Cardiac Electrophysiology Flashcards Preview

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Flashcards in Cardiac Electrophysiology Deck (56):
1

What are the 7 conduction pathways through the heart?

1) SA node (normal pacemaker)
2) Intranodal tracts (controversial)
- AV nodal tract
- Bachmann's bundle to LA
3) AV node
4) Bundle of His
5) Bundle Branches
6) Purkinje fibers
7) Ventricular muscle

2

what is the relationship of the component of the ECG w/ the mechanical events in the heart?
P-Wave

Atrial depolarization

3

what is the relationship of the component of the ECG w/ the mechanical events in the heart?
PR interval

Atrial Systole and AV nodal delay

4

what is the relationship of the component of the ECG w/ the mechanical events in the heart?
QRS complex

ventricular depolarization (atrial depolarization)

5

what is the relationship of the component of the ECG w/ the mechanical events in the heart?
QT interval

Ventricular systole

6

what is the relationship of the component of the ECG w/ the mechanical events in the heart?
T wave

Ventricular repolarization

7

Action potential with a PLATEAU phase are found where?

Atrial muscle cells
Ventricular muscle cells

8

Action potentials arising om the SA node and AV node are biphasic. what does that mean?

they have a depolarization and depolarization phase with no plateau phase.

9

what is the RMP of the cardiac ventricular cell?

-90 mV

10

What are the phases of the ventricular action potential.
Phase 4

Resting membrane potential (diastole)

11

What are the phases of the ventricular action potential.
Phase 0

Rapid depolarization
Na+ diffuses into cell
AKA the upstroke of the potential

12

What are the phases of the ventricular action potential.
Phase 1

Transient (breif) repolarization
Cl- influx
K+ Efflux

13

What are the phases of the ventricular action potential.
Phase 2

Plateau
Ca+ influx
(as always K+ efflux)

14

What are the phases of the ventricular action potential.
Phase 3

Repolarization
K+ Efflux

15

What are the phases of the ventricular action potential.
Phase 4 (last phase 4)

RMP
(diastole)
Na+ / K+ pump operates to restore intracellular Na+ and K+ to appropriate levels

16

See page 103 in sweat book for diagram

pg 103 sweat book

17

What are the phases of the SA or AV nodal action potential?
Phase 4

RMP (Diastole)
Spontaneous depolarization to threshold
K+ efflux
Na+ influx
Ca++ influx (during last 1/3 of phase)

18

What are the phases of the SA or AV nodal action potential?
Phase 0

SLOW depolarization
Ca++ and Na+ diffuse into cell
(side note it is the L-type Ca+ channels aka slow Ca++ channels thus the reason it is slow depolarization)

19

What are the phases of the SA or AV nodal action potential?
Phase 1

Gotcha there is no phase 1

20

What are the phases of the SA or AV nodal action potential?
Phase 2

Gotcha again with nodal action potential there is no phase 1 and phase 2

21

What are the phases of the SA or AV nodal action potential?
Phase 3

Repolarization
K+ Efflux

22

What are the phases of the SA or AV nodal action potential?
back to phase 4

RMP (diastole)

23

R/T the action potential of the SA node..... changing the rate of what phase leads to a change in HR?

Phase 4

24

R/T the action potential of the SA node prolonging the phase 4 does what?

slows HR

25

R/T the action potential of the SA node shortening the Phase 4 dose what?

increases HR

26

then next questions teach you to read the question closely.... pay attention to nodal action or ventricular action potentionals.

read carefully

27

on what phase of the NODAL ACTION potential does digitalis work to SLOW the HR?

Phase 4
- Dig slows the HR by slowing phase 4 depolarization of cells in the SA and AV node

28

on what phase of the NODAL ACTION potential do CCB's work to SLOW the HR

Phase 4
- CCB slow HR by slowing phase 4 depolarization of cells in the SA and AV node

29

on what phase of the NODAL ACTION potential does Lidocaine or phenytoin work to control VENTRICULAR dysrhythmias?

Phase 4

30

to recap why these drugs work on phase 4

in the NODAL action potential Ca++ is in phase 4 there is no plateau phase as with the ventricular action potential

31

on what phase of the VENTRICULAR ACTION POTENTIAL do CCB's work?

Phase 2
Plateau phase

32

The resting membrane potential of the cardiac ventricular cell is what?

-90 mV

33

What ion is responsible for establishing the transmembrane resting potential

K+

34

When the gated Na+ channel is in the inactive state ( phase 2), the cardiac cell is in the ____ _____ period?

absolute refractory period

35

an influx of what ion causes the ventricular cell to produce a plateau in phase 2 of the action potential?

Ca++

36

Ca++ ions influence the opening of the gated K+ channel, with Hypocalcemia what happens to the duration of the plateau phase?

prolong

37

Ca++ ions influence the opening of the gated K+ channel, with Hypercalcemia what happens to the duration of the plateau phase?

shortened

38

on an ECG tracing each mm corresponds to how many seconds?

0.04 seconds

39

The QRS complex results from what and what phase?

Ventricular depolarization
Phase 0

40

The T wave results from what? and what phase?

Ventricular repolarization
phase 3

41

the QT interval reflects the duration of what phase of the action potential?

Plateau phase (2)

42

with HYPOcalcemia what happens to the QT interval?

it is prolonged

43

with HYPERcalcemia what happens to the QT interval?

it is shortened

44

peaked or tented T waves reflect what K+ problem?

Hyperkalemia

45

U waves reflect what K+ problem

Hypokalemia

46

what leads indicate Posterior inferior MI and what coronary artery supplies it?

II, III, aVF
Right (RCA)

47

which leads indicate septal, anterior wall MI? and what coronary artery supplies it?

V2-V5
Left Anterior Descending (LAD)

48

which leads indicates a lateral wall MI? and what coronary artery supplies it?

I, aVL, V4 - V6
Left Circ

49

MAP is determined by what 2 factors?

CO
SVR

50

CO is determined by what 2 factors?

HR
SV

51

SV is determined by what 3 factors?

Preload
Afterload
Contractility

52

Preload is determined by what 2 factors?

IV volume
Venous tone ( when veins constrict blood is diverted to the heart, and vice versa)

53

The major determinant of IV volume is the amount of what in the body?

Sodium

54

what hormone is most important for controlling vascular volume

Aldosterone

55

Compared with the normal heart, the size of the left ventricle chamber is NOT changed what what type of hypertrophied heart?

concentric

56

Compared with the normal heart, the size of the left ventricle chamber IS substantially increased what what type of hypertrophied heart?

Eccentric