Electrophysiology HPIM

Question 1

Repolarization occurs first where… on the endocardium OR on the epicardium?

Answer 1

repolarization occurs first on the epicardial surface and then proceeds to endocardium

Question 2

ion channels that are the primary carriers of depolarizing current in both the atria and ventricles (2)

Answer 2

Na and Ca channels

Question 3

term for the phases (0-4) of cardiac action potential

Answer 3

0: rapid upstroke
1: early repolarization
2: plateau
3: late repolarization
4: diastole

Question 4

What is the principal current during phase 4 of cardiac action potential

Answer 4

Potassium current

Question 5

What current (ion) generates the upstroke of the cardiac action potential (phase 0)

Answer 5

Na current

Question 6

inactivation of what current (ion) causes early repolarization (phase 1)

Answer 6

Na current inactivation

Question 7

phase 2 of the cardiac action potential or the plateau phase is generated by a balance of repolarizing ___ (ion) current and depolarizing ____ (ion) current

Answer 7

repolarizing K current

depolarizing Ca current

Question 8

what phase of the cardiac action potential is the plateau phase

Answer 8

phase 2

Question 9

inactivation of ____ (ion) current with persistent activation of K current causes phase 3 repolarization

Answer 9

inactivation of Ca current

Question 10

classification of tachyarrhythmias according to mechanism (3)

Answer 10

enhanced automaticity

triggered arrhythmias

reentry

Question 11

Spontaneous (phase 4 ) depolarization underlies the property of automaticity. True or False

Answer 11

True

Question 12

what ion channels are involved as a result of parasympathetic nervous system’s effect on the heart

Answer 12

acetylcholine binds to specific G proteins that activate a POTASSIUM CURRENT.

The resulting increase in K conductance opposes membrane depolarization, slowing the rate of rise of phase 4 of the action potential

Question 13

what ion current is augmented by sympathetic nervous system as it affects the heart

Answer 13

L-type Ca current

Question 14

hypokalemia (increases or decreases) the spontaneous firing rate of pacemaker cells

Answer 14

increases

Question 15

when does early depolarization and delayed depolarization occur in relation to cardiac action potential

Answer 15

EAD: during AP

DAD: after AP

Question 16

what is triggered automaticity

Answer 16

refers to impulse initiation that is dependent on afterdepolarizations

Question 17

what is the cellular feature that is common to the induction of delayed afterdepolarizations

Answer 17

presence of increased CA load in the cytosol and sarcoplasmic reticulum

Question 18

most common mechanism of arrythmia

Answer 18

reentry

Question 19

differentiate anatomic reentry vs leading circle reentry

Answer 19

anatomic reentry

• aka excitable gap reentry
• (+) excitable gap

leading circle reentry

• no excitable gap but instead has partially refractory area (so impulse can still propagate… pag aboslute refractory area kasi di na makakapropagate ang generated impulse… para siyang absolute refractory period)

Question 20

explain the process of reentry

Answer 20

**remember also the youtube video about reentry: the car, dusty road, wet bumpy road analogy

Question 21

differentiate Class I - IV antiarrhythmic drugs in terms of ion channels/receptors affected

Answer 21

,

Question 22

class I antiarrhythmic drug is subdivided into 3 based on kinetics and potency of Na channel binding… differentiate the 3 subgroups in terms of kinetics and potency

Answer 22

Class Ia (quinidine, procainamide)

potency: moderate
kinetics: intermediate

Class Ib (lidocaine, mexiletine)

potency: low
kinetics: rapid

Class Ic (flecainide , propafenone)

potency: high
kinetics: slowest

Question 23

example of Class Ia antiarrhythmic drugs (2)

Answer 23

Class Ia (quinidine, procainamide)

Class Ib (lidocaine, mexiletine)

Class Ic (flecainide , propafenone)

Question 24

example of Class Ib antiarrhythmic drugs (2)

Answer 24

Class Ia (quinidine, procainamide)

Class Ib (lidocaine, mexiletine)

Class Ic (flecainide , propafenone)

Question 25

example of Class Ic antiarrhythmic drugs (2)

Answer 25

Class Ia (quinidine, procainamide)

Class Ib (lidocaine, mexiletine)

Class Ic (flecainide , propafenone)

Question 26

example of antiarrhythmic drug that affects all ion channels /receptors thereby acting as Class I-IV antiarrhythmic drug (1)

Answer 26

amiodarone

Question 27

bradyarrhythmia is to ______ while

tachyarrhythmia is to internal cardioverter-defibrillator (ICD)

Answer 27

bradyarrhythmia is to permanent pacemaker while

tachyarrhythmia is to internal cardioverter-defibrillator (ICD)

Question 28

bradyarrhythmia is to permanent pacemaker while

tachyarrhythmia is to ___________________

Answer 28

bradyarrhythmia is to permanent pacemaker while

tachyarrhythmia is to internal cardioverter-defibrillator (ICD)