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Flashcards in dysrhythmias Deck (19):
1

2 ways to change the refractory period

1. change the AP duration
2. blockade of Na channels to recover from inactivation

2

what does the Na/Ca exchanger rely on

concentrations

3

what does active Arrhythmogenesis rely on?

automaticity

4

effect of Ach on phase 4 diastolic depolarization of nodal cells

increased potassium current, reduces slope of phase 4

5

effect of NE on phase 4 diastolic depolarization of nodal cells

increased calcium and funny current, increases slope of phase 4

6

effect of hypokalemia on phase 4 diastolic depolarization of nodal cells

decreased potassium current, increases slope of phase 4

7

effect of mild hyperkalemia on phase 4 diastolic depolarization of nodal cells

increased maximum diastolic potential, increases slope of phase 4

8

effect of severe hyperkalemia on phase 4 diastolic depolarization of nodal cells

significantly depolarized membrane potential, cells become inexcitable

9

what are delayed after depolarizaton (DAD) due to?

cytosolic and/or SR calcium overload

10

what are early after depolarizaton (EAD) due to?

occur earlier (towards end of phase 2/beginning of phase 3); due to altered ion flux during plateau phase

11

what characterizes EAD?

prolonged action potential duration

12

what can result in prolonged APD?

1. reduced K current
2. incr Ca
3. incr Na-Ca exchanger activity
4. incr later Na current

13

in comparison to EAD, DAD is only due to concentrations of what ion?

Ca (thus occurs during phase 4)

14

EAD are associated with ____HR, DAD are associated with _____HR

EAD are associated with low HR, DAD are associated with high HR

15

short PR interval characterized by signal that can reenter atria via accessory pathway and depolarize AV node - what syndrome?

Wolff-Parkinson-White Syndrome

16

passive arrhythmias are generally due to?

cardiac remodeling-->changes in gap jxns, changes in cellular structure

17

role of gap jxns in AV node

there are less-->signal moves slower

18

if there is tissue damage, the AP duration will be ________ after passing thru damaged area

if there is tissue damage, the AP duration will be shorter after passing thru damaged area

19

what is the refractory period dependent on?

Na channels