than 2 boxes_

34
Q

time on EKG

A

1 big box is .2 sec, 200 msec

1 small box is .04 sec, 40 msec

35
Q

voltage on ECG

A

1 big box = .5 mV

36
Q

Count off method for HR

A

300-150-100-75-60-50 from QRS to QRS

37
Q

left axis deviation

A

inferior wall MI

left anterior fasciuclar block

LVH

-30 to -90

if up in I and down in II

38
Q

right axis deviation

A

RVH

acute R heart strain (PE)

left posterior fascicular block

+90-+180

down in 1 and up in 2

39
Q

normal axis

A

up in limb I and limb II

mean axis must fall between -30 and +90

40
Q

RA enlargement on EKG

A

P wave

lead II - higher at neginning

V1 - biphasic

41
Q

LA enlargement

A

P wave

Lead II - higher at end

V1 - p wave is negative!

42
Q

Sign of RVH

A

R>S in lead V1

R axis deviation

43
Q

LVH

A

S in V1 + R in V5

R in aVL>11 mm

or

R in I >15 mm

44
Q

ECG Read Order

A
  1. rate
  2. rhythm
  3. axis
  4. intervals (PR, QRS, QT)
  5. Morphology - P, T, ST
45
Q

RBBB

A

RSR’ in V1 (rabbit ears)

LV first (down in V1, Up in V6)

Widneed QRS

Prminent S in V5

46
Q

LBBB

A

Early R added to big, late L and compound

deeply negative in V1

rS

Widened QRS

broad, notched R in V6

absent R and prominent S in V1

47
Q

RBBB contraction pattern

A

starts on R side of septum

toward R

big toward L

then to R

48
Q

LBBB contraction pattern

A

starts on right side of septum

depol R then big swing to L

49
Q

Left Anterior Fasicular block

A

Posterior to Anterior

L axis deviation

Small Q in aVL and I (first depolarization is away)

Small R in inferior leads (II, III, aVF) - inital downward

50
Q

Left posterior fasicular black

A

start anterior and swing posterior

R axis deviation

small R in aVL and I

Small Q in inferior leads (II,III, aVF)

51
Q

ST Elevation

A

ischemia

acute-hours

52
Q

Q wave

A

with ischemia

begins hours after ischemia and deepens

persists long after MI

53
Q

T Wave Inversion

A

Days after ischemia

will normalize

54
Q

Pathologic Q Wave

A

fibrotic/bad conduction system - can’t gt through (physical block)

eventually jumps over it

25% QRS amplitude if seen in V1-V3

55
Q

Hyperkalemia on EKG

A

Tall, peaked T wave

56
Q

anteroseptal leads

A

V1, V2

57
Q

anterolateral leads

A

V5, V6

I

aVL

58
Q

anteroapical leads

A

V3, V4

59
Q

Inferior Leads

A

II, III, aVF

CV Final (6 decks)

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