Arrhythmia

Question 1

__ current generates the upstroke of the action potential (phase 0)

Answer 1

sodium current

Question 2

phase of action potential inscribed by activation of I with inactivation of Na current

Answer 2

early repolarization (phase 1)

Question 3

phase of action potential generated by balance of repolarizing potassium current and depolarizing ca current

Answer 3

phase 2

Question 4

phase 2 is generated by balance of ______

Answer 4

repolarizing potassium current and depolarizing Ca current

Question 5

phase 3 repolarization is caused by _______

Answer 5

Inactivation of the calcium current with persistent activation of potassium currents (predominantly IKr and IKs)

Question 6

which segment in ECG is predominantly determined by the plateau phase 2 of ventricular action potential

Answer 6

ST segment

Question 7

phase of action potential determined by ventricular repolarization and what segment

Answer 7

phase 3
T wave

Question 8

result of electrically neutral phase of ventricular action potential

Answer 8

phase 4

Question 9

spontaneous depolarizations occuring during phase 4 of AP

Answer 9

automaticity

Question 10

drives the depolarization in the SA node

Answer 10

nonselective Na/Ca If current

Question 11

normal range of SA automaticity

Answer 11

30 to 220 beats/min

Question 12

___ and ____ abnormal depolarizations that occur in the late phases of AP

a

Answer 12

afterdeopolarizations
triggered arrhyhtmias

Question 13

phase of AP where early afterdepolarizations (EAD) occur

faciliatted by _____

Answer 13

phase 2-3 of AP

intracellular Ca loading

Question 14

abnormal depolarizations occuring in phase 4 fo AP

Answer 14

delayed afterdepolarizations (DAD)

Question 15

mechanism underlying DADs

Answer 15

increased intracellular Ca-enhances repetitive depolarization during late phases of AP

As a result, repetitive depolarizations ensue, including the well-described phenomenon of bidirectional ventricular tachycardia.

Question 16

digitalis glycoside toxicity can cause which type of arrhythmia

Answer 16

DAD

Question 17

ischemia can cause which type of arrhythmia

Answer 17

DAD

Question 18

catecholamines can cause which type of arrhythmia

Answer 18

DAD

Question 19

EADs may trigger wavefrontd of abnormal depolarizations resulting in ?

Answer 19

TdP

Question 20

QT prolonging factors that predispose ventricles to EADs

Answer 20

hypokalemia
hypoMg
bradycardia

Question 21

mechanism of arrhythmia of atrial flutter

Answer 21

reentry

Question 22

mechanism of arrhythmia of av nodal reentry

Answer 22

reentry

Question 23

mechanism of arrhythmia of av reciprocating tachycardia

Answer 23

reentry

Question 24

reentry that occurs in the absence of a fixed anatomic barrier

Answer 24

functional reentry

Question 25

targets of AADs
Class I-IV

Answer 25

Class I - Na channel
Class II - Beta adrenergic receptor
Class III K channels
Class IV Ca channels

Question 26

Class IA drugs

possess ____ binding kinetics and potency

Answer 26

procainamide
quinidine

intermediate binding kinetics

Question 27

Class IB agents

___ binding kinetics
___ potency

Answer 27

lidocaine
mexiletine

rapid binding kinetics
relatively low potency

Question 27

Class IC agents

____ kinetics
____ potency

Answer 27

flecainide
propafenone

slow kinetics
high potency

Question 28

Class II agents MOA

Answer 28

beta adrenergic blocking agents

Question 29

Class III agents MOA

example

Answer 29

target HERG potassium chanel and risk prolongation of QT international through effects on the K channel (HERG) that in large part determine phase 2/3 of AP hence ventricular repolarization

sotalol
dofetilide
ibutilide

Question 30

class IV MOA

example

Answer 30

cardioselective Ca channel blockers

verapamil
diltiazem

Question 31

Nomenclature for pacing mode programming

Answer 31

First letter - chamber paced (O, A, V, D, S)
Second letter - chamber sensed
Third letter - response to sensed event (O-none; I-inhibited, T-triggered; D, inhibition and triggered)
Fourth letter - whether rate response is turned on

Question 32

indicators for permanent pacing in SND

Answer 32

• Symptoms that are directly attributable to SND
• Symptomatic sinus bradycardia because of essential medication therapy for which there is no alternative treatment
• Tachy-brady syndrome and symptoms attributable to bradycardia
• Symptomatic chronotropic incompetence
• In patients with symptoms that are possibly attributable to SND, a trial of oral theophylline may be considered to increase heart rate and determine if permanent pacing may be beneficial